250 cc vs 2500 cc

[dougl]

The efficiency of an engine to provide power to the rear wheel depends on a lot more than size.

 

[Jagster]

But the ratio of 250 cc bike i mentioned is not too far if we multiply things by 10 times. We dont have 200 torque which is compensating for 148bhp on rear wheel.
Nothing we have on rocket is 10 times as compare to that 250 cc bike,

so whats going on?

Maybe what's going on is a combination of Triumph trying to ensure long term reliability across all the component set......meaning not just the engine, but driveline too, by dialing down the output some. After all, it's still Top Trumps in quite a few categories. Would be a shame if they dialled up the output to 10 or beyond and lost in the mileage department.
Maybe add to that the small matter of noise and emissions.....Perhaps that plays a significant factor too?

 

[Whylee]

The biggest factor in how you are figuring this is how is the motor built and tuned. You can buy a Aprilia 125 that puts out about 43 H.P. from the factory, but you will be reving the daylights out of it to get there and the motor will last only hours before you need to install new piston and rings.
I had one, and after every track day it got new rings. And every other new piston.
You are comparing apples to oranges, the motors are not built in the same manner. Those 250s may be a mild build, but they will not hold up with higher mileage.

 

[Dr.D]

If Triumph built a 2500 cc four cylinder it would rev higher and produce more hp but you might suffer a loss in torque.

 

[MNC5]

You can get 230+ rwhp from a Carpenter kit (pistons, cams, valves, tune).

When I talked with Bob Carpenter he advised me to just go with the TXL pipe and tune for just under 190whp. Versus spending thousands for another 25-35 hp because of the fact that tuning doesn’t exist currently to raise the rpm’s enough go beyond 220whp.

I also think there were some posts here from someone who went full retard with Heads/Cams/pistons ect and was kneecapped at 220 + - whp

I took his advice and am happy with the outcome and their support

 

[wjb]

I don't think simply multiplying by 10 is a very accurate way to determine outcome. For instance, if we simply take the weight of the bike, 164kg, and multiply it by 10 we get a bike that weighs 1640kg! That's 3515 lbs! So it must be more complex than just multiplying by 10.
If we took the weight of the RIII, say 850lbs then one tenth of that is 85lbs or 38kg but the bike actually weighs 164kg.

 

[Dr.D]

The numbers aside these bikes are fun, quick and muscle strong. They handle great too considering pigs they are.

 

[imcool]

You can get 230+ rwhp from a Carpenter kit (pistons, cams, valves, tune).

not on the new rocket 2.5l, or can I ?

 

[imcool]

I don't think simply multiplying by 10 is a very accurate way to determine outcome. For instance, if we simply take the weight of the bike, 164kg, and multiply it by 10 we get a bike that weighs 1640kg! That's 3515 lbs! So it must be more complex than just multiplying by 10.
If we took the weight of the RIII, say 850lbs then one tenth of that is 85lbs or 38kg but the bike actually weighs 164kg.

yes, I didnt multiply weight we have an advantage of weight in rocket yet we get less ;(

 

[wjb]

The power to weight ratio for the Bajaj Pulsar you mention is .065 horsepower per lb.
The power to weight ratio for the Rocket 3 is .257 horsepower per lb.