Wiseco Piston rings lost compression

[chris4g63t]

Ive had this motor in my car for about 3000 miles and it started with 160psi compression(which is normal for my elevation) in all 4 cylinders. Pistons are 8.3 wiseco's. Just did a compression test and is now 130-130-135-140. I am making about 380 hp on a fairly "safe" tune but I do have over a hundred passes on it. What would cause my piston rings to wear out this fast and how long should one of these motors last?

 

[GVR4592]

What clearances did you set for piston to cylinder clearance, and piston ring end gap? Does it smoke?

 

[chris4g63t]

did you install cams ?

No. The car has a stock head with stock cams.

 

[chris4g63t]

What clearances did you set for piston to cylinder clearance, and piston ring end gap? Does it smoke?

Hewes Machine set all of the clearances to wisecos specs. I talked to the builder of the motor today and he thought it was very stange how all the cylinders could loose compression at once. I'm going to do a leakdown test to see exactly where I am loosing compression but Im 90% positive that its the rings because of the results of the wet cylinder test that I did. Any other suggestions?

 

[chris4g63t]

Maybe your battery is low, old starter, seen results that kept getting worse and worse as the day went on, due to those 2. However, what was your wet test results ?

Definatly start with the basics thou.

The wet results were 160 across the board. My battery was charged and was cranking the motor pretty fast. The weird thing about this is that the car doesn't smoke or loose oil. Is it normal for the numbers to jump up that high when you put oil in the top of the cylinders?

 

[diambo4life]

Is it normal for the numbers to jump up that high when you put oil in the top of the cylinders?

Yes; Because some of the oil ends up on top of the piston crown effectively increasing your compression ratio & consequently skewing your test.

 

[GVR4592]

The rings could've been damaged from detonation, or not set up properly to begin with. Either way that compression seems low and the variance between 130 and 140 is quite a bit. Probably time for a leakdown test.

 

[SlowSpyder]

start with the basics, Engine at operating temp and wot during the compresson test. If nothing changes and its still low check your cam timing. Incorrect cam timing can yield lower compression results on ALL cylinders. Like someone said earlier youll probably need to do a cylinder leakage test to verify if its your rings.

 

[chris4g63t]

Either way that compression seems low. Probably time for a leakdown test.

I didn't think 130 is that low considering I live a 4500 ft above sea level. Hopefully I dont have to tear this motor down again. This will be the 4th time in the last 2 years

 

[GVR4592]

130 might not be that low, but the difference between 140 and 130 is out of tolerance. Why have you had to tear it apart 4 times?

 

[chris4g63t]

130 might not be that low, but the difference between 140 and 130 is out of tolerance. Why have you had to tear it apart 4 times?

Well the problem decided to solve its self. Compression today was 145-145-145-150. The reasons why I had 4 motors in the car in the past 2 years: First time I had a bad case of detonation. second time I decided to buy a motor from M&s Recylcling and it spun a BS bearing with in 3000 miles. That was covered under warranty so I put the new motor in and we had a flood here in Reno. I drove through what I thought was a puddle and hydrolocked the motor. The 4th motor I decided to go with the eagle wiseco solution. It was all put together, started it up and it started shooting coolant out of the head gasket due to a small knick on the combustion chamber of the cylinder head. Anyways this motor has been running good so far and has got me an 11.8@122 with an 18g