hi everyone, just a quick one really!does anyone know what compression figure (in psi) i should be getting on a freshly built engine (cossie 4x4) with 0 miles on it??

thanks in advance

 

Atleast 140psi across the board imo

 

would that be for an engine that has been run in or would the figure be higher on a car that has been run in?

 

If its ran in well and has good ring seal then it should rise a tad.
What do you have at the moment?

 

120 psi

 

And is there a problem?
Where the rings gapped well?(in relation to each other)
Where the valves lapped in?

 

the car is smoking when warm upon accelaration and at idle.if you turn the engine off then restart then the smoking stops.haven't driven the car again after restarting though.the rig gaps were set correctly and the valves were lapped in properly.

 

Thats a strange one. Did the engine blow presvious to the rebuild? could there possible be fluids remaining in the intercooler or exhaust?
What colour smoke? And how much smoke?
how long have you ran it for,and at what rpm?

 

had blown the previous engine yes but the rebuild included new block, new pistons, reground crank and balanced bottom end.also a different head was used and rebuilt!i thought it may have been the turbo (even though that was new also) but i sent it back to be checked and was told it was fine?!want to try another turbo really.the intercooler is also brand new.its definitely oil smoke and there is a quite a bit of it also.the engine has only been driven max 4 miles and never above 3000rpm.

 

how long should i crank the engine for with the compression tester in as a matter of interest?!lol.i crnked it for about 3-4 seconds for my figures.

 

Crank it for about 10 turns(you can sorta here it,lol) with the throttle at 100%. Do each cylinder equally.

 

that may be my problem then!i didnt have the throttle pressed at all!!lol will try it again tommorow.thanks for your help RS1 !

 

if 120 on all bores, leave it and test it once run in.

Compression ratio makes alot of difference on any engine on a compression test.


Dont forget, alot of cheapish compression testers will read different to each other.

Did you test it with good battery, hot oil temp, throttle open, and all plugs removed??


On my cossie, runing 8.0:1 cr, is 165-168 psi on all 4..

 

If its not been run in yet, get it nice and warm and go thrash the pants off it for 200 miles.

 

By 50 miles it should be 90% run in roughly.

Test it after 50 and see what you get, its a bit meaingless now.