Honda engine size Vs power

[Pbassred]

My dad (a one time Spitfire mechanic) always says that power is basically the amount of fuel you can burn x the number of times you can do it.

so a Honda water cooled 125cc makes 13 HP. 13/125= 0.104hp/cc at 11500RPM, but allowing for revs (9.043 x e-5 per rev)

and a Honda water cooled 500cc makes 47HP. 47/500 = 0.094hp/cc at 8500RPM, but allowing for revs (11.06 x e-5 per rev)

so the 500 is less efficient than the 125 but it would be MORE efficient if it was allowed to rev as fast as the 125. Is that what they do with the Australian model? Opening up the rev limit?

[Bender]

Fuel economy/efficiency has to take into weight, rotating mass, gearing etc etc and even then you can have it tuned to run rich or lean depending on what market or task it's been aimed at and it all has an effect on the other, as engines get bigger power increase but rpm drops due to mass and physics, take it to the silly degree go look at ship engines, huge power with very little rpm ie 10' of thousands if hp at a couple hundred rpm

Edited December 21, 2018 by Bender

[Mississippi Bullfrog]

If you get a carb Honda 500 it’s nearer 60bhp but then you can’t ride them on a restricted licence. The output is more down to engine management mapping. Plus the larger engine has more torque which in terms of riding is of more interest than bhp numbers.

[Grumpy Old Git]

The fatter the elastic band and the tighter it is wound makes it go faster - Simples!

[S-Westerly]

Fuel economy/efficiency has to take into weight, rotating mass, gearing etc etc and even then you can have it tuned to run rich or lean depending on what market or task it's been aimed at and it all has an effect on the other, as engines get bigger power increase but rpm drops due to mass and physics, take it to the silly degree go look at ship engines, huge power with very little rpm ie 10' of thousands if hp at a couple hundred rpm

 

Slow speed MAN 6S70ME-C diesel: 21,000 HP at 82 RPM. Top speed about 15 knots (17 mph). Pushing about 180,000 tonnes. Fuel consumption of 55 tonnes per 24 hours.

[Pbassred]

The output is more down to engine management mapping.

Yeah I wasn't complaining. Just curious about how that works. I suppose the silver lining is that its actually impossible to thrash that engine. Underrev it to death, but not thrash.