A customer of mine has a Mitsubishi Galant VR-4 that produced 206kw and 373nm from the factory, making about 160kw ATW. The stock gear ratios are rather short and we are now right at the redline in 4th gear over the 400m, and when cruising on the highway it runs at 3000rpm at 115kmh. First gear is also quite short, but we don't want to make it so long that the car is difficult to drive around town, and 2nd gear doesn't even make it to 100kmh.
The turbos on this car are very small and it starts making boost at 2000rpm and by 2500rpm is capable of 15psi without a problem. It now produces 225kw ATW and has no lag at all, most people compare it to driving a 5.0l V8.
The stock gear ratios are:
3.333
2.105
1.407
1.031
0.761
with a 4.111 final drive, and we are running 255/40/17 tyres.
Fortunately there are other gearsets available from Lancer Evo's that fit straight in, as well as a 3.73 final drive. The gears available including stock are are:
3.333, 2.928, 2.750
2.105, 1.950
1.444, 1.407
1.096, 1.031
0.825, 0.761, 0.721
Originally we were going to go with a set of:
2.928
1.950
1.407
1.031
0.721
Which would make 1st, 2nd and 5th longer, while keeping the gears that would be used most of the time around town close together. Unfortunately this wouldn't drop the revs in 5th gear by much at all, 3000rpm would now get the car to 122kmh from 115kmh.
Then we found out about the 3.73 final drive. I beleive that this would make a longer first and second superfluous, and possibly make it hard to get the car moving from rest, so at this stage we are thinking of keeping the stock 1st and 2nd ratios and ending up with overall reduction ratios of
3.333 x 3.73 = 12.43
2.105 x 3.73 = 7.02
1.407 x 3.73 = 5.25
1.031 x 3.73 = 3.85
0.761 x 3.73 = 2.84
Compared to the stock or Evo ratios of
3.333 x 4.111 = 13.70
2.105 x 4.111 = 8.65
1.407 x 4.111 = 5.78
1.031 x 4.111 = 4.24
0.761 x 4.111 = 3.13
2.928 x 4.111 = 12.04
1.950 x 4.111 = 8.01
1.407 x 4.111 = 5.78
1.031 x 4.111 = 4.24
0.721 x 4.111 = 2.96
This would appear to give the 3.73 final drive with stock gear ratios a very good setup of a first gear that is just the right length, a long 2nd gear which will help 0-100kmh times, and a nice long cruising gear. The only short coming I see with this setup is that 3rd and 4th might be a bit too long, we wouldn't above 6000rpm in 4th at the end of the quarter mile, and because they are so much longer this might make the car a bit difficult to drive around town. On the other hand the car is making a lot more power and torque at the wheels now, and coupled with no lag this might not be much of an issue - thats something I'm not sure about and is my first big question.
Another possible option is using the shorter Evo 3rd and 4th so creating this:
3.333 x 3.73 = 12.43
2.105 x 3.73 = 7.02
1.444 x 3.73 = 5.39
1.096 x 3.73 = 4.09
0.761 x 3.73 = 2.84 (or 0.721 x 3.73 = 2.69)
This means that the first 4 gears are still quite close together and will still give good driveability around town. It then creates the problem of having a shorter 4th gear with a big gap between 4th and 5th, especially if the 0.721 gear is used. Would this drop off, especially with the 0.721 5th gear be too much and cause more problems?
I am not sure, especially considering that the Automatic version of the car has a freakishly identical (to 2dp) 5th gear to what I am proposing, it is 0.731 x 3.684 = 2.69. They get along fine, but of course they have the advantage of a torque converter, and a longer 4th gear of 1.0 x 3.684 = 3.684 (really hah!)
So the final questions: will a 3.333, 2.105, 1.407, 1.031, 0.721 setup with the 3.73 final drive be fine, or should we look at shortening 3rd and 4th, and if we do that, will we need to run the shorter 5th gear as well?
The turbos on this car are very small and it starts making boost at 2000rpm and by 2500rpm is capable of 15psi without a problem. It now produces 225kw ATW and has no lag at all, most people compare it to driving a 5.0l V8.
The stock gear ratios are:
3.333
2.105
1.407
1.031
0.761
with a 4.111 final drive, and we are running 255/40/17 tyres.
Fortunately there are other gearsets available from Lancer Evo's that fit straight in, as well as a 3.73 final drive. The gears available including stock are are:
3.333, 2.928, 2.750
2.105, 1.950
1.444, 1.407
1.096, 1.031
0.825, 0.761, 0.721
Originally we were going to go with a set of:
2.928
1.950
1.407
1.031
0.721
Which would make 1st, 2nd and 5th longer, while keeping the gears that would be used most of the time around town close together. Unfortunately this wouldn't drop the revs in 5th gear by much at all, 3000rpm would now get the car to 122kmh from 115kmh.
Then we found out about the 3.73 final drive. I beleive that this would make a longer first and second superfluous, and possibly make it hard to get the car moving from rest, so at this stage we are thinking of keeping the stock 1st and 2nd ratios and ending up with overall reduction ratios of
3.333 x 3.73 = 12.43
2.105 x 3.73 = 7.02
1.407 x 3.73 = 5.25
1.031 x 3.73 = 3.85
0.761 x 3.73 = 2.84
Compared to the stock or Evo ratios of
3.333 x 4.111 = 13.70
2.105 x 4.111 = 8.65
1.407 x 4.111 = 5.78
1.031 x 4.111 = 4.24
0.761 x 4.111 = 3.13
2.928 x 4.111 = 12.04
1.950 x 4.111 = 8.01
1.407 x 4.111 = 5.78
1.031 x 4.111 = 4.24
0.721 x 4.111 = 2.96
This would appear to give the 3.73 final drive with stock gear ratios a very good setup of a first gear that is just the right length, a long 2nd gear which will help 0-100kmh times, and a nice long cruising gear. The only short coming I see with this setup is that 3rd and 4th might be a bit too long, we wouldn't above 6000rpm in 4th at the end of the quarter mile, and because they are so much longer this might make the car a bit difficult to drive around town. On the other hand the car is making a lot more power and torque at the wheels now, and coupled with no lag this might not be much of an issue - thats something I'm not sure about and is my first big question.
Another possible option is using the shorter Evo 3rd and 4th so creating this:
3.333 x 3.73 = 12.43
2.105 x 3.73 = 7.02
1.444 x 3.73 = 5.39
1.096 x 3.73 = 4.09
0.761 x 3.73 = 2.84 (or 0.721 x 3.73 = 2.69)
This means that the first 4 gears are still quite close together and will still give good driveability around town. It then creates the problem of having a shorter 4th gear with a big gap between 4th and 5th, especially if the 0.721 gear is used. Would this drop off, especially with the 0.721 5th gear be too much and cause more problems?
I am not sure, especially considering that the Automatic version of the car has a freakishly identical (to 2dp) 5th gear to what I am proposing, it is 0.731 x 3.684 = 2.69. They get along fine, but of course they have the advantage of a torque converter, and a longer 4th gear of 1.0 x 3.684 = 3.684 (really hah!)
So the final questions: will a 3.333, 2.105, 1.407, 1.031, 0.721 setup with the 3.73 final drive be fine, or should we look at shortening 3rd and 4th, and if we do that, will we need to run the shorter 5th gear as well?
