>> 91 octane?! I beg to differ! VW engines were built to handle cheap >>low quality gas all around the world, like in places where they say >>"octane? what the hel >> > >When the VW was designed, 93 octane fuel WAS cheap gas. > >The cover to my '68 TII fuel fill says "91 Octane minium". > >I feel that if the VW people tell me 91 is what I need, thats good enough >for me. > >If you run cheap fuel, drop your timing back 2 or 3 degrees to keep from >overheating. > I guess this is one of those discussions that could have the subject heading changed to reflect the new suject matter. I understand octane and timing to be closely related to compression. More compression, less timing. So the 1968 T2 was 7.7:1 and required 91 octane to run cool at 7.5 deg. BTDC. The extreme conditions manual states that if a bus is going where there is questionable fuel, that dished pistons are to be fitted. VW lowered to CR several times since then, down to 7.0:1 in 1971, and I think they're down to 6.6:1 these days and aren't whining about 91 octane. I run 12 deg BTDC on 87 octane with engine compression lowered to 6.7 or 6.8:1. So, y'all should be careful when you ask for a rebuilt or new engine. Make sure the builder gets the compression set-up the way you want it.
Eug, '71 PS check out <http://ram.chem.tulane.edu:8080/f-body/trivia/gasoline.html> for all your fuel questions.
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