Best final drive for 300-350bhp 5e?
- Thread starter ginchey
- Start date
finx
Member +
Quite a few things to consider on this topic
One - where is the power band or where is it going to be
Two - prime use of the vehicle. If in motorsport what type of racing you intend to do will dictate somewhat which one you use to maximize results.
A couple of very simplistic ideas as to the general rule
If you have a very high end power band ie 5k and above a shorter final drive ie 4.3, bringing the gears closer together will suit your application more.
With this in mind the goal is you want to Keep the engine within the higher end of the RPM range for as long as possible to get the most out of the engines power output. shorter gears will acheive this as when you change to the next gear it will be closer in ratio to the the you just changed from thus the engine RPM wont drop down too low / out of the power band.
On the Flip side baring in mind the concept above trying to keep the engine in the power for as long as possible, if you have a long wide power band or low end power band you would preferably use a LONG final drive ratio. ie 3.7 to maximize the amount of time the engine spends on power.
On the type of racing topic you need to consider among others
-Track type
-Top speed achievable
-Suitability to gearing and corners on the track
-The average speed of the track
You look to be using the car in question for all forms of driving / racing this is always going to make it tricky to get the most out of your car in each application using the same final drive. Hence why rally cars and Circuit cars predominantly use different diffs suited to tracks or roads they are on at the time.
I would Probably stick to the 3.7 final drive for all round drive ability. As soon as you put a shorter final drive in on the road at highway speeds you tend to use allot more fuel and it gets annoying driving along at highway speeds with the thing humming at 4000rpm in 5th.
Other side of it is with drag racing the shorter the final drive the more gears your going to be changing. Each change is worth .2sec generally speaking that adds up if your changing gear 4 times in one race unless you have the all out power and set up to justify it. You become top end speed limited too.
Cheers
Ryan
One - where is the power band or where is it going to be
Two - prime use of the vehicle. If in motorsport what type of racing you intend to do will dictate somewhat which one you use to maximize results.
A couple of very simplistic ideas as to the general rule
If you have a very high end power band ie 5k and above a shorter final drive ie 4.3, bringing the gears closer together will suit your application more.
With this in mind the goal is you want to Keep the engine within the higher end of the RPM range for as long as possible to get the most out of the engines power output. shorter gears will acheive this as when you change to the next gear it will be closer in ratio to the the you just changed from thus the engine RPM wont drop down too low / out of the power band.
On the Flip side baring in mind the concept above trying to keep the engine in the power for as long as possible, if you have a long wide power band or low end power band you would preferably use a LONG final drive ratio. ie 3.7 to maximize the amount of time the engine spends on power.
On the type of racing topic you need to consider among others
-Track type
-Top speed achievable
-Suitability to gearing and corners on the track
-The average speed of the track
You look to be using the car in question for all forms of driving / racing this is always going to make it tricky to get the most out of your car in each application using the same final drive. Hence why rally cars and Circuit cars predominantly use different diffs suited to tracks or roads they are on at the time.
I would Probably stick to the 3.7 final drive for all round drive ability. As soon as you put a shorter final drive in on the road at highway speeds you tend to use allot more fuel and it gets annoying driving along at highway speeds with the thing humming at 4000rpm in 5th.
Other side of it is with drag racing the shorter the final drive the more gears your going to be changing. Each change is worth .2sec generally speaking that adds up if your changing gear 4 times in one race unless you have the all out power and set up to justify it. You become top end speed limited too.
Cheers
Ryan
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1st - 3.166
2nd - 1.904
3rd - 1.392
4th - 1.031
5th - 0.815
Final drive - 4.312
The GT C52 gearbox
1st - 3.166
2nd - 1.904
3rd - 1.310
4th - 0.969
5th - 0.815
Final Drive - 4.058
ginchey
Member +
i thought the glanza and the starlet had the same FD - 3.7 ??
dark_knight
Member +
final drive
i thought so too ginchey, but only i was thinking it's at 4.312, not 3.7..
i thought so too ginchey, but only i was thinking it's at 4.312, not 3.7..
So did I, but this is what wiki says. http://en.wikipedia.org/wiki/Toyota_C_transmission#C52 Does say the Differential ratio is 3.722, but thats not the final drive 
It will be hard to select ratio's that will suit your cars use, like Ryan said you don't want to be driving a long the road at 70mph @ 5000rpm will use a lot of fuel and become quite annoying, yet it will be perfect for the track.
It will be hard to select ratio's that will suit your cars use, like Ryan said you don't want to be driving a long the road at 70mph @ 5000rpm will use a lot of fuel and become quite annoying, yet it will be perfect for the track.
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