Pushing water out radiator under boost help
 

Heres the rough setup:
99 Camaro M6
370" ironblock forged internals
Texas Speed PRC 260cc LS3 aftermarket casting heads
Ls9 gaskets and heads were torqued to around 90ft # I believe (dont remember exactly but I know its more than ARP called for)
F1A on about 21# boost
car makes 941/866 on a dynojet

Heres what happened:

took the car out last night street racing. Made probably 7-8 2-4 gear pulls dang near back to back. After a few pulls i started to smell coolant. Didn't think much of it until we pulled off the side of the highway when done and looked like the car was pushing water. I still have a tiny overflow Probably a hair bigger than a coke can (I know I need a bigger one) and it was complety full and running out and also looked like coolant was pushing out around the cap as you could see it running down the radiator and also spray ing the engine bad and bottom of the hood. Even the back bumper had coolant spray all over it. I know I kinda had the same problem with the car even with the stock motor and D1 on it but I never ran it as hard as I did last night so I never saw it this bad. Think its a combination of the small overflow tank and maybe a old/bad radiator cap or are the heads lifting? Car ran completely fine and never got hot ect.

I'd say heads lifting.
Do you have head bolts or studs?

If it didn't overheat and there are no leaks, you more than likely lifted a head an over pressurised the system. I'd pull the heads and take a look.

Studs, slightly overtorqued

yep, lifted a head or split a cylinder wall would be my guess.

You could try changing the cap & backing off the fluid level in the res, but I would pressure test the coolant system & do a leak down.

Kinda my thoughts unfortunately. Im going to get a new radiator cap and bigger overflow and see what happens. It needs that stuff regardless. If it pushes a little water will it really hurt anything? The are thick deck aftermarket heads so wouldn't think they would be lifting at this power level but who knows.

Going to pressure test it later. Highly doubt it went as far as slitting a cylinder wall lol.

If it didnt broke, I'd do a set of better studs, more clamping force and a new gasket will go a long way assuming the decks are good to go

The heads are brand new with maybe 300 miles on them. It has aarp head studs in it now.

Detonation could lift a 22bolt head

It had no detonation when tuning it but i wasn't logging last night when running so no way to say what was going on last night. Wouldn't think it would have been any different though.

If it's not misfiring it more than likely isn't a cylinder wall. I've just had it happen to me & it did the same thing, but would misfire. Fouled the plug like crazy as soon as you put a load on it.

Is it blowing any water vapor out the exhaust? Have you checked the plugs to see if any look like they are burning coolant?

Yeah car runs completely fine. I have the video of a race last night and from the looks of it, all looks clean. Im going to pull a plug in a few and see what it looks like. I dont think its burning coolant.

A dyno is completely different than a long real world pull

I know what your saying. He did a bunch of street pulls with the car as well. Tick Performance tuned the car and I fully trust Jonathon.

Here is a pic of one of the plugs. Same plug, just one with flash and one without. i dont know much about reading plugs. I did a pull dang near right before I shut the car off last night as well fwiw.

Attachment 641674

Attachment 641675

How cold was it out were you were racing? Depending on the temperature the intercooler may have gotten heat soaked with so many back to back pulls. Once the IATs went up it could have detonated and lifted the heads. Do you have a meth system on the car?

Like 35 degrees so doubt they got that high. They were basically back to back pulls. The car does not have meth, but is on E85.

Looks hot to me with signs of det on the porcelin to me. How timing?

What do you mean by hot? i think timing is 21 degrees at the upper RPM's