118k mile SR20 self-destructs for seemingly no reason...

[Antonio Garcia]

Hi everyone,

I'm a long-time list lurker and I hardly post, but I have definitely
learned a ton from this list.

Yesterday I started to hear a loud rpm-dependent metal on metal
knocking coming from underneath the valve cover, specifically near
cylinder #4. The noise started out of no-where after I stalled the car
(oops, heavy ACT clutch pedal) and I made a left turn. No over-revving
at all.

Here's the history of the car: It's a 91 SE-R w/ a few breathing mods.
Nothing major. It used to have S4s, but they were pulled about 3k miles
ago for stock cams. The cam swap went smoothly and the car ran perfect
up until yesterday. Oil levels were good and there were no other
problems. I bought the car not too long ago and it was owned by former
SR20 enthusiasts.

I pulled the VC today and nothing was loose/missing/broken in the
valvetrain. I pulled the #4 spark plug and the electrode looks like
it's been nicked by some other object(s). The gap that I set is almost
gone. From the evidence and the sounds the engine makes, it seems like
the piston is hitting something (maybe a valve?). I'm doing a
compression check tomorrow to what that's like, but I have a feeling
the motor is toast.

Anyone else have any theories?? This is my 2nd SE-R and I've never
experienced anything like this. SR20s don't fail for no reason at all.
I'm stumped.

Thanks for listening,

Antonio Garcia
91 SE-R w/ DET
91 SE-R w/ possibly toasted motor