How do Ducati do it in WSB??

[Fooman]

Air + Fuel = Power

So the more air and fuel you can get in the more power you make. More revs means you can get air and fuel more often, but revs aren't the only way to make more power. There's lots of things that go into it. Compression ratio, combustion chamber shape, ignition, exhaust and chamber scavenging ........ but anyway. They make lots of money and spend plenty of it on R&D.

Sort of correct, but not strictly. Replace "Power" in your first couple of sentences with "Force" (or even more strictly, "Pressure").

The combustion inside a cylinder causes a increase in pressure. This pressure, over the area of the piston, converts to a force on the piston. That force, is transmitted to the crank throw, via the conrod. Thanks to the stroke of the crankshaft, that force is seen by the rotating crank as a torque about the axis of rotation. Because the crank is rotating, that torque is being applied over a circular path, in some amount of time. Which is power.

For linear forces, work/energy (Joules) = force along a distance, (e.g. Newtons * Metres)
power (Joules per second, or Watts) = work done in a certain abount of time

or more simply put, linear power = force times velocity

For rotational motion, work/energy (Joules) = torque (force times the length of the torque arm (stroke)) around a rotational distance (e.g. radians (there are 2*pi radians in a revolution)). Power = work done in a certain amount of time.

or more simply put, rotational power = torque times rotational velocity, or W = Nm * rad/s

If you want to use ft.lbs, hp and revs instead of Nm, W and rads/s, you get the familiar relationship, hp = torque (ft.lbs) * revs (rpm) /5252.

So, if you want to increase power, you increase either the torque or the speed.

To increase the torque, you can:

- increase pressure from forcing more fuel and air in the cylinder (e.g. turbocharging, supercharging, ram air), or using a fuel with higher specific energy e.g. nitromethane, or increase the effciency of combustion, so more of the energy goes into increasing the pressure, rather than heating up the combustion chamber and piston.

- increase the piston area. But you can't keep the displacement the same, as the stroke has to decrease to do so. This will reduce the torque by the same amount. So you displacement has to go up. You also have to use more air/fuel if you want to maintain the effective pressure. This also increases reciprocating mass, increasing the stress in the conrods and crank, for the same revs. So you have to decrease the revs if you don't want to break the bits.

- increase the stroke. Again, this means the displacement has to go up, increasing the reciprocating mass and stresses (for the same revs).

To increase the revs you can:

-Make the reciprocating masses smaller, so that the limiting stresses and inertias are reached at higher revs. But this will decrease the torque - smaller piston, shorter stroke. Unless you use more cylinders to maintain displacement. But that tends to introduce more frictional losses (and more bits to break).

- make everything stronger and lighter, so the limiting stresses on the components are reached at higher revs.

So, in summary, to make more power, 1) make the engine bigger (and burn more fuel) 2) make it stronger and/or lighter so it runs faster (and burns more fuel) or 3) make it more efficient (and burns the same amount of fuel) or any combination of the 3 which will be a compromise in one way or the other.

1) is the cheapest and easist way of doing this - "there ain't no substitute for cubic inches" 2) i$ the MotoGP/WSB/F1 way of doing thi$ (and is the expen$ive way). 3) is the boring, but ultimately the best way of doing it, as it will always be possible to use the other methods as well.

The actual answer to the original question is as somebody mentioned, the way the Dukes lay the power onto the track enable the power to be applied more rapidly than the higher reving 4's - better acceleration out of corners. I 've recently read an interview with Aaron Slight, made just after he had gone to the SP1 - he was blown away by the tractability of the V2's - described it as "finding out what the Ducati's had that the RVF didn't" or something like that. I suspect the V2's have a lower rotational inertia than the 4's, meaning it can turn in more quickly as well.

FM

Oh, 10 characters...

[skelstar]

I saw a doco on Sky about this beasty. They can shut a couple of cyclinders off while in transit and do some maintenance. They assemble the whole thing in a factory, fiddle a bit, then disassemble before putting it into the ship as its too big to move in one peice.

I love discovery channel.

[Adam_B]

I'm not sure if it is the WSB or MotoGP series but I was under the impression the Ducatis are running a V4 with a V4 road bike in the pipeline for homogalation stuff. I read this in Two Wheels magazine but it was the April 1st issue so could be a piss take

MotoGP is a V4, actually an L4 = a 90degree V4, Desmosedici (16valve).
Yep there is a production bike in the pipeline whether or not it makes it into production is another question.

The WSB L twins are allowed under the rules to have more development work done on them from standard than the IL4's are.
So they can bring the power up from 150HP stock to about 190HP.
Some of the IL4's are putting out 210HP.
I quess the aero of the 999's make up the straight line speed difference. They are quite a bit narrower than the IL4's.
And out of the corners I doubt if any are using max HP anyway so they don't loose ground to the IL4's

And yes they are easy to ride and very chuckable and all the HP goes straight to the ground and all the power is available anywhere in the rev range. God I want one.

[Lou Girardin]

It was clear at Monza that the Spewzooks had far more power than the others, but the Duc has better drive out of corners and that kept him ahead. Possibly better corner speed too.
But I've heard that they're spinning the Ducs so hard that they change engines like other teams change oil.