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Old 08-02-2012, 10:55 AM   #1
drostedrummer89
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Join Date: Sep 2009
Fan#: 69059
Location: Royal Oak, MI
What I Drive: 2002 Sonic SVT

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Turbo SVT with possible blow by?

I have been helping my friend Trevor (FocusOnTheD) with his ongoing issues in his fully built turbo svt. it doesn't build boost from a roll until nearly 4,000 rpm, and oil is spraying out of the dipstick tube due to the crankcase being pressurized, and we can't figure out why. We have done compression tests, leakdown tests, and none can completely point to a definate cause. He is going to send it to a professional speed shop if we can't figure it out.

The car was tuned on 13 psi and 18 psi, he doesn't even bother running high boost anymore, for fear that something's going to blow.

leakdown test:
cyl 1: 7% loss through valvecover hole
cyl 2: 10% loss through valvecover hole
cyl 3: 20+% loss through intake tube, also felt lots of air exiting thru cyl 4 spark plug hole when we pressurized cyl 3.
cyl 4:10% loss through valve coverhole

anything under 10% is considered within spec, right? The numbers did not change when we added oil to each cylinder and retested. is there any way a bad headgasket could be causing air to escape into an oil pressure or return hole? we checked cam bucket clearance on cylinder 3 to see if incorrect buckets were holding valves open, they were all at .006". could this mean bent valves?


Mods:
forged low compression pistons, forged rods
arp head studs
arp mains, billet caps
turbonetics t3 super 60 (freshly rebuilt by Turbonetics)
Tuned by tom

any advice is appreciated!
Matt


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00" Red ZX3: Volant, ported throttle body, titanium wrapped SVT header, 2.5" exhaust, Magnaflow res/muffler, FR UDP, Mac cam gears, Lowered 2", Koni's.
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