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Old 10-20-2014, 04:59 PM   #41
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That's a great link thank you.

going on that alone i'm better off with a 5 speed box and my tyre combo. 3rd is quite long and takes me up to 100 mph. I only do one sprint where top speed is 110-120 mph dependent on how big my ***** are on the day and if the red racing mist has descended yet.

Paul
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Old 10-20-2014, 06:29 PM   #42
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Now you will find on almost every car forum or at any car meet guys arguing
I like the 6 speed its quicker i like the 5 speed its quicker!
This is because some people feel they would rather shift less and have a bit more room to use the boost they have made before shifting and having to start building boost again. The solution for this is almost always a upgraded head (valves, springs w/e) to allow you to safely rev higher.
No to everything you just said.

First, 6-speeds are faster than 5-speeds on track. This is an objective statement of fact, backed up by multiple empirical examples as well as common sense (less RPM drop = more average power applied to the tire for a given time period). IOW, not an opinion. The 6-speed ratios are closer together, which results in less RPM drop after each shift and more power available immediately after the shift. As a result, the engine is turning a higher average RPM during the lap, and it puts more power to the rear tires as a result. Simple.

If you don't like how often you have to shift in the 6-speed, what you want to do is increase the speed in each gear without giving up the tightly spaced ratios that make the car fast in the first place. You do this with the rear end ratio, not with the transmission gears. Many members here have figured this out, which is why 6-speed/3.636 combos are so popular.

The whole notion of "building boost faster" or "using the boost you built" is a red herring as well. If you want to "build boost faster", you want a lightweight clutch/flywheel. My old 350whp 2871R used a 7.25" twin-disc clutch, and I was able to shift that car so fast my 10hz datalogger would often miss the throttle lift and datalogged boost levels never dropped below 10psi. In addition, tightly-spaced gear ratios (6-speed) will let you get between gears faster (less work for the synchros to do), which lets you get back to throttle faster.

IOW, 6-speeds are better, factually, unless your usage is extremely narrow (i.e. dyno-classed PTE car making full power across a 3000rpm-wide band).
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Old 10-20-2014, 07:39 PM   #43
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I used to play with the gearing calculator FM has online for hours.

6sp+3.6fd=purrfect
I feel all
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Old 10-20-2014, 09:38 PM   #44
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The whole notion of "building boost faster" or "using the boost you built" is a red herring as well. If you want to "build boost faster", you want a lightweight clutch/flywheel. My old 350whp 2871R used a 7.25" twin-disc clutch, and I was able to shift that car so fast my 10hz datalogger would often miss the throttle lift and datalogged boost levels never dropped below 10psi. In addition, tightly-spaced gear ratios (6-speed) will let you get between gears faster (less work for the synchros to do), which lets you get back to throttle faster.
On that note, what are your plans for flywheel and clutch?
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