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Re: [ST] Higher RPM for racing?


Joel Ashman wrote:

> OK so I need a little education...  When did it become preferable to have
> higher RPM for racing? It seems to me (a non racer) that given 2 motors with
> the same displacement, one with 12000 RPM and 150 HP (and a peaky curve) and
> a 6000 RPM 150 HP (flat curve) that the lower one would be more usable on
> the track.

Yeah, but on a 600cc engine, you're never going to make 150HP at 6000rpm 
on a petrol engine.  Well, not right now anyway.  Technology moves on at 
an alarming rate!

600cc is the amount of fuel/air mix burnt every two rotational cycles, 
so at 6,000rpm we're getting 3,000 "bangs" worth of energy every minute, 
and at 12,000rpm we're getting 6,000 "bangs" worth.  Twice as much bang 
power.  Now things like frictional losses, and reciprocal losses in the 
pistons, the energy a piston loses when it has to change direction at 
the top and bottom of its stroke, also increase with rpm, so the high 
revving engines are really a product of materials and lubrication 
engineering.  You need very light components and very good lubrication 
to get an engine spinning efficiently at those speeds, and even more so 
when you get up to the kind of rotational speeds of an F1 engine, where 
nearly 19,000rpm at 500cc/cylinder is de facto.

But as you said, power produced at low rpms is easier to use, more 
rideable power, especially for street driving, and that's where the big 
triple excels.  Sports bikes are rockets.  Designed to be fast and 
unstable and tricky to ride.  You can get much more out of them when 
they're on the edge, but they HAVE to be on the edge to get anything out 
of them.


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