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Cake day: July 19th, 2024

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  • Isn’t it the case that diesel engines continue to compress air while petrols don’t? This plus the significantly longer stroke might account for some of the difference. Yes the air is decompressed right afterwards but significant amounts of work must be lost as heat.

    I don’t know what to say. It’s just my personal experience. While driving different cars the diesels always braked much more, and at lower RPMs. Coasting down an incline, put the diesel in 3rd, it will spin up to 2000 then go down to 1600 and stay there, braking the car 10-15 km/h. The equivalent petrol will spin up to 3000 and stay there, and not reduce the car’s speed, just keep it from accelerating. Something like that happened across many different cars and engine displacements. Maybe it’s because the petrols go down to as little as 1L of displacement and 3 cylinders while the smallest diesels are still at 1.6L and 4. Or it’s because the diesels are always turbocharged, while the petrols are sometimes naturally aspirated.