PsYcHo_Pilot

good stuff Supercharger, how much do these things weigh ?? i'm guessing too much, or else they'd be in the rx8

Supercharger

Mazda's CVT is designed for front wheel drive cars.

Supercharger

Mazda could build a mid-engine RX-7 and use the CVT gearbox.

zoom44

Supercharger:
i just read in one of the mags yesterday(sorry don't have it in front of me) that an american company (ford? sorry again don't have it in front of me) is going to put a CVT in an all wheel drive SUV. do you know if this has been done before or what the setup would look like?

CraziFuzzy

Just think about the efficiency you could get by building a small gas turbine powered car with a CVT in it. A small turbine is probably the most efficient gas engine (power/consumption) possible when at a constant RPM, so imagine piping that lightweight, low consumption, power through a CVT. This has been a big thing keeping anyone (even hobbyists) from making a turbine powered car. Sure, there have been turbine powered cars based on the actual thrust, but this is incredably inefficient. The turbine is VERY efficient on the shaft... hmmm... just some off the wall brainstorming.. hehe

EDIT: And you think a rotary sounds cool! hehe

CraziFuzzy

hehe, I just found a 400LB gas turbine that makes between 900-1200 HP... hehe... of course, you have to gear it down from 43,400rpm.... hehe

Supercharger

Zoom44:

Ford and Torotrak developed a CVT for the Expedition SUV.
Torotrak's IVT has a very high torque capacity. Ford Expedition's 5.4-liter V8 engine produces 260 hp and 350 lb-ft of torque.

Check out this link for more info:
http://www.torotrak.com/articles_press.html

Driving Impression

The main benefit of the revolutionary technology is improved fuel economy. Figures show savings of up to 20 per cent over a standard four-speed automatic, thanks to a complicated system of gears that, as the name suggests, offers a near-infinite number of ratios. Similar to – but more robust than – a CVT box, the IVT copes with high performance engines. However, this means nothing if the system feels horrible to use. So we got behind the wheel of a Ford Expedition 5.4-liter V8 fitted with the new device to check it out.

Gearchanges are seamless. Floor the throttle, however, and engine revs climb steadily to peak power, rather than racing skywards as with a CVT. As a result, the IVT gives a better driving experience. Another feature is its high overdrive – 80mph is possible at only 1,000rpm. But it doesn't need a clutch or torque converter to pull away from standstill. Because fewer slipping parts mean less wear, the unit should be maintenance-free.

On steep hills, we could use the throttle to hold the big Ford steady for as long as we wanted. By backing off, it was possible to control the rate at which it slipped back – something that would scupper most other automatics.

Supercharger

In a Torotrak IVT the driver sets the wheel torque demand, the computer sets the engine torque and speed, resulting in ratio.

High performance with economy
By responding to driver demand - expressed through the accelerator pedal - and monitoring the engine, vehicle and transmission, the software algorithms generate control decisions for the engine throttle and transmission hydraulic system. This level of control can produce high performance when required, coupled with economy at all other times.

Flexibility of powertrain design
With the Torotrak IVT the driver 'drives' the transmission rather than the engine. This releases the engine from the constraints of driveability, allowing it to be run for optimal economy, emissions or, when required, ultimate performance. Consequently the Torotrak IVT provides ample opportunity for manufacturers to meet the ever more demanding legal requirements for fuel economy and emissions without sacrificing driveability or performance.

Benefits of optimum control
In essence, the degree of control freedom the Torotrak IVT offers ensures the engine can always be run at its optimum operating conditions. This results in:
Improved economy
Better performance
Reduced emissions
Smoother operation
Lower overall noise levels

This IVT layout (as shown in the picture) is designed for front-engine rear-drive cars (ie RX-8).

Supercharger

The good news for us is that a Japanese gearbox company (Aisin) has a Torotrak license. That means Mazda could ask Aisin to design/manufacture an IVT gearbox for the RX-8.

An IVT-equipped RX-8 can accelerate faster than a 6-speed manual RX-8 in rolling starts - such as Car&Driver magazine's top gear 30-70mph tests.

P00Man

so that ting creates rations per rpm? meaning that at each new rpm, it's creating a new ratio. this is the only way i could see the driver inputting torque demand, through mashing the pedal. unless its some other way, like a GUI or something.....do you know how the driver inputs torque demand?
________
Maryjane

Supercharger

Driver input is the same as any car - the gas pedal.

P00Man

thats what i figured
________
Wendie 99

Supercharger

This article compare CVT against conventional gearbox.

http://www.v8914.com/Horsepower-v-torque.htm

wakeech

ahahaha... thanks for the link... this is the page that Rich'd always use to try and educate the low-torque naysayers in the early days of this forum *bookmarks page*

Lensman

Just in case you think that turbine powered cars are a radical new idea the gave a look at this.

globi

CVT in action (click on the video):
https://www.pmtuning.co.uk/News.htm