top speed, quarter mile

[flynrider]

65HP can not push a bike through the wind at 150MPH....

There are exceptions..Rollie Free's HRD Vincent Black Shadow run at Bonneville Salt Flats Sept 13, 1948 150.313 mph

Oops just looked it up, his HRD was rated at 70 hp so guess you are right lol ..a stock Vincent was rated at 45 horsepower

There are exceptions..Rollie Free's HRD Vincent Black Shadow run at Bonneville Salt Flats Sept 13, 1948 150.313 mph

Oops just looked it up, his HRD was rated at 70 hp so guess you are right lol ..a stock Vincent was rated at 45 horsepower
If I ride a bicycle with high gear, my top speed is 40 MPH on flat road. I change gear to lower, my top speed is 15 MPH but I can climb hill at 6%, A very strong rider use the same bike, his top speed on flat still 40 MPH; on lower gear, his top speed is 25 at 6%.

so horse power is just one element of the real power. 65 horse with 105 lb of torques have much better top speed than 65 horse with 50 lbs torques

any engineer can shred light on this?

Not sure what you mean by "real power". HP is a measurement of power. Torque is a measurement of force. Power is derived by measuring how much force can be delivered over time. In other words, torque is one component of power.

Where top speeds are concerned, you want to know how much power is required to overcome the increasing aerodynamic drag as speeds increase. More power lets you overcome more drag and nets you a higher top speed.

I would suspect that a 65 hp motorcycle engine that produces 105 ft/lbs. of torque would have an unusually low redline. While it would probably give your neck a good snap off the starting line, it would redline long before it set any speed record.

A motorcycle that produced 50 ft./lbs. of torque and the same 65hp would likely spin a lot faster to make its power, be slower off the line, and reach the same top speed as the torquier bike (assuming both hypothetical bikes have the same drag profile).

Note: the above applies to top speed only. The relative importance of hp v. torque in other types of applications (i.e. drag races, road courses) is a lot more complex and application specific.

Top speed is basically power vs. drag. You can increase power or decrease drag to go faster.