I came across this info on rennlist, was wondering if anyone else has switched to cup gears and what your impressions are?

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I have posted some data below from an earlier thread some facts (NJ-GT) some speculation (Jean - for in gear acceleration)

Specifically, Jean speculates that 50 to 90 mph with a stock r&p takes 5.1seconds versus 4.2 seconds with a Cup 4.0 R&P


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**** Data posted by NJ-GT*****
997 GT3
R&P: 3.44:1
Stock Michelin Pilot Sport 2 305/30R19 (26.3" tall). 5th and 6th gear redline at 8,200rpm

BGear Ratio -------- Max Seed -------- RPM on upshift
=======================================
1st: 3.82 -------- 50 mph --------
2nd: 2.26 -------- 85 mph -------- 5000 rpm
3rd: 1.64 -------- 116 mph -------- 6100 rpm
4th: 1.29 -------- 148 mph -------- 6600 rpm
5th: 1.06 -------- 176 mph -------- 6900 rpm
6th: 0.92 -------- 203 mph -------- 7100 rpm

997 GT3
R&P: 4.00:1 (GT3 Cup/RSR ring and pinion)
Hoosier R6 335/30R18 (25.6" tall). 5th and 6th gear redline at 8,200rpm

Gear Ratio -------- Max Seed -------- RPM on upshift
=======================================
1st: 3.82 -------- 42 mph --------
2nd: 2.26 -------- 71 mph -------- 5000 rpm
3rd: 1.64 -------- 98 mph -------- 6100 rpm
4th: 1.29 -------- 124 mph -------- 6600 rpm
5th: 1.06 -------- 151 mph -------- 6900 rpm
6th: 0.92 -------- 174 mph -------- 7100 rpm

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******Data Posted by (Jean)********

*Assuming* the stock 997GT3 does (in mph):

0 -60--4.8s
0 -70--5.6s
0 -80--6.5s
0 -100--9.4s

Then the 4:0 R&P will give you this:
0 -60--4.5s
0 -70--5.3s
0 -80--6.7s
0 -100--9.4s

Gear changes are what make the 80mph look worse.

In-gear acceleration is more important:

3rd. Gear with 4:0 R&P
30-50mph: 2.6s
50-70mph; 2.1s
70-90mph: 2.1s

3rd gear with 3:44 R&P
30-50mph: 3.3s
50-70mph; 2.6s
70-90mph: 2.5s
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Any idea as to the cost of the 4.00 R&P. Just over the top it does not seem to be worth it especially if the diff change is expensive.
There is a loss in top end. For us down here in this neck of the woods our rolling start run-off's go over 180 so not good. Good most tracks though.

 

I do not know the cost, I am trying to do more research on it. I know for me 170 top speed would be good enough, what im looking at is the .9 second improvement from 50-90mph

 

Juan,

parts cost is approx $2200
labor rates are local but lets say it is a similar number
so, mod is in the "range" of a full headers exhaust setup
if winter hadn't started yesterday, i was hoping to get the baseline acceleration data for the stock gears as i now have the Durametric Logging Software

Paul

 

Paul,

I look forward to seeing your results on the comparison of the two. If those speculated numbers are anywhere near close, Id say it is a pretty nice improvement in in-gear acceleration from 30-90mph.

By any chance do you have anyone close to you who has a stock geared gt3 that you could compare side to side with yours with the cup gears, so we could also have some real world comparison in addition to the numbers.

 

I hope to do much better than that.
I have purchased logging software from Durametric - it logs many variables including speed, rpms and many others.
I purchased it through FVD (Rhonda) as I'm testing their flash for the GT3 and I plan on doing actual street WOT runs to test how the software really compares to the stock GT3 code - not just dyno stuff.
Before I install the cup 4.0 r&p, i will be doing many street wot runs to get some real 50 to 90mph runs in 3rd gear - this is about the limit for me as I don't want to end up in the courts
I figure this is a much better way than doing pulls against another car as it will remove car to car variation, weight differences, etc and it will be just my car.

In the end I hope to have acceleration data on:
- stock
- stock + fvd software
- cup 4.0 r&p with stock software
- cup 4.0 with fvd software

Paul

 

Hey Paul I'm very interested in what you described concerning the FVD software. I would like to know more. Tomorrow I will call Rhonda at FVD.
Glad that I read your reply. I will follow up with FVD.

Thank you,
Juan

 

Juan,

You can order the software through FVD or directly from durametric - fvd is just a reseller here.
The software is used my most Porsche guys just to reset codes but also has built in logging software.
The software can log the important variables such as:
- rpms
- speed
- O2s (to show fuel mixture)
- timing (how aggressive is the program)
- EGTs (Exhaust Gas Temps)
- Throttle plate angel
- Actual Throttle plate
- MAF - this correlates well to HP

With this software, it will thus be easy to do WOT street runs and then calculate the time it takes to do certain well know acceleration times such as 60 to 90mph in 3rd gear - we do this a lot in the audi turbo world to compare how a car's performance tuning is doing - we call this a FATS run (For the Advancement of The S4) - as an aside, a stock 2000 model year S4 will do a 60-90mph time of 6 seconds but a fast bigger turbo'd S4 will do it in the low 3 seconds

Obviously there is not much that can be done with this car, but there should be some improvement available with weight reduction, re-gearing, exhaust headers, higher octane tuning, etc

Hope to have some data soon

Paul

 

We do the gearboxes and have done several cars already.

You can do as little as the Ring and Pinion or go all the way and actually revise the gear ratio's themselves.

When this is being done we recommend upgrading the LSD with the intermediate motorsports clutch pacs. Severl listers have done with this with us over the years and have been very happy.

Feel free to contact me , You can send in your gearbox to have this work done if you are out of state.

Turn around is only a few days - we have Ring and Pinions in stock.

 

You cannot install "Cup Gears" they will not fit in our gear box. Best bang for the buck is to skip the 4.0 R&P and have a custom gear set made 1st-6th and install the LSD