Torque = Acceleration = Your Best Friend :)


MFactory

MFactory

Gearing Authority
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Jan 23, 2008
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Hey guys,

Here's something that some of you might find interesting. Was explaining torque multiplication to a few of our customers, as they didn't believe me when I said I could give them an extra 60% torque to the ground without even touching the engine.

Most think the acceleration gain from changing gears is due to the change in rpm and/or shift points. Although this does contribute in a sense (i.e keeping you in your powerband), the main reason why your car is so much faster is because of torque multiplication. For example:

1st Gear - 3.230
Final Drive - 4.4

3.230 x 4.4 = 14.212 absolute ratio. What this means is that, for every turn of your wheel, your crank will have turned 14.212 times. From this, we can calculate the total torque produced to the ground:

Absolute Ratio x Engine Torque = Torque to the Ground

Based on stock EK9 with 115lbft engine torque, the following is how much torque you would gain throughout the whole rev range and to the ground. Engine power does not change.

4.928 Final Drive Only:
1st through 5th - 11% increase. That is the equivalent of 127lbft engine torque.

Our most popular close ratio gear set + 4.928 Final Drive:
1st (3.070) - 6% increase
2nd (oem) - 11% increase
3rd (1.695) - 30% increase
4th (1.384) - 40% increase
5th (1.130) - 49% increase!!!

To put this into perspective, what the above is telling you is that in 5th gear, you would have the equivalent of 171lbft engine torque, and that is without doing anything other than changing your gears. A B18C-R (one of the popular modifications on this forum) is only 137lbft!

Now if we substituted our 1.210 5th gear instead, this would give a 60% increase. This is the equivalent of having 184lbft, which is more than the Mugen Civic RR Advanced Concept ;)

Torque = Acceleration. Torque is your best friend :)

Please Note: Top speeds will be reduced, and different applications require different ratios. It is up to the user to decide on what is suitable for his/her application. However, the point of this thread is to explain torque multiplication, how it works, and why it makes your car faster ;)
 
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Yeah, but what would happen with the top speed with such a ratio...it would mean I would continuously hit my revlimiter at the Nordschleife. Not to mention the decrease in mpg and the amount of noise (4900rpm @ 100km/h and 6000rpm @ 120km/h), when driving down the motorway from work ;)

I know what you mean and I realise there's a lot to be gained by using the right ratio's but imho it's not as simple and clear cut as you write it down here. A lot comes down to personal preference (would you mind the extra noise?) and application (from what I hear the UK tracks are really tight so very short gears might work but I drive at the Nordschleife - no way you want a max speed of 180 km/h there ;) )

It's an easy way to get more torque but it has a few disadvantage - it's up to everyone to decide for themselves where the balance for their car lies. Depending on personal preference and application.
 
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Yeah, top speed will be reduced, and different applications require different ratios. It is up to the user to decide on what is suitable for his/her application. I completely agree with you :)

That wasn't the point of the post though. The point was to explain torque multiplication, how it works, and why it makes your car faster ;)
 
Ok, that's true. And thank you for the explenation by the way, didn't knew the calculations were that easy :p
 
Nice piece of info.. kinda begining to understand all this craic about final drives and ratios!!
 
Learned something new today! +rep for you thanks!

Our most popular close ratio gear set + 4.928 Final Drive

Some day I want to have this setup on a B18C, do you have any estimate how much top speed will be lost with this setup?
 
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I got a question, if changing the gear ratios will lower your top end speed, to gain it back will you just have to increase your engine's BHP?
Isn't it like 10hp = 2 mph or something? I think I heard something like that on top gear :p
 
increasing your engine power will not increase your top speed at this point.

The main reason for this is that your rev limit is fixed @ say 8000rpm.

If you increase this to 9000rpm, you will gain a little more speed in each gear all the way up to the tallest (5th/6th) gear which will enable you to have a higher terminal velocity.
 
bhp will affect your top speed (as in potential top speed), but you are still limited to the constraints imposed by your gearing and rev limit.
 
Is it possible to get a custom 5th gear so you could fit a 4.928 final drive but be able to have a decent cruising gear, say 70 mph at around 3500rpm?
 
The longest 5th gear is the oem 5th from the Integra LS, which will lower your rpm.
 
this is very intersting and i actually understand it
could this be done on a d14 engine?
 
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