folex187

Ok, my motor is about to receive a new turbo and aem ems. Before installing this I want to make sure my motor is mechanically healthy. I have been supercharged for several thousand miles. I had an issue before when I first got my supercharger and the motor ran extremely lean for an isolated period of time. My motor has never been over revved.

I did a compression test and received 220, 220, 224, 221. Is this enough to determine that my motor is still healthy? Anything else I can do?

MrChoi

leak down test. measure your bearing clearance. umm maybe measure your thrust bearing clearance. i dont know.

folex187

I was under the impression that if you had tight compression test results a leak down test wasn't needed. Is this wrong?

MrChoi

well you can have two engines which both makes about the same compression. one can leak more air than the other but still can acheive the same compression. but the engine with the leak may need an extra crank or two. its sort of like a leaky air hose, i think.

well doing a leak down will help you figure out how well your rings and valves seal.

Eluded

oil analysis could be helpful.

folex187

I see what you are saying with the leakdown test and it makes sense. I got those numbers by allowing 5 cranks per cylinder. I plan on visually inspecting the cylinder walls when I change my oil banjo bolts.

twohoos

Valve retainers (see Technical forum). Must be examined visually.

Be very careful, and very conservative, with the turbo setup and tuning. History has shown there are two kinds of turbo'd F20Cs: those that have blown, and those that are going to. Good luck.

folex187

It will be tuned by the best and conservatively. This is my daily driver therefore I won't be going for anything crazy. As for the valves, I had a valve adjustment done 5k miles ago so I'm guessing they are still a-ok.

fltsfshr

I agree with this. An oil analysis can not only tell you current conditions by metallurgy and particulate content but it can help you in choosing lubricants, maintenance etc. to prevent or retard additional damage.

Your compression is even but a little bit low, so you are showing some wear patterns.
An oil analysis will tell you what's wearing, if their database is up to snuff, it will make recomendations to you on what to look for specifically to your motor. In addition, it gives you a good baseline to check it further down the road, after your turbo install.

I always write the cylinder pressures with the date and mileage inside the cover, that way whoever follows after me has a good reference right there.

fltsfshr

folex187

Ya I always document the compression also. Funny thing is 9 months ago my compression was 217, 214, 216, 218. It has managed to go up in the mean time

What exactly does a compression test determine? For instance, is it possible to have a knocking motor on the verge of self destruction and still maintain good compression numbers?