Prestonian

Been browsing the website of an IVT developer

http://www.torotrak.com/

The concept looks really interesting - the engine management system will vary the engine rpm to respond to the driver requirements. There is also less power lost through the transmission which means more power at the wheels and greater fuel efficiency/economy. Unless I've misunderstood, this would mean that if the S2000 had one fitted, and you floored it, the engine would go to max power (i.e. 8,200 rpm) and stay there....

Anyone for a GB?

JONeM

I've spoken to some people who worked on a torotrak car for Ford. The test car was working well so they let some members of the public test it.

They hated it! No-one could get used to hearing a constant engine speed whilst accelerating. Ford asked them to re-engineer the system so it drove more like a standard auto box (i.e. fixed changes in ratios) thus defeating most of the torotrak benefits.

People don't like change........

Prestonian

Never really thought of it like that, but I can imagine it would seem strange. I suppose the only variation in rpm would be dependant upon driver requirements, i.e. low rpm for MWay cruising, through to high(er) rpm for flooring it (and all the variations inbetween).

Wouldn't mind trying one out to see how it drove, though.

Red Mist

My wife has a Fiesta auto which is belt driven. This seems to be trying to work in a similar manner. It's very strange to drive as you seem to be always flat out. Imagine driving a car with a slipping clutch and thats just what it's like. To be honest it's bloody awful especially if you are trying to accelerate up a hill.

Colin Andrews

I tried a metro with CVT - you never realise how harsh a car engine can sound until it's blaring away at only one speed.

CVT is such a good idea that I don't think it will go away. To get round the 'user' issues people are trying all sorts of groovy ideas. Fiat and MG/Rover have a CVT that is set up to offer 7 intermediate steps rather than one continuous change - I haven't tried it but it seems more acceptable.

BTW Anyone remember the old Daf with belt drive CVT. It sounded awful, and was a bit cr@p anyway BUT it's party trick was that reverse was an add-on to the CVT. So in theory (and in practice ) any forward speed was also available in reverse.

Think there might be a link to the 'VTEC in reverse' thread here

Nick Graves

Colin, you are quite right.

Apparently the Dafs were popular with Amsterdam police, because they didn't need to turn the car around in hot pursuit.

The idea of a diesel engine tuned to run at max torque rpm would prove a very economical, smooth and fast car with a cvt. As stated above, blind prejudice would rule it out though. People like jerks (make of that what you will )

Spanners

DAF Variomatic it was called.

This has been a target for engineers for years. If youtink about it the current gearbox is a compromise. The problem is a variabel ratio device is usually inefficient - loosing a lot of power. I have not read about this new one - it may be different.

Has to happen though.

Electric motors have different characteristics. They can produce high torque at low revs, yet rev highly - so can have relatively flat power vs revs curves. But then you have the energy loss in the conversion from prime mover to electricity and then back to rotation in the motor.

The acceptance by drivers is an interesting point, and one that will be addressed over time.

BigTed

This was aided by the fact that the DAF 33 had a perfect three-box profile so the aerodynamics going forwards was pretty much the same as going backwards!