Hey whats going on guys.

I have a 98 coupe with a Poor mans R. I did a compression test today and in cylinders 1,2,4 had 248-252psi and then cylinder 3 was 190. I added a teaspoon of oil to cylinder 3 and the psi went 225. After reading I found that the results show the piston rings in cylinder 3 are failing.

Is it worth dropping the motor and rebuilding the bottom end?

 

Worth it to you ? Me? Money, time or both? My thought is always that when something is broken you are supposed to fix it.

 

I didnt know if those results or that low of a psi needed fixing now or if it was going to hold up for X months or years. I planned to boost the car over the winter and have it ready to go by early spring. Only plan to make around 300whp as this is my daily just want something fun to mess with.

 

You can't boost anything unless your compression tests show more consistent numbers than what you have.

 

Thats what I figured. Guess Ill pull the motor and rebuild over the winter instead of going boost. Cylinders 1,2 and 4 are good/average for the motor. Damn you cylinder 3!

 

I would do it again in addition to a leakdown test before coming to the conclusion that you need a rebuild.

Is it smoking after decelerating in gear down a hill?

Also are you testing with the gas pedal depressed?

Imo you should turbo it as-is, if you're going to rebuild the motor you might as well get some forged rods and pistons to make that 300whp reliably as you want, provided that you get a good tune. The most bulletproof motor will blow if you don't have a good tune.

 

I wouldn't turbo anything that was exhibiting these kinds of symptoms. We're not talking about a bad tune sine we haven't even gotten to that point yet. We're talking about a problematic engine.

IMO build the engine for boost and boost it since it has problems now. That plus good tune equals reliability.

 

I wouldn't say for certain that it does have problems yet - it's fishy that even with some oil added the cylinder never rose above the other three cylinders. It may not be piston rings but rather valve seals.

My old D15's compression results were something like 140,140,100,140. When I added oil it shot up to 200psi in that cylinder.

I agree that you shouldn't boost a problematic engine, but make sure it is indeed problematic before deciding to pull the motor and rebuild. A leakdown test will tell you exactly what's wrong with the motor.

 

That's true. I always forget about valve seals.

 

I plan to do a leakdown test this week. I also wanted to state after reading what you guys were saying, The car has S100 in a p28 and is tuned.

The car had a messed up ecu and replaced that with a the s100 and the tune. Have a couple good connections at a shop that helped me out. I was not there for the tune ( I was working). They said the car was down about 20ish whp.

Also if I rebuild the bottom end, just like the turbo build was all a budget build. This is my secondary vehicle that I planned to drive daily once finished. Ps, there are pictures of the car in the 2006-current thread. There's a picture thread stickyd at the top.

 

Do you smoke after decelerating in gear down a hill?

Smoke on startup after the car has sat for a while?

 

Not that I know of. The car does smoke (black) very little when Im getting on it. Buddy told me about it. He said it was less then smoke then my 07 si.