What's Under The Hood?!?
 

I bought a 2001 s2k that seems to have a built motor and a precision turbo setup. What's the best way to know what I actually have? Teardown? Take it to tuner? I couldn't get a whole lot of info out of the previous owner. Any suggestions?

Best person would be the previous owner. Why couldnt you get info out of him, he'd be the only one to know for certain.

a teardown would be costly and unnecessary especially if its just to know what has been done.

The previous owner isn't the one that built it...

Crazy and risky buy. Hope its tuned well. Find out who is the most reputable s2k tuner in your local club and take it there to get checked out would be my advice. Probably should have him get a laptop hooked up to your ems and see what he can find, decide if you should get it on the dyno for a tune or not, just so you know its running in top shape.

[left]That's a bold move to buy a boosted car you know nothing about

First thing I would do is compression test. Change all fluids. Then get a baseline dyno and take it from there. Happy motoring :drive:.

If you can't get a solid history of the build you have to do a Compression AND leakdown test. The compression test won't be informative without knowing the compression ratio (compression test with 9:1 CR will have different numbers than 11:1 *IF* the motor is healthy). A hurt 11:1 motor can have the same compression test numbers as a healthy 9:1 CR motor. A good leakdown will tell you if your sealing surfaces are good and then you can infer your CR from your compression test numbers. However, even then you can't be certain if your motor is built if you end up with stock f20c numbers.

You'll need to pull the oil pan and windage tray and look at the rod caps. If you see forged caps you'll know you're built. You'll now also have a decent idea of your compression ratio and the condition of sealing surfaces (rings, valve seats). Your tuner is going to need to know the compression ratio anyhow.

Additionally, pull the valve cover and cams to see if you have headstuds. This way you can make sure when you reassemble the cam timing and valve lash are set correctly. Just because it's "built" doesn't mean the builder wasn't lazy. Verify EVERYTHING. Your motor and your wallet depend on it.

HTH