BADSS

iTrader: (7)

What sort of numbers are considered in-spec for a compression test on a LS1? My car has been running poorly, and it was theorized that a cylinder might be down. All cylinders showed compression of approx. 150, plus or minus 5%. The local shop that did the test says the results are acceptable, but they do not claim to be a high performance shop. They could not diagnose why the engine is running poorly. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

wrencher

iTrader: (2)

150 is down a little but all cyl. are even? 185ish is more the norm. What exactly is running poorly?

SixPak

150 could be considered low, but was the engine warm or cold? on a cold engine I wouldn't be to worried about that as things tend to tighten up as they get warmer. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

BADSS

iTrader: (7)

Thanks for the replies, guys. I don't know if the engine was cold or hot at the time of the test, I wasn't there (just dropped the car off). The engine used to consume alot of oil, but that seems to have stopped since JPR modified the PCV system. The engine has developed the cold engine knock problem within the past few thousand miles, and it has a sporadic miss. It idles roughly, and hunts and surges at idle more than it should, IMO. I know some of that is normal with a cam (TR 224/224 112 LSA), but I do have custom programming and it is definitely running worse than when I left JPR. Joe felt I was getting excessive blowby- you could see smoke coming out of my Metco valve cover breather all the time- and the power was about 10-15 HP less than he was expecting, even after a dyno tune. Joe felt I might have a cylinder going down, and the car has been running progressively worse and worse since the heads and cam install. The power seems to have dropped off a little bit, too. Any ideas? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />