2004 LLY Power & Torque curve

[u00jdh]

Does anybody have a power & torque curve for the 2004 LLY?

[Kennedy]

I have the 2005 LLY curve stock and with my exhaust. It will be on my site shortly at:

http://www.kennedydiesel.com/photogal/pages/dynoplots.htm

[mark45678]

Hey Jon, can you help me understand how the TQ has huge spike at 2250? The power curve is showing a nice gain all the way threw but A 70 ftlb gain in a very limited RPM range is odd . Have you done any testing with power booster to see if this gain is there with " boxes" in play?

[Kennedy]

I believe this spike to be a transitional turbo position. It happens in some tunes, and not in others. If you look closely, there is a sag prior to the rise. The sag is much worse , and higher RPM on the stock exhaust. Hard to feel on the road though...

[DMAXdreamin]

The stock LB7 curve looks much flatter than the stock LLY and appears to have an "average" torque rating above the LLY. I thought the LLY was supposed to be the stronger engine. Am I missing something?

[OC_DMAX]

John K - Great informational plots. Thanks for taking the time to take the data and post it!!


The torque curves on the stock LLY look really strange. Looks like GM needs to invest a little engineering time to tweak the ECM to smooth things out. I'll be interested to see what your 2005 LLY looks like.


Also of interest is the substantial difference in EGT's between the stock LLY and stock LB7. Not sure what to make of it other than there is a different turbo involved. Makes me glad I have the LB7 (until the injectors go out, then I'll be wish'n I had an LLY).

On the modified LLY with KD exhaust, did the truck have the CAT or did you loose it somewhere along the way?

Any EGT info on how various tuners perform? (In particular, the Juice level 2 vs stock). Many people tow with this tune, it would be interesting to see how the EGT's get modified by the aftermarket box.

[Kennedy]

My LLY is still a little fresh as of these tests. There was only approx 3k when tested. The LB7 has 14k on it.

For testing purposes only, the cat was removed. ;)

The LLY runs pretty nice in general. Pedal response is pretty touchy, but it doesn't have the follow through that the LB7 does.

One interesting thing is that the LB7 likes to have 3 or more runs till it produces best numbers, and remains pretty steady beyond that. The LLY seems to di it's best runs at the first or second run, and drops from there. I run them pretty hard, and it almost seems as though the intercooler heats up more on the LLY. I'll be monitoring compressor out temps some time in the future.


I've been driving the LLY more as of late, keeping the miles and salt off of my LB7. The LLY seems more responsive to lesser pedal inputs, and more spunky to drive at the lower levels of the boxes. It may pick up on the upper end once the transmission is beefed.

Still no beating the modified LB7. Been playing with the transmission to get it to behave with the big VA. Saturday I was out and was having real problems that I never had before. I'd flat can the pedal from a standstill w/o any boost, and it left with the usual cloud of blcak that rises to be seen from a mile away. The problem is, once the turbo got going, and it hit second gear, it started leaving twin dark black stripes that did not stop until about 70mph where the tires smoothly and gradually bit in... :D