Why do diesel engines have so much Torque

google BMW M3 petrol, VS Alpina diesel 3.

a good comparison of two almost identical BMWs

So identical that one costs £8-10k more than the other, for an extra 36 bhp and 52lb ft, plus better chassis, suspension and proper tyres (no run flats on the Alpina) to give better handling and feel. Plus a whole host of subtle changes and mods to the standard car.

Sorry, what was the original question?

Why do diesel engines have so much Torque?
That's been answered.

Could petrol engines be tuned the same way to give loads of low end torque and power?
Yes. I have experienced the Impreza 2.5 and the low end torque on that engine is immense. With a remap aimed at low down grunt one can make it more so.

(one of the reasons why hi-octane petrol burns slower,longer push time).
sorry just want to say something about this. Hi-octane fuel doesn't "burn slower". It can be compressed more before it self detonates (which is what engine knock is), meaning the pistons can push the fuel down further so when it is sparked the piston has a longer power stroke back, giving the "longer push time".
to add to the Diesel knowledge,, Diesel engine produce the MOST Torque when exhaust smoke goes full black loaded!
that is using diesel as fuel, other types of fuel auxialary injection can reduce smoke a lot!

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