There is an old saying in the automotive world: “Power will get you over the mountain, but Torque is what moves the mountain for you.”
Whenever car enthusiasts start talking about performance, it is way too easy to get lost in the hype of engine power (horsepower). We love to brag about how much HP our cars make. However, when the conversation shifts to performance clutches, horsepower isn’t the most important number.
When choosing a clutch, Engine Torque is what truly matters. Please allow us to explain why.
How is Clutch Performance Measured?
To pick the right part, you first need to understand how a clutch is rated. A clutch’s performance isn’t measured by how fast the car goes; its Torque Capacity measures it.
Torque Capacity is the maximum amount of force (twist) the clutch can hold through the driveline before it begins to slip. If your engine twists harder than the clutch can have, the clutch will let go, and you won’t go anywhere.
The Simple Difference Between Torque & Power
To understand why your clutch cares about torque, we need to define the terms.
- Torque: Think of this as “twisting force”. Imagine using a wrench to tighten a bolt. The harder you push on the wrench, the more torque you apply. In a car, the higher the engine torque, the harder it twists the wheels, and the faster the car accelerates.
- Power: This is a measurement of how fast work is being done. It measures the rotation over 1 second caused by the applied torque.
Think of it this way: Torque is how heavy a weight you can lift. Power is how fast you can lift it repeatedly.
Peak Engine Torque vs. Peak Power Output
Engines don’t produce the same amount of power or torque at every speed. They change as you rev the engine.
- Peak Engine Torque: This is the specific point in the rev range (RPM) where the engine is twisting its hardest. This happens independently of how fast the motor is spinning.
- Peak Engine Power: This is usually higher up in the rev range. It is the point at which the relationship between the engine speed (RPM) and torque is most efficient.
Why Choosing a Clutch Based on “Peak Power” is a Mistake
This is where many drivers get into trouble. As we mentioned, Peak Engine Torque is the maximum amount of force applied to the driveline at any one time.
The problem is that you cannot calculate Peak Torque just by looking at your Peak Power number.
Generally, the amount of torque your engine makes when it hits “Peak Power” is actually lower than its “Peak Torque.”
If you look at a dyno chart (like the one above), you will see two lines. The torque line usually spikes early, while the power line keeps climbing. If you buy a clutch based on the Power number (which happens later), you might end up with a clutch that is too weak to handle the massive Torque spike that occurs earlier in the revs.
Basing your selection on peak power can lead to a clutch that slips due to severe deficiencies in Clutch Torque Capacity.
How to Find Your Peak Engine Torque Figure
So, how do you ensure you get the right Exedy clutch? You need the real numbers.
Anyone who has tuned your car on a dyno can give you the peak engine torque figure. All you have to do is ask for it. If you have a stock car, the manufacturer specifications will list the “Max Torque.”
Whether you need extra torque capacity for towing a heavy boat or intend on taking part in a track day, knowing this number ensures you get a clutch that fits your needs.
Trusted by the World’s Best
You don’t have to figure this out alone. EXEDY has a rich heritage in motorsport, including successful partnerships with Ferrari in Formula 1 and multiple world championships with the Yamaha factory racing team in MotoGP.
As one of the world’s leading OEM clutch manufacturers, we use this expertise and our comprehensive engineering test facilities to apply advanced technologies to the EXEDY Racing range.
From our Sports Tuff and single sports organic/ceramic series to the Hyper Series Carbon-R triple plate, the EXEDY Racing range caters for all disciplines of motorsport. We engineer our clutches to handle the Torque so that you can handle the road.
Frequently Asked Questions (FAQ)
Does horsepower affect clutch choice? Indirectly, yes, but torque is the direct factor. High-horsepower engines usually have high torque, but not always in the same ratio. A clutch holds “twist” (torque), not “speed” (horsepower), so you should always look at the torque rating first.
What happens if I choose a clutch with too little torque capacity? If the clutch’s torque capacity is lower than your engine’s peak torque, the clutch will slip. This means the engine will rev up, but the car won’t accelerate properly. This causes excessive heat and will destroy the clutch very quickly.
Can I put a high-performance clutch in a daily driver? Yes, but you need to choose the right material. An “Organic” face (as in the Exedy Sports Tuff range) provides smooth engagement for daily driving. “Ceramic” or “Carbon” clutches can be “grabby” and harder to drive in stop-and-go traffic.
How do I find out how much torque my car has? If your car is unmodified, you can find the torque specs in your owner’s manual or on the manufacturer’s website. If your car is modified (tuned), you should ask your tuner for the dyno sheet, which will show the exact Peak Torque number.
