Thread: 1/4 mile times
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kellcats521 kellcats521 is offline
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Join Date: Feb 2005
Location: Atlanta Metro
Posts: 219
I do have a 930, an 87 slant. The main reasons why a factory 4sp 930 can produce good 60' times by dumping the clutch is simply the gearing - our 4sp is factory geared for roadracing, not the drag strip. First gear in the 930 is waaay too tall for the drag strip, but it does allow you to almost hit 55mph in first gear from a standing start, and actually downshift to first while moving to get in and out of a tight corner. The G50/50 5sp has a little bit shorter first gear, but even it would benefit from a higher numerical ratio R&P to bring it on the pipe faster. The main reason that the guys who 1/4-mile turbo Porsches start out with n/a cars is the gearing - the turbo is 9.495:1 first gear (2.25:1 gear set and 4.22:1 ring/pinion) while the G50 Carrera is 12.04:1. The 915 trans is also better geared for off the line starts with a 12.33:1 first gear.

Basically, if a 930 was geared from the factory like most other 'street' cars are (~12:1 first gear to the wheels), dumping the clutch at say 3000 - 3500 RPMs whould put the tires up in smoke - effectively the stock 930 first gear is closer to second gear in most 1/4 mile setups. You would need to slip the clutch on a 930 if it was properly geared for the strip in order to get the most out of it....

Also, not trying to have a pi$$ing contest or start anything - although as I said, I don't have much interest in this kind of racing anymore. But, for the record, here is a link to the shop I worked at as a kid - the vocational school was not in operation when I was there, but now they are a highly regarded machinist trade school.


Pat Kelley
Old 04-17-2007, 06:11 PM
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