87 Shelby Z - 2.2L
Forged Venolias
Ported head (unknown as to how much)
Mild cam. Has a very subtle tone at idle.
S60 turbo .63 a/r
+40 injectors.
11mm ARP Head studs.
Stage 4 BoostButton Cal. (Burned myself. Only the CEL flash option is enabled.)
Fuel pressure set at 55psi (after last increase) and base timing at 12 degrees.
Manual boost controller.
Was helping my friend get his car dialed in last night after redoing the vacuum line system and adding some proper instrumentation to the vehicle. We were slowly inching up the boost 1 or 2psi at a time and adding fuel pressure as needed. We started at 45psi and ended up at 55psi although it was a bit rich at that point. The car was doing awesome clear up to and including our last couple 15psi boost pulls. The wideband was reading fine, no CEL ping flash, just smooth all the way to redline. We figured it could do a little more and I dialed in another turn on the MBC. I started another 2nd-3rd-4th gear pull but as soon as the boost hit 16-17psi the engine stumbled hard for just a second then resumed running smooth again. We pulled to the side to inspect, nothing looked out of place so we limped it back without hitting boost because any time I'd give it throttle and the boost gauge would even think about creeping over 0psi, we were getting CEL flashing due to pinging. Everything looked fine after pulling it in the shop and the engine was still idling and free-revved smooth as ever.
After sleeping on it, I'm thinking we got some pinging on that last pull at 16-17psi and damaged the head gasket. What are all of your opinions on this assumption? I know I will need to do tests to verify, but it's currently the only idea I have. My friend is working today so I don't have access to the car.
Also, neither myself, nor my friend assembled the engine. He bought the car 80% completed where it just needed a bunch of little odds and ends and dialed in. I cannot attest to how the head was originally torqued down. Engine has very few miles on it as it was never running properly before he bought it
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