ESE's works engine tuner

[rgvbaz]

I did a quick graph of the 30 hp and 28 hp curve and rescaled the 30 hp curve by .9.

As you can see there isn't much difference between the both of them, the 30hp wins at the top-end where the 28 hp curve is still a little better up the slope. I'd guess, on average, they would both perform about the same.



Dave

[Frits Overmars]

I did a quick graph of the 30 hp and 28 hp curve and rescaled the 30 hp curve by .9.
As you can see there isn't much difference between the both of them, the 30hp wins at the top-end where the 28 hp curve is still a little better up the slope.

That is why I suggested rescaling it by 0.85 .

[Ocean1]

From the Gates Corporation

Nice work mate. You do have to be a bit careful with comparisons using an interested manufacturer's numbers. Modern belts of all types are very good, and are often a better choice than chain for a given application, but it does get complicated. There's a reason 99.9% of pushbikes, for example use chain, it's transmission efficiency might be arguably smidgeonally lower than a particular selected synchronous belt in the lower torque, higher speed ranges, but that application has to deal with large variations in torque and velocity. Over that range of variables chain remains about the most efficient choice.

If you have a static or narrow rpm and torque variation then selecting a high spec’ modern synchronous belt close to its maximum rated speed using the largest, lightest pulleys you can will produce a slightly more efficient transmission.

For most applications I’m involved with Vee belts are less efficient than both the above, but their use in a cvt system is a straight trade-off between efficiencies gained from optimising engine rpm and the slightly higher transmission losses.

[Frits Overmars]

....For most applications I’m involved with Vee belts are less efficient than both the above, but their use in a cvt system is a straight trade-off between efficiencies gained from optimising engine rpm and the slightly higher transmission losses.

From what I've seen on the test bench, first measuring CVTs and then replacing the V-belt set-up with a synchronous belt set-up for more precise measurements ( http://www.hvg-engineering.com/index...aid=17&lang=NL ), the V-belt's losses are not just slightly but markedly higher; up to 10%.
Even so, the CVT is unbeatable. Not only because the engine can be kept at max.power rpm all the time; keeping the gas dynamics in the engine going without gear change interrupions is at least as important. In a gearbox engine, after each gear change the engine noise returns immediately, but engine power does not. It can take up to a second before resonance is restored and full power is once more available. But on a tight track chances are that you will have to change gear again within that second, so you will never have the power at your disposal that you saw on the test bench.

[bucketracer]

In a gearbox engine, after each gear change the engine noise returns immediately, but engine power does not. It can take up to a second before resonance is restored and full power is once more available.

TeeZee has often commented, that a lower powered FXR on his flank rounding a corner was able to get its nose in front on the drive out from the apex. That second before resonance is restored realy hurts 2-Strokes. CVT has its appeal.

[Ocean1]

Even so, the CVT is unbeatable. Not only because the engine can be kept at max.power rpm all the time; keeping the gas dynamics in the engine going without gear change interrupions is at least as important.

Not to mention avoiding the not inconsiderable losses through quite so many gears/bearings/bushes. To what extent is the usual trade off between larger pulleys/lighter & more efficient belt and smaller pulleys/lower innertia but less efficient belt dictated by engine rev limits?

And have you encountered steel sectional belts in bike CTV applications?

[husaberg]

Not to mention avoiding the not inconsiderable losses through quite so many gears/bearings/bushes. To what extent is the usual trade off between larger pulleys/lighter & more efficient belt and smaller pulleys/lower innertia but less efficient belt dictated by engine rev limits?

And have you encountered steel sectional belts in bike CTV applications?

I Don't know these have been posted before, the second one is similar to sketchy's supercharger drive

[husaberg]

I asked this questiop before but i am not sure wob and frits understood what i meant.
the Aprilia race bike's rsv rsa rsw all ran a servo controlled power valve (2 stage for sealing.)
How is it the servo actuation superior (not the two stages bit i get that) to the simpler solenoid actuation shown here

Is it too Fast? it certainly appears faster than a servo?

[Flettner]

No, you are all off on a tangent, gearing is still the way. Some industrial variable speed gearboxes run what would be easily explained as a planetary system with the out side ring speed controlled ( normally anchored). 70 HP gearboxes controlled with a five horse electric variable speed motor plugged in the side, controlling the large torque by changing outside gear ring speed. Minimal losses. If it were not for oil pumping losses ( oil through the gears ) then gear drive would be most efficient as the gear teeth are just rolling against each other ( involute ), not rubbing.

[Ocean1]

No, you are all off on a tangent, gearing is still the way. Some industrial variable speed gearboxes run what would be easily explained as a planetary system with the out side ring speed controlled ( normally anchored).

Like an old pushbike hub gearbox?

If it were not for oil pumping losses ( oil through the gears ) then gear drive would be most efficient as the gear teeth are just rolling against each other ( involute ), not rubbing.

Aye. Some more commercially derived industry data:

http://www.powertransmission.com/iss...efficiency.pdf

"Gears mesh through a combination of
rolling contact and sliding contact. Spur, helical, and bevel
gears are considered rolling contact gears, because the majority
of the contact is of the rolling type. A typical estimate of
the power loss in rolling contact gearing is 1.5 percent per
stage."

How many stages in a multi-stage epicyclic gearbox?

[Ocean1]

I Don't know these have been posted before, the second one is similar to sketchy's supercharger drive

Little bit, although his isn't variable.

'Er indoors Toyota Blade has one of these lurking somewhere inside:

[rgvbaz]

That is why I suggested rescaling it by 0.85 .

I see, Frits!

But then you could rescale the 28 Hp curve by .95 and this would re-align the curves the same, visually, as in the graph I posted before. I chose .9 as it aligned the two curves from the end of the over rev and gives a quick visual comparison of both.

Dave

[Frits Overmars]

To what extent is the usual trade off between larger pulleys/lighter & more efficient belt and smaller pulleys/lower innertia but less efficient belt dictated by engine rev limits?

I don't know.

And have you encountered steel sectional belts in bike CTV applications?

Only in cars, not in bikes, although I've heard rumours that one large Suzuki scooter is using it.
The problem with a push belt (a Dutch invention, by the way) is that the friction coefficient between the steel belt elements and the heaves is much lower than the friction of a rubber V-belt. Therefore a much larger clamping force is needed, necessitating hydraulics, a pump and a much heavier construction altogether.
For racing I can imagine a heave fitted via a pitch on the input shaft. Advantages: no hydraulics needed and a clamping force that varies with the torque that has to be transmitted.

[Frits Overmars]

I asked this questiop before but i am not sure wob and frits understood what i meant. the Aprilia race bike's rsv rsa rsw all ran a servo controlled power valve (2 stage for sealing.) How is it the servo actuation superior (not the two stages bit i get that) to the simpler solenoid actuation shown here.Is it too Fast? it certainly appears faster than a servo?

The Aprilia power valve gradually opens from 10,000 rpm to fully open at 12,000 rpm. A solenoid does not understand the word gradually.

[Frits Overmars]

No, you are all off on a tangent, gearing is still the way. Some industrial variable speed gearboxes run what would be easily explained as a planetary system with the out side ring speed controlled ( normally anchored). 70 HP gearboxes controlled with a five horse electric variable speed motor plugged in the side, controlling the large torque by changing outside gear ring speed. Minimal losses. If it were not for oil pumping losses ( oil through the gears ) then gear drive would be most efficient as the gear teeth are just rolling against each other ( involute ), not rubbing.

You have a point regarding efficiency, Flettner. And there have been (and maybe still are) transmissions like you describe, where the electric variable speed motor has been replaced with a small belt variator . But if you wish to sell zillions of cheap scooters you have to stick to the KISS principle.