So I bought an SC'd S2000 and went to get it retuned to make sure all was well. Well, I was running lean under boost (the previous owner hadn't had it properly tuned). I know, rookie mistake buying the car. Live and learn. I did a compression test with these results:

210
210
225
230

Plus, I have felt a couple misfires! She's all tuned up now but she was running lean and I'm afraid the damage is done. I'll just drive around until I grenade this motor. Drives fine, really...I bet it'll go a long ways but she's not healthy. There's likely damage in the block. I am going to have Inline Performance do a leak down to see what's up.

J

 

Hmmm, firstly that much variation in the cylinders is not that bad.

Secondly, there is a huge difference between a burnt valve and a holed block.

Don't make another rookie mistake and turn a $1000 problem into a $5000 one.

YMMV

 

I though that some superchargers worked fine out of the box, no tunning need it.

 

Ok...so help me out. What would you do? Get a leak down test...diagnose the problem. Would you ride it out until the motor goes or would you pull the motor and have the bottom end rebuilt? I don't think it's going to be a valve...I didn't over rev...it's the tuning that was the problem so I really think it's going to be a problem with the bottom end of the motor. If it's not I'll do a built head )

 

They do unless you're irresponsible and buy a VAFC and injectors but don't connect the EMS and don't get it correctly tuned. The previous owner had me convinced that the car was properly tuned and getting enough fuel. This is ultimately my fault for not doing my homework properly. I should have done a far more extensive checkup on the car but the guy really had me convinced.
At least the damage isn't catastrophic. Better to know the damage is done and that I need prepare for a bit of a rebuild than not to know. Right?

 

We really need to hear from Slow or one of the real mechanics here but I'm not sure you've presented evidence of a problem. I seem to remember the the acceptable variation being in the 30's and you're at 20 (or +/-10).

I would get a bore-o-scope or head off inspection and go from there. And regardless of the current state of your engine a good tune is always appropriate.

 

Will do! Thanks!

 

Compression test #'s are an inncomplete picture of the engine's health. You don't have enough variance to condemn the engine at this time. The factory spec is 135-228psi max variation of 28psi.

Most crank out 220+.

A cylinder leakdown test needs to be done on a fully warmed up engine. 10% leakage max is in the "acceptable" range. 5% or less is a healthy leakage number. Just because a cylinder is at 8% doesn't mean the engine is a hand grenade. If you do have a leakage higher than 10% you need to look for the source. It can be rings, or valves not sealing. There are many causes for both.

A boroscope can take a peek inside without taking the cylinder head off.