Power and Weight
Drivetrain Loss: Why the Dyno Reads Lower
The familiar rule that a rear wheel drive car loses 15 per cent between crankshaft and wheels does not survive contact with the components....
Section 04
Power and Weight
PS, hp, kW and kerb weight. The four places a spec sheet quietly changes the rules.
Power and Weight
Dyno Correction Factors: How One Engine Makes Three Figures
A dynamometer measures torque on a particular day in particular air, and without a correction factor it is recording the weather. Every...
Power and Weight
Combined Output: Why Hybrid Power Figures Do Not Add Up
A hybrid's system power is almost never the engine figure plus the motor figure, and the reason is simple arithmetic that gets lost in the...
Power and Weight
Kerb, Dry and DIN: Which Weight Is the Real One
There are at least four weights for every car and only one of them is defined in law. European type approval defines mass in running order...
Power and Weight
Power to Weight: The Ratio That Decides More Than Power
Power to weight is the most useful single number on a specification sheet and the easiest one to calculate dishonestly. It predicts...
Power and Weight
PS, hp and kW: Three Numbers for One Engine
The same engine carries three different numbers because PS, horsepower and kilowatts are three different units, and a fourth source of...
Power and Weight
Specific Output: The Engineering Bragging Right
Specific output is power divided by swept volume, and it measures how hard an engine is working rather than how fast the car is. The...
Power and Weight
Torque vs Power: Which One Actually Accelerates the Car
The question has a settled answer that the argument keeps ignoring. Power accelerates the car, because power is the rate at which energy is...
Power and Weight
Unsprung Mass: The Kilogram That Counts Double
A kilogram at the wheel is worse than a kilogram in the body for two separate reasons. First, mass at the rim has to be accelerated...
Power and Weight
Weight Distribution: Why 50:50 Is Not Always the Target
50:50 is a marketing figure that describes a compromise, not a peak. Weight distribution decides how much load sits over each axle before...