Understanding the horsepower (HP) figure of your BMW M240i, or any vehicle for that matter, often starts with comprehending how car manufacturers actually measure engine power. It’s a common question for enthusiasts and potential buyers alike: how much power does the BMW M240i really have? The answer lies in standardized testing procedures performed at the engine output shaft, using an engine dynamometer, not a chassis dyno.
Different standards have evolved over time to quantify this “brake horsepower” (BHP). In the muscle car era, BHP represented gross power, measured without ancillaries like the alternator or radiator fan attached to the engine. This changed in the early 1970s with the introduction of SAE standard J1349, which shifted to net power measurement. This net power standard includes all power-consuming accessories, emissions controls, and the complete exhaust system, providing a more realistic figure.
Further refinement came in 2005 with ‘SAE Certified Power’. This standard requires manufacturers seeking SAE certification to conduct tests in accredited labs, witnessed by third-party accredited observers. Similarly, the German DIN (Deutsches Institut für Normung) standard mirrors the SAE net power approach, also measuring power at the crankshaft with all ancillaries connected, expressing power in PS (Pferdestärke). Across various European standards, the consistent principle is crankshaft measurement.
Crucially, official horsepower figures, like those for the Bmw M240i Hp, are derived from engine dyno tests, not chassis dyno measurements at the wheels. Chassis dynos, while valuable for tuning and modifications, can be less reliable for stock turbo cars like the M240i. The application of correction factors for temperature and elevation can often lead to inflated and inaccurate HP figures when using chassis dynos on turbocharged engines.
For accurate BMW M240i HP figures, it’s best to rely on the official numbers published by BMW. Chassis dynos serve their purpose in performance tuning, allowing for baseline measurements and tracking the impact of modifications. However, when it comes to understanding the factory-specified horsepower of your BMW M240i, trust the manufacturer’s data obtained through standardized engine dyno testing.
