Low Compression on new build

[wird06DSM]

Ok I know there is a lot of threads about this but.. I need to Vent i guess. Well i just finished my full motor build that now has about 20 miles on it. Well i did a compression check today after seeing my catch can smoking after come moderate driving yesterday. Compression was 1 140 2 135 3 130 and 4 95. I have build head with bc280 and weisco 8.5:1 compression. Well i let the car idle for 45 mile straight today at 1200rpms and the catch can never smoked one bit. On Initial start up i ran into a few problems with dsmlink socketing ( NOT TOMS FAULT) and idling issues. There now fixed but i still don't understand why my compression is so low and all over the place. My break in was half buschur style and half motoman. Idle at 2k for 30min then go out and do pulls and let vacuum seat rings coming off of a high 3rd gear pull. Max boost seen was 8-10psi

 

[BoredDSM]

I would hardly call 20 miles of driving on an engine a break in period. Compression will go up in the next few hundred miles if anything. What kind of oil are you using? Best way I have used to seat rings are to just drive and do some engine braking. Make sure you change your oil in closer intervals with conventional oil for the first few thousand of miles.

 

[wird06DSM]

10-30 castrol conventional. I got to fix my IAC leak, its driving me insane. I always heard rings seat within the first few min of start up?

I just dont understand the big variation in compression.

 

[JacksonAuto]

With modern ring technology, the engine should be broken in by now. They should be seated after just a few minutes of driving under light loads.

Do a leakdown test next. That will tell you where the compression is leaking. Could be the rings, head gasket or valves.

 

[wird06DSM]

How is it that in other threads other people where talking how they had the same problem but the rings seated in a few hundred miles?I used the search button prior to my thread

 

[JacksonAuto]

Like I said, the rings should be in by now. If not, then the block wasn't honed properly or the rings washed out due to a crappy tune. The problems that other people had can most likely be traced back to shoddy machine work or poor assembly, too. Just trying to help you with your problem bro.

 

[smokeyjpn221]

Like I said, the rings should be in by now. If not, then the block wasn't honed properly or the rings washed out due to a crappy tune. The problems that other people had can most likely be traced back to shoddy machine work or poor assembly, too. Just trying to help you with your problem bro.

x2...good advice on both posts

 

[joe sobo]

With modern ring technology, the engine should be broken in by now. They should be seated after just a few minutes of driving under light loads.

Do a leakdown test next. That will tell you where the compression is leaking. Could be the rings, head gasket or valves.

i am trying to find on this site where it tells you how to do a leakdown test to no avail.... any help guys?

 

[Rengar18]

Leak Down Test VFAQ

The search button is a wonderful feature...