MFactory Knowledge Bank: About Torque

Torque: Your Best Friend

One thing that has always stood out among the All Motor and/or Street crowd is that one variable stands at the top of the modification food chain, and that variable is Power.

I understand that in a lot of peoples heads, speed rules, but what I would like to do is differentiate between Speed and Acceleration:

When I talk about speed, I mean the physical speed that the vehicle is moving at. HP determines the maximum achievable speed (within the constraints of your gearing)
Similarly, when I talk about acceleration, I mean the physical rate that the vehicle is moving at in order to achieve the above mentioned speed. Torque determines your rate of acceleration

When changing your gearing, in most cases, this means a reduction in Speed but at the same time, an increase in Acceleration, and this is the point where a lot of people get confused and ask us: "How can my car be faster if I'm losing speed?"

The simple answer to this is; Efficiency - Making the most of your current or proposed setup. If you will only ever drive at maximum 120mph, why would you want to have an inefficient transmission that is geared to 170mph?

Not only does this affect your vehicles rate of acceleration, contrary to wide belief, it also affects your fuel economy. Cruising on the freeway for hours on end aside, a Daily Driver will benefit greatly from a more efficient transmission setup. rpm is only 1 of several variables that contributes to fuel economy.

So back to the topic at hand, how do we make the most efficient use of our current or proposed setup? The answer lies in gearing, and using the various information and tools available on the Internet to help you achieve the most efficient transmission setup for your application. I can't stress the importance of that last point any further, as just changing your gears will not guarantee to make you faster. If done properly though, there simply is nothing currently available in the multi-billion dollar modification marketplace that can compare at similar cost.

The following information takes a completely different approach to "making power", called torque multiplication. As you will soon see, there really is a Replacement for Displacement!

Ask yourself this, which of the following would you choose (Naturally Aspirated):

1) Big engine modifications to increase power, or
2) Mild, or even no engine modifications, but changing your transmission setup to utilize your available power to the maximum potential

Most people (probably 90% plus) would choose no.1, and for good reason. Make more power and your car will go faster, that's common sense. However, if you are able to balance your top speed requirements with your noise/mileage requirements, for a Naturally Aspirated Motor, engine power takes a very distant 2nd place in terms of putting power to the ground. Let me explain....

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 Ratio - 3.230
Final Drive Ratio - 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. This is what you actually make to the ground, not what your dyno graph tells you.

Based on a stock USDM Integra Type-R with 122lbft peak engine torque, the following is how much more torque you would produce throughout the whole rev range and to the ground. Engine power does not change.

4.928 Final Drive Only:
1st through 5th = 12% increase. That is the "equivalent" of 137lbft peak engine torque (i.e How much torque an engine with a stock transmission will need in order to accelerate at the same rate)

To take a very extreme example (one that is only used by Rally Drivers, as it tops out around 100mph), let's use a 1.210 5th Gear + 4.928 Final Drive: When driving in 5th Gear only = 60% increase!

To put this into perspective, what the above is telling you is that in 5th gear, you would have the "equivalent" of 195lbft peak engine torque, and that is without doing anything other than changing your gears. No engine tuning, no I/H/E, a 100% stock vehicle (besides the transmission). The following is a torque comparison graph, as pictures paint a thousand words:

Green Line - 100% Stock USDM ITR
Blue Line - Custom Race Setup, with 2ltr block, Portflow Head, Hytech Header, Skunk 2 Pro 2's, fully tuned with Hondata S300. Cost - $4000+ with supporting parts? + Labor
Red Line - 100% Stock USDM ITR, with 1.210 5th Gear + 4.928 Final Drive. Cost - $900 + Labor
http://www.teammfactory.com/images/template/mfvs2l.jpg

Please note that this is a very extreme setup, and only compares 5th Gear. Other gears will be different depending on the gear ratio. This is only an example to help explain what I've been talking about.

You may also be wondering: "Why does this not show up on my dyno graph, if torque to the ground increases?". The reason why this will not show up on a dyno graph is because dynos are calibrated to calculate torque on a 1:1 ratio (hence why a dyno run in 4th gear gives the most accurate results, as it is closest to a 1.000 gear ratio). They are not calibrated to take into account your gear ratios.

As mentioned earlier though, what will determine whether your vehicle will be faster or not is your application. To put it simply, match your gearing to your application, and you will guaranteed to be faster. Conversely, mix and match gearing that is unsuitable and you may find yourself to be slower.

Here are some tools that you can use to determine what setup is best for YOUR application:


MFactory Gear Calculator
MFactory Torque Calculator


Torque = Acceleration. Torque is your best friend, and engine modifications alone will never get you this sort of increase for the same money. Gearing = NA Motor on Steroids :-)

Stephen Yeh - President & Co-Founder, MFactory Competition Products


MFactory Competition Products - THE Replacement for Displacement!