how mant teams use CVT?

The university at buffalo team uses a CVT from Gaged Engineering. They are designed for jr dragsters. Really small, light, and easy to package. Great customer service too.

There is usually a couple teams using a cvt at every event. I would estimate 10-15 teams worldwide.

Why so few?

Because most teams use 600 CC motorcycle engines.

Almost all of these engines have a six-speed transmission that is mounted within the engine case.

Separating the transmission from the engine is nearly impossible.

Running a six-speed AND a CVT is dumb.

That's why =)

Separating them is difficult, but removing the shift linkage and 5 of the 6 gears and locking the trans in that one gear is pretty easy, removing both weight and rotational inertia.

That being said, these cars are so light that there is usually a substantial weight penalty, plus tuning a conventional mechanical CVT is really it's own specialty - you will note that many teams who use them are in areas where the students may likely have had experience with snowmobiles. There are whole books on the subject of tuning clutches and CVT's. You need accurate dyno prints of the torque curve for your particular engine and drive configuration to really do it correctly, otherwise it might end up hurting performance more than it would help.

Best,
Drew

How about using an engine with CVT?

Does it cost too much for an engine with CVT?

Any team using an engine with CVT?

Using a snowmobile engine that is 4 stroke will be an excellent idea. The newer Yamaha Phazer four stroke (NOT the old 2-stroke) is a beautiful engine package. Fuel injected, liquid cooled twin with a CVT. While only 500cc, it puts out 80hp stock. And with the tuning available for the CVT you can maximize that horse power at all speeds with no shifting required.

So far, no teams are using it that I am aware of. Someday, someone will and I believe it will astound people. Someday....

James

hm...wpi is using one this year...

quote:

So far, no teams are using it that I am aware of. Someday, someone will and I believe it will astound people. Someday....

I totally agree. For the current SAE format, CVT can be a perfect part in the car.

It would take dedication to set it up and you would have to be willing to take the risk but once you got a year of using it and good knowledge it will mean you would get some great results.

I have heard of teams in the past trying out CVT but as far as I know, no team has stuck to one and tried to make it a good system over a couple of years.

University at Buffalo ran a CVT last year and, after the results, you can expect to see it again.

I will give you guys a heads up that you need to tune your engine differently to work well with a CVT and then the CVT tuning itself can take a long time to get it dialed in correctly. Our CVT had at least 5 parts that could be changed to affect the shifting rate, engagement RPM, backshift rate, etc. To complicate matters more, each part tends to have affect at least two of the clutches' characteristics.

quote:

Originally posted by JagLite:
Using a snowmobile engine that is 4 stroke will be an excellent idea. The newer Yamaha Phazer four stroke (NOT the old 2-stroke) is a beautiful engine package. Fuel injected, liquid cooled twin with a CVT. While only 500cc, it puts out 80hp stock. And with the tuning available for the CVT you can maximize that horse power at all speeds with no shifting required.

So far, no teams are using it that I am aware of. Someday, someone will and I believe it will astound people. Someday....

James

The WPI team for the 2009 competition will be using the Phazer power plant. We have a team member who has CVT tuning experience.

I have read that more outboard motors and personal watercraft are switching to four stroke motors. Those might be an intersting place to look for powerplants suitable for using with a CVT.

The first FSAE car I worked had a CVT. Converting motorcycle engine that already had a gearbox was a major pain. It lead to a spectacular failure when our student made output shaft broke. The primary came loose, hit the frame of the car and broke into about 25 pieces, some of landed more than 20 meters away from where it failed. We were (stupidly) running the car without any belt or chain guards in place. No one got hurt, but it was a little unnerving to be standing at the edge of a parking lot while pieces of the car landed behind of us.

Fantastic!

Finally, someone will use the Phazer engine. You go WPI!

I am looking forward to reading all about your design and progress. And success too of course!

I just checked (and bookmarked) your website so I can keep up with your activity.

James

JagLite - there were 2 teams that used the Pahzer motor last year (08). Michigan - Dearborn was one of them. I'm an alum of the team there and tho they did not prepare the car well there is much potential from that engine. Some of that has been mentioned already. Hopefully the second iteration will be more impressive as they plan to run it again this year.

Thanks jsmooz,

I will see what I can dig up on the Dearborn car. If you (or anyone else?) can remember the other team, please post so I can follow their progress too.

I am not a fan of CVT's as such but for FSAE design and the events run as well as the variety of drivers I believe it is the way to go in FSAE. And the Phazer engine is very nicely designed for the cars.

James

Edit: I just did a search and have found nothing. The website is a couple years old so no help there. Anyone know of any information on the Dearborn car?

Last year at Detroit, the Université de Sherbrooke used a Phazer powerplant with a a different CVT from the one that comme with it. We'll be using a phazer powerplant too at the Université du Québec à Chicoutimi this year with the original CVT.

Having team members that have done snowmobile drag racing is usefull sometimes...

We'll be running the Phazer motor as well. Half our team (read: 3) are avid snowmobilers with tuning knowledge, so hopefully that will ease the tuning process.

If this engine could be bored out to 600cc's, it would be hands down the best engine for this competition. We ran a KTM 510 single last year, and this engine is only 2 pounds heavier than the KTM. Coupling that with the CVT (which is superior to a traditional transmission) made it a no-brainer to run this engine for us.

Kyle-

Not being a yamaha expert (Go green or go home), does the Phazer have jugs or sleeves? And has anyone checked for big bore kits for it? Anyone who's punching it out should be able to help with upping the bore and sourcing pistons.

But that is just speculation...

I'm not a yamaha guy either- I bleed red.

The engine does not have individual jugs though, the cylinders are one casting with sleeves.

I have looked into boring the engine. There really isn't a lot of room to bore it out. It sounds like 1-2 mm and that's about it.

There are high compression pistons and over-sized pistons available for the engine...

Then it just isn't worth cracking the case for that little gain