ZR1 on the dyno
10-07-2008, 11:39 PM
#22
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I really did like this car! Very nice quality and excellent overall package. Wish I had the 3LZ interior on my own car as it too is a very nice addition.
The car was off the charts rich with the stock calibration. Suprisingly timing was around 25deg tapering off to 23deg with a coolant temp of 190, IAT at 75. 10psi boost. I was expecting the car to have very low timing from the factory.
I ended up setting the air/fuel ratio at 11.5-11.6 and did not modify the main timing table. I did slightly modify the power enrichment vs timing table. No hint of knock and the factory IAT vs timing table remains stock.
The car was allowed to cool off between runs but was brought back up to 190 deg coolant temp for each run in an effort to maintain consistency. (there was no super cool-down money shot)
Overall I think they are very nice #'s for an otherwise stock vehicle
The car was off the charts rich with the stock calibration. Suprisingly timing was around 25deg tapering off to 23deg with a coolant temp of 190, IAT at 75. 10psi boost. I was expecting the car to have very low timing from the factory.
I ended up setting the air/fuel ratio at 11.5-11.6 and did not modify the main timing table. I did slightly modify the power enrichment vs timing table. No hint of knock and the factory IAT vs timing table remains stock.
The car was allowed to cool off between runs but was brought back up to 190 deg coolant temp for each run in an effort to maintain consistency. (there was no super cool-down money shot)
Overall I think they are very nice #'s for an otherwise stock vehicle
10-08-2008, 10:18 AM
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The boost for the ZR1 is controlled through the ECM (Maybe Speed Inc can confirm this). One of the magazines interviewed a GM engineer about turning up the boost on the ZR1 and he said it works, but also increases heat soak dramatically as a result. I'm sure it can and will be done, but one will have to exercise more caution about turning up the wick on the ZR1. I'm going speculate GM has the boost regulated for the first 500 breakin miles just like Ford did for the new GT500.
10-08-2008, 11:02 AM
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The boost for the ZR1 is controlled through the ECM (Maybe Speed Inc can confirm this). One of the magazines interviewed a GM engineer about turning up the boost on the ZR1 and he said it works, but also increases heat soak dramatically as a result. I'm sure it can and will be done, but one will have to exercise more caution about turning up the wick on the ZR1. I'm going speculate GM has the boost regulated for the first 500 breakin miles just like Ford did for the new GT500.
10-08-2008, 11:08 AM
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10-08-2008, 12:39 PM
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The same bypass valve is used to control boost at high engine speeds, but in that instance, pressure acting on the other side of the actuator opens the valve. The pressure is controlled by a solenoid operated by the LS9's engine control module (ECM). When boost reaches 10.5 psi, the ECM energizes the solenoid and the actuator opens the valve, venting manifold pressure to the blower intake and limiting boost.
10-08-2008, 12:46 PM
#32
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sounds like a bypass valve all you need to do is fix one table, well thats how it was for me on the cobalt.
As for the pulley its as simple as a pulley puller no? My understanding is no one had a hub yet for it to produce pullies. I sure someone could contact harrop and get something.
As for the pulley its as simple as a pulley puller no? My understanding is no one had a hub yet for it to produce pullies. I sure someone could contact harrop and get something.
10-08-2008, 12:54 PM
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So it sounds like there was no heat soak or detonation issues on the dyno? I wonder why GM has been so adamant about saying that the cars wouldn't be able to handle much more power than stock? I wonder if that factory A/F is a safeguard based on a problem that they developed in extreme testing? I guess there is a rumor that says the ECM is very, very agressive about pulling timing with increased IAT's and that they had a problem with high rpm detonation.
10-08-2008, 02:00 PM
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I really don't think the reason for the super rich "safe" tune was solely for the longevity of the motor. In fact, GM would not even think about building such a car like that 'on the edge'. It doesn't make since and isn't worth the risk.
I think the stock tune somehow ties into the issue with traction issues that GM claimed to have about 6 months before production. I distinctly remember in some article I found on digitalcorvettes about GM claiming 700 hp would have been relatively possible for a street configuration but due to the fact that the engineers couldn't get the car to hook up properly with only a shade over 620hp given the current suspension/wheel/tire combo--they opted for a less aggressive setup. I think it's cool to have 700+hp and what not, but if you can't find a way to effectively use this power on the street then it's gonna be considered a failure in the eyes of an engineer.
That statement would explain two things right off the bat:
-Rich "safe" tune (if that is what you would call it)
-Restrictive exhaust
I think the stock tune somehow ties into the issue with traction issues that GM claimed to have about 6 months before production. I distinctly remember in some article I found on digitalcorvettes about GM claiming 700 hp would have been relatively possible for a street configuration but due to the fact that the engineers couldn't get the car to hook up properly with only a shade over 620hp given the current suspension/wheel/tire combo--they opted for a less aggressive setup. I think it's cool to have 700+hp and what not, but if you can't find a way to effectively use this power on the street then it's gonna be considered a failure in the eyes of an engineer.
That statement would explain two things right off the bat:
-Rich "safe" tune (if that is what you would call it)
-Restrictive exhaust
10-08-2008, 08:15 PM
#39
its been said a few posts up. gm is backing this car with a warranty and expects it to runs for several yrs to come and get beat on in the process. so their level of maxed out is going to be diff then the average person. pulley swap, long tubes, air intake and a good tune and id bet a few will crest that 700 rwhp quickly.
10-08-2008, 09:31 PM
#40
With all the adders the timing will run up into the 26.5 degree range on the stock tune. Thats what we where seeing when we did 2 here. They will fit some more timing in comfortably, especially down low and at the beginning of the run.