compression test

[ybp 095]

Hi what should the gauge read when doing a compression test on a cold car with open throttle

[Mark Barber]

whar engine and what spec

[ybp 095]

It`s a YBP engine and has cp pistons oversize, std rods, std crank, ported and polished cylinder head, t04e turbo turbonetics, BD16 inlet and exhaust cams, 6 long studs, uprated oil and water pumps and DTA engine managment, thats basicaly it.

Thanks

[richyx]

its hard to say what you should be looking at, id say roughly anything over 140 is good, and should read the same or almost the same on all 4, if one is very low then you have problems

whats it doing for the need to have a compression check?

[Mark Barber]

around 125-130 with low comp pistons is good

[ybp 095]

I have 3 pistons that read 125 psi and one reads 123 psi, is that bad ?

[Mark Barber]

absolutly fine in my eyes

[ybp 095]

on idling it`s smoking white and after each time i go out with it the oil level is going down at a fast rate any ideas what might the problem be?

[richyx]

try bypassing your water feeds for the turbo and see if you get any white smoke then, sounds like turbo is on its way out

[ybp 095]

My turbo has no water feeds

[Mike Rainbird]

Let me guess - Cometic head gasket?

[ybp 095]

no it has the rings in the block and the carton is from italy

[Sunnysidebb]

no it has the rings in the block and the cartoon is from italy

You may need to do a cylinder leakage test and not just a compression test. Your figures are all even, that's what counts. your figures are less than 2% deviation. anything in the 10% area is still deemed to be good !!
I'm sure my 7.1:1 engine had around the 130 psi mark. IIRC one my standard engines had a spread from 175 to 190 psi and that was still fine and less than 10% deviation between cylinders.

[richyx]

if you have no water feed for turbo and its white smoke straight from start up then you have water getting into the comustion chamber or somewhere its close the the exhaust manifold, do you ahve any oil water mix ? how does the car run when its started up

[ybp 095]

It runs ok but after some time it start blowing white smoke, I taught it was oil not water