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I was able to do a baseline dyno on my ZR1 today, but the results were less than spectacular. It seems to be pulling a ton of timing. The car is stock other than the gm performance intake. I’m going to try to get some better HP tuner logs to check it. We only had an OBD scan tool at the dyno because I wasn’t expecting to have problems. I know this car had a P0325 code set one time with the previous owner, but he reset it and the dealer couldn’t duplicate it. It apparently never came back. The max timing we saw on the pull was 11deg and I’m told it should be around 20. The engine felt really hot after the first pull like it was pulling timing. My thoughts are bad gas, bad knock sensor, or air in the intercooler system. Any other ideas?
What fuel are you running? 91 and you'll pull timing. If you have air in the heat exchanger that will also pull timing. With 11 degrees that's why you're low hp wise.
What fuel are you running? 91 and you'll pull timing. If you have air in the heat exchanger that will also pull timing. With 11 degrees that's why you're low hp wise.
The pump said it was 93, but maybe they filled the tanks wrong. How do I check the heat exchanger?
The pump said it was 93, but maybe they filled the tanks wrong. How do I check the heat exchanger?
If these are like the LT4, the Heat Xch loop is filled and sealed from the factory, and cant be checked easily. The dealers need a special tool to fill them, and even then they have a hard time getting the air out of the loop. Doesnt take much trapped air in the coolant to cause problems. The simplest solution on the LT4 was to incorporate an overflow/surge tank that allowed the air to escape into the tank.
Curious if the LT5 is similar
Even with 93 octane, the LT5 will pull timing unless the IAT is super low. For maximum performance with no KR, in even reasonably good air, you'll need about 96-octane unleaded.
This is why GM recommends for track use people run 100-oct. unleaded fuel.
It is possible the charge air cooler system needs to be bled. A lot of cars came out of B.G. with air in those systems. The LT5 charge air cooling system is very difficult to bleed such that virtually no air is left. The problem is that it takes 1 to 3 hours of bleeding to get to a very low/no air condition and few dealers are willing to do that. Buy a 3-day sub. to GMSi then read the procedure used to bleed the charge air cooling system and you'll get why most dealers don't want to do the procedure properly if it's a warranty claim situation. In my conversations with Jim Mero about what they did when GM had the ZR-1 at Nurbergring, I learned getting all the air out took a minimum of 3 hours. I had 1878 bled on a non-warranty basis, by Abel Chevrolet in Rio Vista CA and it took a little over an hour to get to where no air bubbles were visible in the hoses of the bleeding equipment.
All that said, the first thing you need to do is mix your fuel 1:1 93-oct to 100-oct and go test, again. That gets you to about 96.5-oct and may eliminate the KR unless the air in the dyno cell is really hot. If it is, use straight 100-oct unleaded. If the engine knocks on that, then you may have air in the cooler cooling system.
11 degrees is pretty low timing and looking at the dyno curve it indicates it was pinging or at least thought it was, could also just be a byproduct of the very low timing as well. Need to log manifold air temps and see what they are climbing up to, could be that you need to bleed the charge air cooling system or could be bad gas.
Even with 93 octane, the LT5 will pull timing unless the IAT is super low. For maximum performance with no KR, in even reasonably good air, you'll need about 96-octane unleaded.
This is why GM recommends for track use people run 100-oct. unleaded fuel.
It is possible the charge air cooler system needs to be bled. A lot of cars came out of B.G. with air in those systems. The LT5 charge air cooling system is very difficult to bleed such that virtually no air is left. The problem is that it takes 1 to 3 hours of bleeding to get to a very low/no air condition and few dealers are willing to do that. Buy a 3-day sub. to GMSi then read the procedure used to bleed the charge air cooling system and you'll get why most dealers don't want to do the procedure properly if it's a warranty claim situation. In my conversations with Jim Mero about what they did when GM had the ZR-1 at Nurbergring, I learned getting all the air out took a minimum of 3 hours. I had 1878 bled on a non-warranty basis, by Abel Chevrolet in Rio Vista CA and it took a little over an hour to get to where no air bubbles were visible in the hoses of the bleeding equipment.
All that said, the first thing you need to do is mix your fuel 1:1 93-oct to 100-oct and go test, again. That gets you to about 96.5-oct and may eliminate the KR unless the air in the dyno cell is really hot. If it is, use straight 100-oct unleaded. If the engine knocks on that, then you may have air in the cooler cooling system.
Thanks Hib. I’ll try the 100 octane and log it this time. Luckily my local dealer is very race car friendly. They have GPI a performance shop in house and the service manager is a buddy that drives a highly modified C6 ZR1 so they should do it right if it needs to be done.
If these are like the LT4, the Heat Xch loop is filled and sealed from the factory, and cant be checked easily. The dealers need a special tool to fill them, and even then they have a hard time getting the air out of the loop. Doesnt take much trapped air in the coolant to cause problems. The simplest solution on the LT4 was to incorporate an overflow/surge tank that allowed the air to escape into the tank.
Curious if the LT5 is similar
Bossman429, have you got a part number for that special tool? I like doing my own work when possible. Thanks.
Don’t look at MAT for blower temp, look at B1S3 under intake temps, it reports correctly and will tel you if the supercharger coolant flow is moving due to temperature.
my guess is it’s very high and pulling timing to save itself due to temp
If these are like the LT4, the Heat Xch loop is filled and sealed from the factory, and cant be checked easily. The dealers need a special tool to fill them, and even then they have a hard time getting the air out of the loop. Doesnt take much trapped air in the coolant to cause problems. The simplest solution on the LT4 was to incorporate an overflow/surge tank that allowed the air to escape into the tank.
Curious if the LT5 is similar
I'd bet on heat being the culprit here. I dyno-ed mine right after coming off the track at Daytona. The best out of three pulls there was 505 HP. The heat was aweful.
Bossman429, have you got a part number for that special tool? I like doing my own work when possible. Thanks.
There are several out there for the Camaro LT4's, I pasted just a couple of them below . , I couldnt find the one my son used but it was similar to these two, and it looked very OEM. You wouldnt know it wasnt oem, unless you knew what you were looking at. Concept would be same for the LT5. Dealer that my son took the car to originally had no idea how to bleed the intercooler. Son bought the kit with tank, dealer said they'd install it and it wouldnt affect the warranty. It worked great, car would pull ten mph faster on straights at RA w/o air bubbles in the lines.
There are several out there for the Camaro LT4's, I pasted just a couple of them below . , I couldnt find the one my son used but it was similar to these two, and it looked very OEM. You wouldnt know it wasnt oem, unless you knew what you were looking at. Concept would be same for the LT5. Dealer that my son took the car to originally had no idea how to bleed the intercooler. Son bought the kit with tank, dealer said they'd install it and it wouldnt affect the warranty. It worked great, car would pull ten mph faster on straights at RA w/o air bubbles in the lines.
I was able to do a baseline dyno on my ZR1 today, but the results were less than spectacular. It seems to be pulling a ton of timing. The car is stock other than the gm performance intake. I’m going to try to get some better HP tuner logs to check it. We only had an OBD scan tool at the dyno because I wasn’t expecting to have problems. I know this car had a P0325 code set one time with the previous owner, but he reset it and the dealer couldn’t duplicate it. It apparently never came back. The max timing we saw on the pull was 11deg and I’m told it should be around 20. The engine felt really hot after the first pull like it was pulling timing. My thoughts are bad gas, bad knock sensor, or air in the intercooler system. Any other ideas?
WOW!!! Talk about being underpowered!! ZR1'S baseline in the 630's as I was told by a Katech engineer. Mine baselined at 644.
My first question to you is: How many miles on your ZR1? I'm assuming you bought her new? If not, did some shade tree mechanic tune her? I'm NOT a tuner nor do I pretend to be one but, if some yahoo tuned her, therein lies the problem. If no one tuned her, well, that presents a whole bunch of questions I honestly cannot answer.
I've last thing: Again, I'm NOT a tuner but could the ECU/ECM need to be reflashed from GM?
I hope you find the problem and wish you the best.
Even after having the dealership attempt to bleed the supercharger coolant system the MATs on my car would get high very quickly and pull tons of timing... I haven't bothered attempting to bleed the system myself but I definitely should while it is still under warranty in case there is something more going on.
03-16-2021, 05:52 PM
Stock ZR1 not making expected power.
