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356-930 356-930 is offline
Acceleration Junkie
Join Date: Aug 2007
Location: Laguna Beach, CA
Posts: 263
Originally Posted by fredmeister View Post
Anyone running anywhere around 34-35 degree BTDC at 4000rpm on pump premium gas?
I ran 48 deg at 4000 rpm, 0.8 bar, 3.3 930, sc cams, 0.8 bar, water/meth injected, no intercooler. Distributor boost retard pulled out 8 deg leaving 40 deg adv net. Drove 3000 mi and it didn't blow up. Low weight vehicle, no prolonged boost, no hill climbing under max boost and no audible ping (doesn't mean it wasn't there).
Now running 40 deg at 4000 rpm, 1.0bar, added MSD boost retard taking max timing back to 29 deg by 12 psi.
Always 91 octane CA gas.
I believe the only sure method of determining max safe advance will be a dyno and instrumenting the engine with knock sensors.
A $600 MSD unit seems like a reasonable investment compared to a $16000 engine rebuild.
Old 04-17-2008, 01:50 PM
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