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Colin Wood
Colin Wood Associate Editor
8/30/21 2:51 p.m.

I know, I know, the CVT is pretty much the worst thing ever™, but hear me out on this one–and, for full disclosure, my car is equipped with a CVT and, yes, it is probably the least engaging transmission on the market.

With that being said, is the CVT's lack of gears and ability to (potentially) hold the engine at its peak power output make it a suitable transmission choice in any form of motorsport, or is it best that it stays off the track?

I'm not looking to get into any events with my car, but just genuinely curious what the hive has to say.

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) PowerDork
8/30/21 3:00 p.m.

They must work well in snowmobiles. I think they're the standard setup for those. 

I don't have any personal experience with which to make that observation, snowmobiles aren't real common around here. The only time I ever hear a snowmobile engine and transmission set up run is at an autocross.
 

There's a class of open wheel race car that runs a 2 stroke snowmobile engine and CVT. And BTW, they sound awful. Without googling to confirm, I think it is F mod. 

newrider3
newrider3 HalfDork
8/30/21 3:03 p.m.

Yes; theoretically and with correct tuning, a CVT would be well suited for any and all four-wheeled motorsport.

Perhaps not your particular example, CVT as a concept is great but most manufacturers have poor implementation.

 

Real world example - SCCA A-Mod autocross specials.

Colin Wood
Colin Wood Associate Editor
8/30/21 3:10 p.m.

In reply to Floating Doc (Forum Supporter) :

Yeah, a quick YouTube search revealed that at elast cars with CVTs don't sound any cooler when you open up the exhaust, really just lots of droning.

racerfink
racerfink UltraDork
8/30/21 3:14 p.m.

Well, there was the Williams F1 car...

 

https://youtu.be/Sp228-39WhQ

Colin Wood
Colin Wood Associate Editor
8/30/21 3:15 p.m.

In reply to newrider3 :

Good point. That reminds me of that time Williams experimented with a CVT for one of its F1 cars:


Edit: Looks like I posted my Williams F1 video at the same time as racerfink's Williams F1 video.

ShawnG
ShawnG UltimaDork
8/30/21 3:17 p.m.

Scooter racing.

Joe Cheng used two CVT's, one driving each rear wheel in The Vancouver Special. 

He was taking home first place trophies in A-Mod about 10 years ago.

 

ojannen
ojannen Reader
8/30/21 3:17 p.m.

Here you go: https://www.youtube.com/watch?v=4or9hXkA5HU

For the full experience, turn your volume up to 100% and press your ears against the speakers.

Colin Wood
Colin Wood Associate Editor
8/30/21 3:23 p.m.

And thanks for the real-world examples. I'll admit I'm still learning all of the autocross classes out there, so I'm glad to see CVTs are getting a little motorsports love.

Trent
Trent PowerDork
8/30/21 3:24 p.m.

I spent a few years in the moped world watching folks tune their tiny motors to a very specific powerband and then tune their "variators"  (primitive belt CVTs) with springs and flyweights to do their thing right in the meat of the available power. 

It was alarming just how fast a 70cc bicycle would move when those things happened simultaneously.  Ever since then I have wanted to build a silly drag race oriented car on those principles. 

I would choose a DAF 66 with the Variomatic transmission and build a very peaky small cc turbo motor to go with it

 

the variomatic in action

 

It would be hilarious to see one of these slingshot down the road after a slight crawl to get rolling

File:1978 DAF 66 pic1.jpg

buzzboy
buzzboy Dork
8/30/21 3:34 p.m.

Evil Genius Racing has shown how amazing a snowmobile drivetrain works in a Lemon.

ShawnG
ShawnG UltimaDork
8/30/21 4:34 p.m.

In reply to Trent :

That's what the wife's Vespa 300 is like. She beats my airhead out of the intersection and will keep up with some bigger bikes for a little ways.

You just twist the throttle to full open and let the variator do it's thing. It's like getting pulled along on a rubber band.

Keith Tanner
Keith Tanner MegaDork
8/30/21 4:39 p.m.

They really should be effective in a lot of different motorsports, as they allow the engine to operate at peak power (or efficiency) without interruption. Sure, they'll sound awful to ears used to the constant varying of noise in race cars, but noise doesn't win races.

I'm honestly surprised one hasn't contested Le Mans. 

Apexcarver
Apexcarver UltimaDork
8/30/21 5:03 p.m.

 

F500 owner here, they work exceptionally well at autocross. They work pretty well for roadracing too. The biggest problem is other people misunderstanding them and hating on the sound. Fun as hell to drive, no waiting on the powerband, power on demand.

Now, is it just the 2stroke? This is a snowmobile with basically a yahama r1 with a cvt instead of the bike trans.

 

Now bigger power for longer times for roadracing run into the eternal problem of heat management. There are lots of different ways cvts are built, much evolution from counterweight driven rubber belts like the snowmobile stuff, pusher belts that are like a stack of coins living in an oil bath (automotive oems), but managing heat for racing is the challenge. No one to my knowledge has really developed one for a motorsports program with more than 250-300ish hp (Dakar side by sides)

aircooled
aircooled MegaDork
8/30/21 5:12 p.m.

Air Racing.   Most planes (except the F1) use constant speed props, which are essentially CVT's.

sleepyhead the buffalo
sleepyhead the buffalo Mod Squad
8/30/21 6:18 p.m.

Bracket Drag racing

no shifting, so it should be one of the most consistent output performance profiles, outside of a good launch (which again, I'd think could be rather consistent)

sleepyhead the buffalo
sleepyhead the buffalo Mod Squad
8/30/21 6:22 p.m.

They'd be really good for driver training on track... because it'll be *very* obvious if the student as at "Full Throttle" or not, and if they could be carrying more speed through a corner

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
8/30/21 6:22 p.m.

Came here to say drag racing.  You're constantly monitoring a tach to shift at just the right point to maximize the areas around the hp peaks.  Gotta think that a properly tuned CVT would just hold it at whatever you want.  Logic seems to say that two equal cars, one with a CVT and one with something not CVT lined up at the strip, the CVT should win.

newrider3
newrider3 HalfDork
8/30/21 6:35 p.m.
Curtis73 (Forum Supporter) said:

Came here to say drag racing.  You're constantly monitoring a tach to shift at just the right point to maximize the areas around the hp peaks.  Gotta think that a properly tuned CVT would just hold it at whatever you want.  Logic seems to say that two equal cars, one with a CVT and one with something not CVT lined up at the strip, the CVT should win.

 

Honestly, dedicated drag cars are damn close anyway, just using old tech. When you think about it, a Powerglide with a very high stall converter is kind of an inefficient way of emulating a CVT. 

Woody (Forum Supportum)
Woody (Forum Supportum) MegaDork
8/30/21 6:46 p.m.

I would think that CVTs might work well in Land Speed racing.... 

...but I'm basing this on exactly Zero experience with either CVTs or in Land Speed racing. 

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) PowerDork
8/30/21 6:53 p.m.
newrider3 said:
Curtis73 (Forum Supporter) said:

Came here to say drag racing.  You're constantly monitoring a tach to shift at just the right point to maximize the areas around the hp peaks.  Gotta think that a properly tuned CVT would just hold it at whatever you want.  Logic seems to say that two equal cars, one with a CVT and one with something not CVT lined up at the strip, the CVT should win.

 

Honestly, dedicated drag cars are damn close anyway, just using old tech. When you think about it, a Powerglide with a very high stall converter is kind of an inefficient way of emulating a CVT. 

Good point.

I'm stretching the point, but in that context, the top fuel and fuel funny cars essentially have a variable final drive ratio if you account for the change in tire diameter through the run and the effect of clutch tuning on the timing of the application of engine torque to the tires. The result is the same, they just do it without a transmission. 

ShawnG
ShawnG UltimaDork
8/30/21 7:39 p.m.

https://en.wikipedia.org/wiki/Turboglide

One of our customers has one in a '58 Chev.

Feels like a CVT, no shifting, just a constant pull.

TurnerX19
TurnerX19 UltraDork
8/30/21 7:50 p.m.

Brabham used the DAF CVT in a Formula 3 car in the late 1960s, when F3 had a one liter class limit and extremely narrow power band. They won some races with it.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/30/21 9:34 p.m.

I would LLOVE to try rallycrossing a CVT.  Engine braking/throttle modulation might be weird if the trans controller "upshifts" off throttle.

Tom1200
Tom1200 SuperDork
8/30/21 9:51 p.m.

I also run an F500; I road race and autocross mine.

My run starts at 2:26.

https://m.youtube.com/watch?v=j3J3g-I3kw0

The CVT works great for autocross; you never have issues being stuck between gears. Geared properly the car is always in the powerband.  

The other great thing about a CVT is you can buy about $150 - $200 in parts will allow you infinite gearing changes. This is way more economical than coughing up 3-6K for a close ratio gearboxes. They also don't break unlike some of those fancy gearboxes.

Note while most of the F500 road race cars are.not motorcyle powered cars at last years RunOffs James Weida damn near won with a a CVT powered car.

I initially thought I would miss the gearbox for road racing but now having done a few races with the car I can honestly say I never even think about it once I'm on course.

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