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Anyone know FOR SURE what boost they have been hitting with their LLY trucks when at high altitudes? People have said that the LLY is reaching more boost than the LB7 did. At sea level that's great, but at altitude it may be causing high heat problems. Anyone have solid data or noticed the boost readings on the gauges when up above say 4000ft???

Thanks for the help!

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Edited by: TxChristopher

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Wow! There isn't ANYONE out there that has a boost gauge on an LLY that goes into high altitude????

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What specific do you want to know?? I live at 4800 feet and go to
10000 on a regular basis, and have NO over heating problem. The
only problem the DMax runs too cool at 182 to 188 F.



Pilot

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Trying to find out how much boost the LLY is making up in high altitude, under full throttle specifically. This can be done loaded or not, just so long as you have enough road to keep full throttle long enough to see what the boost level reaches and holds at.

Do you tow up there or just run the truck around unloaded?

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OK tested tonight results:


OAT 50 degrees F, 4500 feet MSL, no mods stock excrpt EDGE in level mode 3, all number from the EDGE unit.


55 mph no load stright and level 4-6 psi


0-95 mph max boost reccorded 23-25 psi


Minimal acceleration off the line fron the light 6-9 psi


Do you need any thing else??


Pilot

For me to get good boost #s, i had it T/H in 4th on a long hill w/ trailer.


Just accelerating w/o load didn't give me as much boost.

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The truck should make the same boost loaded or unloaded when at full throttle, main difference is that with a load you can hold the rpm up and steady to see what the reading settles at. The fact that it is reaching those kinda numbers is what I am after. Getting 23-25psi boost out at altitude on a hot day, say 95* to 100* with a big load would be a BAD thing, and is the reason I believe the LLY people are reporting overheating. The math shows outrageous turbo outlet temps to pressurize that hot thin air up to those psi levels.

Pilot: I know it won't be as much fun since the truck will feel like a total dog now to you when stock, but can you set the juice to level 0 so we can see if the truck makes the same boost stock?

Dmax Tim: how much boost did you see when you pulled your load, and at what elevation?

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Another thing, can you see how much the boost falls off by just barely lifting the throttle off the floor? Trying to see if GM allowed boost mapping for altitude or if it is only that full throttle is overiding that mapping. If boost falls off dramatically when you barely lift then they did take into account altitude mapping, if it just slightly drops then they didn't.

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Just tested today: Altitude about 3500 feet. Outside temp about 50. 2004 LLY. Juice level 0 max boost displayed 26.8, juice level 1 max boost displayed 29.6 Hope this helps.


Eric

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You guys are golden. This data will go a long way towards the overheating LLY problem. If you held 25 or 26lbs boost on a 95* day towing a heavy load (lets say over 10k up to 15k) up a steep hill then you would be on the really fast track to getting overheated. The turbo outlet temps would be unreal.

Seems GM didn't address LLY boost at altitude correctly.

Anyone have boost numbers for even higher elevations?

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Want to thank the people again who took their own time and tested. I live on the Texas coast, there aren't mountains close to me at all.

This forum is a great place to learn things and swap info.

Anyone else have boost numbers when up at high elevations please post them, the more data the better!

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Edited by: TxChristopher

Give me a boost pressure guage and I will let you know... I live at 10,400





Howard

Give me a boost pressure guage and I will let you know... I live at 10,400





Howard








Get a J/A and join the fun.


I live in OH so max was 1500', saw just less than 30psi w/ juice on level 1.


I don't have pyro hooked up because I was waiting on my 05 to switch everything over to.


W/ the J/A on 4 w/o trailer I was up to 100mph fast so I didn't see as much boost, I think top was 27.X.

This is strange the most boost I see in level 5 is 28Psi?

I was out playing on a straight road last nite and level 5-5 J/A WOT and saw 29.6psi.


That was in OD on it's way to 100mph http://www.dieselplace.com/forum/smileys/hihi.gif

Dmax Tim, and at what altitude would this have been at? JJ http://www.dieselplace.com/forum/smileys/hihi.gif

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Anyone else out there run an LLY at altitude and have a boost gauge?

Still looking for stock settings more than anything, although any data you have is useful.

Sure wish someone at 8k or 10k elevation would post what boost they see......

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Remember I live in FLAT Ohio, 1300' or so.

<font face="Arial, Helvetica, sans-serif" size="1"><font size="3">Here
are the results from this weekend. I wasn't towing anything so it
was hard to get high RPM's w/o running over someone. </font>



Juice in level 0, normal highway driving ~70MPH.</font>

<font face="Arial, Helvetica, sans-serif" size="1">Altitude<span style=""> </span>Boost<span style=""> </span><span style=""> </span>Eng.
Tmp (F)<span style=""> </span>Egt’s (F)<span style=""> </span>RPM’s<span style=""> </span><span style=""> </span>OST (F)</font>



<font face="Arial, Helvetica, sans-serif" size="1">5700<span style=""> </span><span style=""> </span>7-10<span style=""> </span><span style=""> </span>190<span style=""> </span><span style=""> </span>800<span style=""> </span><span style=""> </span>2000<span style=""> </span><span style=""> </span>45 </font>



<font face="Arial, Helvetica, sans-serif" size="1"> </font>


<font face="Arial, Helvetica, sans-serif" size="1">Juice in level 0</font>



<font face="Arial, Helvetica, sans-serif" size="1">Altitude<span style=""> </span>Max
Boost<span style=""> </span>Eng. Tmp (F)<span style=""> </span>Egt’s (F)<span style=""> </span>RPM’s<span style=""> </span><span style=""> </span>OST (F)</font><font size="1">

</font><font face="Arial, Helvetica, sans-serif" size="1">6000<span style=""> </span><span style=""> </span>19<span style=""> </span><span style=""> </span>196<span style=""> </span><span style=""> </span>1000<span style=""> </span><span style=""> </span>2800<span style=""> </span><span style=""> </span>45</font><font size="1">

</font><font face="Arial, Helvetica, sans-serif" size="1">8100<span style=""> </span><span style=""> </span>16.4<span style=""> </span><span style=""> </span>196<span style=""> </span><span style=""> </span>1100<span style=""> </span><span style=""> </span>2700<span style=""> </span><span style=""> </span>35</font><font size="1">

</font><font face="Arial, Helvetica, sans-serif" size="1">9700<span style=""> </span><span style=""> &nb

colodmax, good data! Should be very useful. Do you happen to know what the humidity was?


Tx, note his boost levels are well below what others are posting and exhaust temps 1150-1280 in 27*-45* temps.


Pilot: 0-95 mph max boost reccorded 23-25 psi


1SAST: Just tested today: Altitude about 3500 feet. Outside temp about 50. 2004 LLY. Juice level 0 max boost displayed 26.8, juice level 1 max boost displayed 29.6


THE ONE: This is strange the most boost I see in level 5 is 28Psi?


DmaxTim: I was out playing on a straight road last nite and level 5-5 J/A WOT and saw 29.6psi.


Outside temps dropped in conjunction with high altitudes (normal) which might explain the exhaust temps, even then they rose slightly. Pump 95*+- air in there and one can only imagine how hot it would get.


Why did his boost pressure go down the higher up he went? Colodmax, have you done any mods, e.g. exhaust, AFE stage II, ??? JJ http://www.dieselplace.com/forum/smileys/smiley4.gif

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Already I have noticed a 1 to almost 2psi diff from truck to truck, hence the 25 to 26psi or so numbers. He may have a truck that starts out lower so take that into account.

His boost went down exactly as I would expect it. Even our turbo has limits, and he is able to find them. The air is too thin up there for the turbo to hold the line on boost. It may try but it can't do it, and its abilities should fall off more and more as you rise since what it has to work with (air) gets more and more difficult to compress. He is running way up higher than the other people, they were in the 4500ft to 5000ft range. You lose roughly .5psi per 1000 feet.


The lower temps up high go a million miles toward eliminating overheating under the big boost. That 30* compared to 100* intake air temp is a massive difference, just look at the calcs I posted if you lowered intake air temp 20* you end up with 100* less on turbo outlet.

I think the sweet spot to overheat an LLY is gonna end up around 3000 to 5000 ft, maybe 6000 if it was hot enough outside. Down lower (3000 to 5000ft) with the big boost you could do it on a mild day at 25psi for very long.

Below that the compression is way lower and above that it is unable to reach the big boost due to poor supply quality of air and the temps are low enough to keep thermal loading in check.

I am still impressed with the 19psi at 6000, as well as the 18 at 7500. Our turbo is the little engine that could :)

What altitudes have the guys been at that are overheating?

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No additional mods other than the Edge J/A. One thing to keep in
mind with the EGT's and Boost, these were max readings that I
saw. Everytime I put my foot on the floor I would hit the speed
limiter in a hurry even at 10000 ft, and when your running up Vail pass
at 97MPH w/ 9000 other people on the road you can't keep it there for
very long. No clue on the humidity, my guess would be between 30
and 45...



D

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I bet you were haulin ass! That low temp did wonders for your horsepower. I have seen car lose a full second in the quarter at the track on 30* days versus 85* days.

A load behind you would have helped, but oh well, beggers can't be choosers!

I would like to see what the LB7 did for boost at 6000ft. I doubt 19psi........

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One other thing, since our power is limited in 1st and 5th, to protect the allison, do you think that boost is limited in those gears? Because I think the new power in the LLY is coming mostly from an increase in boost.

Colodmax, next time you are out playing use tow/haul so that you hold 4th gear.

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I will check the data again next time I have the horse Trailer on, I may take it with me when I go over for Thanksgiving.



And yes, I was haulin ass, just ask the guy in the Lebaron who kept
trying to pass me going up the West side of Vail pass, no go!! He
did pass me coming down the East side but not until I had slowed down
to 70 and set the cruise...





D.

I did use t/h and even down shifted to keep the rpms up, didn't seem to
make much differnce in the boost. It was the only way I could get
the rpms above about 2500 w/o running someone over.



D

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I don't have the speed limiter, I love stomping the crap out of cars!

Good, glad you used tow/haul. So it may be that the capability tails off much above 4500ft or so. It really does get harder and harder to raise that thin air up in pressure, the work the turbo has to do gets greater and greater as the air thins.

It would also have been easier for GM to miss a certain band of elevation than to miss elevation completely

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I would love to get rid of the speed limiter, kind of a pain when you
go to pass a couple of cars on a 75mph highway and get stopped at
95. As soon as I can find a reasonably priced way to get rid of
it without changing any other settinngs (dont need it with the juice
and no tranny upgrades) I will do it.

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The speed limiter was a big player in my decision to go with the quad over the juice or any of the others. That and the ability to correct for the tires (several good reasons more as well!). With the speed limiter off and 285/75's and the rpm limit at 3600 I can hit 120 on the money.

Big difference betwwen 120 and 95 on the open road. The truck flies right up to it too!

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"Big difference betwwen 120 and 95 on the open road. The truck flies right up to it too!" http://www.dieselplace.com/forum/smileys/smiley5.gif Tx, that truck is going to be the death of you! Then again what a way to go! http://www.dieselplace.com/forum/smileys/hihi.gif


Tech check: Does T/H being engaged keep the truck from going into 5th gear, or does disengaging the overdrive do this? When I'm towing my 5ver it sure seems like I'm in 5th gear with o/d engaged even with t/h on. Or is it torque converter lock-up in 4th? The rpm's lead me to believe it is in 5th even in t/h unless I override OD. http://www.dieselplace.com/forum/smileys/smiley5.gif


Interesting thought about boost being limited in 1st and 5th. You would assume the guys towing heavy at higher altitudes that ran hot would have been in the lower gear ranges at high RPM's producing max boost. Tx, I don't see where RDL, c45, Fingers and others are following this post, maybe we should put something on the overheating LLY post re your t/h question and boost? JJ http://www.dieselplace.com/forum/smileys/smiley4.gif

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I guess I should have differentiated more the two modes. I relate them together more (towing modes).

Tapping tow haul turns on tow haul mode which locks the tc in 2 - 5, and yes you still get 5th gear. Holding it locks out 5th.

I know the power is cut in 1st, maybe not 5th......thought I read somewhere that it was cut in 1st and 5th......since I am not sure don't take that as truth until verified.

My truck runs good but still feels like a slug to me, 14.7 quarters aren't fast. After owning several low 12 high 11 sec cars that hit 113 to 115 in the quarter, as well as 6300rpm in overdrive with a 3.23 gear.........in effect I have slowed down by choosing to play with a 3/4 ton crew cab 4x4

Good thing......my current wife thinks this truck is already too fast.......she would have a real coronary from the performance and wild manuevers I used to pull in LT1's and the like!

Sneaking in the performance on her is my method.......but baby, that Mercedes Benz E55 is a 4 door family car, not some sports car like a vette or camaro!

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The only thing I recall on 1st and 5th gears with the Allison is with too much power guys have slipped the tranny in those 2 gears, not 2-4. I believe the PCM has some sort of built-in protection to avoid this.


Tx, you are never going to be satisfied with your truck until it rips the rubber off the tires! http://www.dieselplace.com/forum/smileys/hihi.gif Just give me a heads-up if you ever in the J'ville area so I can stay the he$$ out of your way. JJ http://www.dieselplace.com/forum/smileys/hihi.gif

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No, the truck really has an actual leash on it in 1st gear for sure, GM says so openly. We are limited to the 520lb/ft torque in first, then the new power is there the rest of the gears. I think you are right, I am mistakenly tying the slipping to the limiting. But the first gear thing I am sure of.

Don't worry, I am fast but safe. I drive 130,000 miles a year (drive for a living) and I only have one entry on my driving record, which is an accident (old lady backed into my car, which was parked and unoccupied). I don't even get charged on insurance for that one.

We have friends in plantation (pleasanton?) right there by ft lauderdale.....I'll be around lurking your area randomly :)

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