2014 transmissions

[autogyro]

This image from Cosworth demonstrates pretty well why the gearing wont be a huge issue.

Really? And when it's not being assisted? I sure don't read it that way. I don't see it as a broad power band.

There are still many performance gains to be made through the gearbox technology.
If the teams prefer to ignore the potential because of the standard gearbox packages offered, tough luck.

[rscsr]

A lower rev limit, turbocharging, and KERS should lessen the impact of transmission gear ratios.

It isn't really true what you are saying. Even if the power is almost constant over a wide range, the gearing defines the acceleration.
Once I get home, I will make a nice graph to show it.

[PhillipM]

If the power is constant between the gears then so is the acceleration.

[rscsr]

No!? Because power = torque x rpm !?

[Juzh]

No!? Because power = torque x rpm !?

Torque is much more with 1.6 turbo. V8s had no torque to talk about.

[PhillipM]

Yes, so if you're making 600bhp at 10krpm in one gear, and 600bhp at 13krpm in the lower gear, you're still going to accelerate the same because the ratio difference in the gearbox is cancelled by the torque difference at the engine....

[xxChrisxx]

No!? Because power = torque x rpm !?

Not sure where you are going with this because power is constant through a transmissib. So torque x rpm = torque x rpm.

You can accelerate faster by having a shorter ratio, but that increases engine speed for a given road speed.

[rscsr]

But this also means that it is still important to have the best possible transmission ratio. It's basically the same as before with the V8. You just want to optimize your gear ratios to have the best possible acceleration.

[xxChrisxx]

But this also means that it is still important to have the best possible transmission ratio. It's basically the same as before with the V8. You just want to optimize your gear ratios to have the best possible acceleration.

Obviously you cant pick anything you want. But a broad power curve is much more forgiving than a peaky one. It means you can realisically chose a ratio spread to suit a season.

The best metric for this is the rpm band for 0.8x Pmax.

If you take this to its ultimate extreme of a constant power output you'd only need a single gear. Which is effectively what electric motors do.

[autogyro]

But this also means that it is still important to have the best possible transmission ratio. It's basically the same as before with the V8. You just want to optimize your gear ratios to have the best possible acceleration.

Obviously you cant pick anything you want. But a broad power curve is much more forgiving than a peaky one. It means you can realisically chose a ratio spread to suit a season.

The best metric for this is the rpm band for 0.8x Pmax.

If you take this to its ultimate extreme of a constant power output you'd only need a single gear. Which is effectively what electric motors do.

So why do we develop multi stepped ratio gearboxes for EVs?
FE cars have got one.
As I said, there is a performance benefit way above the current 19th century concept lay shaft gearbox they still insist has to be stuck between the engine and the wheels.

[Tommy Cookers]

........ If you take this to its ultimate extreme of a constant power output you'd only need a single gear. Which is effectively what electric motors do.

this is what most electric motors will do (less than well) if they are forced to do it

their fundamental characteristic is to produce torque proportional to current
ie constant torque, not constant power
with many motors, the constant power illusion is a byproduct of the simple but inefficient use of a fixed voltage
other motors have the electrical equivalent of mechanical gears or CVT

so according to EM type, mechanical gears often are almost as useful to EM vehicles as they are to ICE vehicles

[langwadt]

........ If you take this to its ultimate extreme of a constant power output you'd only need a single gear. Which is effectively what electric motors do.

this is what most electric motors will do (less than well) if they are forced to do it

their fundamental characteristic is to produce torque proportional to current
ie constant torque, not constant power
with many motors, the constant power illusion is a byproduct of the simple but inefficient use of a fixed voltage
other motors have the electrical equivalent of mechanical gears or CVT

so according to EM type, mechanical gears often are almost as useful to EM vehicles as they are to ICE vehicles

but the voltage is fixed, it is the battery voltage so in the ideal case it is constant power

in reality there is limits of resistive loses and magnetic forces at the low end, and magnetic loses from high
frequencies at the high end, but in a wide band it is just the battery voltage limiting power

[langwadt]

If the power is constant between the gears then so is the acceleration.

exactly, x joules of engine work (p*t), has been converted to x joules of kinetic energy (½*m*v^2)

[Tommy Cookers]

...... with many motors, the constant power illusion is a byproduct of the simple but inefficient use of a fixed voltage
other motors have the electrical equivalent of mechanical gears or CVT
so according to EM type, mechanical gears often are almost as useful to EM vehicles as they are to ICE vehicles

but the voltage is fixed, it is the battery voltage so in the ideal case it is constant power

in reality there is limits of resistive loses and magnetic forces at the low end, and magnetic loses from high
frequencies at the high end, but in a wide band it is just the battery voltage limiting power

to drive a road vehicle smoothly and safely you must have torque proportional to accelerator deflection (ie 'constant torque')
all road EVs are arranged to have this characteristic (however it is done) over much or all of the speed range

not power proportional to accelerator deflection (ie 'constant power')
maybe the old UK-type 'milk float' that delivered milk house-by-house had this, but it was limited to about 10 mph/15 kph max

[xxChrisxx]

I wish I'd never mentioned bloody electric motors. As its not salient to the point.

The point was you want maximum usable power at the wheels at all times for maximum acceleration. A broad power band makes this easier to reach this condition with a finite number of ratios.

Either you use a power source of constant power over a full rev range and use 1 gear. The ultimate conclusion of a wide power band. Or power at a fixed speed and use infinite gears. The ultimate conclusion of a narrow power band.

The wheels will see the same in both cases.

The real world lies somewhere inbetween the two.




Road cars have flat torque curves to be easily drivable by lead footed plums.

WRC cars for years had a flat power curve. 300bhp from 1800rpm ish through to redline.

It just highlights the radically different requirements of road car and race car engines.