02' vette

Did 5 back to back highway pulls yesterday in my buddies (stick Z) on the Lake Jesup bridge in Orlando Florida. 3 one direction and 2 heading back the other way. All the runs were 2nd, 3rd and 4th gear pulls. We ran my buddies 1998 Supra with 453rwhp.

1st two runs it was exactly what I thought would happen, not even close. We immediately jumped out and put 5 or so cars on him.

On the 3rd run, we could feel it did not feel quite as strong, only put 3 cars tops on him.

Turned around ran back the other way and on the 4th run did not jump out at all really, and by the end of 4th only had about 2 cars on him and we were like wtf?

5th run, basically did not pull on him at all, maybe 1/2 car tops by the end of 3rd. In 4th the traction control light was blinking. During all of 4th gear he was literally dead even.

Granted it was fairly warm yesterday, here in Florida, humid too, but the car was never stopped, so air was always moving through it.

Was set to Race mode. 100% stock. 680 miles on it.

Will the PCM really (or can it) pull that much power due to heat soak?

Car threw no codes and ran totally perfect afterwards.

2015 2LZ 7 speed.

OBSSSD

10hp per car length is a pretty reliable rule, so 30hp?

Nitemare9

6 Speed????

02' vette

Fixed, stick car. 7 speed.

02' vette

Almost seemed more like 75+ hp. Car pulled clean, just was way down on power. Did not hesitate or seem to "miss" or anything.

I just find it hard to believe it will "pull" that much power, but maybe it does.

CONMAX

since the new Z doesn't offer a 6 sp, you should have the dealer fix this for you and repeat the runs.

Higgs Boson

5-10 degrees of timing could easily add up to 75 hp.....especially if there is any throttle closing involved.

02' vette

Okay thanks.

Nitemare9

Exactly. I'm always trying to put my '13, 427, C6 into 7th gear.

jim2092

Engine coolant temp pulls 1* of timing at 198* ECT and up to 7* at 230 ECT and goes up from there.

Intake air temp pulls up to 4* of timing at 132* IAT and goes up from there.

And there are other issues as Higgs suggested.

02' vette

Yea yea, it's a habit when referring to a stick car. He has a 7 speed obviously.

02' vette

Holy crap. Was running about 208 degrees at the end of the pull when I looked over at the screen.

Not sure what the IAT's were not sure he had those on the screen, but it was over 90 degrees here yesterday and this was about 1pm so the sun was full blast too. Car is black which I am sure does not help.

So it easily could have easily been pulling 6-8* timing then I guess. That's considerable.

He will need some cooling mods for sure here in Florida then for the summers.

bringe

What temp thermostat can we put in the c7 zo6 to lower the temp? Who sells them? I called around and no one knows??? So the stock computer won't throw a code.

Higgs Boson

There are 160s out there, no guarantee on the code...99% do not get a code, a couple people have.

bringe

Looking for a 170 ??? For a c7 zo6.

jim2092

But a lower temp thermostat will not help after 5 back to back races.

vetteLT193

Yeah, when I had a 160 I found it only delayed the inevitable. It might have gotten him through race 3 before things went south but won't get it much more than that. It also really has to be tied to a tune that will run the fans at slower speeds to keep the temp down as well.

Thomasmoto

Honestly I don't know if it's the ecm pulling timing or just that the warmer everything gets the mixture just isn't as dense as it is at lower intake temps. Either way really still results in less power. I experienced it a couple weeks ago at a 1/4 mile drag strip by running round robin to try to figure out the best launch technique. I was really concentrating on my 60 foot, but the mph's were exceptionally affected by the increased air temps.

DaveN007

"Heatsoak" = lower performance because the supercharger is pushing hotter air. The car doesn't have to do anything to deliver less HP.

I had a Dinan Supercharged BMW M3 (Vortec Supercharger) and it would make noticeably less power after the car heated up and was really noticeable on hot days. I didn't have an intercooler but the actual centrifugal unit wasn't sitting between two banks of monster pistons...

Let's not confuse the car overheating with "heatsoak".

Higgs Boson

Sure it will. The 194 stat car will heat up after 5 races just like the 160 car but the 160 car starts lower and stays lower.

I've been hammering on my 160 car and the temps are always lower than when I was running a 194.

"The heat up the same" argument is a myth in practicality.