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Sr20Det Engine failure

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Hi Everyone,

Well we have to speak about the wins and the losses in this cause a lost, this is my engine and setup, or it was:

Sr20det Redtop, Forge pistons and rods 8:5CR, 264/264 dropin cams, new valve guides, cosworth headgasket, arp headstuds, tubular exhaust manifold T3 Holset HX35 turbo with .43AR, running pump gas (97 octane ron) with the vpracing octane booster. The last tune was at 22psi peak and 20psi at redline 7500rpm making 430whp with 1.5 exhaust back pressure, EGT had a problem so we couldnt read exhaust temperature. The engine on the dyno didnt make any noise (knock) or pressent problems but at the track was a different story, it was tune at 0.77-0.80 lambda, and the timing was pretty much like all the times that we have run this engine on the dyno with more than a year racing on time attack with no problems, we have never run more thatn 18psi in the past.

At the track on the first session the engine had some minor coolant temperature problems, after two laps it heat up and the engine protection kick in (105°C), it was a firts session with 2% more fuel and -2 degree timing. We didnt found leaks or low coolant level so everything good for the second round. On the second round I take one flying lap, the feel great, then one cooling lap and then when I started the second flying lap I heard a noise and slow down just to see a giant with smoke cloud behine the car, turn the engine of (oil pressure OK).

When we take the head of this is what we found. The block have damage on the cylinder 2, I am guessing that we run into to much heat cause we found some light marks of overheating in the exhaust turbine aswell. Even the pistons looks OK the second cylinder is a little rough on the surface but didnt make any damage on other parts or in the head.

First what do you think that cause this? I thinks is a overheating problem not just or not knock, and the second question is what would you make to solve this problem, I was thinking in going .86AR for the turbo, fix the EGT gauge, run 116 50% and 97 pump gas 50%, and probably a richer mix to stay safe. Slevee the engine ofcourse...

Let me know what you guys think

Attached Files

I guess that in chile is difficult to find e85 right? that would help you a lot with egt problems.

suerte ;)

There isn't... I mean we have sunoco E85 but cause is race grade fuel is very very expensive...

is that the head gasket that still layin on top of the bores?

It looks like you've lifted the head and breached the gasket, I seen this on 3 different engines last year. I'm not sure if it's coincidence but all of them had Cosworth head gaskets and ARP head studs.

thats good info, Chris250...

the engine is gonna be putting back together with JE headgasket and the same ARP head studs. I'm gonna tune the engine a little richer and the change in the exhaust housing... so for you is not a problem of "heat"?