Trumpet diameter

[xpensive]

Don't know to what extent this device is at all used nowadays, but I think it was originally intended for truck-diesels.

[safeaschuck]

just had a look at some Kawasaki carbs from the mid nineties ZXR600 which were lying around, they have different length O.E.M. trumpets, two centre cylinders get longer ones (about an inch) than the outer two (about 10mm). This could be due to packaging (they are extremly tight against the frame and difficult to get in and out) or possibly the exhausts cannot be made equal length (again packaging) so the trumpets compensate, however I imagine it is most likely that they are hedging their bets and spreading the torque/power out over the rev range.

There is an outside chance that it's to do with lessening the demand on the inner cylinders at certain speeds (i'm reaching here, I don't know if that is even feasible with trumpets alone but the idea makes sense) in the old air-cooled days the inner cylinders (or even inside of outer cylinders in the case of twins) on an in-line engine used to get hotter, but as this is a water-cooled unit I imagine this is highly unlikely.

[zed.inc]

The frequency of a spring is given by (1/2pi)*(k/m)^0.5 where K is the stiffness and M is the mass. We can apply this to a gas like air since it is effectively a bundle of masses separated by springs.
When we apply it to air the stiffness becomes the air pressure and the mass becomes the air density, you can imagine a higher pressure chamber of air has more stiffness.

This formula's been bugging me for a while now... Replacing stiffness with pressure and mass with density is dimensionally inconsistent. The substitution's dimension is [L/T] as opposed to [1/T].

Jonny6001, something's missing in the formula. Please fill us in if you can.

[riff_raff]

xpensive,

The reason the Comprex supercharger was dropped by Ferrari on the 126C GP car, was because the Comprex supercharger rotor required a drive belt from the crankshaft. And Ferrari could never get the belt drive reliable enough for race conditions.

Except for the limitations of the rotor drive under race conditions, the Comprex supercharger worked very well. It basically consists of a rotating series of acoustically tuned reversion chambers that utilize exhaust energy pulses to supercharge the intake flow. When done correctly, it is an extremely efficient use of exhaust energy..

[xpensive]

Terry,
Inability to make a drive from crank- or camshaft reliable enough seems a little too simple an explanation to be honest.

However, I seem to remember that the driveability of the engine was marvellous, when compared to the light-switch caracteristics of the turbos of the time?