Quote:
Originally Posted by getz
Went out for a spirited drive today and ran the rpms up to around 6.5 grand and suddenly billowing smoke out of the exhaust, and the oil gauge bouncing all around. Oil pressure didn't appear to be affected, and the car seems to run okay. Any thoughts as to how much I broke her? On the upside I have been saving to send her out to Turbokraft.
Info: Modified 88 930 with EFI. I bought her from an old fella in Florida and she has driven well for the past 2 years. I don't know much about the components, but apparently increased displacement, new pistons, and a bigger turbo.
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The bouncing oil gauge is the mystery -- for sure the level gauge, correct? You say that pressure didn't appear to be affected.
Oil still blowing out the exhaust? Is she still running okay?
A cold, dry cylinder leakdown test will tell you a lot about the internal condition of the engine.
These scenarios are another reason we advocate for a -0.5 -- 1.5bar 935-style boost gauge: you get a sense of what "normal" vacuum for your engine is at idle, A/C off.
If you mechanically hurt the engine, either break a ring or blow a seal, you typically lose some vacuum and it registers on the gauge. If you're drawing the same vacuum as always, it's more likely everything is fine mechanically (no blown out o-rings or top rings) and it's something else (turbo seal failure, etc.)
FWIW: stock cams are usually done by 5,500rpm, and most factory sport cams (SC, 964) peak by 5,800-6,200rpm. Once the cams peak, there's really no sense in revving it higher.