THIS THREAD IS BEING USED AS A CONFERENCE THREAD - PLEASE DO NOT POST. THANKS!

This thread is reserved for the following members and their invited guest(s) to work on the LLY overheating issue. All DP members are invited to follow their progress, but please do not post unless you are invited to by one of those designated to conference here. THANK YOU FOR YOUR COOPERATION! :ro)

If the following members are agreeable they can use this thread to work as a team on the LLY overheating issues: killerbee; fingers; RickDLance; Idahofox; mahilkita; tbalz; mike330r; bettered; dan diesel; cit1991; TheBac(TISH=technical input and some humor); kennedy; McRat(TISH); and oilburnr.

These members have taken the lead and invested their time towards resolving the overheat issue. IMHO they offer our best hope in getting this fixed in the very near future. :ro) I certainly don't want to offend other members, if your disappointed at not being on the list, please PM me and we'll iron it out. I tried to keep the team to as small a number as possible. :) Yes, personalities did play a role in my composing this list. Someone had to do it! :o: NOTE JJ's name isn't on the invite list either! MODERATORS: If possible would you delete any posts that are uninvited or inflamatory in nature. Thanks!

If anyone has valuable intel that will assist the team PM it to the individual that has the lead in that particular area, or PM me and I'll get it to them. The team members can also can invite other DP members to post or participate with them as they deem appropriate. They can also ask that individuals be removed if they are not providing constructive input or participation. This will be done tactfully through PM's. FAIR ENOUGH? :D

killerbee started the thread below in an attempt to address the technical issues of overheating LLY's without having to sift through loads of non-technical issues and avoid personality conflicts. To say that was a miserable failure would be a gross understatement! :(

So we'll take a more direct approach and request everyones cooperation. Think of this moreso as a conference room for them to use, that's really its purpose. In the end this will mean better running trucks, more pulling power, and better resale values. GOT YOUR ATTENTION I HOPE! ;)

MODERATORS: IF I'M BREAKING SOME DP RULES BY DOING THIS, WELL ....

killerbee, I copied your initial post from your original thread. Over the next few minutes I will copy/paste the technical posts from the other members over to this thread so you guys will have them at your disposal. GOOD LUCK WITH TRY #2! JJ :)

Posted by killerbee:

It has been suggested we create yet another OH thread to focus on a creative effort. As the title suggests, this thread is to move forward in:

1. identifying the sources of overheats in our trucks, mainly LLY's, but not excluding LB7's, due to inherrent design weakness.
2. implementing solutions based on above.

This will become more clear as the thread develops.

Please do not post here unless:

1.) You have an interest in solving this problem
2.) You believe there is a solution(s)
3.) You don't have a personality problem that prevents you from adding to a collective, productive effort.
4.) Want to keep your truck and maximize its utility in severe environments

This is not a political thread, there are other threads to voice your feelings on GM's policies. That is a debate that is not welcome here. Let's begin with what we have learned so far from the Overheat thread in the last month. The next few threads may be transcribed from that source.

Fingers:
Quick review:

I have been measuring the differential pressure across the stack as a means of quantifying the amount of air flow across the stack. All my measurements have been in the same probe locations using a Kuhlman guage. Units are inches of water. I can measure other differntial pressures, but have been focusing here for right now.

In short, I have found that the unengaged fan still draws between .25 and .75 inches depending on RPM, maxing out around 1500 RPM at .75 inches. I have not had the chance to check when the fan is engaged, yet. I had one brief period when the fan was drawing more, but I think the clutch was cold and partially engaged.

Stock:
At speed, I never saw above what the fan was drawing (.75) regardless of speed. I even shut the engine off and the max I measured was .25 at 50 and 60 MPH. I didn't try 70

My conclusion is that there is essentially no draw from speed.

Ghetto Air dam:
I have blocked the area between the frame rails from the bottom of the Radiator bulkhead to the bottom of the frame. Below that I have installed a removeable air dam.


It is not as wide as I would have liked, but the material was limited.

Measurement showed little differential over fan draw below 35-40.

MPH | w/Ghetto Dam | w/o Ghetto Dam

25 MPH | .75 | .5 - .75 *
35 | .85 | .5 - .75 *
50 | 1.0 | .5 -.75 *
60 | 1.25 | .5 - .75 *
70 | 1.5 | .5 - .75 *
note * ( w/o varied with Revs, with did not)

I extended the dam closer to the ground today and did a run but the extension didn't hold up at 75 MPH and I had to abort. Inial reading showed even greated differential across the stack.

KB will be mapping the hood for pressure drop zones later this week, that is on the menu.

Once we determine just what static pressure of the stack front is, as well as the underhood area, and compare that against alternative low pressure areas (like the hood) we can make calculated mods. I'm not much of a 'lawn dart' solver, and the hood is on the list.

Just as an aside for you few to try, one change that is simple that has apparently created an improvement was the removal of the plastic splash guard under and behind the bumper. Leads me to think, that it may be helping raise the pressure under the truck, an "air plow" of sorts. Cold air has proven it's worth the effort you put into it. Some of us are putting the gasser/old LB7 airbox that seals up to the fender openings. A simple mod brought down IAT's by 70 degrees (at 250 ECT), a significant power recovery.

We are not worried about ghetto here, if it works, we figure out why, and impliment a test in a proposed mod.

The first rule of air movement here is:

Air will, without exception, move from an area of hi-static pressure to an area of low static pressure, in a straight line. As simple as that.

The main problem appears to be that the pressure on the front of the stack, vs the back of the stack, is almost the same, even at 70 mph. Whatever will increase the front, or decrease the back, (or both) will increase cooling flow.

Diesel man, were you serious? What did you do and what were your observations?
B:

CIT1991:
Just an FYI, expect actual volumetric flow (ACFM, if you like) to vary with the square root of delta P.

e.g., double the deltaP, and get 44% more ACFM.

FYI2, the dynamic head of 100F air at 70 MPH is 2.17 inH2O.
1991:

TheBac:
Is the radiator in the LLY the same as the LB7? If not, has anyone done a flow test of the cooling system to determine flow rate, cooling capacity and rate of cool-down? I'm not talking about Fingers air-flow tests.. BTW, those sure were extensive...

If it is the same, could the head redesign for the LLY's be the culprit? Sure, easy-to-change injectors are nice, but at what cost? Maybe water passages not run right, or a blockage at the headgaskets?

Do we have any radiator-shop guys willing to try to build an aluminum, racing-style crossflow radiator that could flow more?

Also, has anyone determined if the overheat is coming from a specific area of the engine, or is it a "general" overheat condition? The reason i ask is, I used to have a 455 Olds that would overheat and the problem always seemed to come from the rear of the engine. The problem turned out to be the aluminum aftermarket intake, it had no rear crossfeed like the stock one did. I had to tap the manifold to accept hose nipples, so I could run a hose to connect both heads. The overheat condition disappeared.

Just throwing out ideas...

Tom

cit1991:
I ran a computational fluid-dynamic simulation of the truck in a synthetic wind-tunnel. The truck solid model is clunky, but I'm a bit new with Solidworks, though old hat with CFD. Anyone who's better with Solidworks, and wants to model the truck in more detail, can send me the .sld* files for Solidworks 2005. No the mesh isn't super-fine, but a 28000 degree-of-freedom differential equation is about all my little Athlon can handle.

The model was run for 70 MPH at 1 atm and 68F. It's not a thermal sim...just CFD. It gives an idea of how the air distributes, and where the pressure zones are. No, I did not make it hollow to model air through the engine bay.

The first pic is just the model in the synthetic wind-tunnel.

The second pic shows the surfaces colored by local static pressure.

The third pic shows the underside pressures.

The fourth pic shows the streamlines that interact with the topside surfaces...lines are colored by pressure.

A few learnings...

The stagnation zone on the front is fairly low on the front face. That explains the bumper inlets, and why they raised the hood "forehead"...to raise the stagnation zone (highest pressure) higher toward the radiator.

The other "wow" are the low pressure zones on the fenders, created as the air bends around the headlight area. This will tend to draw air through any leaks near there from the engine bay to the outside. And, one is right where the airbox is....the worst place on the whole truck.

The last pic (different pressure scale), is for you guys looking at hood vents. There's where to put it..just forward of halfway, and you have about 0.05 psi differential to deal with.

Next I'll add a "ghetto dam" and see how things change.
Attached Thumbnails



__________________

Fingers: Probably too much to ask, but can you show the streamlines for the underside surfaces? I expect a compression zone at the lower front of the bumper.

One other feature of note is the crossmember between the front wheels is about 4"-6" lower than the bottom of the front bumper. I know, I know, draw it yourself. Wish I had a copy of solidworks to help out.

cit1991:
Old rule of thumb for engine energy balance...1/3 shaft work, 1/3 exhaust, 1/3 coolant loss. Ok, even if it's a rule of thumb, let's see how the loads compare, since thermal load (not temperature level), is what determines how hot the cooling air gets (along with the airflow).

AC:

say 3 tons at R=3 (lots of duty and not very efficient, a house is typically 4 to 5 tons, and the biggest 110V window unit is about 1 ton). ==> 4 tons of heat load, 1 ton=12000 BTU/hr, so a high estimate of condenser heat load would be 48000 BTU/hr

Intercooler:

Say, turbo inlet at 1 atm, and 200 F, boosted to 34.7 psia, adiabatic efficiency of 70%. Engine is at 3000 RPM, with a VE of 70%. Intercooler cools the charge air to 150F.

Compressor discharges at 460F, and takes 55.7 hp. Flow is iteratively calculated to provide the required ACFM after the intercooler, and is 77.7 lbmol/hr. The intercooler cools the airflow from 460 to 150, and this means losing 168800 BTU/hr.

Using the rule of thumb, the engine, making 310 hp, also needs 310 hp worth of cooling. The calc is a simple change of units (of power), and 310 hp is equivalent to 789303 BTU/hr (duty of the radiator).

Total thermal load is 1006103 BTU/hr. Even with a 200F inlet temperature to the turbo, the estimated heat load of the intercooler is less than 17% of the total.

Now lets say we want to remove that total load, with 110F air, by heating to 200F. How much do we need? 1473 lbmol/hr, or 11145 ft3/min at 110F, 1atm. I guess that's why electric fans won't cut it.

I'll leave it to you guys to argue whether changes in 17% of the heat load(vs 18, 19, or whatever) is enough to tip the scale or not.

mahalkita:
cit, I like your calculations but how do you estimate the BTUs for the A/C that high? 48000 BTUs can cool a small 1600 sqft home which has a 100 times bigger air volume to cool. Even if the A/C in the car is much less efficient and might have a higher duty cycle I doubt it will ever produce even 12000 BTU of heat - so its negligible compared to IC and Engine Cooler IMHO

cit1991:
It does not matter how heat gets from the IC to the rad, either by convection of the moving air, or by radiation. There's only so much of it to move, and it's much less than the heating of the rad by the circulating coolant.

But, if you really want to know, 5.4 ft2 of aluminum (Face area only, unpolished, emissivity=0.07, from the Bosch Automotive Handbook), at 450F, will radiate a total of 129 W, or 442 BTU/hr.

The radiator (at 210F) actually radiates more toward the IC, because it's black. Subtracting the unreflected radiation coming from the rad, you get a net rate of about 325 BTU/hr from IC to Rad. Technically, both fluxes bounce back and forth, and you have to iterate, but the 325 BTU/hr will be close.

But, this just means the air between them is a smidge cooler, since photons are helping move the heat. It's the total heat load you need to worry about.

KB:
Ed, yes it is huge. I went into the design parameters and functions of various heat exchangers on the OH thread.

It has to be huge. It get's one shot to cool charge air, batch cooling. Water holds 1000 times the energy of CAC air, the energy offloaded is vastly different because one is air-air, the other air-water. Plus the radiator is a recycle process, if the first pass doesn't do it, the coolant will be coming around again.

But what is revealed, is that if air flow is low enough, that CAC will input pretty hot air to the rad at 20+ boost. So, in a sense, you might consider the CAC too large. Bear with me.

If it were smaller (or not there at all, forget the consequences of that for a minute) then the air leaving the CAC stage would be significantly cooler for the rad.

The beneficial aspect of a larger CAC, if it weighs more, it will be a better heat sink, which as we know, can absorb transient spikes in thermal production. Then release it over time. i don't see it helping here, the overheats are on pulls long enough to exceed the heat sink characteristics of the largest CAC's.

Folks, we are more or less stuck with a finite amount of front end, without cutting off the entire nose. The only reason I could see to replace a heat exchanger, is if it had poor restriction internally, or in the fins.

cit1991:
I simulated the truck at higher accuracy (more cells). Total number crunching time was up to about 3 hours per run. I ran it with and without an Ghetto Dam (tm).

Nice work Fingers. I looked at the average underside pressure in a square region just under the engine. The air dam (at 70 MPH with 100F air at sea level) reduced the average pressure in that zone by 0.5 to 0.6 inH2O...in reasonable agreement with the data shown so far.

The dam also increases the air pressure under the bumper which should help stop the air leaks from the stack inlet out toward the bumper.

The aft component of force on the dam is about 44 lbf (at only 70 on a hot day). It will be much higher on a cold day at 90 MPH. So it better be fastened well.

Total aerodynamic drag with the dam is 219.7 lbf. Without it's 193 lbf...so it ain't free...over 20% more drag, which makes sense, the frontal area is getting larger.

Aerodynamic lift with the dam is slightly higher, but not much. It's probably due to the higher pressure in front of the dam (it goes from way negative to positive with the dam, and reduced pressure on the hood. I guess this is why racing airdams are at the very front of the body. There's more pitch-up torque too, probably for the same reason...though not enough to lift anything up in the air.

Conclusion is that the dam does add a bit of extra DP to the stack, but costs in drag.

If some of the data seem counter-intuitive, join the club. Sometimes fluid flow just doesn't cooperate with what you think it'll do.

The third pic is the streamlines Fingers wanted.

If the air wants a way out, has anyone tried removing one or both of the plastic fender-well covers? There's a low pressure exit there too.
Attached Thumbnails

Fingers:
My buddy laser cut the pattern for me so I just had to install the prototype.

DP with the new dam and without the valance was up over 3 iw at 75 no fan. Low speed DP was better too. I didn't run with the valance tonight, but it is back on. I hope to tow at 26,000 gross sometime Thursday on the ball buster hill and friends to see what she will do.

Invited guests, as you can see I'm copy the more technical posts from the original thread, but can't get your pictures to post. Please copy/paste them to your post here. Thanks. I'll only post here while I'm setting things up. JJ

Fingers:
Mixed results

--------------------------------------------------------------------------------

Not a hot day here. In the low 80's, scattered showers.

Excavator on the trailer. Trailer 7,500 lbs, machine 12,000, and truck. cross the scales a little over 26,000.

Hills were ballbuster (Dravosburg hill for any locals), Library hill, and South Park hill.

Finally found out what the fan pulls when fully engaged. 3.5 inches of water. That's a lot of suck.

Today I rarely got over 40 MPH. At these low speeds the dam is nearly useless, and you gessed it. No Joy. Got hot in all the usual places. Temps up to 244 or more. The onset was delayed, but the result was the same. There may be better results at highway speeds, but I have not tested that.

Personally, I am gonna keep the dam installed. Cool downs seemed faster and I like the look. But I will not be selling them.

Fingers:
IATs were fine (12* over ambient) till the fan kicked in.

Fingers:
KB,

Longer answer. The dam seems to push a lot of air through the openings in the bulkhead near the air filter. However, when the fan kicks in, it seems to overwhelm that outside air.

oilburnr:


--------------------------------------------------------------------------------

Quote:
Originally Posted by killerbee
With stock intake? How is that possible?

What was the highest it got?


It is possible KB until the fan kicks, and then watch out!

With my getto tube, I can stay within a few degrees of OAT, and when the fan kicked, the highest I saw was 8-10* above, BUT that was not towing heavy. Though I don't know how much that plastic box and intake snorkel will ultimately absorb.

I want my 6.0 experimental box!

KB:
A few people monitoring this thread understand dyno's, I'm not one of them. Do they have the abilty to take a load for 10 minutes?

I would really like to see what the correlation is between heatquenched air intake, and HP output. But we would have to get one of these trucks to 250 degrees on the dyno. Can it be done? Can a dyno dissipate 300 HP for 10 minutes?

If anyone is asking "why?" it is because, if HP drops signifiacntly underhood with rising ECT's (and rising IAT's), then a cycle is developing on the extreme tow, that leads to less power, yet more heat. This has been something I would like to prove/disprove for good.

KB:
I know I asked this question before, and I thought I knew the answer to it. in statement form:

The turbo is more efficient with an intake of 50 degrees than an intake of 200 degrees, true or false?

Something about heating air to 500 degrees, then sending it across a CAC with (seemingly) poor airflow, sounds wrong. There is a reason we have a CAC. hmmm

RDL:
page 197

7-16 3 horse trailers on wedge to Tucson
S&B bottom & side feed,no plastic plate,
air bags & Predator Tow Tune


time--------11am--noon

temp---------88----86

load--------28k

wind-------calm----med

hills-------med----med

speed--------77----68

boost--------17----19

egt---------1425--1575

iat----------116---131

ect----------222---240

fuel---------194---213

elev--------4750--4890

ally---------195---205

ccs-----------78----78

lowerhose----138---142

upperhose----188---205

road---------25 south

state--------NM

Temp drop across the radiator was descent, especially
considering incoming air temp.

What we have done has definately helped. Despite higher egts,
and pushing the truck as hard as I can, I could not get over
240* ect so far for the day.


for the last leg of my trip I am going to remove the
Predator.


time----3:30--noon---4pm---5pm-

temp-----100----86---99-----96

speed-----70----68---71-----68

boost-----20----19---21-----19

iat------159---131---143---149

ect------244---240---246---248

fuel-----226---213---226---228

rpm-------?-----?---3115--2770

egt-----1425--1575--1400--1400

elev----4290--4890--3902--4530

ally-----235---235---240---240

ccs-------78

load------28k

wind-----med cross

hills----med

road------10 west

state-----NM & AZ

OAT does go up with fan!! Even at highway speeds!! The more you
slow down on a hill,& the faster the fan, the higher the OAT reads.

Time to go cat-less, add a egr blocker plate, and a finger stick!

KB:
I am going to measure the stack exit and inlet flow rates, in the driveway, fan engaged. My suspicion is that exit flow rate will greatly exceed inlet for a number of reasons.

1.)lack of integral sealing between stack components. Allows air infiltration from the sides of the components. My guess is also that when the truck is hot, that this "contaminated" leakage is also hot. If so, this can be remedied

2.) Poor fan shroud design: I have over an inch of space between fan tip and shroud, probably necessitated because the fan is connected to a motor on flexible mounts and moves, in relation to the stationary shroud. Yuk. Leakage! Fingers shows that it works, but I wonder how well it could work in a low tolerance shroud. Not such an easy solution to this one.

That new 06 fan sure looks tasty.

So the objective is to see if there is room to improve the stack effectiveness by dismantling it, and sealing it into an airtight integral stack.

Idahofox: Set up on the Dyno; direct the discharge from a construction type "Space Heater" ( a safe distance back, the output can approach 200 ° F, don't want to Burn Down The Barn ) at the grill area of the subject vehicle.

May take less the 10 minutes to heat saturate the stack and create IAT in excess of 200 ° F, ie reduced power...etc.

FWIW.

KB:
Quick and dirty flow test:

In driveway, fan engaged(aka morning sickness), ac on

Exit: Shroud exit velocity avged 17 mpg, 25 ft/s, on a 22" shroud opening the fan is pulling 3950 cfm, in the drive idle.

Inlet: Across the 4.5 sq ft stack, Measuring at the surface of the CAC and condenser, speed avged, 5.4 mph, 8 ft/s or 2160 cfm. about half of what is being ejected by the fan.

I'd guess accuracy on this test at +/- 20% at measurement.

Conclusion:30-60% of the air being pulled into the engine compartment by the fan is probably recirculated air from the heated engine bay

not great.

tbalz:
Guys,

I am an engineer that spent the last 5 years working on cooling systems that use radiators. I worked with the two companies that make most of the worlds radiators, and tranny coolers.

I have not read all the pages, but i did read the first 5 or so and the last page. It seems you guys are focusing on the airflow velocity through the rad. Velocity is not a good measurement for figuring out the problem because is varies based on density (i.e. temperature). Mass flow rate is what you want. While increasing the air mass flow rate will make a difference in cooling, the real heat rejection comes from the mass flow rate of the coolant through the rad.

The othe problem is you need to log the data at when the coolant is ok and when it is over heating at the same speed and rpm so that we can tell where the issue lies.

I suspect that there are either major line size changes 9limiting the ouput of the water pump)or the Variable vein turbo/higher horsepower rating in the LLY is adding an additional heat load over the LB7 system. The measurement that you should focus on are the water temps at the inlet and outlet of the radiator. The mass flow rate of the water would be nice as well but I dont think anyone want to drop $1500 on a flowmeter. I recently took another job so i cannot "borrow" the proper equipment to make the measurements on my truck. Although I do not have any indication of over heating I do not pull loads over 5000lbs at this time.

So, what are we looking for?
If the inlet and outlet water temps are very close to each other than there is not enough airflow(edit.assuming the rad is close to the size needed). If the outlet water temp has a big delta from the inlet temp than there is not enough coolant flow. Q=m(dot)*Cp*deltaT (where Q is the total heat rejection, m dot is the mass flow rate of the coolant, Cp is the density of the coolant, and delta T is the temperature differential across the rad). Also, If your outlet water temp is within a few degrees of the air inlet temp than your cooling system is plenty big enough for the heat load. if this is the case and we are over heating then we are screwed( if this is the case it means that there is too much heat load for the ambient temperature and we are totally screwed. yo could make the rad and fan the size of a lake and it wouldn't make a difference.).I do not know how much themal load that the engine makes or the mass flow rate of the coolant is or else I could take a stab at what the outlet temp of the rad should be.

If there any any calculations that need to be done i will gladly try. PM me with them.


tbalz

oilburnr:
Quote:
Originally Posted by killerbee
2.) Poor fan shroud design: I have over an inch of space between fan tip and shroud, probably necessitated because the fan is connected to a motor on flexible mounts and moves, in relation to the stationary shroud. Yuk. Leakage! Fingers shows that it works, but I wonder how well it could work in a low tolerance shroud. Not such an easy solution to this one.

That new 06 fan sure looks tasty.



I re-looked at those pics that Kat put up over at:

http://dieselplace.com/forum/showthr...958#post634958

Notice that there is a ring attached to the engine that looks to float inside the shroud, with a flexible skirt around it. Note it attaches at the upper point to the oil filler tube. Also note that the radial struts are scolloped in a fashion to take the cyclonic air from the fan and direct it straight back to the engine...

So is the point of this new ring to redirect airflow or close the gap as KB suggested or BOTH? Further, it makes me think a TSB retrofit is going to be a bit more costly for GM. Is that oil filler neck pressed into the block/intake or is it bolted? The lower connecting points to this ring would be of interest as well. There has to be at least two more down there somewhere...

TxC, are you going to follow up with your contact at GM today? Seems to me that these pics give us some new ammo to go after them with, as they indicate, without a doubt, that the cooling system was altered, and you know that they wouldn't do that in the final model year if they didn't have to.

tbalz,
If we could get rpm vs coolant mass flow rate on an LLY and an LB7 we could tell if anything changed on the cooling system water flow rate side of things. This would lead us to something like random small cooling lines or a different water pump.

bettered:
But I think it's significant information. We know from Fingers work that once the temp starts going up after the fan comes on, it keeps going up. Thus between KB's experiment and Fingers data, there is clear evidence of the recirculation issue. So I'm wondering where this recirculating air is coming from, i.e. how's it getting from the engine compartment to the front of the stack.

Part of it is that 1" clearance. In another business, we used honeycomb seals with the hexcel material set perpendicular to the blades at the shroud area, i.e. a strip of honeycomb around the inner circumference of the shroud. The design was such that we expected some interference as heat made the blades grow longer, but once that interference had been cleared (by the operation of the blades themselves) we had a tip seal that was the smallest it could possibly be. (We weren't mounted on rubber bushings either...) There will always be leakage, but there's no point in building in ANY more than necessary.

Re: RickD's experiement with the splash guard off.. Is that another name for the fan shroud or is it something different. Not sure exactly whether that fits.

I've already sealed up my POS flap in the ghetto. Now I'm going to see what other recirc paths might be present to contribute to the problem. There's got to be something besides that 1" clearance around the fan. How about over the top of the shroud under the hood? I remember other vehicles with a seal running alond the top. I don't recall one on mine. Maybe I'm wrong.. Maybe it's on the hood. I'll look.

Ed

tbalz:
recirculation is always possible but it relies on defeating the high pressure casued by the velocity of the vehicle with the fan. At idele not moving this is very possible becasue there is not any pressure in any of those openings. At speed I do not think it is possible to have hot recirculation.

Idahofox:
LB7.

Parameters:

Driveway @ idle, ECT 205° F, hood @ safety latch.

Observations:

Strong fan flow (Prop Wash {PW}, fan not locked) of HOT air, interalia, over right headlight to 12" past the shroud center.

Close the hood and there is no HOT air in the areas noted obove, the PW must Go some where.

My truck doesn't have a seal between the top of the shroud and the hood.

I believe Ed has made a valuable observation.

I have some material, I'm going to try and divert the PW.

Idahofox

RDL:
My OEM extension has my truck running 10* cooler mt than ever before! 195* ect @ 75 mph. Thats in 98* weather. Will be towing in 2 hours.

tbalz:
you only need one flow meter if you are measuring mass flow. It will run you $1200 to $1500 (you need to know what flow rates to expect to get the correct one. any one want to unhook a coolant line at max rpm and collect the coolant in a 5 gallon bucket and measure how long it takes to fill it up?)then you need $200-$500 of data collection hardware and a computer to throw it into an excel spreadsheet. You also need 2 temperature probes they run $30-$50 each.

tbalz:
The mass flow meter is only needed if you want to calculate total heat rejection or to compare the LLY vs the LB7 mass flow rates. we could figure out what is going on with the temperature probes and data collection only.

tbalz:
It is possible that we are at the limitations of the rad and/or water pump. I do not know how much of a factor of safety they put in, but I do have an example of how tight it can be.

I have a 1988 K1500 with a 350 and 5-speed. I replaced the rad with a china special, everything was fine for 18 months, I then replaced the engine with a brand new GM Goodwrench crate engine that was built to 1993 specs (has 20-25 more hp than the orginal engine) in 5th gear at high load(lotta pedal but not accelerating) and low rpm it will overheat. if i down shift to 4th and get the flow up out of the water pump it cools off instantly. It is kinda scary that it is designed that tight and cost of parts is even more of a concern to GM now compared to 1988.

I also have a too much flow story. I have a 1972 Pontiac GTO 400ci. If you are a Pontiac man you know there is a baffle in the water pump. The previous owner figured the baffle was limiting his cooling capability and removed it. He then proceded to overheat his newly rebuilt engine and spin a main bearing. So that engine over heated due to too much flow.

I dont think too much flow is our problem because they only seem to overheat with a full load going uphill. If it were too much flow it would happen in other situations as well ,like traffic jams.

bettered:
There's more on the air recirc pathway. My '00 gasser has a relatively thin hood. The Dmax hood is ghastly thick. The area on top of the stack is covered by a very smooth plastic cover in both designs, but in the '00 the inside of the hood is also very flat in this area and is sized such that when you close the hood, the plastic cover slightly compresses the underhood insulation - all the way across the front. You can see the pattern in the insulation where the two parts 'seal'. I'm sure it's not a great seal, but it is certainly no flow path.

Now comparing that to the Dmax hood, the area above this plastic piece over the stack is part of the new transition to the thicker hood. I haven't measured the gaps yet (I'm thinking plumber's putty), but just visually, that area of the underhood is anything but flat, it looks like the underside of a boat, complete with chines. The designers of the new hood were clearly oblivious to it's former function of sealing off that pathway.

But that's not all. Look between the sides of the stack and the frame. On my new Dmax there's a gap of 3 or more inches the entire height of the stack - on both sides. On the '00, on both sides, there are two of those cardboard / plastic POS flap thingies that block off the possibility of any recirculation AND force the incoming air through the stack.

My guess is that there was one engineer who spent his entire life assuring that incoming airflow went through the stack and could not recirculate. He did this in a number of subtle ways. And it also looks like he retired and was replaced by a gaggle of whiz kids who cost reduced out the side flaps, because they were a pain to install with all that stuff under there and either didn't know or didn't care that they had designed in three recirc paths, the third when the max thick hood (I liked the old one better) came along.

I'm not familiar with the '04 models, but what's the underhood area look like immediately over the nice smooth plastic piece on top of the stack?

bettered:
Don't know, Tx. I'm not familiar with any more models than the two I have. The design of the '00 flow path appears sound, where the design of the new flow path looks completely incompetent. I see no reason for building in recirc paths under any circumstances.

We do know that once the fan comes on in an overheating unit, the temps start climbing and they don't stop. That's a recirc problem. Nothing to do with fluids since the only thing that changed was the fan coming on.

We also know that there is some variation between units of the same run and that some have the problem and other don't telling me that the design is marginal. We know it puts out more heat than the LB7.

We don't know for instance if some units have side flaps and others don't. It's at least a possibility worth exploring.

McRat:
You will need those temp differentials from a truck that does not overheat (LB7 would be OK, or LLY without heating) and a truck that does, and record the values for a long hillclimb that will cause the temp to go over 220'ish.

Here's the problem - When you are going uphill loaded, at first you are not using 100% of your cooling capacity. The temp says 205, and the thermostat is only feeding a little water into the radiator. As the engine gets loaded down, the thermostat must open more and more to keep it at 205. Once the thermo is open 100%, the temperature can now climb higher than 205.

On a truck that does not get hot, the thermostat will not fully open. On a truck that does get hot, it will. Now a truck with the thermo open 100% that stablizes at 205 deg, should show a lower delta across the radiator than an engine that a truck that is at 205 but pushing less water through (partially open).

If in fact the problem is in the radiator system (pump, radiator, airflow), the "cool" truck will show a higher delta at full load than the "hot" truck will show at a partial load (thermo not fully open yet). The "hot" truck just cannot get rid of the same heat. If the problem is the engine generating more heat in the "hot" truck, then both deltas will be about the same.

Or am I missing something?

Fingers:
Good up to the last paragraph. The "cool" truck never opens its themostats fully, or at least is in equalibrium with them full open. The "hot" truck goes fully open before full load. If the radiator is overloaded, the delta T will grow to a point then both the inlet and exit temps will get higher and higher with little increase in delta T. If the Rad is OK, then the exit temp will stay about the same (small increase) as the delta T gets bigger and bigger.

Idahofox:
Hood to shroud clearance: (nominal)



Spot #.....Clearance

1....5/16"
2....3/8"
3....1/4"
4....3/16"
5....1/4"
6....1/4"
7....1/4"
8....1/4"
9....1/4"
10...1/4"
11...1/4"
12...3/16"
13...1/8"
14...3/16"
15...3/16"
16...1/8"

The distance from #1 to #8 is nominally 44".

The area between # 10 and # 11 also # 14 and # 15 (hood latch area) is a bi-directional labyrinth seal, no flow, IMO.

Idahofox

Idahofox:
The only, at least the shortest, Cold Air path to the air cleaner is behind the right headlight and infront of the right fender liner. Oh no is that the 06 way?



We know that the prop wash, Charges the area surrounding the air cleaner with Hot air (high P).
Finger’s Dam, spans tire to tire, including the area in front of the r fender liner (low P). The result should be flow from engine bay to the area in front of the r fender liner.

If the air cleaner was shouded from prop wash and Fingers Dam did not extend to the area of the r headlight, could the turbo be enticed to draw air from in front of the r fender liner?

Wandering minds.... ops.

Fingers:
Dam does not cover the openings behind the right headlight. If anything the dam should increase the flow through the holes. Should also increase the lower P in the fenderwells an pull more air out there but I am not sure. Best solution would be a baffle to deflect the prop wash. JMO

Idahofox:
Fingers agreed,

However, properly shouded, if the low P was at the air cleaner and an high P was at the bottom and in Front of the fender liner and behind the headlight, would not the turbo draw be Cool Air, (not being drawn from the engine bay, thereby not contributing to Themo Feed Back)?

Idahofox:
Quote:
Originally Posted by bettered
I'll get the same data on mine. I'll bet they're not even close..

Did you happen to note the wide gaps between the sides of the IC and the framing? They're only about 16" tall on each side.

Ed


Prime feed back path. I believe a significant issue.

KB:
The more you guys make me look at the front end, the more I really want CAC and RAD in/out temps. The gap on the sides between the CAC and rad bugs me. Also there are large holes in the shroud where the ECM is buried, that is the ECM, correct?

Fingers, others, a little help. If the CAC outlet temps (or IAT maybe) run high enough, the computer starts to reduce output in the form of torque management, or something like this????????Anyone aware of the ECM output in severe temp conditions??

I talked with a guy, Patrick, at vararam that develops aftermarket air intakes, he is very familiar with this problem, and has done a lot of testing, though he admits, they haven't heated up like we have in testing. He also builds race trucks and has been inside the LLY block. It won't be the first time this was mentioned on this forum, but he wasn't impressed with the cooling passages.

He is just finishing testing on an intake that does much the same as some of us are doing. HERE

Hailing Rick? How did the air "lip" work out? Wondering if the tranny lockup functions start to change when you get to 250. Could be monitored an an edge attitude.

Fingers:
--------------------------------------------------------------------------------

Quote:
Originally Posted by McRat
Hmmm...

Seems on the same day, same load, same speed, the radiator's delta at full open thermostat should be the same on both trucks. Unless one truck is not passing the heat as well.

The air temp is going to be constant, this is why we need to go up just high enough (220) to insure the thermostat is 100% open. The truck that does not overheat will need to be be run harder perhaps.

Dunno. Lemme think about it after a couple of beers.




Let me revise this a little after some thought.




The "cool" truck never opens its themostats fully, or at least is in equalibrium with them full open. The "hot" truck goes fully open before full load.

On the "cool" truck, inlet temps will remain within the bounds of the thermostats range (180 - 210 On our trucks IIRC) The exit temps, however, will vary with variations in water flow, air flow, ambient air temp and radiator coolant inlet temp.

The "hot" truck will respond the same as the "cool" one untill the thermostats open fully. Then, the radiator inlet temps start to rise undampened by coolant flow control. If the radiator is overloaded, the delta T will remain about the same and the inlet and exit temps will get higher and higher nearly in unison. If the Rad is OK, then delta T gets bigger and bigger. In other words, the radiator is bring the coolant temp down to some reasonable level.

I hope this makes more sense.

KB:
Take a closer look at this fan for 06. It was discussed earlier. Note the fan and it's shroud are singularly constucted and attached to the block. That way the fan and shroud move with the block, and no big gap is necessary, it can be built with 1/4" space tolerance that allows minimal bypass. The entire assy sits inside a sealed frame attached shroud, with flaps that suck down to the fan shroud. And note, it has no holes in it like ours. The ECM looks to be completely external with it's own heatsink (God help it if this truck heats up like ours)

I wonder if this bigger looking clutch is thermo-viscous, or something else.

I like. Now I'd like to see what they did to isolate the stack members from contamination air.

Q: Is tht heatsink to cool it off, or heat it up in cold wx.?

Fingers:
Ran the truck today with the ghetto dam but without the valance. Some preliminary observations.

OAT 80*
IAT as high as 160* till truck got to about 35 MPH then dropped smartly to within 10*-20* of ambient even with fan engaged.
Differential pressures across stack were up ~.5 iw or more over runs with valance.

Max ECT was 220* on Ballbuster. WOT all the way. ECT was actually dropping at the top of the hill. Odd. Fan was on at top but I never heard it kick it? Same load yesterday got me 240 and rising.

Library hill held steady at 213* from 1/4 way to the top. Steady 35-40 MPH run. Near WOT.

Conclusion is that the valance was changing the airflow in a negative way.

Idahofox:
--------------------------------------------------------------------------------

Quote:
Originally Posted by Fingers
Ran the truck today with the ghetto dam but without the valance. Some preliminary observations.

OAT 80*
IAT as high as 160* till truck got to about 35 MPH then dropped smartly to within 10*-20* of ambient even with fan engaged.
Differential pressures across stack were up ~.5 iw or more over runs with valance.

Max ECT was 220* on Ballbuster. WOT all the way. ECT was actually dropping at the top of the hill. Odd. Fan was on at top but I never heard it kick it? Same load yesterday got me 240 and rising.

Library hill held steady at 213* from 1/4 way to the top. Steady 35-40 MPH run. Near WOT.

Conclusion is that the valance was changing the airflow in a negative way.


The fan did not Kick On, but was On at end-of-run.

Opinion: The Rate of temp change was slow and the fan engagement followed the delta T curve, ie no sensation of kicking on. The stack temps would follow the same curve.

Opinion: The valance is Not aerodynamic and is for esthetics Only. Your test verified that.

Ricks Add On is looking positive.

oilburnr:
OK, watch for my upcoming post, where I'll show what I've done for a Getto CAI. Give me a couple of hours and I'll post it up.

bettered:
Quote:
Originally Posted by bettered
I'll get the same data on mine. I'll bet they're not even close..

Did you happen to note the wide gaps between the sides of the IC and the framing? They're only about 16" tall on each side.

Ed


And they're not. This is the clearance between the top of stack cover and my hood (inside) in accordance with the scheme initiated by the IdahoFox. I didn't do both sides. With these kinds of numbers, I didn't figure it was worth the effort in the 90 + heat. All Dims in inches

1: 7/8
2: 1 1/8
3: 1
4: 1 1/8 to 3/4 tapering down from back to front

9 1 5/8 to 1 3/8 tapering down from back to front
10 1 3/4 - 1 1/4 tapering down from left to right

13 1 1/4 to 3/4 tapering down from left to right.
14 1

There is no seal, this is a huge leak (recirc) path across the top of and around the fan.

With an F250 Stroker friend we made a deflector from piece of leftover siding. Probably not designed for these kinds of temps, but for the moment it's working. It's a straight 'L' shaped piece with an acute angle of about 60* at the base and it's about 4' long. It fits under the top (flat) piece over the top of the stack and grill. When the hood is closed, the insulation bends it a bit further forward and creates a seal across the top. In the area of the latch, the heat of the hood against the plastic actually self formed a lip that fits against the metal part of the hood.

The side clearances remain.

While ECT has never been a problem for my truck, it was down a few degrees on my return although the OAT was about 10* higher (95*) than when I made the trip over, though this is a perceived, not a real difference.

Towing next week up a mountain side.

Ed

KB:
ED, I am sure recirc is also an issue, just unsure of where that is happening, don't let me stop you.

I just went out and got a reading on flow through that crack. 9 mph as best I can get, that's w/o the entire sensor exposed to the crack. It's going in there. The avg stack velocity on the front you may recall was about 5.4 mph. Again, fan locked, truck cold (MAF is linearly related to velocity, since there is nothing heating it up)

Translation: air will go through the path of least resistance, if one is made available. And this is a high resistance stack.

Idahofox:
Remove headlights, close hood. Eyeball the area from the hood stop/support back to the shroud cover edge. There is an area 3 - 4 X 10 " gap. Follow it to the pre stack/post grill area, then to the radiator/radiator frame gap. Looks like tornado alley.

Sealing these areas tight, is essential.

I have an LB7 with No overheating issues. However any efficiency improvements are applicable across the board.

Idahofox:
Quote:
Originally Posted by killerbee
idaho, here is a pic of the area you described. What now?


From the stack lateral edges to the fender is Open, both sides, (less mounted hardware). This area is then Open to the pre stack/post grill area.

Passages from the engine bay around the stack mounting frame (frame to fender area) to the stack front are numerous.

We know that the fan @ idle (low temps/minimum coupling) forces prop wash to the areas behind the headlights, we can feel it. Remove PS headlight, close hood, idle engine; prop wash Flows out of the opening.

Driving: The prop wash starts a vortex, engine bay to stack front to engine bay, through unsealed passages around stack. Stack air mass flow creates a venturi draw that augments the vortex flow and re-circulates HOT air several degrees above OAT.

If the stack temps enters this enviroment at a marginal state, the outcome is predictable. IMO

Idahofox

Idahofox:
Quote:
Originally Posted by killerbee
I hope I am not stepping on anyone. If someone else gets credit for this already tell me

Pull off the top black cover to reveal the space between grill and stack. Stand back and look toward the fan shroud, over the top of the rad. I have almost 3/4" of space between the top of the rad and the top rad support. You can SEE the engine block and fan from in front! Huge bypass being fed by frontal hi-p air. That has got to be sealed up.

Don't know if the bottom is the same way. Can someone else look and verify?


Perfomed some dissection yesterday: LB7.

To the Bottom First; There Is 3/4 - 1 " gap between stack bottom and the stack frame. The stack frame (engine bay side) has a 3/8" virtical lip (pointing up) that the lower half of the shoud sets in. The shoud does not mate clear across (can stick you finger under the stack from the engine bay side). The fan may pull this into position however, might not, couldn't verify. ( Refuse to stick my hand in there with the engin running. )

Now the Top: There is a gap, cann't really see through to the engine bay. However; the top of the radiator core is assembled with a 1/4 X 2" U channel edge for strength, the top of the stack frame has a 1/16 X 3/8" lip (pointing down). The U channel "Brackets" the lip, leaving a Large but not a direct path, from stack front to engine bay

KB:
The magnehelic. Showing still idle pressure drop, fan locked, of around .4 iw.

Will be testing throughout the day. I'll post deltas for each stack component, then we'll add up the numbers, and that way we can see how much is being lost in leakage at each stage.

For the sake of simplicity, I am placing the front sensor on the condenser, not the cooler. Since the cooler really cannot be integrally sandwiched to the stack, I think this is the best route to go. My numbers may vary from Fingers initial posting as a result.

Off to church and number crunching.

Idahofox:
LB7.

Some stack measurements:

Fan blades > radiator 3 1/2" > CAC 3/4" > A/C 3/4" > T/C 2 1/2" > Grill 5".

Working surfaces:

Radiator: 34 1/2 X 20"
CAC: 38 X 19"
A/C: 28 3/4 X 16 1/2"
T/C: 10 3/4 X 5 1/8:

Bumper openings: 12 X 1/2 ".

Idahofox:
I belive the consensus Here is that there is Not One Problem.

Collectively a group of conditions takes our trucks to an OH situation and/or the threshold of an OH situation.

The LB7's operate in this same world and will benifit from the same changes made to address the LLY OH situation. Increase Tow Capacity, increase margins, Tunes of choice, etc.

I believe there are Two fundamental issues, Stack Flow and IAT.

Fingers took a BIG bite out of the Stack Flow issue with his Getto Dam. Damn sure did ! Thanks Fingers.

Rick showed that an OEM item can help. Thanks Rick. Also Rick, thanks for the rolling lab.

JJ has shown that Plugging the Holes, HELPs. Thanks JJ.

Others with the Flow programs, math skills and an interest in solving the ProblemS, have brought us closer to resolution. Thank you ALL.

When you draw water from a deep well with an o' pitcher pump, and you Stop to rest.......the water falls back to the bottom. You get to start all over again.

Please, lets not Cut of our collective noses.

Idahofox:
Rick shown an improvement by removing the baffle at the base of the stack.

On inspection, the baffle (without holes) is 360 sq", the holes total 115 sq", 32%. It cann't be doeing the job GM intended. It doen't lie flat, the wrinkles and holes may be resposible for considerable Turbulence on the stack face.

Turbulent air will not flow smoothly through the stack, and require additional energy (push/pull) to streighten its direction. Air mass striking the stack at an angle will be reflected and disturb overall efficency.

I intend to rebuild the baffle, minimizing the holes and to mask the bumper openings (reserving them for Cold Air input, future).

KB:
Well I pulled delta P numbers on my way to/from church.
Fingers I'll PM them to you, I think they will interest you.

These are GMC deltas from the condenser face to the rad face, fan off. Top stack cover is removed.

MPH Delta(" H20)
0 -.35
30 .75
60 1.50
70 1.75

As important as the delta is, it is important to know each absolute value front and rear.
Front absolute pressure
MPH P(" H2O)
0 -.05
60 1.10

Rear absolute pressure
0 -.35
60 -.35 (the same)

Compared to Fingers (Chevy), this is pretty good inherrent flow. I had stated earlier that I felt I had some speed induced flow, since I could silence the fan at faster speeds. That is confirmed. Now it gets interesting.

The next numbers are delta's for each component, a sensor on each side of it, at 60 mph. Recall that total drop was 1.5 "

condenser .55
CAC .40
Radiator 1.35

total 2.30

Quote:
Originally Posted by killerbee
Good, play it safe.

The second pic, Yours is a little less prominent than mine, good gap nonetheless, sealerup.

I haven't really spotted a weakness on the bottom, I'll look again.


I looked at mine, and couldn't really see what you were talking about at the top. Mine looks like the gap pictured. Where exactly are you sealing. If I go with the front rad, I'm blocking flow to the second. Don't want to do that, but I could block between the second and back to the frame in front of it..

I'm not sure about the bottom. I can put my fingers underneath it, but I can't reach anything but the bottom of another cooler. I don't think that's a problem.

Sides look like JJ's now. Covered over with Aluminum tape. Plus the little flange we made to block off the over the shroud route. I left the headlight holes alone, because particularly on the intake side I want to make sure there is some way for outside air to get in there. I haven't yet done anything on the drivers side behind the lights. Waiting for my pull next week to see if I have a problem or not.

OK invited posters, it's all yours! I tried to capture the technical data posted, unfortunately I couldn't copy the pictures.

If everyone will respect the integrity of this thread and let you guys do your thing hopefully we will see something productive very soon. I will do my part! JJ :)

Let me know if u need any help w/ keeping it on topic, man these long threads are hard to keep up on.

On a side note my LLY is ok even w/ the extra power.

Thanks Tim

JJ, is there a list of invitees? That could be on post#1, JJ you could update that maybe. a thought

I started typing to bliz but didn't know what I should do.

I want to personally apologize for any role I played that led to this, hope it works out.

Thanks Tim

JJ, is there a list of invitees? That could be on post#1, JJ you could update that maybe. a thought

I started typing to bliz but didn't know what I should do.

I want to personally apologize for any role I played that led to this, hope it works out.
post 1 HAS the list of invitees.

On edit, I can't read through all the pages but my attitude is 10-20* lower than truck temp, have the true temps been measured?
I'd assume the attitude is correct and the gauge is wrong.

My last post here unless I'm asked to mod anything.

My testbed truck:

2004.5 Chevy 2500HD EC/LB

365/65-16 Nitto tires on 10x16 weld rims. (35x14x16)
Cutout Fender Flares front and back.
Front wheel wells heavily modified.
Air bags.
No crank, no lift.
Bed cover.
EGR blocked, Finger Stick.
5" Summit exhuast.
SC III
Currently running Predator 85 HP tune.

Additional mods/deletions from this configuration will be noted when listing data.

I am working on trying to determine if the flow numbers are worse on the chevy, something that has been on my mind a long time. My flow numbers bettered Fingers by a large margin, and I'm wondering about that "valence" removal discovery he made. I got a suspicion the body diffs are to blame for the delta P discrepancy between the 2. If there is a chevy owner that can drop by, I will be glad to hook it up for pressure drop. PM me

It now strikes me (a little) funny that we correlated this to being a LLY cause/effect. Might have been climbing the wrong tree. It was about the same time the chevy nose was redesigned. And the cases we have been working on, and the majority of participants are chevy owners.

McRat you own both, does the GMC stay cooler (stock)?

I was thinking about the redesigned nose issue on my way home from work on friday. I have a little bit of information to offer with respect to that.
A farmer friend of mine has an identical truck to mine except it is a 2004 LB7, with stock tires. He is a farmer and tractor pulls for a hobby. He lives in Central NY which has many short steep hills (45-55mph roads). On many occations he is pulling combined load of trailer and tractor up to 21,000lbs. He has never complained about the truck getting hot on any of the trips to the pulls.
He also made a road trip out to Ohio with a load of 17,000lbs at 65mph and drove back to NY with 21,000lbs at 75mph without ever shutting down the engine. He did not see the temp guage rise above 210deg.

We are spending most of our time trying to get more flow through the stack. I want to caution you guys again that it will help, but not as much as changing something on the water side. I understand that we really do not have any other choice. But, i will give you someground info on why this topic started my posting and where I am coming from. One of the reasons why I left my old job is because the managment and other players higher on the totem pole than me refused to accept that their overheating problem was due to coolant flow. They destroyed 5 years of a vendor relationship, lost 3 engineers, and hundreds of thousands of dollars becasue they we too close minded to listen to the peoples opinion who had the data and the answers. Lets not make the same mistake with each other.

Yes, we are extremly limited with what we can do as it pertains to the water side, but data collection is the key to that. The more data with inlet and outlet temps of the rad at different speeds, loads, grades, and types of trucks the better we can define the problem. ideally we would run the same conditions with the different trucks and look at the results.
The was some early testing like this a few pages back ( i do not remember the gentlemens name) with one truck and it showed a 40deg drop at 60-65mph rad in temp 195ish and a 63deg drop at 70-75mph rad in temp 205ish. This is good news. Even though the rad in temp was higher there was a larger temp delta across the rad. That means there was enough airflow to pull out the extra thermal load. The rad out temps we within 3deg of each other which also is very good and is probably within the tolerances of the ambient conditions and temperature reading euipment.

My biggest question is what is happening as the truck over heats. Does the rad out temp increase at all, Is the rad in and rad out temp increasing together at the same rate, or is the rad in temp skyrocketing and the rad out temp increasing at less of a rate. This is important to figure out where the problem lies.

The best solution of course as others have said is anyone who hits the overheating code to bring it into the dealer. This is the only thing that will make GM do anything about it.

Has anyone with the problem tried a product like Water Wetter? If so did it help or not make a difference?

I completely agree. Without some valid temp drop numbers, monitored during the heatup, we don't have the foundation for cause.

I thick RDL is the truck you refer to. In his testing, he taped sensors to the rad in/out. So his readings may or may not have been accurate, but it was for sure minimal.

So to be clear, we should establish a test case, where the rad in/out and the CAC in/out can be plotted over time, with rising ECT, agree?

Totally agree. If you try and measure fan out temp note this. The temp will be different for every square inch of the rad surface area. The temp changes in decreasing fashion in a serpentine pattern following the coolant through the radiator. Also, the air flow rates will be different from leading edge to trailing edge of the fan therefore causing hot spots here and there. That is why I want to focus on coolant temp and ambient air temp into the rad.

as a review, RDL, with his various mods, has brought one of his vehicles to a config that no longer approaches overheat in his extreme conditions. Cold air, tow tune, and factory air dam being the significant improvements. He also did free up his exhaust a bit only recently, removed the cat. also blocked egr

I recently spoke with Rickdlance, and probably figure he'd be about the best test bed for my quickie trial. Just waiting for a reply as to if I can get the part. While it may well turn out to be unrelated to the fan clutch, this is exactly what the 6.5 did and while some schools beleive that the since clutch does eventually enagage yet temps still climb, the 6.5 responded extremelywell to a properly calibrated clutch in the sveral hundred ought cases (I've sold a bunch) and except for some cases where the temps ramped up extremely quickly on inital run in, they've been able to keep up.

May be totally off, but you never know...

Fingers, I have a little something for you as well if you are still capable of testing.

FWIW, JK and I talked last week about overheating. Considering how much the cooling system depends on the fan to move air, a better functioning clutch can't hurt. My temp ramp up is very rapid (2 min) compaired to the highway pullers.

Something new JK? I'm all ears...

Whoa! What the he!! happened over the weekend?

Well, just a quick update, and then tonight I'll come back and edit this with pics.

I did receive the 6.0 air box this past Friday, and I did modify it to utilize the 4" hose straight out the bottom. Additionally, I made a baffle out of 1/4" Baltic Birch plywood to try and prevent the fan prop-wash from flooding the fender intake openings behind the headlight.

Results? I'd say good. The highest IAT that I saw with the fan running was 12* above OAT. Not as good as my modified stock box in which the only source of air was what came through the 4" hose. However, the filter-minder did not budge with my new setup. So, for roughly $50, it appears that at least I won't be ingesting superheated air anymore. Will it help that much? Dunno yet, but I don't see how it can hurt!

Again, sorry for no pics now, but it was a busy weekend and I didn't have a chance to upload and resize them for posting.

During non scientific testing of the automatic elevated idle feature I found that IAT rose quite rapidly compated to OAT (cold started engine) even with the hood open, and in very short order we had 50°f+ IAT on a sub freezing day. Really made me wonder why they used the IAT sensor rather than the OAT sensor as this one stayed stable.

Email sent to Fingers. Please contact me if you do not receive.

That could well bring IAT's into control, but at the expense of selling the stereo. I'm not discouraging it mind you, I'm familiar with its usefulness on the truck w/o a CAC in the stack. If a fan could be designed that pulled a bit more in its disengaged status, that would be an improvement to the idle condition, IMO. I am a fan atic. I'd love to kiss it off, not use it more, if that can be achieved, but certainly we have already shown that the stack can be configured so that the fan removes more heat.

I have run the postulated theme that (free) airflow would be critical to the Chevy. Free meaning inherrent flow sufficient enough under normal conditions, that would keep the 20HP depleting fan off by itself, at speed. Fingers flow numbers (chevy) and mine (GMC) are significantly different, the GMC out ahead on speed induced flow. My IAT's would seem to corroberate the difference also, though I've never loaded it heavy.

While waiting for the temp drop numbers from a willing someone, please go to this POLL (http://www.dieselplace.com/forum/showthread.php?t=38875) and cast your vote, the more the better.

In the Ghetto style, I extended part of the fan shroud from the top down the passenger side to the seam. (about 1/4 way around)

Idle standing still, IAT within 10-20 of ambient. Lower if the wind was coming from the front of the truck. Anything above 10 MPH and IAT drops to ambient.

Fingers, are you going to try using some of that conveyor belt as an extension then? I'm assuming that the IAT's mentioned, were with the fan 'freewheeling?'

On my truck at least, even freewheeling, the IATs would stay high when sitting still.

Yes, fan not locked up. I expect similar results with it locked up. There is essentially no prop wash in the air intake area now.

JJ, heroic effort, thanks.

Here's how to analyze the system. Like all such problems, the hard part is getting quality data.

Heat load...we need to know the heat load on the radiator under contitions where the overheat is happening. Two ways to get it, massflow and deltaT (DT) of the air or massflow and DT of the water.

Water flow can be measured ultrasonically with a strap-on ultrasonic flowmeter. DT is easy, just two temperature measurements.

Heat load (Q) will be in BTU/hr. We know that:

Q=m Cp (Tout-Tin) for both air and water. Getting a good sample of blended air means taking the temperature in the fan discharge, since the left side of the rad will be slightly hotter and we need the bulk average.

Cp (heat capacity):

air: 0.24 BTU/lb/F at 120F and that lb occupies 14.6 ft3
coolant 50/50: 0.75 BTU/lb/F at 210F and that lb occupies 0.015 ft3

You can see why liquid cooling is better. BTW, water is 1 BTU/lb/F.

Find Q by Q=m Cp DT for the waterside.

Now we can find airflow since:

Q = m Cp DT for the air too...invert to get m=Cp DT / Q ... remember bulk average temperatures.

Now we have the airflow too in lb/hr

For a given little bit of heat exchange area (A),
U=heat transfer coefficient (all the complex stuff is buried in there).

Q (transferred) = U A (Thot-Tcold) as long as A is so small that Thot and Tcold don't change much...

But they do change by many degrees across the whole exchanger, so you get a differential equation (acosss all the area), which when solved:

Q = U A DTlm

DTlm=log mean temperature difference (hold on to your socks):

DTlm = [ (Thot,out - Tcold,out) - (Thot,in - Tcold,in) ] / ln[ (Thot,out-Tcold,out) / (Thot,in-Tcold,in) ]

It's just a simple equation for DTlm as a function of all 4 temperatures. lm[x]=natural log of x.

So, if we know Q, and the 4 temperatures, we can calculate UA. And, that's the characteristic performance number for the radiator...can be thought of as its "heat transfer horsepower"...more=better.

The nice thing is, we can get UA at idle or unloaded. A will be fixed (obviously), but U does vary. It will go up slightly with increased airflow and waterflow, but not too much. That's why more flow results in better heat exchange. In commercial heat exchangers, we use multiple passes on the tubeside to increase velocity and thereby U...at the same A.

The next thing we need is something called a pressure survey at a few conditions. Pressures:

Stack in
after condenser
after IC
after rad (engine bay)

These should all be referenced to static outside the truck.

Then with the other data, specifically m(air)(mass airflowrate), we can develop:

V = alpha SQRT(dp,rad) = actual volumetric airflowrate.

I don't know how to get all the data (like I said at the onset), but with them all, we can characterize the system and see what is different between trucks, Q?, m(air)?, UA?.

I'm just spelling out the formal engineering approach, and everything here is freshman-level engineering.

Just sharing the tools.

So there.:eek:

Gotta be someone who can data log an overheat. Cit, very daunting looking eq's. The math is not real tough using some simple assumptions and an average or 2.

We're spinning wheels hoping for this in/out data to just show up. In the absence of said data, we can't evaluate stats and water pump function.

So we may as well move along. FWIW, I can provide all kinds of pressure data across the stack, but w/o an OH, and coolant/charge air temps, it's trivial.

Fingers "Anything above 10 MPH and IAT drops to ambient."
...and with a load on BB?

PS: Glad you reengaged Maverick.

I uploaded a few pics of the Getto CAI part duex. This site is sophisticated enough that I could not reload pics from the other day showing the rest of the mod, so you'll have to cruise over the the original overheating thread if your really interested. ON Edit: Sorry, how do I link actual posts? Please look at page two...

With today's running around here in Phoenix, it seems to be doing a pretty good job, keeping IAT within 10-15* of OAT even with the fan on. That being said, if Finger's approach to shrouding the fan, and keeping the stock air box works it would be better. Less crap/bugs getting in the box, and elimination of the possible rain intake. On second edit, I meant to comment that while I was pumping $85 worth of kerosene into the 'brnr today, I walked around to the closed hood and felt the hot air being blown out of the gap on the passenger side. My wife and kids were inside, so the engine and A/C were on. Amazing is all I can say. While this idea of ingestion of heated air is not new, nor the cause of this problem, it has to exacerbate the situation.

Now, onto the next point of getting data. If you guys think it would help, I'm up for ordering a couple of the electronic thermometers like Rick used to get ECT inlet and outlet temps. I have two trips planned to N. AZ. over the next couple of weeks where I could record data with the same trailer/scenario/route. The weather should be similar, though with the summer monsoons here, things are a bit more humid. Significant enough, probably not.

Let me know, if it would help, I'll put an order in tomorrow for the thermo's.

-Don-

On third edit, how is the shovel collection coming along Fingers? Last pic I saw, your wall was pretty full! Any new additions? ;)

I uploaded a few pics of the Getto CAI part duex. This site is sophisticated enough that I could not reload pics from the other day showing the rest of the mod, so you'll have to cruise over the the original overheating thread if your really interested. ON Edit: Sorry, how do I link actual posts? Please look at page two...


-Don-

;)

Don,

Which thread and post # ? I'm interested in more pic if you have them/posted them.

Thanks.

Idahofox

http://dieselplace.com/forum/showpost.php?p=625069&postcount=1686

is the original pics. Note that the air box there is the OEM. The first hole I drilled was in the wrong spot. Don't ask how I did that.

With the 6.0 box, it is a bit more centered.

http://dieselplace.com/forum/showpost.php?p=638740&postcount=74

I also pushed the hose back, and put the tow hook back in place. It did not seem to effect IAT or the Filter-Minder. I zip-tied it to a hole that I drilled in the valance scoop for the hook.

Before we get bombarded with PM's. HERE (http://www.dieselplace.com/forum/showpost.php?p=625628&postcount=1721) is the source we found that can supply the factory cold air box. It is available for $37 shipped, $250 at the dealer. How you modify it for additional flow is up to you, speculation is that a simple 4" hole out the bottom may have close to the same temp reduction as oilbrners. Use your judgement. Besides factory appearance, the big advantage in THIS (http://www.dieselplace.com/forum/showthread.php?p=625628&highlight=#post625628) cold air design, is the continued use of the delco element so many of us like for filtration effectiveness.

Testing has confirmed IAT temp drops of 70-100 degrees while towing, you decide what that amounts to in HP recovery, and/or heat reduction and EGT reduction.

The Here link didn't work for me. Can't log in as KB.

Idahofox

Oil,

IF you check your User CP, at the very bottom of the left frame is a link to all the attachments you have uploaded. You can link to those directly from within any post without uploading again.

Like this of your first air box

http://dieselplace.com/forum/attachment.php?attachmentid=6293&d=1121142347

Fox, Jus log in as yourself. BBoard glitch.

and this of the 6.o box

http://dieselplace.com/forum/attachment.php?attachmentid=6838&d=1122354554

Todays fun:

Pic of the 2" magnehelic. Yes, that is a factory Nav TS. Not a Plug n Play option, somewhat involved.

http://www.dieselplace.com/forum/attachment.php?attachmentid=6766&d=1122224799

Pic below shows the front sensor location, the foam I used to seal out bypass, and finally, my ghetto project. Side blocks.

Recall that last weeks measurements for stock cfm in/out as follows:

5.4mph avg in on the stack face (avg of 8 points)
17mph avg out through the fan

2160 cfm in, 3950 cfm out, 55% throughput at idle, fan locked

With todays mods:

6.4 mph in
15.2 mph out

2560 cfm in, 3530 cfm out, 71% throughput, using just a little foam

about 19% more cool ambient air pulled in, 2560 vs 2160


Next, the pressure measurements, admittedly surprised me. Delta front to back, wasn't better today, in fact it was ever slightly less. What wowed me was the absolutes.

Total stack drop was 1.4 iw at 60 mph, same as before. The absolute P on front was 1.4, .3 iw higher than stock. The shroud back sensor read (positive) .1 iw! Before it was -.35

What seemed to be happening, with more flow through the (now sealed) stack, is that air was moving through it quite a bit more, at speed, and ram air was overwhelming the fan more. This took me a while to assess.

I flogged her for 45 minutes, running up and down the gears around town, 104 on the mirror. The type of driving that results in a lot of TC work and high ally temps. Left a lot of smoke behind. I had to work at it to get the tranny to 190, and that's as far as I could get it. A workout that would have easily exceeded 210 before. ECT topped out at 198 (edge), couldn't get it higher, tow tune plus level 1.

I couldn't get the fan to come on, except by stopping. And it did, as I expected. It would go off 10-20 secs after leaving the light. Normally I can get the fan to come on more.

Lastly, and I have nothing to qualify this, ac seemed a bit better. Not sure.

Conclusion: the front P mod, plus some sealing, made the heat offload more effective at idle (fan), as well as at speed (ram).

Thanks Fingers.

Idahofox

OK, I can't believe I'm gonna say this. If you guys can get a vendor to donate an electric water tempature gauge and 2 senders I will make adapters and put them in my radiator hoses.
I will not at this point un-due what I have done, nor will I stop doing modifications I think will help. But at least we will have a starting point and I will make a second set of adapters to install in another truck if needed.

hmmm,

not too impressive I guess. Little things impress me.

One other measurement I forgot to mention in the sealing of the CAC to the rad, I obtained 15-20% more idle air flow through the CAC. Should help with heat quench phenom.

Turns out the stock cooler isn't so bad afterall. All it needed was a little airflow.

Any comments? Suggestions for further testing?

Great thread guys!

I don't have an valuable data to add.

I am running a volant air box which has the opening for a cold air tube. In my case (diff bumper) I installed a piece of hose from the box to the bumper area. IMO the hose needs to be longer as I think the bumper is forcing air away from the hose opening.

Also I am willing to collect data although I a can't afford to buy many probes etc etc.

Local dealer called the other day and seems to be getting up to speed on this issue. Says there is a brand new flash update (so new they couldn't download it as of 2 days ago) and a possible fix with replacing both T-stats. Claimed if one gets stuck you will only over heat while towing and there is no way to test the T-stats.

Info on my 'over heat' conditions.
1. My truck is lifted with 35" tires.
2. I use the Edge on setting 2 and have the cat delete pipe and a 4" cat back (basically a 4" from turbo back)
3. I never let the temps get into a true over heat condition as I don't want the motor damaged. I have had it to 235 before I either slow way down or crank up the heater to suck hot air out of the engine.

4. While towing to the desert I leave the hood in the un-latched position to get more air flow. it seems to help some but not enough.

5. EGT: I can get it to 1400+ very easy in over drive and even with OD locked out. (if this matters)

Another thing:
I have a friend with the same truck, lifted w/ stock bumper, w/ no tune. He claims he never overheats. I am sure I could get him involved in testing.

We could get together one weekend at tow my trailer up the same hills to collect data.

http://dieselplace.com/forum/showthread.php?t=14625&page=224

Measured the fan rpm yesterday with the following results:

- motor idling with 700 rpm
- ECT between 185 F rising to 205 F during warmup engine
- ambient temp 90...95 F
- fan rpm "free wheeling" 700 rpm
- fan rpm "locked" 900 rpm

Conclusions:

with a crank dia of 7.5" and a waterpump pulley dia of 5.5" the fan can spin at max. 950 rpm at idle (crank 700 rpm). This means the slipping is 5 % when the fan is "locked" which I was expecting.
BUT "free wheeling" at 700 rpm means that the fan rotates with 74 % of max. speed and slips therefore only 26 % - which I did not expect to measure.
I was not able to measure any fan speed lower than 700 rpm at idle (same as crank) - even with ECT at 185 F.

Tried this morning continue measurement on a cold motor but heavy thunderstorm prevented this.

I had no second person to check if slip increases with rpm (should possibly a little).

I am surprised that the fan rotates basically at crank speed when "free wheeling" and increases only by 30 % in rpm when "locked".

Since mine is a 2005 maybe fluid clutch parameters have changed by GM to rotate the fan with higher speed at all times.

I cannot confirm 3 different speeds (looking for a lower speed than 700 rpm at idle when I have time and weather permits).

I know thats NOT a solution to any problem but maybe helps to understand how the cooling system is designed. :)

mahalkita, Maybe the fan clutch relies on the fans resistance to move at speed and will increase slippage rates at RPM??

Measured the fan rpm yesterday with the following results:


...BUT "free wheeling" at 700 rpm means that the fan rotates with 74 % of max. speed and slips therefore only 26 % - which I did not expect to measure.


at higher rpms, much higher resistance, and slip

The silicone will get thinner when hot and the resistence will get lower than. When spinning faster the friction will also decrease a little bit. Both of this facts will increase slipping at little bit. Still I am surprised that the "free wheeling" speed is that high - but since we all know that the engine runs so hot its somewhat logical.

I assume the second speed you are hearing for hours it what I have measured as only 26 % slip compared to 5 % at full speed. I just have to find a lower speed than crank....

Brings up a thought. At higher RPM, the clutch self-generates more heat.

Trimmed the valance. It was sealing agaiinst the air dam at speed preventing the high pressure air from getting to the rad and air intake. Removed a large section in the middle and trimmed the bottom flange to keep a gap between the dam and valance. Much better now. The flap behind the bumper get pushed up above the bumper from the air flow. I am thinking of removing it.

Reworked the Ghetto shroud extension. I didn't go far enough over the top on the first attempt and IAT would rise a little. Added more extension towards the driver's side and everything is good again. IAT will stay within 10-20 degrees of ambient at all times while moving, fan or no fan. IAT will rise depending on the wind when sitting still. Still can't believe it is so simple. I would be interested in someone else testing this to check that my results are repeatable.

A word on the IAT sensor. The temperature probe is part of the MAF sensor. Adjacent to the temperature sensor is a heated wire for mass air sensing. Indications are that the heated wire throws off the IAT reading at low air volumes. Probably 10*-20* depending on flow.

Will try to measure at higher rpm but its already damn hot in there at idle!

Fan RPM:

The resistance at low RPM is much less than at speed. You will need to run the engine at ~2000 RPM to really see the difference.

Paraphrasing an engineering reference source

"The fan drive is a modulating design. However, there are some additional factors at work . There's a thing called "slip heat" -- the viscous drive will generate heat internally. That's why it's finned: to dissipate that heat better. Well, there are some conditions where more slip heat is being generated than can be dissipated, and the fluid inside will get hot enough that its properties change. After that, it won't transmit as much torque as before, and we say the drive has "drooped". So the fan drive is calibrated to dance around -- or pass quickly through -- that area."

Just another reason to keep the air flowing over it, cooler

This morning I got a call from the mechanic. He talked to a GM engineer this morning and was told a fix was close. More BS I assumed! Then he started asking about my monitoring device, specifically would it read "calculated fuel rate"? I checked and it does. They have asked me to monitor that for them.



Somebody like Fingers chime in here, but monitoring the 'calculated fuel rate' sound like an attempt to nail you for the Predator, i.e. you are causing the overheat by using a different fueling program then OEM.

Hope I'm wrong on this...

Does anybody know of a good source for foam we can use to stuff the gaps around the stack, that has the correct properties to last, and is easy to obtain? NAPA?

Trimmed the valance. It was sealing agaiinst the air dam at speed preventing the high pressure air from getting to the rad and air intake.

how did you figure that out?

Reworked the Ghetto shroud extension. I didn't go far enough over the top on the first attempt and IAT would rise a little. Added more extension towards the driver's side and everything is good again. IAT will stay within 10-20 degrees of ambient at all times while moving, fan or no fan. IAT will rise depending on the wind when sitting still. Still can't believe it is so simple. .

are these results on xtreme load? We don't have much of an IAT issue mt. I could be misunderstanding

Fan RPM:

The resistance at low RPM is much less than at speed. You will need to run the engine at ~2000 RPM to really see the difference.

Whats the high idle rpm? I could get some data without a second person - high enough or waste of time?

1200 I think. You can get it to go to high idle if you unplug the MAF, assuming you've changed it via the DIC.

I might be wrong, but the calculated fuel rate is not accurate when running a tune from the Predator anyway. Monitoring the stock tune would be accurate. I would make sure that all conversations with them are in relation to monitoring a STOCK tune.

FWIW, the fuel rate is an indication of the amount of BTU's the engine is consuming. Some of those go out the exhaust pipe and some get converted into rotational power. What is left over goes into the cooling system. I suspect they will be asking for fuel rate and EGT's or something like that.

Does anybody know of a good source for foam we can use to stuff the gaps around the stack, that has the correct properties to last, and is easy to obtain? NAPA?

FireStop construction sealer.

how did you figure that out?

The stock valance has tabs on the back. I noticed a matching set of marks on the air dam. The pressure in front of the dam must be huge to fold the valance up and in.

Oilbrner, closed cell foam is probably as good as any. You can by it at fabric stores, some sleep pads. Usually it's dark grey in color. At hardware stores, you can get PU foam rope in different diameters, it can be squeezed into small cracks. It is used for expansion joint applications I think, again grey or dark grey.

If it acts like a sponge with water, it's not closed cell, and will have issues. It also will pass air easier, defeating the purpose.

Don't use polyurethane. It is nasty if it burns. Burn fumes have killed a lot of people

are these results on xtreme load? We don't have much of an IAT issue mt. I could be misunderstanding

I disagree, IAT do rise even without a load. Check it yourself. I was seeing 180* or more with the fan engaged MT.


Have not checked with load. But this is an airflow problem anyway. I have checked with the fan engaged and not engaged. I will check with the trailer the next time I hook.

The stock valance has tabs on the back. I noticed a matching set of marks on the air dam. The pressure in front of the dam must be huge to fold the valance up and in.

Isn't your dam more flexible than the valence? Just eliminating the possibility that the dam came forward, I know, not intuitive.

Whats the high idle rpm? I could get some data without a second person - high enough or waste of time?

Wind speed while driving down the road will also be an issue. Can you monitor "real life"? If not it may not be accurate of what is happening. Also my so called 3rd speed will need extreme heat to trigger. Can you generate that? Do you have hills and a heavy load near by? Can you also get the fan pulley rpm versus the actual fan rpm. That will tell us the gearing, for lack of a better word, of the fan drive. Engine RPM may not be the same as fan pulley RPM. I see from you preliminary test the fan pulley is overdriven. Need to know how much.

Wind speed while driving down the road will also be an issue. Can you monitor "real life"? If not it may not be accurate of what is happening. Also my so called 3rd speed will need extreme heat to trigger. Can you generate that? Do you have hills and a heavy load near by? Can you also get the fan pulley rpm versus the actual fan rpm. That will tell us the gearing, for lack of a better word, of the fan drive. Engine RPM may not be the same as fan pulley RPM. I see from you preliminary test the fan pulley is overdriven. Need to know how much.

To answer your questions:
- cannot monitor real live (hand held device)
- max speed is with 5 % slip only, there is NO higher speed possible at any heat, so I don't need to generate more heat, my truck engine generates enough heat while idling to drive fan at max speed (for a limited time till "free wheeling" again")
- gearing is as posted: crank dia is 7.5" and waterpump pulley dia is 5.5" that means 36.4 % overdriven at all times

[quote=mahalkita;640896, so I don't need to generate more heat, my truck engine generates enough heat while idling to drive fan at max speed (for a limited time till "free wheeling" again")
[/quote]

ifyou will look at this again. You will se that the ECT's are lower 190's, fan fully engaged, at idle, or not engaged. This, by itself, won't keep the fan engaged. As we discussed, it generates much of it's own heat, 24/7, the more slip the more heat, right? Add poor recirc stack qualities, the clutch just never gets cooled down at idle in front of the heat quenched motor. That is, till you gun it, clear some cooler air over the clutch.

I seem to recall also that the rpm centrifugal force is what drives the silicone out, to enable disengagement.

Rick has some type of modulation with increased IAT, , that much I remember. not many of us have seen his conditions. Right or wrong, should we pursue this?

Fingers, we figured you were running along side the truck, ON FOOT, with a video camera.

Fingers, we figured you were running along side the truck, ON FOOT, with a video camera.:D

mahalkita, I might have found the missing key. I talked to my mechanic and he said he had heard that these clutch's had a mechanical lock system, IE one to one drive! That would account for the 3rd speed and the instant no ramp up speed change I have commented on. If you have a space heater or something and are willing, it only ac-cures at approx. 250* engine temp and may require a space heater.
Good luck and God speed.

That would be incorrect. I am told that the engaged speed target is 3,000 RPM. Disehnaged 1750.

jk, can you elaborate. I have 3 speeds. I have 1 when the engine is cool, I have a second at approx. 210*,it has a slight ramp up to it. I have a 3rd at approx. 250*. There is no ramp up. It almost has a clunk when it engages and disengages. I thought my dealer had a dead on explanation for this.

Measured the fan rpm yesterday with the following results:

- motor idling with 700 rpm
- ECT between 185 F rising to 205 F during warmup engine
- ambient temp 90...95 F
- fan rpm "free wheeling" 700 rpm
- fan rpm "locked" 900 rpm

Conclusions:

with a crank dia of 7.5" and a waterpump pulley dia of 5.5" the fan can spin at max. 950 rpm at idle (crank 700 rpm). This means the slipping is 5 % when the fan is "locked" which I was expecting.
BUT "free wheeling" at 700 rpm means that the fan rotates with 74 % of max. speed and slips therefore only 26 % - which I did not expect to measure.
I was not able to measure any fan speed lower than 700 rpm at idle (same as crank) - even with ECT at 185 F.

Tried this morning continue measurement on a cold motor but heavy thunderstorm prevented this.

I had no second person to check if slip increases with rpm (should possibly a little).

I am surprised that the fan rotates basically at crank speed when "free wheeling" and increases only by 30 % in rpm when "locked".

Since mine is a 2005 maybe fluid clutch parameters have changed by GM to rotate the fan with higher speed at all times.

I cannot confirm 3 different speeds (looking for a lower speed than 700 rpm at idle when I have time and weather permits).

I know thats NOT a solution to any problem but maybe helps to understand how the cooling system is designed. :)

Great Post, valueable data.

If I post different verbiage/numbers, it is for clairity in My mind and no disrespect is intended, that said.

OB=observed, Th=theoretical, Ca=calculated.

Silicon oil has very unique properties, Some information Here (http://dieselplace.com/forum/showpost.php?p=640069&postcount=61)

Water pump overdrive (Ca)=(1-(5.5/7.5))=27%
Max fan RPM @ idle w/100% coupling(Th),(Ca)=(700/.73)=958.9 RPM.
Min coupling @ idle (Ca)=(700/958.9)=73%
Max coupling @ idle (Ca)=(900/958.9)=94%
Coupling range delta(Ca)=(.94-.73)=21%

RPM constant, temps changing; coupling will follow temps, temps up/down, coupling up/down. (Due to bi-metal switch function, Silicon Oil ingestion).

Temps constant, RPM changing; coupling will follow RPM,
RPM up/down, coupling up/down. (Due to Silicon Oil centrifugal viscosity change).

An observer noticing a change in fan RPM is an aural perception (frequency/amplitude) and will vary with the individuals ability to sense a change. There is No doubt when it Roars, LOL.

FWIW.

Idahofox

Great Post, valueable data.

If I post different verbiage/numbers, it is for clairity in My mind and no disrespect is intended, that said.

OB=observed, Th=theoretical, Ca=calculated.

Silicon oil has very unique properties, Some information Here (http://dieselplace.com/forum/showpost.php?p=640069&postcount=61)

Water pump overdrive (Ca)=(1-(5.5/7.5))=27%
7.5/5.5 = 1.364 = 36.4 % overdrive, (circumference = PI*d; rpm just changes with d)
Max fan RPM @ idle w/100% coupling(Th),(Ca)=(700/.73)=958.9 RPM.
700 * 1.364 = 955
Min coupling @ idle (Ca)=(700/958.9)=73%
700/955 = 73 %
Max coupling @ idle (Ca)=(900/958.9)=94%
900/955 = 94 %
Coupling range delta(Ca)=(.94-.73)=21%
900 rpm/700 rpm = 1.29 = 29 % speed increase

RPM constant, temps changing; coupling will follow temps, temps up/down, coupling up/down. (Due to bi-metal switch function, Silicon Oil ingestion).

Temps constant, RPM changing; coupling will follow RPM,
RPM up/down, coupling up/down. (Due to Silicon Oil centrifugal viscosity change).

An observer noticing a change in fan RPM is an aural perception (frequency/amplitude) and will vary with the individuals ability to sense a change. There is No doubt when it Roars, LOL.

FWIW.

Idahofox
Thanx!
Calculations are slightly different IMHO but thats minor - whoever is correct. But thats all hypothetical anyway since heat and rpm will change the slipping of the fluid coupling...
Looking at your clutch pictures I don't see a part what could lock 100 % solid without slipping (like Rick said at 250 F) but who knows whats inside the lower part? That would make the roaring fan super roaring....to me it feels like power is already cut in half with standard roaring...

ifyou will look at this again. You will se that the ECT's are lower 190's, fan fully engaged, at idle, or not engaged. This, by itself, won't keep the fan engaged. As we discussed, it generates much of it's own heat, 24/7, the more slip the more heat, right? Add poor recirc stack qualities, the clutch just never gets cooled down at idle in front of the heat quenched motor. That is, till you gun it, clear some cooler air over the clutch.

I seem to recall also that the rpm centrifugal force is what drives the silicone out, to enable disengagement.

Rick has some type of modulation with increased IAT, , that much I remember. not many of us have seen his conditions. Right or wrong, should we pursue this?
Thats exactly what I have observed. But on Ricks super hot motor I would assume the fan stays locked all the time because the heat of the clutch and bimetal spring in it - or what type of modulation are you talking about?

Is it possible I have some defective fan clutch's? Is it possible that the tolerances when they were built is too tight? With the extreme heat my trucks produce could I have a heat generated lockup?

I'm sure he stays locked up because his CAC and rad is on fire, at that point!

Is it possible I have some defective fan clutch's? Is it possible that the tolerances when they were built is too tight? With the extreme heat my trucks produce could I have a heat generated lockup?

you trying to be funny?

Lets get you a data logger.

Here is my vote. With type K t-couples this would run $400, shipped. Anyone interested in pitching in? $25 contributions? I'll put up the first $100.

More information HERE (http://www.superlogics.com/data-logger/stand-alone-recorders/templog-309/87-1147.htm), include plotting software, cables, etc.

Not trying to be funny, just concerned that there are reports of differant fan clutch operations. mahalkita, is yours an overheater? If not can we trade clutches? Somebody else e-mailed me concerning a test fan clutch. If he wants to reply he can.

kb, too rich for my blood. I have 4 truck payments to make. I do like the fact it shows all four displays at the same time.

it downloads the data real time on to the laptop. Just hit "record"

Rick you are doing all the work, I wouldn't expect you to anti-up.

KB,

I'm in for a C-note.

PM where to send it.

Idahofox

I was just at the dealer picking up the wife's Denali XL, and ordered the front airdam extension for my GMC so here are the part numbers. (Chevy number is floating around here somewhere, but is different and x-refed to an Avalanche)

10386200 F-Extension $32.15
11517841 Nut $ 3.58 (2 required)

Should be in next week.

hmmm,

One other measurement I forgot to mention in the sealing of the CAC to the rad, I obtained 15-20% more idle air flow through the CAC. Should help with heat quench phenom.

Shouldn't this/wouldn't this improve (lower) EGT's ?

Turns out the stock cooler isn't so bad afterall. All it needed was a little airflow.

Any comments? Suggestions for further testing?

Wandering minds.

Idahofox

depends, the computer may just take advantage of it. It should either lower EGT, increase power, or both. This is the same idea behind water injection

Ok guys, I'm going to post in the private thread. I hope I don't get flamed for it!
JJ had mentioned that he was hoping somebody would make templetes or a kit for a air shoud that would fit in front of the stack. Well, I did it. I Fabricated both sides and the lower section to take the place of the POS (JJ's term) flap. I pm'ed acouple of guys here in phx that is on the DP so they could check it out. The materail I used was 3/8 thick rubber w/reinforced 2ply nylon thread. Both side sections start at the stack bulkhead and go all the way to the grill including inside the bumper. The lower section starts at the stack and slides about 1 1/2 under the IC and runs all the way to the inside of the bumper. I made the mat long enough so the bolts for the license plate would keep it from flipping up.
Both side piece's are bolted using the exsisting holes in the bulkhead. I used # 10 bolt, 1" long. I put the bolt through the most upper hole on the bulkhead and secure with nut. Now you have about 3/4" of bolt just hanging there. You can use the bolt to mark exactly where to drill the mat. Not only do you need the bolts to hold up the side mat, you also need it (in that location) to make the rubber curve to the outside to the point it can't be seen when the grill is installed
I spent two days and many many templetes to get a very tight seal around everything and I mean everything! Its so tight it will hold water! (Not really but you get my drift) OK, so I have templetes that I am willing to share with the group. This is a great forum and I just want to contribute. I have been following this thread since last summer when It all started with the EGR/blocker plate. JJ,do you remember me? I also fabricated cold air induction. I ran a 4" air duct from the bottom of the air box to the rideside flap I made which is right in front of the stack. The second 4" duct is ran again from the bottom of the box to the ride side tow hook. The air duct that runs to the stack needed a drain incase water made its way through the grill. So I added water to see the lowest point in the duct and made a drain with a well nut. The air duct materail is made of saturated neoprem (sp?) cloth and is rated for 250 degrees. I found all of this materail at "Southwest Rubber company" located here in Phx. They have everything you need along with a huge selection of hose,etc... If anybody is interesed let me know.

Mike

We monitor IAT (MAP), is CAC temps (in or out) monitored.

Idahofox

MDHD2500,

Have camera, will PIC, sure would help. I'm interested.

Are you Chevy/GMC ?

Idahofox

I'm going to hookup with Killerbee tomorrow to take pic and get them on line. I have a chevy.. I have noticed that my fan clutch runs probably 50% (or so) less now and the AC is frosty. My fan clutch has aways ran alot. When it was new and it was 100+ OAT it ran all the time! Now that it has broke in, its not as bad. My fan will kick in wayyyyy before I ever see the temp gauge move. It sounded like some folks fan doesn't engage until the temp gauge is already on the move.

Oilbrnr and MDHD2500 talked, he was invited to go ahead and post.

As soon as he gets his butt over here, we will post some pics, of his long awaited front shroud. Thanks Mike

We monitor IAT (MAP), is CAC temps (in or out) monitored.

Idahofox

No, doesn't make sense does it? Go back and look at the list of changes for 06, tell me what sticks out.

the other day I talked to a cold air aftermarket engineer, for vararam. The testing they did under extreme conditions (stock) left conclusions about this. If the computer doesn't know the air is thin (hot) because of poor CAC function, how can it reasonably compensate? The computer pulled power, he said, because ...

I'm sure fingers may elaborate.

Oilbrnr and MDHD2500 talked, he was invited to go ahead and post.

As soon as he gets his butt over here, we will post some pics, of his long awaited front shroud. Thanks Mike

NO problem, welcome Mike and thanks for your effort.

I intend to plagiarize to the max. :cool2:

:grd: KB, waiting.

Idahofox

If the computer doesn't know the air is thin (hot) because of poor CAC function, how can it reasonably compensate?

Then may we presum that a "Reduction in Power by the computer" is totaly a function of ECT ? Dumb !

Idahofox

Just measured fan fluid coupling slipping with higher rpm. Unfortunately not much time so I could only get the data for 2000 rpm "free wheeling". I waited forever to get the fan "locked" at 2000 rpm (not enough heat) but no chance to measure because speed returned right to "free wheeling" again before I could measure.

With 2000 rpm at the crank the fan rotates exactly at 1250 rpm (instead of 2000/5.5*7.5 = 2727 = max). This means only 46 % of max. speed and 54 % slipping - BIG difference between idle and high rpm. Will do further testing ....

Point:

Run a truck for periods @ +++ temps (what ever) degrade the function of the Viscous Fan ??? It's broken !!! Oil leaks ??? Bi-metal switch takes a Set (intermittent function) ???

How do you diagnose that ???

Wandering minds.

Idahofox

Point:

Run a truck for periods @ +++ temps (what ever) degrade the function of the Viscous Fan ??? It's broken !!! Oil leaks ??? Bi-metal switch takes a Set (intermittent function) ???

How do you diagnose that ???

Wandering minds.

Idahofox

From the pictures you posted there might be the possibility that the silicone oil will be pumped in and out of the lower part (modulation) because the orifice will come out permanently. An oil leak will cause permanent free wheeling from what I have learned on this forum...

Idaho, here is the part for 06 I was refering to:

"Second Intake air temp sensor to monitor IAH and also for fuel timing strategy based on actual air temp going in engine"

I wouldn't presume ECT is doing anyhting re power (until the end is near). But that "new for 06" statement all of a sudden makes sense to me.

If charge mixture is overly hot, due to CAC innefficiency, how can our truck compensate timing? ECM has no idea what charge temps are.

Perhaps that was a feature that should have come with the VVT. Could this all be due to an ECM that doesn't have quite enough inputs?

Power loss induced overheating?

In regards to high IAT and poor CAC function.

What do you expect the ECM to do? All it really cares about, and all that matters, is air mass being ingested by the cylinder. In regards to LLYs, there is nothing to be done. Reduction of boost will actually increase EGTs. More on that in another post. But for now, trust me on that.

On the 06's I can see high post CAC temps being an input to kick the fan higher to reduce charge temps. Sounds like they may even increase boost (imagine that) to incease mass air flow.

Now I am not bashing the impact of IATs. But there is nothing the ECM or engine can do to compensate for them once they are there.

Temp of air entering the cylinder does affect the "optimal" time to squirt fuel. You can get away with retarding timing more with hot air than cool. Probably a cold weather strategy.

In regards to high IAT and poor CAC function.

What do you expect the ECM to do? All it really cares about, and all that matters, is air mass being ingested by the cylinder.

Right, and it can only take finite sized gulps. We have visited this before.

The CAC serves a function, and that function is not monitored. It's function is to make every gulp of O2 as dense as it can. It's a darn big hunk of metal, we must need it.

In any event, maybe we can get a CAC drop reading on the LLY and LB7 to compare.

A cooler charge, with more O2, will exhaust cooler and horse more power. Did I miss something in your statement?

After we get a couple more donors, I'll place the order for the data logger.

Idaho, here is the part for 06 I was refering to:

"Second Intake air temp sensor to monitor IAH and also for fuel timing strategy based on actual air temp going in engine"

Uh, oh ! See what you mean.

I wouldn't presume ECT is doing anyhting re power (until the end is near). But that "new for 06" statement all of a sudden makes sense to me.

If charge mixture is overly hot, due to CAC innefficiency,

Lacks a, Grill to Stack, air conduit. ):h

how can our truck compensate timing? ECM has no idea what charge temps are.

Perhaps that was a feature that should have come with the VVT. Could this all be due to an ECM that doesn't have quite enough inputs?

Bit/word capacity ??? New ECM.
Do I smell an LLY fix ???

Power loss induced overheating?

And more bit/word for the computers in '06. (Hoot's post ?)

Wow, we good !

Idahofox

Right, and it can only take finite sized gulps. We have visited this before.

The CAC serves a function, and that function is not monitored. It's function is to make every gulp of O2 as dense as it can. It's a darn big hunk of metal, we must need it.

In any event, maybe we can get a CAC drop reading on the LLY and LB7 to compare.

A cooler charge, with more O2, will exhaust cooler and horse more power. Did I miss something in your statement?

After we get a couple more donors, I'll place the order for the data logger.

Great work, I'm in for the logger -- PM me...

In regards to high IAT and poor CAC function.

What do you expect the ECM to do? All it really cares about, and all that matters, is air mass being ingested by the cylinder.....

.....
Now I am not bashing the impact of IATs. But there is nothing the ECM or engine can do to compensate for them once they are there.

So we manage them, Before....they are there.

Idahofox

Just measured fan fluid coupling slipping with higher rpm. Unfortunately not much time so I could only get the data for 2000 rpm "free wheeling". I waited forever to get the fan "locked" at 2000 rpm (not enough heat) but no chance to measure because speed returned right to "free wheeling" again before I could measure.

With 2000 rpm at the crank the fan rotates exactly at 1250 rpm (instead of 2000/5.5*7.5 = 2727 = max). This means only 46 % of max. speed and 54 % slipping - BIG difference between idle and high rpm. Will do further testing ....

Did it show Morning Sickness, (cold Roar)?

RPM up, Temps down (flow across hub), Silicon Oil returned to reservoir, reducesd coupling ???

Postulate: The quantity of Silicon Oil @ the "Grooves" when the hub ceases to rotate (shut her down) will remain @ the "Grooves". On restart (of rub rotation), with sufficent RPM, the Quantity of Silicon Oil @ the "Grooves" will adjust, based on temps/RPM.

Without sufficent RPM (post startup) the quantity of Silicon Oil @ the "Grooves" will remain, essentially the same as @ shut down.

High RPM/low temps are required to de-couple (equalize) the fan, Morning Sickness.

Postulate: Idle after morning start (short periods of higher RPMs not with standing) the coupling will be as it was @ shut down. High RPMs (2000 - 2500) for extented period (2 - 5 minutes) and low temps may "Reset" coupling ???

What do I know. FWIW.

Idahofox

Just measured fan fluid coupling slipping with higher rpm. Unfortunately not much time so I could only get the data for 2000 rpm "free wheeling". I waited forever to get the fan "locked" at 2000 rpm (not enough heat) but no chance to measure because speed returned right to "free wheeling" again before I could measure.

With 2000 rpm at the crank the fan rotates exactly at 1250 rpm (instead of 2000/5.5*7.5 = 2727 = max). This means only 46 % of max. speed and 54 % slipping - BIG difference between idle and high rpm. Will do further testing ....

Would sealing off the grill area (temporary) with cardboard or such, help warm it to Hot ???

We lost coupling with RPM, predicable if the system had not "Balanced" before hand and the temps were low. IMO.

Idahofox

I appreciate the help guys. I will order the logger as soon as there are enough folks to pay for half of it. I still need a little help with that. If there is an LB7 here in PHX reading this, please PM me. It would be a great help if you would let me inspect your front end.

Here is what I postulate and I hope it can be proven, I want to get my life back:

Postulation: It is possible for charge temps to be so high, as to cause performance loss early detonation, much like a gas vehicle. Yes I believe fuel timing can compensate for that, much the same way, and analogous to "knock sensing" in gas vehicles. Delayed injection.

This whole time we have been looking for a heat source. Performance loss is just as viable, as a possible cause for OH. If this is right, we solve everyones EGT concern also. At least this represents something different. We're not chasing ghosts. Spot something, prove or disprove it.

Rick I pm'd you.

could someone chime in with the diff in comp ratios between the LLY and LB7?

Rick, clear off your PM's, inbox is full

kb, resend pm or better yet e-mail me.

I may have one of the "snorkeled" air boxes (like the gassers use) if someone wants to try it, but these were used only in 2001 on the Dmax and updated due to problems:

http://www.kennedydiesel.com/dmaxairintake.html

And more bit/word for the computers in '06. (Hoot's post ?)

Wow, we good !

Idahofox



Coolant fan.... is now ECM controlled by an electro-viscous clutch.

Faster 32 bit ECM will support up to 5 injection pulses per combustion event

ECM GPCM and TCM are CAN protocol

Cann't find Hoot's post. Had a lot of information on the computer changes.

Idahofox

KB, e-mail me your paypal address and balance needed to pay in full Friday and I'll make up the differance.

Hold the fort, I don't have a rs-232 port on my laptop!! check for usb version and I will check to see if my backup computer has it.

Does anybody know in the Predator computer interface will monitor and record engine data. How does it hookup?

mdhd2500, if your patterns do indeed help lets get fingers to lazer cut them for resale.

fingers, I have 10 years cnc programing experiance, I currenly have a cnc mill, lathe, and home made cnc plazma. If I can help me know.

http://www.professionalequipment.com/xq/ASP/ProductID.2494/id.22/subID.176/qx/default.htm

KB, check this one, I'm driving and have limited reading capability.

This DT40 logs only min/max temp without a time stamp. Might be a little difficult to see all temps via the toggle function to reference with each other - depends how fast temps are changing (probably slowly). IMHO the other logger KB suggest is better suited for the purpose but the DT40 can be used also for little less money...

KB, e-mail me your paypal address and balance needed to pay in full Friday and I'll make up the differance.

Hold the fort, I don't have a rs-232 port on my laptop!! check for usb version and I will check to see if my backup computer has it.

Does anybody know in the Predator computer interface will monitor and record engine data. How does it hookup?

mdhd2500, if your patterns do indeed help lets get fingers to lazer cut them for resale.

fingers, I have 10 years cnc programing experiance, I currenly have a cnc mill, lathe, and home made cnc plazma. If I can help me know.

Rick, you don't have to do that. I really appreciate it though. You will be the backup plan. Sweet.
It will be USB, no worries. Should be able to just use an adapter. I'll check that.

The predator has no other plug-ins, so I don't know how we could record it. I think you could use it anyway.

Got some new pics of Mikes slick front end shroud, I'll get them up soon. Fun day. He actually got me out of the house!

http://www.professionalequipment.com/xq/ASP/ProductID.2494/id.22/subID.176/qx/default.htm

KB, check this one, I'm driving and have limited reading capability.

that's the same one I saw for you a few days a go. I decided against it, for it's temp limitations and poor response time (thermistor). Plus it doesn't have a slick computer interface.

Here you go all. Mike (MDHD2500) takes credit for all the effort. Thanks very much Mike. AND HE HAS TEMPLATES!

I made a copy also, will see how they cut for the GMC. Nice project Mike

We forgot to shoot the airbox. He has (2) 4" ducts. One you can see in the pic. the other is by the hook, Like oilbrnrs original. He sealed off the opening in the box ,and routed both ducts out the bottom. A+ effort. We went for a ride, IAT never topped 118, stock, mt, 100 on the mirror (sorry it was only 10 AM, LOL)

Next time we'll measure his before/after stack drops.

Thanks for sharing your effort. Fill in what I missed here.

Nice job!

FWIW I have a revised version of my air dam for anyone interested.

http://dieselplace.com/forum/attachment.php?attachmentid=6647&d=1121922915

FWIW I have a revised version of my air dam for anyone interested.

http://dieselplace.com/forum/attachment.php?attachmentid=6647&d=1121922915

I am. hows the shroud working out.

BTW, for reference, Mikes truck had very cool IAT's, under 115 all day while moving, about 8* over mirror temp on avg. I will will check my stock configuration IAT again tomorrow, before converting to a 6.0 box modified.

IMO, he has the coolest CAI I have seen. And no fan engagement whatsoever. Disclaimer: we drove like old men, no tuner either.

I am. hows the shroud working out.

BTW, for reference, Mikes truck had very cool IAT's, under 115 all day while moving, about 8* over mirror temp on avg. I will will check my stock configuration IAT again tomorrow, before converting to a 6.0 box modified.

IMO, he has the coolest CAI I have seen. And no fan engagement whatsoever. Disclaimer: we drove like old men, no tuner either.

The metal shroud extension is not as effective as the cardboard one. But that will not be the case for long. :)

Interesting stuff today. OAT appox. 90*, 22K thru OK and TX
No chip, no cat, egr blocked, S&B air box, oem lower valance extension
JJ full frontal tape job.

Could not get truck over 220* no matter how hard I tried. I stopped
and floored it and ran it up to 75 MPH and nothing doing.
Interesting stuff to report though,

My fan is now acting more like it should. It would appear the heat
is getting to it sooner and better. @210* the fan ramps up to a certain speed
and stays there. This is earlier than ever before. Then @ 217 - 220* it now
speeds up again. This is a new thing. I have not been able to get the ECT over 220*.
@ 197-199* it slows back down. I still expect a "lock-up" as soon as I can get it
hot. Is it possible that the heat was not getting to the clutch soon enough to
overcome the heat, JK ??

Another interesting thing is my IAT's have gone up. About 15-20* across the board.
I beleive this is due to increased airflow thru the stack. I also believe we still
have to deal with the underhood pressure. I will place the 2 temp probes I have
tonight and I will hit the big hills tommorow.

My fan is now acting more like it should. ... I have not been able to get the ECT over 220*.


With your improvements, especially stack sealing, the fan is drawing much more high energy air across it, much less of that air is originating from the motor bay, and also the clutch is now, not so dominated by it's own slip heat production. So it is not "auto-engaging". (Before, mine would engage with a cool rad, but heatsoaked bay. I know the rad and CAC weren't offloading, they were cool, but my bay was HOT, when I used the IR gun on the clutch, I was SHOCKED at how hot it was. The clutch was being triggered by the influence of hot bay air, which you have now isolated from the equation, and its own slip heat.) The fan was meant to see the air from the source(s) it is trying to cool, that's what you have improved.

Would you believe, that now, if your numbers are like mine, your fan is moving a little LESS air across/over itself than before? The result of sealing out leaks and recirc. Yet it is pulling at least 20% more through the stack, which previously was the path of more resistance, to air that is lazy and wants to take the easiest route. No leaks. digest that.

Add a front shroud, you'll get down a few more. I see a smile finally.

on your IAT observation: to me that sounds right. Clinches the essential nature of CAI. You are pumping much more heat into the bay area. That's what effective cooling systems do.

But I'll bet you anything that bay is a gazillion degrees cooler than when you saw 250 ect., so I'm not worried about it. If you are, just do a delta P mod, Fingers dam, front shroud or both. BTW, just a note. I have some numbers from a few days ago, on the effect of riding angle on P drop, they were inconclusive, so I need to run the test again with steeper angle changes.

My fan is now acting more like it should. It would appear the heat
is getting to it sooner and better. @210* the fan ramps up to a certain speed
and stays there. This is earlier than ever before. Then @ 217 - 220* it now
speeds up again. This is a new thing. I have not been able to get the ECT over 220*.
@ 197-199* it slows back down. I still expect a "lock-up" as soon as I can get it
hot. Is it possible that the heat was not getting to the clutch soon enough to
overcome the heat, JK ??



Still working the fan clutch angle. Problem is, 120 unit minimum buy, and 6-8 weeks lead time. I do this with the 6.5 clutch, but that was tested and proven. This is still a hunch/WIP. I've been scrounging to find one somewhere and believe I located one yesterday...

KB, have you had a chance to check Mike's templates yet for our GMC applications? Also, would it be worth a comprehensive post here to outline everything that we've done so far as a 'recipe' for trial? i.e. each area specifically to foam up, tape, etc.? Oops, just read your post over on the other thread regarding this idea. I'd say that it is worth it, though I don't know if the tech. portion is really needed. That will just cause more debate, IMHO.

I would think that the material that Mike used, would also work well for the Finger's shroud extension should it prove to be helpful.

I'm curious as to how Mike got two 4" tubes into the bottom of the box, but with the 6.0 box I don't think it is necessary anyway.

I plan on pulling the trailer next weekend up on the Rim somewhere, so I'd like to get all these mods in place to see if they help. I might even try filling the grey and black tanks for more weight in the trailer (~100 gallons).

Still working the fan clutch angle. Problem is, 120 unit minimum buy, and 6-8 weeks lead time. I do this with the 6.5 clutch, but that was tested and proven. This is still a hunch/WIP. I've been scrounging to find one somewhere and believe I located one yesterday...

How about the Hayden 2843 severe duty clutch?

KB, have you had a chance to check Mike's templates yet for our GMC applications?

No, but I will, phew. I need some rubber, want to get some? I'll do a couple sets on the band saw so you'll have it. I will fine tune his templates for GMC first. It would be great if you could do that. Did you see where he got it? Can you think of a way to get some 3/8 fabric reinforced scraps somewhere? The more you get the more I can make.

I figured that he must have used a band saw (one of the few items I don't yet have :mad: ).

If you'll cut it for me, I'll go get enough for the two or maybe three sets. Just let me know the dimension you think would get the most pieces out of. It won't be until Monday though...

The rubber will wear out the blade almost instantly. Skip tooth works best and lasts longer. Slow speed and coolant.

McMaster-Carr carries the rubber and will sell any length. Do a search under conveyor belt.

Well it seems WE have hit on something. My fan now has more levels of speed than I problably need. I have tried my heart out to make this truck overheat. Now on a hill when it downshifts I have actually seen the temp drop. I do not have a good head wind and oat is in the mid 80's, but we have " ALMOST ENOUGH BANDAIDS" on it.

The cac temp spread is normally 50*, but I did see 81* out and 160* in. I have a couple of big hills left, but I don't see over 220* ect in my future!

81*? Lower than ambient? don't think so.

degrees C?

edit: on conference with Rick, he will have to mount his probes differently, they are completely exposed.

probably the limits of contact temp measurements. OAT was probably 81.

Short update:

Valance mods improve flow, but still not as good as no valance at all.

Converting shroud extention into a plyable material. Probably the same as the air dam is made of. IAT are greatly reduced by blocking the prop wash from the fan.

I have two prototype testers to send air dams out to. The dams should get cut early next week. I might be able to get the shroud extensions made at the same time and send them out for testing too.

Ordered an 8 channel Data Aquasition module (USB) and thermocouples. All for about $500. It should be here late next week. This is for my testing of OH and other projects I have going and is independent of the effort to support RDLs testing. This will let me use my laptop as a data logger.

which module Fingers.

http://www.measurementcomputing.com/cbicatalog/cbiproduct_new.asp?dept_id=414&pf_id=1692&mscssid=VRA9D67844KA8PS9GFSV85XQDB9N2W9D

[quote=Oilbrnr;642918]I would think that the material that Mike used, would also work well for the Finger's shroud extension should it prove to be helpful.
I'm curious as to how Mike got two 4" tubes into the bottom of the box, but with the 6.0 box I don't think it is necessary anyway.

The materail I used, 3/8 thick,2 ply.

Well, It took a little doing,but it can be done. For the air box, I use a 4" 1/4 hole saw. I cut out both holes in the air box on the portion that was the flatest. (Rad side) One hose I ran through the bulkhead to the front air shroud, the other runs striaght down. I removed the brace for the bumper,ran the hose to the hook and reinstalled the brace. I did have to fabricate a strap to pull the hose away from inside of the fender. Its real tight. Once completed, the hoses are very secured. One other thing, I did have to relocate the horn and I did loose a rubber mounting point to the air box. The fit of the air duct hoses into the air box is very snug. Which helps secure the air box making up for the lost mounting point.
It turned out pretty nice. Still working on something to fit up the hook/valance hole to air duct. I don't think the 6.0 air box will deliver what I was after. Which was just acouple degree's above Ambeint.

Mike

I don't think the 6.0 air box will deliver what I was after. Which was just acouple degree's above Ambeint.

Mike

I'm getting the same 6-8* above OAT that you got with KB, which is good enough IMHO. I just remembered that towards the fender side of the box, I didn't want to drill/cut through the brace, and that is why I went more towards the engine. What you did though is the only way to make the stock box get enough air.

The 6.0 box seems fine with the one additional 4" intake.

I hooked up the pred and ran around stock, after racing around for a while, I sat and idled, went from 109 to 180, 75 over ambient. Mikes cold air stayed below 18 over ambient. But he drives like an old fart with my family in his truck.

I'm getting the same 6-8* above OAT that you got with KB, which is good enough IMHO. I just remembered that towards the fender side of the box, I didn't want to drill/cut through the brace, and that is why I went more towards the engine. What you did though is the only way to make the stock box get enough air.

The 6.0 box seems fine with the one additional 4" intake.

Yeah, I didn't want to cut the fender side either. I was able to aviod that by mod'ing the eng. side bracket to get both air ducts in. Not much though. About an 1" 1/4 notched out of the top of it. The 6.0 box should work pretty good then. Maybe I should of went that way.

Mike

Raised the "flap" on my blue 05 for the last leg of our trip into Arizona. My wife was driving the truck and said the temp gauge only moved 1/2 a mark on the biggest hills. She said fan operation seems the same. Might still be a problem if you are already on the edge of overheating.

My red 05 is now better than ever. I'm not saying its cured. The oat today only reached a high of 92* and although my load was approx. 22k, there was no wind to speak of and not that much for wind resistance. I did indeed gain a ton of differant fan speeds. I also saw for the first time ever, the ect dropped going up a hill. At one point there was some road construction on I-25 in the bottom of a valley. They had reduced the speed limit to 45 and I slowed down even more than that. Coming out of this I floored the truck. I went up the hill and continued on the floor until I hit 80 MPH. 224* ect was the highest, and when the fan picked up speed it actually started dropping ect before I got to the top of the hill.

My next experiment on my own is going to be hood vents and refinements to my cold air intake. Anybody with suggestions or idea's please e-mail me @ the link in my signature.

here ya go Rick. Extremely promising. The Chevy hood should be similar. The numbers on the hood are 60 mph iw absolute. Underhood absolute pressure ranges from slightly negative to pos .4" static (depending on speed and fan)). The low pressure on the hood, is going to determine the vents effectiveness. I can't wait for you to do it. The marks are every 6" and 12" from the rear of the hood. The front went off my 2" scale at around 30 mph, so I estimated them, and I am probably conservative. The second mark back on center says -3.5 iw! I was at -1.0 iw at 30 mph, so you see the low speed benefit as well, but hi-speed that location will rock. I would probably just do one large NACA or vent, centerline. That's me. I would like to see a vent/NACA you can close, or cover.

Consider something. If you throw everything at it the way you are, I really believe you are going to have some cold weather issues, so be ready to cover tranny, and possibly the front grill. Imagine that.

But, in my opinion, a vent mounted just aft of the fan on the hood, represents an absolute great avenue to increase stack airflow. Fan-on deltas will be over 5-6 iw at 70 mph

I went from 0-60, no less than 20 times today. I worked the truck till the brakes were starting to smell.

I can't get my tranny over 190 with 100 oat's. 2 cardboard flaps and 50 cents worth of compressed foam!

When I pulled in, my IAT's went to 191, stock box. She's a workin better.

I pulled a bunch of absolute static P numbers to help with defining airflow. I'll post them soon.

Hey guys,

I was in the dealer this morning to get my radio re-VINed, and I asked the tech if he'd seen many O/H 04-05 Dmaxs come in. He said that he had not seen any. BUT he also told me that he had heard of some from other dealers and that the same problem had happened to Trailblazers and Envoys, and the problem was in the fan clutch. Some clutches were not "turning on" at the proper RPM, or turning the fan at the right speed. He said it was in the "calibrations", but how that affects a mechanical part escapes me.

Since I'm no where near being a tech, I can't make any assumptions based on his info...but I wanted to let you guys know.

Hey guys,

Some clutches were not "turning on" at the proper RPM, or turning the fan at the right speed. .

Rick will be glad to tell you why. I figured we all had a better understanding of this. The fan in the unmodified vehicle is recirculating hot bay air over itself, creating a condition where, combined with it's own slip heat, the clutch engages. Then at other times, when engaged, it disengages prematurely due to low stack airflow and motor bay outside air infiltration (which is also being recirculated).

When the truck is working hard, especially at low speeds, the motor bay heats up (IAT goes north). Then you crest a hill or take the foot off, at speed, and the motor bay air quickly cools (IAT goes south), and we know the fan is recirculating that, so the fan disengages prematurely with some very heatquenched stack members and 1/2 ton of motor.

And this all makes sense and fits right into the inherrent limitations of a thermostatic device (clutch) whose main input is the air running over it, and not the coolant or charge air itself. Unless that fan is integrally bonded to the stack, this is going to happen. That is the foundation of the sealing mod.

Watch the CAC with your mods.

This morning I found some "Split Poly" that covers the headlight wiring had melted in two places. It had been resting against the CAC.

Use caution with flammables Touching the CAC, it Will melt Poly.

Idahofox

Good warning, no polyurthane foam, burns with deadly odors.

New static P numbers today, all absolute referenced to the cockpit:

60 mph, GMC, 1.5" lift.

Grill:
Upper 0.4
Mid 1.5
Lower 1.6

note the low center of pressure. The logo would have been better near the top, cooler at the bottom.

Left Fender, 3" below the hood: -0.4 iw

Lower valence: +.8 iw

Driver Headlight: +1.6 iw (at center)

Wheel well: sorry, forgot

hood crack: this one was strange. I taped the hood to the grill, and put the sensor right there, on the tape that represented the crack. Abs P was positive until 40 mph, where it was exactly 0.0 iw. Over 40 it went negative, about -0.6 iw at 60 mph. Then I located the sensor in the same location with nothing behind it, except crack, and got +1.25 iw at 60. So I think there is alot of bay contamination/stack bypass, (at least I don't think air is cming out that crack at speed), but in the spirit of sealing, it should be sealed.

a couple more, again 60 mph

Bumper: 1.5 iw
Open Slot in bumper .9 iw

want more stack pressure, open up those slots

[quote=idahofox;643910]
This morning I found some "Split Poly" that covers the headlight wiring had melted in two places. It had been resting against the CAC.

are you talking about the grey stuff you put in?

I had taped one of my probes on the tube beside where you make your Edge connection. It melted the tape and the probe fell off. Imagine what the temp would have been if I had been overheating on this trip. Anybody know what temp Scotch brand black electrical tape melts at? and how to get it off the tube after it does?

[quote=idahofox;643910]
This morning I found some "Split Poly" that covers the headlight wiring had melted in two places. It had been resting against the CAC.

are you talking about the grey stuff you put in?

No. OEM stuff, covers most of our wiring.

My point was that the CAC gets that hot.

When I construct my mods, I intend that the material Not Touch the CAC, .125 - .25 " clearance.

Smaller Hole than what is there now. LOL.

FWIW.

Idahofox

I had taped one of my probes on the tube beside where you make your Edge connection. It melted the tape and the probe fell off. Imagine what the temp would have been if I had been overheating on this trip. Anybody know what temp Scotch brand black electrical tape melts at? and how to get it off the tube after it does?

Pretty low temp, its PolyV.

Let cool, (get hard again) and scrape with sharp knife (carefully).

Idahofox

I think we need a new test buggy. I seemed to have cured mine. Who is willing to step up and try my modifications to find out if they really work? Maybe someone who hauls cars for a living? I would consider getting with them and helping on the install?

Todays Test, Body angle:

testing if angle of the body has an appreciable impact on stack pressure drop

I used my airbags, to raise/lower the rear of the truck 2", and measured static drop, no discernable difference, if anything, with the rear squatting, drop may have been a bit higher, .1 iw at the most.

another one down.

This however does not test the importance of lowering the front closer to the ground. That I suspect might yield a different result. But I don't think I'll press it.

I am introducing OTEO125 here. He is going to be our next guinea pig. He ran some numbers on his vehicle. They are consistent with what we have seen already, "we can rebuid him, we have the technology..."

Oteo?

.................flat land............small hill...........large hill
tech boost.......15...................19............... .....26
my boost.........11...................15............. .......19
egt...............9500................1200........ .......1475
ect................195..................220....... ..........233
iat..................93..................190...... ............230
temp...............72...................73........ ...........74

It did not overheat today being as it was only 74 and mechanic could not go far to climb bigger hills. I did get some interesting data.

i find it interesting that my boost was so off from his. It is also interesting at how hot the intake air was as motor heated up. he said he would give me a data recorder to record these numbers next time its hot outside. i cant believe that 30 degrees on the motor that my iat would go up 137 degrees. i wonder what it is when my motor is running 250. the motor went from 205 to 233 in half a mile and was still climbing but then we hit top of hill. it cooled down really fast, about 1 minute or so. he believed me that it will peg red but had no answer on how to fix it. he said he would call gm tech. i bet after that call, they will tell him nothing wrong with those temps. . i hope this helps you guys in fixing the problem.

Tranny temps?

what was your SOTP assessment of power when you had the higher iats? falling off?

tranny temps were around 200 to 205. never could work it hard enough to get them highier. i have had the tranny as hot as 240-250 once when motor was 250. the tranny will only overheat when the grade in more then 5 miles

as truck started to get real hot i lost about 10 mph on the top end if thats whats your asking.

ok, that makes sense. I would like to try something different. This will be a big help.

Can you ask your dealer if they are willing to swap an 06 air intake (it's cold air) into the vehicle, and test again. You are basically going to giftwrap the solution for him, and he will be famous, probably get a promotion, LOL.

I am assuming maf sensor compatability.

as truck started to get real hot i lost about 10 mph on the top end if thats whats your asking.

yup

they don't have one on the lot. i wanted to show him the differences. he should call me in a day or two and ill ask him.

If you suggest that it has been a solution, he may just order it in.

Testing a new Granatelli Big G Diesel Power Module w/In-Cab Monitor for a local vendor on my next run. Seems to be their version of a Juice/Attitude combo. One nice exception is dual EGT probe capability. I have probe 1 in my exhaust manifold and probe 2 in my CAC out tube to the engine. Might be able to get some interesting and accurate info here. One thing I have already noticed is on their highest level, 120 hp and 240 ft., my EGT's are only about 1250 degrees at WOT from 0 to 85 MPH. I hope this transmits to lower level towing. Waiting impatiently for UPS and hood vents.

Final stack sealing results. Just foam, nothing permanent.

Cold idle fan locked (cfm)


in out throughput
Stock 2160 3950 55%
Full seal 2800 2750 98%

I was surprised to get that close too 100%
This is 30% more ambient (and 30% less hot bay air) at idle. This equates to about 40 mph of forward speed in the stock vehicle.

I would expect, at high loads, if the fan comes on, it will pull approx 50% more ambient, 60-70% with the nose shroud in place. Without all that 220 degree bay air cooling a 200 degree, that should just about cover overheating.

Except for in the morning, I haven't heard my fan run in 2 days, mt, over 110 oat.
Tranny has stayed under 160!

This is now the vehicle I thought I had bought.

I am getting the logger today or tomorrow, and will report CAC drop and tranny drop improvements.

KB,

If the Nose Shroud is Not in place.

What parts (locations) of the Stack are sealed ?

Idahofox

I have nothing but foam strips sealing the shroud to the rad, then rad to the CAC. Plus the two large radiator support cracks, top and bottom. Very clean, invisible. That's it nothing else. With that, almost all of the motor bay recirc is gone.

When the nose shroud is in place (very detailed) it will block flow from around the head light area, and serve as ram air P enhancement. With this, I see no reason anyone would need hood vents. This setup will easily flow 2-3 times the stock configuration (at least on a GMC). Some type of dam appears to be useful. From the sketchy information I have (will be testing), I rank effectiveness this way, subject to change. I hope I am not in trouble now.

1.) sealing (by far, no contest)
2.) nose shroud
3.) CAI (this could rank number 1 or 2 in the extreme tow scenario, not sure)
4.) air dam (no hard data)

so, grain of salt.
I will revise this after I test fingers dam.

I will also test each of these seperately, for CAC improvement, where I think CAI improves things dramatically.

In my honest opinion, I think the sealing alone may, by itself, inhibit IAT rise, like what oteo and Rick saw. That means lower under hood temps. JJ, you may disagree with this, how about investing in a underhood thermometer, and see what I am talking about.

Something didn't sound right, I went back and found an error, 98% seemed to good to be true.

Cold idle fan locked (cfm)

in out throughput
Stock 2160 3950 55%
Full seal 2800 3200 87%

I knew there had to be some bypass in the fan-to-shroud space itself.

and repeating, this means more than just a 32% throughput improvement, or a 30% improved stack flow. What is not shown, is the benefit from not ingesting/recirculating hot bay air.

I would like for JJ to post here as his questions are common to a lot of the DP members. I would prefer not to post elsewhere regarding these mods. So I hope that is good reason to give him a decoder ring.

mechanic is still waiting on word from gm tech. i will discuss with him the 06 intake. if they wont do anything for me i'm ready to try the mods.

Something didn't sound right, I went back and found an error, 98% seemed to good to be true.

Cold idle fan locked (cfm)

in out throughput
Stock 2160 3950 55%
Full seal 2800 3200 87%

I knew there had to be some bypass in the fan-to-shroud space itself.

and repeating, this means more than just a 32% throughput improvement, or a 30% improved stack flow. What is not shown, is the benefit from not ingesting/recirculating hot bay air.

KB,
could you explain what you exactly measured and where please? I am a little confused as your output is much higher when stock and very close when everything is sealed. Do you have any pictures (or did I miss those?)
Thanx!
MK

KB,
could you explain what you exactly measured and where please? I am a little confused as your output is much higher when stock and very close when everything is sealed. Do you have any pictures (or did I miss those?)
Thanx!
MK

sure

I measured volumetric flow on the cold motor. sampled 8 total areas, velocities, on the condenser and CAC, averaged those, and multiplied that by the stack face area. Similar process at the fan face, a little tricky due to room constraints. The fan shroud opening is a 22" diameter circle, area pi*d^2/4. No temperature variation, there no mass flow corrections necessary due to temp increase. (normally you would want to compare mass flow, vs volumetric flow, as I did here)

Followed the same procedure each time, so even if my accuracy is 20% off, the repeatabilty will be good. The % improvement over stock should be stressed, not the absolute numbers.

As for what you observed, good observation. Any fan that sees more resistance will flow less air. So the fan output should reduce, if sealing the stack made any difference at all (I would have been pissed if fan out didn't drop). The significant dropped is great evidence of all the leaks and recirc present in the stock configuration.

The important numbers are the 2160, and 2800 figures. A 30% increase in stack flow, all substituting motor bay air recirculation. It is a mammoth improvement, much more than the numbers suggest at first glance.

Probably answered more than you asked, hope it made sense.

Oh, BTW, the foam I used, I had lying around from subwoofer projects, it is open cell, and poor for this use. The closed cell dense neoprene sponge foam (black), brought this throughput number up to 92%. I put it on the (outdoor) grill yesterday, and baked it at 400 degrees for 5 minutes. When it came off, I could handle it easily, stuff is like a space shuttle tile. I got it to 450-500 before it stated to char, then I ignited it. It put itself out. What was left was still somewhat functional. Recommended.

Hooked up the data recorder tonight. All Thermocouples are contact style. I will be monitoring Radiator In/Out and CAC In/Out.

Radiator TC's are clamped between the hose and engine outlet pipe and between the hose and pump inlet nozzle. The temps are tracking close to what the Pedator says the engine temps are, so I feel I am getting close if not good data.

The CAC TCs are clamped to the turbo outlet pipe and the inlet pipe just before the EGR valve. I insulated both probes with fiberglass insulation.

Tested the logging software. Way cool. I might pick up another set of these contact style TCs. They work very well. I have some thin wire TCs for air temps, but have to adapt them.

First impression was how effective the CAC and RAD are. I havn't towed yet. Maybe Thursday.

.

First impression was how effective the CAC and RAD are. I havn't towed yet. Maybe Thursday.

meaning they exceeded your expectations? Numbers?

The CAC especially was interesting. Inlet temps to 200+ and outlet was almost rock solid just below 100* with OAT 82*. I thought the probe was wrong, but no. I went out and put my hand on the post CAC pipe and it was warm, but not even close to hot.

I just have a real suspicion, all that will be radically different, with a load on your BB hill climb, stock. The number I want to see most is CAC out at 250 ECT, with stock intake! That's the one, the nut cracker.

The CAC has a lot of heatsink capability for short duration performanace spikes, get the big boost on for a few minutes and ... I can't wait to see your charts! I live for this. (nerd)

My logger showed up today, I'll be doing much the same thing you are doing Fingers, without the load. My focus is CAC and cooler drops, with the various mods. Speaking of mods...is there a chance you can do your first pull, no dam, no shroud extension? Stock configuration.

If there is avolunteer here in AZ that wouldn't mind sitting next to a laptop, while pulling, PM me. But fingers may have this covered.

Today, the new GMC nose shroud! The first ram air dedicated helper.


60 mph, fan off

Stock static pressure (nose) 1.1 iw absolute
Modified nose with shroud 1.65 iw absolute

to be fair, most of the sealed stack foam was still in place. as I recall that gave 1.3-1.35 iw. So the improvement with the shroud should be about 0.35 iw. Coincidentally that is the same number as the idle fan shoud at 3000 cfm. Did we improve 60 mph stack flow by another 3000 cfm?

That does it for mods. The next posting will be the CAC and cooler drop improvements with the mods, vs stock.

Oilbrnr will be inheriting the shroud in the pics for his towing trip this weekend. Pray for hot weather. He has been on the edge of overheating with this load, and had tranny over 230. My prediction for this weekend is 210 ECT, and 200 tranny.

I saw something in somebodies post I want to talk about. I think it was oteo125 that posted the tech2 showed a 26 pound boost figure. I monitored my boost today via the ecm and also noticed it saw 5 to 6 pounds more than my gauge. Now bear with me, I may not say this right. If the computer thinks we are higher than we actually are we will not make full power, but more importantly it will add the amount of full needed for 26 pounds boost, not the 21 pounds I am actually getting. More full means more heat. Is there anything here??? Do I have a defective boost sensor??

I saw something in somebodies post I want to talk about. I think it was oteo125 that posted the tech2 showed a 26 pound boost figure. I monitored my boost today via the ecm and also noticed it saw 5 to 6 pounds more than my gauge. Now bear with me, I may not say this right. If the computer thinks we are higher than we actually are we will not make full power, but more importantly it will add the amount of full needed for 26 pounds boost, not the 21 pounds I am actually getting. More full means more heat. Is there anything here??? Do I have a defective boost sensor??

Fuel would be calculated via the MAF sensor. The 21-22 PSI boost is typical across LLYs. The boost displayed on the Tech is a calculated number. Boost sensor minus Baro. Not sure where the 26 is coming from. At that 26 PSI, the sensor would be reading about 4.8 volts according to the measurements I have taken off of my truck. The manual says the expected sensor range is 6 to 36 PSI absolute. That makes 22 PSI gage. So they are not expecting over about 22 PSI.

Fuel is also POWER and you are stuck burning a given amount to pull your butt up a hill. The amount of air can vary a fair bit. There is a balance to be struck between the amount of air ingested for a given fuel load. More air, lower EGTs and chamber temps but higher exhaust backpressure and cylinder pressures. Less air, higher EGTs and chamber temps, lower cylinder pressures and backpressure. The turbo is a big factor here. As you pump more air, the turbo's efficency goes down. SO at some point, you are consuming power to pump air that you do not need.

Overfueling is a hard term to define. No, there isn't too much fuel to burn or you would be smoking like a race truck. Yes, more air would keep the EGTs lower.

KB,

Did you get the same module as me? If so, you can control and save the strip charts fairly easy.

I've caught the Tech 2 displaying some WACKY numbers at times. Not sure on the how/why, but it has shown me big numbers at idle at times...

No, I got the one with led temp readings, as well as computer monitoring. It was a tough choice to make. I may eventually get the software you are using, I'll see how "testlink" goes.

It has the similar kind of GUI you are talking about, I had looked at a demo, and I know what you mean, slick! I just wanted something I could stick on a laptop in another persons vehicle, have them hit one "record" button, for the trip. Then it collects data on the TC's till they end it. Graphic output via the software.

You have the ability, I think, to throw a voltage sensor on boost, MAF, etc. a great way to look at the plots. You'll be able to see where you had the foot in it, etc.

The question Rick asks is the type that starts 10 days of discussion, and nobody picking up a test probe. It fits in the OH thread well, brainstorm an anomoly, the kind of thing I lose patience with, so I'll stay out of it.

Last P test before running temp drops.

Splash/rock guard removal: No mods, No grill, 60 mph

...............Before......after
P Front....+1.85 iw.+1.85 iw
P Back........+.5 iw....+.5 iw
delta..........1.1 iw......1.1iw

Underhood...+.25 iw..+.15 iw

lower underhood pressure, letting more ambient air through the stack, a modest improvement. The guard seems to act as an air "plow" pushing up pressure just behind the fan shroud. Probably the best way to resolve this and reduce pressure further is to fab an undercarriage tray that connect the lower valence to this guard.

or an air dam :)

knew that would get some activity, I'm lonely. Probably a good thing.

This will keep you busy KB. These thin wire TC are very responsive. I will have to get more.

http://mysite.verizon.net/mcelravy1/boo.jpg

could you link something a tad smaller? LOL

you can sure see when the thermostat opens up!

Very slick Fingers. Now hitch her up, I know you can't wait.

Rad in vs Rad out. Doesn't gel for me. They cross. If that steep change is the stat, why wouldn't rad out shift also, at least a little?

I thought those bolt-ons might be a heavy drag. Were they? Are you using the adhesive pads to hold the thin wire T-C's?

The bypass dumps into the hose before the pump inlet. My probe is on the pump inlet. So you see a gadual climb. I need to be in contact with a metal surface for best results. The Rad tanks are plastic.

The response of the bolt ons is a function of how tightly they are clamped to the object of interest.

The thin wires are responsive in almost any situation. I used the adhesive pads plus a layer of insulation for them.

So for clarification, no mods here?

Fingers and his new toy!

It looks like you were doing hole shots, or at least multiple WOT runs, I will also guess by that chart, you never came to a stop. I see no real IAT rise.

damnation Fingers, my TC's just showed up and it's meet the teacher night. How am I going to sleep?

Man that CAC in/out is impressive.

Man that CAC in/out is impressive.

typical of the CAC's heatsink capability, it never quenches in these (short) runs. That's all going to change.

typical of the CAC's heatsink capability, it never quenches in these (short) runs. That's all going to change.

With respect KB, the CAC is that efficient. Proof when I can tow.

Data is from me running an interesting program plus boost enhancer. After almost each CAC spike is a full stop. at the very end of the strip is a longer stop with a tail wind. IATs were climbing a little. Air dam and shroud extension.