Hi all
I ve just begun my engine running in and everything is fine, no leaks, no smoke, pulls nicely (only using 0.5bar boost and not going over 4000rpm).
decided to do a compression test as a bench mark figure to keep track of the engine's health over its life and I m a bit surprised....
I have a perfect 130psi on each cylinder (no variation between cylinders) bit this figure seems a bit low.... and has got me worried !
engine has stock pocketed pistons, grA Head gasket, refurbed head but only one skim on it and bd14 inlet, std exhaust.
What do you guys think ?

 

What does your engine builder/tuner say that's who I'd be asking

 

Well actually I m my engine builder / tuner and I think my piston pockets and grA headgasket have lowered my compression ratio slightly more than alticipated.
but the engine works perfectly (no smoke, no misfires and pulls fine) so I m reassured

 

I suppose I really wanted to know if anyone knows the figures of what their stock compression test values are or even better what their pocketed piston values are.
anyhow I ve just done 200km of run in and the engine is doing great, leak down test is fine, no smoke no nothing really so I consider myself sorted.

 

If the engine is now run in you need to get it on boost to see how it performs on the open road.

 

I'm pretty sure my old 4x4 Cosworth was 150psi on first oversize standard pistons

 

Cheers, thanks for that.
I did ŕ leak down test and have under 10% leakage from each cylinder so I know now that my engine build is perfect and my rings are definatly seated ok. So my 130psi compression figure is definatly coming from my piston posckets and headgasket.
The engine is perfect at the moment (only done 350km run in ) I ll report back when I can finally put my foot down and see what it s like with réal boost (I ll probably break the gearbox &#129315

 

Different cam timing can also make a difference, didn't notice that you had a bd14 cam!

If there's more overlap than standard the cranking compression will be less...

 

Yes I m taking that into account as well. Thanks for the help !

 

I reckon the compression ratio will be about 7.5 to 1 which is the same as my 2wd Saff and is now thought of the "old school" way of tuning. Nothing wrong with that as with other modifications you could easily be over 400bhp!

 

Thanks for the info. Yes I think I ll be hitting the 400bhp mark.I m running rplab programmable ecu with greys and t36 turbotechnics and all the other mods to follow including chassis and brakes.