Cup 8-32 rear diff against stock 9-31?
11-06-2007, 06:30 AM
#3
Drifting
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As far as the GT3 is concerned, in Germany owners will drive them for extended periods at their maximum speeds. As far as the US is concerned, changing the final drive so that the maximum speed is no more than 150 mph would help acceleration without affecting the perceived top speed, which is in territory rarely visited. The downside is that gears are changed with a higher frequency whilst accelerating through the box.
As far as the track goes, I do not believe that there are many tracks in the US where restricting the top speed to 150 mph would hurt lap times, there are obvious exceptions, of course.
Some manufacturers fit shorter final drives in the North American cars as a matter of course, and even alter gear ratios to the benefit of the 0-60 times. Anybody considering changing their final drive ratios might also like to consider changing their individual gear ratios to achieve their aims.
R+C
11-06-2007, 09:16 AM
#4
I will be doing this during the winter.
It is going to be expensive as this is a new gear box from Japan and is different than all previous porsche gt3 / cup gear boxes
Parts and labour is likely in the 5grand area
The big decission is weather to just do the R&P and keep all your gears (maybe better from a noise / quality / streetability perspective - maybe?) or picking the exact gears that you want (likely keep 1st, maybe 2nd maybe, then redo 3,4,5 and likely reuse 5th as your new 6th)
As every track is different there is no way to quote a specific number, but my guess is that in in a short acceleration straight that in the current car you would do entirely in 3rd from 4000rpms to 8400rpms (front straight at Mosport) the car with re-gearing would be .2 seconds faster per short straight
Add up the straights for your track that you regularly visit and my guess is that on a 1minute track the car would be 1seconds faster per minute
I personally think another way to think about it is that it would be like adding 40hp to a car with 400hp so a 5-10% faster car during acceleration.
This is why i will be doing this mod as from a performance bang for the buck, for this already highly tuned engine, I think it is the best bang for the buck once the car's suspension / alignment / tires have been tweaked for good track performance.
Paul
11-06-2007, 09:53 AM
#5
Drifting
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Paul
I read all that you write, and have a simple question
What on earth is the point of saving 1 second per lap on a car that isn't a race car?
It will be noisier, 'busier', probably less pleasant to drive normally on the street....
R+C
I read all that you write, and have a simple question
What on earth is the point of saving 1 second per lap on a car that isn't a race car?
It will be noisier, 'busier', probably less pleasant to drive normally on the street....
R+C
11-06-2007, 02:08 PM
#6
- if i was really smart i would just buy a gutted race prepped 300whp E36 and learn how to drive faster and not worry about putting the car into the wall
- i just don't have a place to store a race car, trailler, etc
- there is really no logic to spending the money and if the gearbox after the re-gear is not like stock then i will just reverse it