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Originally Posted by digitalmind
1.4 bar? That's almost double than what they are supposed to go, 0.8. I'd be scared to blow it up.
I have a 1986 turbo 
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The poster used race fuel to avoid that explosion, and feel glorious power. Plenty of resources for this online -- watch final compression ratio, usually not to exceed ~25 BAR on race fuel. This is the boosted charge, then pressed again (multiplied) by the stroke's compression ratio.
Pre 1995 compression is very low. Though the low compression is good for keeping heads cool and using junk fuel, it's great for brief sprints of up to 2 BAR on >93 octane. If a common piston/head/stroke combo is used to produce 7:1 compression, at 2.0 BAR of boost, final/effective compression is 21 BAR, enough to start knocking diesel. I think an EFI 930 can manage a piston+head combo, not stroked, at 8.5:1 at 1.0 BAR for a final 17 BAR, and great response with intermediate power, as the ECU delays ignition during trouble.
This California street fuel is max 91 octane. An Audi S4 at 9.3:1 at a simple 1 BAR is already near a final 18.6, with careful electronic ignition management for its long stroke, and if "economically" injected it knocks and delays ignition. Injecting extra fuel and delaying ignition is a sloppy workaround. I figure California fuel racketeers don't care about efficiency, favoring low octane, sending more fuel to be eaten by catalytic conversion.