25 years of sportbike development

[Dave]

Originally Posted by karl_1052

Torque is a function of engine capacity and engine efficiency. The only way to increase torque is to increase breathing capacity.

HP is a function of torque at a specific rpm. Raise the RPM capacity and the HP goes up, but torque will always be the same.

My bike makes 80lb-ft from about 3000 rpm to over 10000rpm, with a peak of just over 100lb-ft at around 8000rpm. All due to the long stroke motor with an additional 340cc over a liter.

fixed

[karl_1052]

Originally Posted by Dave

fixed

But with a given capacity, cylinder filling can only be so efficient, unless there is a giant leap forward in breathing technology. The only other way is a bigger cylinder.

[No Worries]

Torque X RPM divided by 5252 = HP. You have to increase torque and/or RPM to get more HP. But there is a maximum speed that the piston can travel at, as it accelerates from 0-100MPH (or more) and then decelerates as it goes up and down.

Changing the stroke changes where the torque peak occurs. For the riding I do, I'd much rather have an early R1 (long stroke) than a newer one. And for racing across an intersection, a cruiser, with it's torque peak right off idle, will win without any fuss. Plus, they are impossible to stall at a light.

[karl_1052]

Originally Posted by No Worries

And for racing across an intersection, a cruiser, with it's torque peak right off idle, will win without any fuss. Plus, they are impossible to stall at a light.

I would take that challenge.

[derf]

Originally Posted by karl_1052

I would take that challenge.

Yup, based on just an engine vs engine comparison maybe, but when you look at the ability of a cruiser to take off vs that of a sportbike. A cruiser weighs in at between 500 - 1000 lbs, a sportbike is in the 350-450 lb range, that is alot less weight to move around. There are also a host of other factors that will come into play too