You just got your car tuned and the shop handed you a dyno sheet. Before vs after. Numbers everywhere. What does it all mean?
What a Dyno Actually Measures
A dynamometer measures the power your car puts to the wheels — not at the engine. This is called wheel horsepower (whp) and wheel torque (wtq). It is always lower than the engine's output because power is lost through the drivetrain — transmission, driveshaft, differential, and tires.
As a rough guide, rear-wheel drive cars lose about 15% between crank and wheels. All-wheel drive cars lose about 20%. So a BMW with 500hp at the crank might show around 420-425whp on the dyno.
The Power Curve
The dyno graph shows power output across the entire RPM range, not just at peak. This is where most of the real information lives.
- A flat torque curve means strong, linear pull from low RPM — great for daily driving and real-world acceleration
- A peaky curve means big numbers at high RPM but less usable power in everyday driving
- The area under the curve is what determines how fast a car feels — not just the peak number
Before vs After — What Good Looks Like
A well-executed tune should show improvement across the entire RPM range, not just at peak. At House of Power, we focus on building the power curve — pulling it up from idle through redline — not just chasing a bigger peak number.
What Numbers Should You Expect?
Stage 1 gains vary significantly by platform:
- BMW B58 (340i, M340i): +60-80whp typical Stage 1
- Mercedes M177 (C63 AMG): +50-70whp
- Porsche 992 Carrera: +40-60whp
- McLaren 720S: +60-80whp