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So I was an idiot and let people talk me into racing this built fox body 5.0 mustang shortly after I cranked the boost back up 18 psi (was about to go to 20-22 psi) on a new fuel map I started after I significantly changed my timing.
I had not had time to properly tune. We raced twice, back to back (yes the story just got stupider). I did walk on him both times, but both runs I was hitting rpm ranges that I've only guessed at the tuning.
My timing is about 18* for the most part at 18 psi, my EGT's hit 1675*F according to the peak and hold on the Zeitronix display. Looking at the MS datalog, AFR was about 13.0 at the most critical points. I leaned out.
Ever since I start to over heat, when my coolant temp hits 200* (I have a 180* thermostat btw) I begin to push boiling coolant out of the reservoir.
Compression test shows 170 170 170 ~163
Leak down test on all cylinders checks out except for 4. It *slowly* raises the coolant level looking at it with the radiator cap off, until after a while a small air pocket will seep through the jiggle valve in the thermostat.
I'm planning time, and finishing unpacking my garage so I can tear it down. I'm just wondering what the most likely scenario would be, a cracked head, a blown MLS headgasket (no fluid interchange going on), or a warped head (despite me using ARP head studs).
I can drive the car non-boosted for about 30 minutes, or boosting for about 5 before it pushes coolant out, it's slight.
Anyone else have anything similar to this happen to them?
Edit: This is one of the first times I'm actually glad something happened, for me to have a reason to tear down. I'm hoping that I'm not going to have to replace the head, so that I will have some money to throw some cams, and over sized valves in since they are long due.  Joel Baldridge, ASE Certified Master Technician, Audi Certified Expert Technician
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