So I passed 1000 miles...and...compression question!

[Sean]

It's running fine...but...I have some problems.

First - I'm leaking oil somewhere. It's from up front, and it's really really small. it's getting the bottom right of my front engine bracket wet with oil - so I'm pretty sure its one of the front rocker shaft plugs. They fit in there real tight...actually, didn't really go in real well - but I thought they were tight. The front seals on the head were all redone. Any ideas?

Second - and this issue is really bothering me. I did a compression test - and I was slightly disappointed with my results. With the throttle wide open - I get 150 PSI ACROSS ALL SIX. it's good that they're consistant - BUT 150?!!!????? I can't figure out why they are reading that low. Would it maybe be restriction in my air intake - maybe I should remove the airbox?

Granted, this is a perfect number for boost - but I'm really not impressed. That's quite low. Hell...that's lower than my other engine did - STOCK! My other engine, before being pulled, hit around 165 on the first three, then dropped to some odd numbers between 135 and 125. Mind you - I had my head shaved .015" - so it should be DMAN close to stock IS compression!

So...yea. Love to get everyone's take on this.

Other than that, the car is running great! Spark plugs look fantastic!!

Reply soon...yes.

[EtaSport]

Compression psi numbers really aren't that proportional to static compression. You have to take a lot of things into consideration like camber cc, cam duration, and piston dome. If its 150 on all 6 within 5-10 psi, then you should be satisfied. Plus keep in mind your motor does have a lower static compression at 8.5. My eta is @ 9.0 and only has about 160 on all.

[nando]

I'm already at about 750 miles, and I haven't driven much in the last few days (have a tranny leak I need to take care of). bummer about the leaks, mine hasn't leaked a drop since I put it together, allthough my front diff is leaking a little bit. it's nice to have a clean engine though, because I can actually tell where they are coming from..

[Sean]

I'm already at about 750 miles, and I haven't driven much in the last few days (have a tranny leak I need to take care of). bummer about the leaks, mine hasn't leaked a drop since I put it together, allthough my front diff is leaking a little bit. it's nice to have a clean engine though, because I can actually tell where they are coming from..

Yea, tell me about it. The leak is really pissing me off.

Thanks for the reassurance. i suppose the combination of the different cam and my bottom end can cause for that compression, huh?

[EtaSport]

Probably.. in reality you may have like 8.7:1 or something like that. You'll never really be able to tell by looking at your 150 psi number.

[Ender.]

From what I have been told and as previosuly stated as long as they are all with in 5-10 psi of each other, everything is good.

Goodluck tracking down the leak!

[rs4pro3]

check that upper forward corner of the headgasket. I've heard on many people having a leak from there even with a new gasket.

[mspiegle]

If you replaced your cam with a longer duration one, you may have changed your 'dynamic compression'. Since you're just doing a compression test, you might be getting less air in the cylinder because the air is moving very slow (as opposed to how it moves above 5K rpm).

[Sean]

Yea, that's what I was thinking.

In time, I'll do headwork, and open this motor up more. lol

rs4pro3 - if it's the headgasket - the only thing I can do is change it, right? I'm hoping it's something else. I'm really lost on this though. I cannot figure out what's causing it. The side of my bell housing is wet with oil - but only on the drivers side of it. I felt up above the bell housing and behind the head (thinking the headgasket was leaking) but I seriously saw nothing.

so confused!

[nando]

I seriously doubt it would be the headgasket, because you would have to be losing compression in every cylinder - and headgaskets aren't *that* difficult to put on. I think it's because of your longer duration cam.

[Sean]

I seriously doubt it would be the headgasket, because you would have to be losing compression in every cylinder - and headgaskets aren't *that* difficult to put on. I think it's because of your longer duration cam.

Nah, I'm thinkin about the oil leak.

Compression wise, I'm pretty sure it's the cam too.

[Ender.]

You wouldnt be leaking oil b/c of the headgasket... at least not outside of the motor. Unless there is oil in coolant, coolant in oil, or a variance in compression b/t cylinders it is highly unlikely to be your HG.

[rs4pro3]

remeber Jordan had this same issue with his stroker, that corner of the gasket sticks outside of the rest of the block, and dosn't have as much clamping force on it from the headbolts. I can't remeber if he just retorqued the bolts or what.

[rs4pro3]

Here is a post from James about the problem

http://www.r3vlimited.com/board/showthread.php?t=57114&highlight=Oil+leak

[Sean]

I'll try to track it down. I'm going to attempt to take some stuff apart this weekend - and see if I can tell where the leak is comin from.