What diff ratio is best for 380bhp cosworth?

[andy1980]

Running an Atlas axle but cant get my head round diffs? what way to they go ie 3.09. 3.44. 3.75 which will give me top end or acceleration?

 

So ideally which one do i want?

[Neb]

of the lot you have mentioned 3.75 will give the best acceleration, 3.09 the highest top speed.

 

Don't forget that the gearbox ratios & tyre size will also make a difference but with that much power you want strength.

 

There are various speed calculators online which could be worth running the numbers through.

 

This is probably the best one i've used - http://www.kabamus.com/garage/gears.html

 

Good luck it's a bit of a minefield picking the right one.....

[Vista]

When I chose mine for the van I initially favoured the 3.44 but having run the numbers with my chosen gearbox and tyre size, I took some further advise from the axle builder (Fostek) and changed my mind and went for 3.75

[andygfc]

I've got 3.75

280/300 bhp

13.5 at santa pod, should easily get below that, and 135mph easily (on private roads of course)

[turnover]

3.75 mate

[andy1980]

of the lot you have mentioned 3.75 will give the best acceleration, 3.09 the highest top speed.

 

Don't forget that the gearbox ratios & tyre size will also make a difference but with that much power you want strength.

 

There are various speed calculators online which could be worth running the numbers through.

 

This is probably the best one i've used - http://www.kabamus.com/garage/gears.html

 

Good luck it's a bit of a minefield picking the right one.....

 

Im trying to calculate it but whats the Transmission Gear Ratio of a T5 cosworth box?

[Neb]

nicked from Alcoholics Anonymous - so don't quote me on it.....

 

1st Gear ratio 2.9515

2nd Gear ratio 1.932

3rd Gear ratio 1.323

4th Gear ratio 1

5th Gear ratio 0.8

 

might be worth getting out a tippex pen & start counting teeth! or check it with the haynes manual.....

 

For reference on our gravel stage car we run a 4.6 but considering a 5.1 as we have a long first gear.

[andy1980]

nicked from Alcoholics Anonymous - so don't quote me on it.....

 

1st Gear ratio 2.9515

2nd Gear ratio 1.932

3rd Gear ratio 1.323

4th Gear ratio 1

5th Gear ratio 0.8

 

might be worth getting out a tippex pen & start counting teeth! or check it with the haynes manual.....

 

For reference on our gravel stage car we run a 4.6 but considering a 5.1 as we have a long first gear.

 

All i have to fill in is the following;

 

Original Equipment Tire

Tire Width in (mm):

Aspect Ratio:

Rim Diameter in (inch):

Transmission Gear Ratio:

Differential Ratio (final drive):

 

Any ideas??

[Vista]

Do you know what your tyre size is?

[andy1980]

tyre size on the back is 225/45/15

[Vista]

These are the ratios I have in my gear calc program for the T5, I've entered your final drive ratio options of 3.09, 3.44 & 3.75 with your chosen tyre size. Sorry, I've tried repeatedly to get the images larger but failed miserably. They are legible just though

 

If you want to download your own version and run them yourself, here's a link. The T5 ratios are preprogrammed, you just need to select them under tools and ratios.

 

http://locost7.info/gearcalc.php

 

3.09

 

 

3.44

 

 

3.75

 

[andy1980]

Vista your a legend! brilliant bit of software that, my choice is a 3.75 so thanks to everyone for thier advice.

[Vista]