Gear ratio's for turbo ek9

[ek9mike]

Got a s9b gearbox on the car, iis used as a trackcar and i feel the ratios are just a bit to high. As there is no way i will hit 174mph out on a track, also I feel 4th gear at 142mph is a bit much.

Using the MFactory gear calculator these are the current ratio's

Redline:9000rpm Tire size:215/50/15 Final Drive:4.266

1st gear-46mph
2nd gear-78 mph
3rd gear-108mph
4th gear-142mph
5th gear-174mph


So I still have the original s4c gearbox from the car, and was thinking of dropping a 4.78f FD into it. Im also making a switch to 16's over the winter so on the front I will be running 245 wide tires. Which will obviously alter the gearing.

Here is breakdown of the speeds again in each gear, using this setup

redline-9000rpm Tire size- 245/45/16 Final Drive-4.785

1st-43mph
2nd-66mph
3rd-95mph
4th-125mph
5th-163mph

So I was thinking these speeds in each gear would be ideal for track use.
Was just wondering what gearboxes and ratios do the guys on here with turbo'd civic run??

 

[CR1S]

I would personally say that is a bit long but that depends on how much power your car has? Also what track you plan to be using it on if there is a specific one

 

[ek9mike]

I would personally say that is a bit long but that depends on how much power your car has? Also what track you plan to be using it on if there is a specific one

The car makes 487bhp on high boost. I use the car at knockhill for just now but plan on getting to a few rounds of time attack next year

 

[Kozy]

With that sort of power I would say what you have now is pretty spot on, you'll not really gain a great deal for under-gearing the car with a 4.7 but you will make traction a big issue. Maybe just look at a shorter 4th and 5th if you feel they are too long, could you use the S4C ratios in the S9B box?

 

[ek9mike]

With that sort of power I would say what you have now is pretty spot on, you'll not really gain a great deal for under-gearing the car with a 4.7 but you will make traction a big issue. Maybe just look at a shorter 4th and 5th if you feel they are too long, could you use the S4C ratios in the S9B box?

That is very true kozy i never thought in doing that. Just done a comparsion between the 4.4 and the 4.266 with ek9 3rd,4th,,5th and it would work out very similar.

4.4 FD 4.266FD

1st-48mph 1st-48mph
2nd-73mph 2nd-82mph
3rd-106mph 3rd-106mph
4th-140mph 4th-140mph
5th-182mph 5th-183mph

 

[CR1S]

The car makes 487bhp on high boost. I use the car at knockhill for just now but plan on getting to a few rounds of time attack next year

Ah I see lol
Ignore me completely