Quote:
Originally Posted by einzlr
As OP I'll make another decree that it doesn't have to be a car as long as your post contains some interesting info about engines that contributes in some way to the general topic. I didn't know that about sport bikes, so that qualifies as interesting  |
hp/L is pretty much a function of how high it revs, at least for road cars. Well, the bigger the engine the harder it is because for a car to pass EPA certification there is a maximum quantity of toxic emissions allowed, rather than maximum ppm. For bikes they can make more torque because they don't need to worry about emissions and noise (I think? The sport bikes going past my apartment are f***ing loud even compared to the diesel buses and trucks and modified sports cars). That's why that Hartley V8 hits 133Nm/L whereas Ferrari can only hit 120Nm/L. The highest "factory" specific torque I've seen is the TRD 3S-GE with 13.5 pistons, short trumpet ITB, cams, etc. etc. at 125Nm/L.
A CBR600RR on the other hand makes about 100Nm/L, which doesn't sound that great until you realize it's only 600cc, so the engine has to deal with proportionally much more friction and heat rejection than any larger car engine.
Bike engines have miniscule strokes (600cc bikes are typically 42mm or something like that) and hit 12000-15000rpm. 600cc bikes are IMO the coolest thing a normal consumer can buy, 15000rpm, power peak at 13500rpm, 180hp/L +. Not far from an F1 engine at all. Previous season F1 engines had minimum stroke of 39.5mm says Wikipedia, and 2014 they will be rev limited to 15000rpm