Why the Same BMW Engine Can Have Different Power Outputs
Image: BMW B48A20E Complete Engine with just 60K miles, for £3,299.00, mtautoparts.com Look at BMW's model range and something quickly becomes apparent. The 318i, 320i, and 330i all share the same B48 engine code, the same 2.0-litre four-cylinder, the same displacement, the same basic architecture. Yet the 318i produces around 156hp, the 320i around 184hp, and the 330i around 258hp. How does the same engine produce three entirely different power figures? The answer matters practically, especially when buying a used BMW engine as a replacement. It Starts With the Turbocharger The biggest variable in BMW's turbocharged engine family is boost pressure: how hard the turbocharger forces air into the engine. More air means more fuel can be burned per cycle, which means more power. On the B48 family, higher-output variants run higher boost pressures, achieved partly through different turbocharger specifications and partly through different mapping in the engine management software....