cipher315 t1_iugckgj wrote on October 31, 2022 at 2:42 AM

Reply to comment by davmeva in ELI5: How exactly do we get some much power from engine now, than we did 40, 50, 60 years ago? by Micromashington

The Allison V-1710 aka the engine in the p38 lighting, thats a airplane from WWII, makes about 1600hp with 28 liters of displacement and two huge superchargers. The Bugatti Chiron does the same with a 8 liter engine.

By today's standards WWII airplane engines are incredibly weak for their displacement.

Reinventing_Wheels t1_iuh0845 wrote on October 31, 2022 at 7:17 AM

There's a big difference between how airplane engines and automobile engines are rated for power output. Airplanes have to be able to put out their full rated power for extended periods of time, without suffering any ill effects. Cars only put out peak power for a few seconds at a time while accelerating. Once the car reaches cruising speed, it may only be using a tiny fraction of the peak power output the engine is capable of.

MrJuniper t1_iui5opv wrote on October 31, 2022 at 2:51 PM

While the Chiron's engine is undoubtedly more efficient then the Allison, there are some more considerations. The vast majority of piston engine aircraft are rpm limited to 3000rpm or so to prevent the propeller tips from entering the trans/supersonic region.

Automotive engine designers often increase rev limits as a strategy for increasing horsepower - in the Chiron's case it redlines around 6k and generates peak HP, if I had to guess, at around 5300 or so. The Allison would have been limited to about 3k, and as the other poster has said, would be expected to run near peak rpms for longer durations.