Hey folks,
I did quite a bit of homework for what transmission to buy for my SLC build. It wasn't so much the "where's the best deal" homework, but rather an exercise in what are the right gear ratios in a transmission to match with the engine I'm planning to run. I put all the various transmissions I could consider into an Excel spreadsheet to compare them against each other on shift points, gear speed ranges, entering RPM on next gear up if shift at redline, top end speed and highway cruising RPMs.
It was pretty enlightening to me and I learned quite a bit about transmission gearing, so I thought I'd share what I put together if it's useful to anyone. I'd also be happy to add more transmissions if you send me the gearing list. So far it's a bunch of Porsche transmissions and the Ricardo just to get a comparison of what a V8 transmission is geared like (I wasn't considering it). I'm planning to run a late-model naturally aspirated Porsche engine that should redline around 7500 and have a power band from about 4000 upwards.
Here are the things you can enter at the top of the sheet for your specific application:
1) Motor RPM (redline)
2) Tire and wheel size (uses SLC stock 325 / 30 / 19 rear)
3) Desired highway cruising (default 75)
In the end I went with a G96/96 partially because I was able to get a good one, but also because it's geared the way it is for a reason: it's mated to a high-revving naturally aspirated engine, not a turbo or a V8.
Anyway, without further ado, grab the Excel sheet from here: http://www.timtt.com/slc/Transmission%20calculations.xlsx
Comments, additions or any other suggested items I could calculate with this data is highly appreciated.
Thanks,
Tim
I did quite a bit of homework for what transmission to buy for my SLC build. It wasn't so much the "where's the best deal" homework, but rather an exercise in what are the right gear ratios in a transmission to match with the engine I'm planning to run. I put all the various transmissions I could consider into an Excel spreadsheet to compare them against each other on shift points, gear speed ranges, entering RPM on next gear up if shift at redline, top end speed and highway cruising RPMs.
It was pretty enlightening to me and I learned quite a bit about transmission gearing, so I thought I'd share what I put together if it's useful to anyone. I'd also be happy to add more transmissions if you send me the gearing list. So far it's a bunch of Porsche transmissions and the Ricardo just to get a comparison of what a V8 transmission is geared like (I wasn't considering it). I'm planning to run a late-model naturally aspirated Porsche engine that should redline around 7500 and have a power band from about 4000 upwards.
Here are the things you can enter at the top of the sheet for your specific application:
1) Motor RPM (redline)
2) Tire and wheel size (uses SLC stock 325 / 30 / 19 rear)
3) Desired highway cruising (default 75)
In the end I went with a G96/96 partially because I was able to get a good one, but also because it's geared the way it is for a reason: it's mated to a high-revving naturally aspirated engine, not a turbo or a V8.
Anyway, without further ado, grab the Excel sheet from here: http://www.timtt.com/slc/Transmission%20calculations.xlsx
Comments, additions or any other suggested items I could calculate with this data is highly appreciated.
Thanks,
Tim
