Danno wrote:

Years ago it was discovered that increasing horsepower in a flat-track engine did not go hand in hand with a reduction of lap times. It was postulated that any more than around 100-105 bhp was useless because it could not be put down on the track and only brought on excess wheelspin.

Wellllll, there is that famous story of Kenny Roberts on a TZ700 (TZ750 ?), where he cruised with the pack and really opened the throttle on the last lap, and BLITZED em !

And reportedly parked it and quipped "they don't pay me enough to ride that thing" and never rode it again.

And they (multicylinder roadracing strokers) were banned.

But it did show that all the perceived wisdom about hp and torque and traction was just talk.

A good rider can use as much hp as possible...

Danno wrote:Then, someone out of the inner circle took a look at a dyno graph of an XR 750 and discovered something curious: We all know the hp and torque graphs intersect at 5250? rpm, but most graphs show hp continuing to rise while torque maxes out and starts falling off. The XR 750 chart showed the lines intersecting and crossing the opposite way; as the hp fell off, torque continued to rise.

Technically, we'd need to see those graphs.

The torque curve is merely a reflection of how well the engine breathes.

It is not impossible for the most efficient/effective breathing to happen at higher rpms,

to or even beyond redline in some cases.

However, the hp curve is CALCULATED from the torque curve, so if torque keeps rising,

then the hp HAS to keep rising as the rpms increase - its a strict mathematical relationship.

You can't have torque with no power, or power with no torque - they are rather solidly bolted together...

5252 rpms is significant only because its part of the formula twixt torque and hp.

At those particular rpms, the torque in ft-lbs is numerically the same as the hp.

Thats why the graph lines cross (providing the ft-lbs and hp scales are drawn the same).