OK, I've been noticing an annoying hesitation from my truck when I floor it while on the On-Ramp entering the expressway or passing a slower vehicle. (Pure Stock 2006 LBZ ExtCab/SB 4x4 with approx. 2800 miles on the odo.) So I figured I would run a quick 0 to 60 MPH test to see if my performance is in the ballpark with other LBZs. I realize this is not the same as passing someone, but it gives me an easy way to duplicate my test. I still need to run some 30 to 70 times to check performance while passing.

I had the truck weighed at the local truck stop and it weighs 6,800 lbs with 3/8 tank of fuel and me in it.

Unfortunately, the only place I was able to run my test was on the local expressway.

I used a calibrated stopwatch and the truck speedometer for this test. Yes, it's a crude test, but I just want to see if I'm in the ballpark with others.

I pulled off the side of the road just before the entrance ramp so that I would be able to use paved roadway as I took off. I waited for traffic to clear and ran a quick 0 to 60 test.

Here is how it went:

Shifted the Allison into Tow/Haul Mode and let it do the shifting for itself, brake-torqued it to 1000 RPM and launched it with some slight wheelspin.

My unscientific 0 to 60 time was 8.14 seconds.

Does this time sound to be in line with other LBZs or should I run more controlled tests and then go to the dealer to see about a re-flash?

Thanks for any comments and suggestions.

Ray

pretty fast for a 7000lb 4x4 id think.

sounds about right...

now just wait for all the tuners to come out for the LBZ!!! I did 5.6 (according to Edge timer, tire size set correctly) with a stock transmission, and ive also got a bit toolbox in the bed...

was the entrance ramp flat or uphill??

was the entrance ramp flat or uphill?? Ramp was flat. That's why I picked that one.

I'll check mine today and repost later. What is the signifigance o using Tow/Haul mode?

I dont think you'll see any difference in tow/haul mode. It does lock the TC a lot sooner, but at stock power levels it really doesnt matter.

Tow/haul will prob make a little difference. It starts the tranny in 1st gear not 2nd. Also might try manual shift??

The tranny starts in 1st gear regardless :confused: at least thats what the Tech 2 tells me

:iamwithst :D

I wouldnt do the break stall.....it will throw off you measurments a bit.

Maby they do start in 1st???

So is tow/haul just to prevent the tranny form shifting into overdrive?

The Allison always starts in first and goes thru the gears 1,2,3,4,5,(6). Its not tricky like the Jeep or Ford tranny's that have like 2 second gears, skip gears sometimes or junk like that.

this is what tow/haul does:

1. locks the torque converter and keeps it locked from 25mph/second gear on up
2. raises shift points/holds truck in gear longer
3. different shift algorithm to keep the tranny from "hunting" for gears with heavy loads/traiers
4. activates brake pedal based grade braking and keeps the torque converter locked all teh way down to 25mph so grade braking actually uses the engine to help slow down. Which is why it feels "clunky" around town with T/H mode on. Its because the TC is locked. It will still shift into 5th gear (overdrive), jsut at like 60 mph versus 45-50mph. You can also HOLD DOWN the tow/haul button and it will lock out overdrive. Its pointless tho as the TCM is smart enough to select the right gear.

--Ben

What he said or http://www.dieselplace.com/forum/showthread.php?t=18123 for answers to tons of allision questions.

on the 06's instead of using the hold the TH button to lock out OD you do that by going to the manual mode and clicking down in the - button.

OOOOOO you oh-sixers and your fancy schmancy tip-tronic buttons):h

Maby they do start in 1st???

So is tow/haul just to prevent the tranny form shifting into overdrive?
On the '06 it doesn't even do that.

pffffft......I look down on you:rolleyes: You and your outdated 5 speed :p: ):h

Only reason for them fancy scmancy buttons is for 1. Lotsa people think the "manual mode" is some sorta cool new feature that it isnt so it helps with sales 2. the number of detents and a shifter throw to make a truck with 6 gears plus P N and R would make it a PITA

:iamwithst :D

I wouldnt do the break stall.....it will throw off you measurments a bit. So, would you just sit there at idle and then "mash" the throttle to the floor when you take off?

How does brake torquing thow off your measurments? I'm not doubting you; just curious.;)

Bake stall will introduce MANY variables more than normal launch from idle. If you do that you would have to give us the RPM that you stalled to and the amount of time before you took off..........OR you would have to give us your BOOST reading at launch (and hope our boost gauges read the same, if we have one). Lets say you stalled to 1500 rpm. Then the truck would start to build boost over the next few seconds. It won't be instant. Then it would be at ?? value when you launched. If I bring my motor to 1500 rpm it may take shorter or longer to build the same amount of boost or perhaps I only went to 1475 rpm because I cannot see that good etc.......If you want a good comparason you should just mash the throttle from a dead idle. That would be the best way. Also a boosted/break torqued launch will introduce "WHEELSPIN" which will vary from truck to truck depending on boost at launch(HorsePower and engine response), cab configuration(weight bias) and road conditions(coefficient of friction). Hope this helps.

Ok, Thanks Ben and everyone else

Thanks, Dragrcr, I will try it again from idle so that you will have a good comparison. It's snowing here today, so I'll have to wait for dry weather.

Couldnt have said it better dragrcr.

No break stall will be much easier for others to duplicate.

RayMich, this may or may not be what you are experiencing...

I've noticed on my LBZ that if I go from almost no throttle and stomp on it to pass, the Alli takes about a day and a half to downshift and get going. If I'm light on the throttle behind some slow poke on the freeway, I'm probably in 6th gear doing like 40 mph. When I stomp on it, it has to drop down to 2nd or 3rd and that takes a while. Plus, you have some turbo lag on top of that. If I roll into the throttle, I seem to get betetr results.

Is that hesitation to downshift normal? If so, that might be the explanation. IT only happens when you go from very light throttle, to almost WOT.

tested my LBZ this evening with similar results in the low 8's

"OK, I've been noticing an annoying hesitation from my truck when I floor it while on the On-Ramp entering the expressway or passing a slower vehicle."

I noticed that hesitation while doing a test-drive, just prior to purchasing my new truck. The salesman said is was caused by the turbo spooling up. If you brake-torque on your 0 - 60, you may miss that effect, as the turbo will be spinning better at the start.

Not sure, but made some sence to me, as my Dodge/Cummins did the same thing.

OK, I finally got a chance to re-run my test today.

I drove the truck for approximately 30 miles to get it warmed up. I tried to get the trans as warm as possible by driving in 4th gear for about 10 miles, but 130*F was as hot as she would go. I did NOT have the winter cover on during these tests.

Time of day: Approx. 2:30 pm
Weather: Clear & Sunny
Outside Temp: 28*F

ECT: 185*F
Trans Temp: 130*F
Fuel: Approx 1/4 Tank (Flying-J Diesel fuel with Stanadyne Preformance Formula @ 4 oz/15 gals of diesel)

Here are my times:

0 to 60 MPH: 7.93 sec (average of 4 runs)

30 to 70 MPH: 7.69 sec (average of 2 runs)

I ran the 0 to 60 test by letting the engine idle for 30 seconds stopped and then floored it. I left the transmission in Drive and let it shift by itself.

The 30 to 70 times were run by driving at a steady 30 MPH for approximately 30 seconds and then floored it. Again, the trans was in Drive and let it shift by itself.

One thing that was quite noticeable was that it appears that the engine de-fuels at each shift point. I don't know if this is normal, but it is very noticeable and annoying.

I hope that this helps others duplicate my test.

I'm not trying to create any type of competition here. I'm just posting these to see if my truck is in the ballpark with other 2006 LBZ 2500HD.

Thank you for any additional input and comments.

-Ray

On Edit: During each test, there was a very noticeable turbo lag when I floored it.

One thing that was quite noticeable was that it appears that the engine de-fuels at each shift point. I don't know if this is normal, but it is very noticeable and annoying.
Totally normal... that's the ECM's way of protecting the tranny while the clutch packs are engaging and disengaging.
On Edit: During each test, there was a very noticeable turbo lag when I floored it.
Yup... same here. At 55-60, when I try to pass someone on a 2-lane road, it takes a good 2 seconds for it to "catch" and take off. Took some getting used to, as my Tundra would take off like a rocket and be at 90 before I knew it. With the D/A, I now floor it BEFORE I make my lane change to pass.

It's still at 90 before I know what hit me, it just takes an extra second or two to hit me.

Thanks Rich, I appreciate your comments.

Ray

Looks like about 1.5-2 seconds behind the Chevy SS.

I read where the 6.0 Performance Edition Sierra 1500 is at 7.5

Not too shaby. Maybe with some tunning it can get into the low sevens or sixes....

Looks like about 1.5-2 seconds behind the Chevy SS.

I read where the 6.0 Performance Edition Sierra 1500 is at 7.5

Not too shaby. Maybe with some tunning it can get into the low sevens or sixes....

Not even tuning just a real 4x4 launch.

True... I think what we were shooting for in this thread was a consistent real-world expectation... not an attempt at the quickest possible 0-60 run.

These trucks are QUICK on a boosted launch.

True... I think what we were shooting for in this thread was a consistent real-world expectation... not an attempt at the quickest possible 0-60 run.

These trucks are QUICK on a boosted launch. :exactly:
My intent was establish a measuring stick to see what times other unmodified trucks are consistently getting in order to determine if a truck is performing like it should. This was not intended to start any kind of competition to see who can modify their truck to run the quickest. There are a number of excellent racers and pullers on this forum who have proven themselves and can run circles around any stock unmodified truck.

If anyone wishes to post their times along with a description of their truck, we can use this information to see if our trucks are running in the ballpark of other similar trucks.

I picked 0 to 60 and 30 to 70 times because they are representative of what we will experience in the real world and they are fairly easy to duplicate without running the risk of damaging the truck or risking a speeding ticket.

Keep on Truckin':ro)

I need a stopwatch :)

And I need a truck!



I do however have a BMW M5 that will get to 60 pretty dang snappy. :ro)

It just can't haul anything like ladders or tow tractors...bummer.

I haven't clocked my 0-60 times but I can tell you the downshift/turbo lag deal is pretty normal based on my truck and the one I test drove prior to buying. It works much better just rolling into the throttle to pass I think the extra load and not downshifting as far helps spool the turbo faster. I can say this a spooled up brake torque launch in 4wd is pretty cool :ro) I left my brothers trailblazer by about a full truck lenght at a stop light :cool2: not too shabby for a 7000lb truck