I recalculated my tables for you guys.
Tire size:
255/40/17
Redline:
8000 rpm
Cruise RPM:
80 mph
This is a screenshot from my own spreadsheet that I have setup so that all I have to do is punch in the gear ratios, and everything that I want to know is automatically calculated. Some of these values will be obvious and apparent to you guys. Others will not. I will explain one the less obvious, calculated values are.
Example: NSX USDM 91-94
The
0.5624 to the right of the
1.727 2nd gear is (2nd gear/1st gear). This tells me what the reduction is when shifting from 1st to 2nd gear. Multiply this
0.5624 by the previously defined
8000 rpm and you get the RPM that you will be in after you take 1st gear up to 8000rpm, and then shift. The rest of these values calculated between each gear is calculated (e.g.
0.7122 = (3rd/2nd), or (
1.230 /
1.727))
The teal
3365 is the cruising RPM in top gear at the previously defined cruising speed. In this case, 80 mph.
The yellow
2.23995 is the quotient of (2nd/5th) = (
1.727 /
0.771). This is a very simple formula that I use to quickly calculate and assess how
close the spread is from 2nd to 5th gear. The lower this value is, the closer or 'tighter' your gear spread is across these gears.
In my close-ratio Frankenstein concoctions, I generally try to get this number as low as possible. To do this using OEM gears, I look for the 'tallest' 2nd gear that is available, and I pair it with the shortest 5th gear that I can use. NSX doesn't have as many gearing options, however something like D-series does.
BenseBuilt D-series gearing
1st = 3.083 (custom gear-x gear that I had made)
2nd = 1.762 (1992-1995 Civic cx/dx/lx/vx -- non ex/si)
3rd = 1.259 (1988-1991 Civic dx/lx)
4th = 1.033 (1988-1991 CRX HF 3rd as 4th gear -- can also use 88-91 ZC 4th gear, its same ratio)
5th = 0.878 (1988-1991 JDM ZC)
Fnl = 4.058 (92-00 DX/LX)
This was a 'junk' trans that I pieced together 10 years ago while I was a student using left over parts from transmission builds that I did for other people. I had already made profit from the other parts. While at first glance it may seem like some junk, Frankenstein trans, in several ways it was one of the most optimal setups that I ever ran. Take a look at the (2nd/5th)=
2.00493. It had very tight gearing across the 2nd -> 5th spread.
Now, granted I recognize that the crowd here that might be interested in a setup like this is the antithesis of a poor mechanical engineering student that was experimenting with gearing on the Honda D-series platform. However this is the experience that I'm able to bring to the present table, that some may find useful.