As some of you may remember.. I rebuilt my LSJ 8 months ago. She now has 10,500 miles on her since she's been back on the road.

Replaced most of the valvetrain with OEM replacements, resleaved the block, ARP Headstuds, Cometic H/G, Clevite bearings, Diamond pistons.. the remainder of the block is basically stock. Brand new S/C with stock pulley and even had my transmission rebuilt.

My Diamonds are 10.5:1 compression and I used (New) OEM piston rings.. (long story).

Well this past weekend my friend & I did a compression test, just to check up on it. I was a little concerned with how well my piston rings were holding up. Had no signs of blowby, but, with what little information there is on this combination, and what there is, being negetive, I had my concerns. I followed the GM build book as one of my resources while re-assembling the engine, and they did use this combo, however, after the fact, I found on here that there are some precautions to consider..

Well the results are as follows:

1= 200... 2= 205... 3= 195... 4= 200

Needless to say I was more than happy with the results.

Just wanted to share

 

Very nice, those numbers should be even enough to consider you have a good ring/valve seal going on.

 

Thanks Aaron. I am really happy with the results =] I was really expecting to see some lower numbers.

Oh, and I believe 180-210 is what I heard for a healthy LSJ, so to be on the upper end of that range is comforting.

 

I wouldve expected a little bit higher since youve got 10.5:1 pistons in the but 195-205 is perfectly acceptable, thats not even a 5% variance between cylinders. beyond 20 is where you need to start getting concerned.

 

Yeah, exactly.. Im assuming that may be part of the reason why im on the higher end of the acceptable compression range, thats If I am correct with what I remember hearing.

Eventually I may do a leak down test, to see if it is actually holding compression under boost. But with there being no need for concern with the compression check passing, and not seeing any visual signs of blow by under load.. I certainly am in no rush, just more so curious.

 

this eases my mind a little bit about my 10.5:1 build in progress

 

Just FYI: Im running stock pulley, 42.5# injectors, 1 step colder plugs, and slightly advanced timing even, if your responsible and are tuned properly you will be fine. I got ALOT of **** talked to me on here about how irresponsible and stupid it was and what a failed build it was... since I upped compression on a boosted car.. these type of comments are ignorant.

My Cobra heat exchanger is going on in the spring, may do a dual pass endplate set up, and possibly meth in time as well.. and certainly would do all this if I decide to pulley down.. take a lil extra precatuion with the comp ratio.

 

yea ive taken all the proper steps/percautions to have a successful build. i just cant wait to get my beast back on the road and really see what its gonna do.

 

I know that feeling. My SS was on jackstands for a year.

You'll love the pistons tho.. Im in no rush to pulley down, because of them. Nice little addition to the powerband

 

Dont listen to the ignoratii Jazer, while it may not be the way to go for a 600hp build, it sounds like youre perfectly safe.

 

My kind of diamonds boys, haha.

 

i thought your block was sleeved?

 

stock sleeves!

 

Yeah, resleeved with stock replacement. Almost had my machinist put Dartons in, but It just wouldn't be worth it, for what I wanted out of the engine.

 

oh... gotcha

 

Yup.

Everything seems to be holding up good and strong, so I couldnt be happier... Now to get to that POS belt tensioner.. lol.