Project Frankenmiata – Failure is ALWAYS an Option

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Eyesore Racing Frankenmiata - Failure is always an option

You'll notice none of these repairs had anything to do with fixing the inevitable carnage that screw caused inside the cylinder. We really wanted to see the damage and come up with a fix, but we burned up all our weekends fixing other damage. We did a leakdown test on cylinder #1 and it was horrible, but not really any more horrible than the rest of the engine.

You can see the record of multiple compression and leakdown tests performed over the years on this engine, but no pattern showing #1 is really much worse than the others. The dramatic drop in compression from 210 to 167 psi has more to do with a change in cam timing (we advanced the intake cam one tooth on the timing belt to get more torque) than cylinder wear.

Eyesore Racing Frankenmiata - Failure is always an option

We even tried borrowing Mark DiBella's boroscope to look inside the cylinder, but the images were blurry and inconclusive. The piston looked wet, just like the others, and our attempt to spot valve seat damage revealed, well… this picture…

In the end, we just ran the engine without any internal repairs for about five more races.

 

Gasket

8 Months of reliability later, our failure clumping started up again at Buttonwillow Raceway. The first sign I had that anything was wrong was when a little squirt of coolant splashed the inside of the windshield. Our radiator is mounted in the passenger's seat, inside a box made from an old hot water heater shed. Apparently there's just enough of a gap where shed meets firewall to put a little splash on the glass when the coolant overflow hose gets blown off. It was then that I suddenly realized I hadn't looked at the temperature gauge in about six months. Early in this car's racing career, I watched the gauge more than the track, but as the cooling system proved itself to be dead reliable, my attention wandered to the 170 idiots sharing the track with me. 

My first glance at the temperature gauge was 230 degrees. My second, 240. Game over.

Normally, when a head gasket goes, we try filling it back up and seeing how far we can run. This failure, though, was so much more catastrophic than the slow head gasket leaks we were used to, we went straight to the head bolts. We actually had a spare head gasket with us, but if the gasket mating surfaces are damaged enough to blow one head gasket, they're usually bad enough to blow another.

Eyesore Racing Frankenmiata - Failure is always an option

It didn't take long to find the cause of the gasket failure. All the pistons and all the combustion chambers showed detonation pitting like this, but #3 was the most severe by far. This particularly nasty pitting worked its way up under the combustion ring of the head gasket, causing the failure that put us out of the race. A new gasket would suffer the same fate almost immediately.

Eyesore Racing Frankenmiata - Failure is always an option

The intake side of the combustion chamber (both piston and head) had almost all the detonation damage. The edge of the #3 piston was eroded away so severely you can actually see the top of the #1 compression ring when the piston is at BDC. This is never a good sign. 

Eyesore Racing Frankenmiata - Failure is always an option

This was the first time we had the head off since the screw incident. Funny, this is exactly what we imagined a screw in the cylinder would do. We had imagined a combustion chamber like this would lead to worse detonation, since the sharp edges are typically thought to cause hot spots that lead to detonation, but all the detonation damage was on the opposite side of the cylinder, which had far less screw damage. The worst detonation was also in a non-screw cylinder.

Eyesore Racing Frankenmiata - Failure is always an option

The parts of the piston that were slamming the screw into the head didn't look as bad as you'd expect. The little pock marks across the whole piston are from the screw dancing around when it wasn't being slammed into the quench pads on the cylinder head. The severe damage in the foreground is actually detonation damage and looks nearly identical to (but not as bad as) the damage on the #3 piston. All the pistons showed some of this detonation damage, though.

Eyesore Racing Frankenmiata - Failure is always an option

Surprisingly, there was some foreign object damage in other cylinders too. We have no idea where this dent came from. Perhaps it happened in the 180,000 miles before we got the engine.

Eyesore Racing Frankenmiata - Failure is always an option

This cylinder even had a little piece of steel embedded in the quench pad. No clue where that came from, or when.

 

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