Ever wondered why your car’s dyno sheet shows less power than what the manufacturer advertises?

It’s a question we hear all the time at 5ive Performance. The answer comes down to the difference between Crank Horsepower (Crank HP) — the number car manufacturers publish — and Wheel Horsepower (WHP), which is what dynos actually measure.

Let’s break down what these numbers really mean and why you shouldn’t panic when your dyno sheet looks “lower” than factory specs.

Crank HP (Advertised by Manufacturers)

Crank horsepower is the power measured directly at the engine’s crankshaft, before the drivetrain and wheels come into play. This is the number you’ll see in brochures or spec sheets.

• Why it’s higher:

  • No drivetrain resistance or wheel loss is included.

  • Measured under controlled conditions with specialized equipment.

  • It makes for stronger marketing numbers that look better on paper.

Wheel HP (What Dynos Show)

Wheel horsepower is the actual power delivered to the ground — and it’s always lower than crank HP. This is what matters when you’re driving, racing, or tuning.

• Factors that affect WHP:

  • Drivetrain type (FWD, RWD, AWD)

  • Tire size and grip

  • Transmission and gearing losses

  • Dyno type and calibration

Drivetrain Loss Explained

Every drivetrain absorbs some power before it reaches the wheels. Here’s the general rule of thumb:

• FWD: 10–15% loss

• RWD: 12–18% loss

• AWD: 20–25% loss

Example:
A car rated at 300 crank HP will typically show 240–260 WHP on the dyno, depending on drivetrain and setup.

Why Dyno Numbers Matter

Don’t get caught up in comparing dyno sheets like trophies. The real value of dyno testing is consistency.

• Measure the before and after gains from mods.

• Track improvements over time.

• Tune safely with accurate real-world data.

What matters most isn’t the biggest number — it’s how your car responds and performs.

Mustang vs. Dynojet vs. Hub Dynos

Not all dynos are created equal. Different machines read differently, so don’t compare results across platforms.

• Dynojet: Reads slightly higher, very popular in the aftermarket world.

• Mustang Dyno: Reads lower, often called the “heartbreaker” dyno.

• Hub Dyno: Measures power directly at the hubs, very precise.

👉 Always compare before vs. after runs on the same dyno for an accurate picture of gains.

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If your dyno numbers don’t match what the manufacturer promised, that’s normal. What matters is how much power your car is putting down to the wheels — and how your setup performs in the real world.

👉 Ready to see what your car is really making? Book a dyno session with 5ive Performance and get the most accurate numbers for your build.