continuously variable transmission

[Jay!]

And motorcycles.

[Morpheus XIII]

If there's any engine manufacturer who can design a production 15K rpm powerplant, it's Honda. With a firm background in the motorcyle industry and Formula 1 (and other racing series), it should be quite doable--but not easy.

I have to agree with IntegraR0064 that it will probably be expensive, and that single drawback leaves far too many good ideas at the drawing board. However, I don't think that a higher rpm engine with a shorter stroke requires much more air/fuel than the standard design. In some cases, they burn cleaner than the norm since high rpm engines are required to be more efficient in combustion, as in the S2000. As for audible noise, it probably wouldn't be the sound that would get frowned upon (high rpm engines have an IMO nice high pitched banshee-like scream, which can be eliminated if necessary through good resonators and mufflers), but it would most likely be the vibration echoing through the cabin at high rev that would get thumbs down.

Another problem to add would be lubrication. If this engine were to be used on the road in an automobile, the driver would need to get a hell of a lot of oil changes, something that's not a problem on the track for two hour races.

God, imagine the bragging rights one would have with a tachometer that DOUBLES the average car. Heck, even the Autometer tachs wouldn't work with it. Of course, if it were to be used with a CVT, there wouldn't be a tach in sight.

[V.S.]

Couldn't the gearing between the engine and the cvt allow normal engine operation and ultra high rpm(therefore low torque) on the CVT itself? Same problems with making the CVT work at these rpms, but no significant modification to the engine.

[IntegraR0064]

like 13k...

And that's redline, not what you're constantly running at.

Plus you have to consider that they rebuild their engines every race or so....

And again, even if they can do that, that's not the main reason. I very much doubt that cvts can handle much power, since they can't handle torque.

[hakka]

Originally posted by F=ma


Don't Indy Cars and F1's rev to 14-15k? And rotaries as well?

Actually, F1 cars rev to 18K Doesn't Audi have a CVT in the A6?

[hermunn123]

yep, Audi has a CVT in their A6. dont rotaries only get up to 9Kish???

[enginerd]

The CVT was pioneered by DKW. In the 60's their cars were equipped with a crude CVT. The engine output shaft was connected to a set of pulleys transverse with the chassis. Connected to the drive wheels were a special set of pulleys where the diameter of the pulley was variable: at low speeds, the diameter was large and as the pulley sped up, the diameter shrunk. Newer CVTs are vastly superior of course, but DKW was the first.

[Primera-TDLX]

Originally posted by hakka


Actually, F1 cars rev to 18K Doesn't Audi have a CVT in the A6?

Yes Audi has one, but also Nissan has one, wich came before AUDI!! In the 2000 Primera (G20 in the US), has a CVT Tranny, the Primera was the first car in the world (within its class, (no equal sized or bigger sized car) had got CVT when the Primera got it! Nissan sets the pace!

Nissan, king on-road, king off-road!:smoka: :smoka:

[F=ma]

I was reading a few years ago about a Nissan Concept vehicle, kind of like the Audi Steppenwolf... a Sportyish SUV kind of thing. Anyways, it had height adjustable suspension and CVT or a 6 speed. It was going to be something of a big to do. I can't remember if it was turbo or not, but I remember it making a really good impression on me at the time. When I read about it, Nissan called it the Trailrunner. Anyone know any more details on it?

[Primera-TDLX]

Originally posted by F=ma
I was reading a few years ago about a Nissan Concept vehicle, kind of like the Audi Steppenwolf... a Sportyish SUV kind of thing. Anyways, it had height adjustable suspension and CVT or a 6 speed. It was going to be something of a big to do. I can't remember if it was turbo or not, but I remember it making a really good impression on me at the time. When I read about it, Nissan called it the Trailrunner. Anyone know any more details on it?

Yeah, I rember it. I had a SR20DEV Engine, with 190 HP. Same engine as delivered in Primera 2.0GT in Japan. It also had 4wd, it was based in Primera platform I belive.
I`l try to dig up some old Nissan News broschures and scan some pics and specs.

[hermunn123]

Yes Audi has one, but also Nissan has one, wich came before AUDI!! In the 2000 Primera (G20 in the US), has a CVT Tranny, the Primera was the first car in the world (within its class, (no equal sized or bigger sized car) had got CVT when the Primera got it! Nissan sets the pace!

Nissan, king on-road, king off-road!

the nissan m6 hyper-cvt sucked. it gave the feeling of a slipping clutch because the engine revs and it takes a long time for the CVT to catch up. the nissan extroid CVT was better because of the use of pairs of rollers.

[Thunda Downunda]

Perhaps post DKW, the little Dutch 1960s-70s Daf range would have to be the first commercially successful CVT vehicle. Known as 'the rubber band car' and initially with a 2-cylinder engine it was perfect for Holland's ultra-flat terrain (their biggest 'mountain' is 300 metres high!) though not quite the deal for touring the Italian Alps. The CVT was nevertheless durable enough to later cope with Daf's excellent 1300cc 4 cyl engine, which became a successful powerplant in Formula 3.
btw: The Daf platform eventually evolved into the Volvo 3 & 4 series, which explains that model's rear-mounted gearbox/transaxle.
I hear that the new Audi CVT which has been widely lauded as the worlds finest auto transmission uses electronics to maintain a higher ratio and 'torque it out' under medium power demands, as even mild acceleration has previously resulted in unacceptably high revs as Hermunn explained.

[Psman32@af]

The tach readings on most rotaries go to 9k RPM on the tach, but the engine itself is doing three tiems that, so at redlines the engine 27k RPM.

[Seabass]

You sure about that? The output shaft sping three times the speed of the motor. I'm not sure which RPM you were talking about. So at 9K the output shaft is spinning at 27K..not the motor.

Seabass

[Hudson]

Originally posted by Psman32@af
The tach readings on most rotaries go to 9k RPM on the tach, but the engine itself is doing three tiems that, so at redlines the engine 27k RPM.

It was my undestanding that the tachometer read the speed of the engine AND the speed of the output shaft, since they were the same thing. You're saying that a rotary engine is "geared down" 3:1 before it gets to the transmission?

I've been around engines all my life and this is the first I've ever heard this. Do you have any proof of this?