When car enthusiasts or performance-minded drivers start talking about modifications, the subject of limited slip differentials (LSDs) often comes up. One of the most common questions is: “Does a limited slip differential increase horsepower?”
At first glance, the answer is simple: No, an LSD does not increase engine horsepower. Horsepower is a measurement of the work an engine produces, and the differential is not connected to the actual generation of power inside the engine.
However, the longer and more accurate explanation is that while an LSD doesn’t create more horsepower, it does allow you to use more of the horsepower you already have. In fact, in real-world driving, an LSD can make a car feel noticeably faster and more responsive. Let’s break down why.
Understanding Horsepower and Torque
To answer the question fully, it helps to understand what horsepower really means.
- Horsepower (hp) is a unit of power, measuring how much work an engine can do over time.
- Torque is a measure of rotational force — essentially how hard the engine can twist the crankshaft.
The engine produces both horsepower and torque. But the real challenge is transferring that power effectively to the road surface. This is where the drivetrain — including the differential — plays a critical role.
What a Differential Does?
The differential is a gear assembly that splits the engine’s torque between the left and right wheels. It also allows the wheels to rotate at different speeds, which is necessary when turning. Without a differential, both wheels would be forced to spin at the same speed, making cornering awkward and damaging tires.
There are three main types of differentials:
Open Differential
- Most common in standard vehicles.
- Sends power to the wheel with the least resistance.
- Cheap and simple, but wastes power if one wheel loses traction.
Limited Slip Differential (LSD)
- Distributes torque more evenly between the two wheels.
- Limits how much one wheel can spin freely compared to the other.
- Provides better traction during acceleration and cornering.
Locking Differential
- Locks both wheels together so they spin at the same rate.
- Excellent off-road, but not practical for everyday driving.
Why an LSD Feels Like More Horsepower?
Now let’s answer the core question. If you replace an open differential with an LSD, your car’s engine output on a dyno will not change. The engine still makes the same horsepower and torque.
But in actual driving, the story is different.
Reducing Wheel Spin = Less Wasted Power
Imagine accelerating out of a corner. With an open differential, the inside wheel — which has less grip — starts spinning, and most of the torque is wasted. With an LSD, torque is shared more effectively, and the outside wheel, which has better traction, puts that power to the ground.
Improved Acceleration
Because more torque reaches the wheels with grip, the car launches harder, especially from a standstill or in slippery conditions. A car with an LSD may run quicker 0–60 mph times than the same car with an open diff, even though the horsepower is identical.
Better Corner Exit Speed
On a track, an LSD allows drivers to apply throttle earlier when exiting a corner, because both wheels share power instead of one spinning uselessly. The effect is faster lap times and a car that feels “stronger” when pushed.
Confidence and Stability
On wet or uneven surfaces, LSD-equipped cars feel more planted. Drivers can accelerate without fear of one wheel spinning uncontrollably. This stability translates into a perception of more available power.
LSD Does Not Increase Horsepower
Here’s the key point:
- Horsepower: A static number determined by the engine.
- Performance: How effectively that horsepower is translated into acceleration, cornering, and lap times.
An LSD does not raise your horsepower figure, but it maximizes usable horsepower. In real-world terms, that means your car will accelerate quicker, corner harder, and put down power more consistently.
Conclusion
So, does a limited slip differential increase horsepower? No, it doesn’t. Your engine’s horsepower rating stays exactly the same.
But in practical terms, an LSD makes your car faster, more predictable, and more efficient at putting power down to the road. It ensures you get the most out of the horsepower you already have. That’s why car manufacturers install LSDs in sports cars, and why racers and enthusiasts consider them essential.
If you want raw horsepower, you’ll need engine upgrades. But if you want your car to feel stronger, accelerate harder, and corner better, then a limited slip differential is one of the smartest upgrades you can make.
