After a bit of a boost last night the car sounded like a subaru and was down on power. Car was at good temperature when this happened.

Today I removed spark leads for cylinder 2 & 3 with no change to rough idle.

I replaced the coils and igniters to help solve it with no change.

I just done a compression test, here are the results:

175 25 25 175

The engine has now done 600kms from rebuild. Timing was all set and things were running smoothly with nice power. I had not yet had the head re-torqued and only just done first oil change.

Oil color is still golden and still nice clean coolant.

Anyone can please help me i am in "freak-out" mode as they say.

 

who built your motor and do you know what the ring gaps were ? was it an OEM rebuild (pistons, rings ?) or were after market pistons used ? if after market what kind and C/R ?

 

If you have that low compression more then likey you got wacked valves. Did you put oil in the cylinder before the compression test?

 

Low comp on 2 adjacent cylinders usually indicates a blown headgasket between the 2 affected. Could be something else though hope it's not too bad but speak to your engine builder 600km is not even run in yet.

 

I bought the engine already rebuilt... no warranty

 

Im going to pull head off tomorrow, get steel head gasket and arp studs.

 

I was thinking the same thing, since the two cylinders with low compression are adjacent to each other it seems like the head gasket isn't sealing properly. Do a leak down test to ultimately determine where you are loosing compression. Set cyl 2 at TDC and screw one end into a #2 spark plug hole and blow compressed air into the cylinder, take your radiator cap off or reservoir tank cover and if you see bubbling it means the compressed air is getting into the water jacket (bad sealing of the headgasket) Goodluck man!

 

that sucks, like every one said your gunna have to tear it down. hopefully its something small

 

Hopefully it's just a HG, but why were you boosting on it so soon? Under 400 miles means everything just got past that "tightening up" point. I've always gone 1000 miles on conventional oil to insure proper break-in and then switched oil and introduced boost there.

Why don't you check torque on the center two studs and see where it's at? 95 lb-ft is the magic number for most studs.

 

Head is off and sure enough the bridge between 2 and 3 is broken. Head is to be check/pressure tested tomorrow.
Once the pistons rings have sealed it should be good to go. and I wasnt thrashing it, 1 bar isn't that much boost ya know,
Not all of the head bolts had the "crack" when loosening.