I know this is off topic for cars...but...

Hello everyone,
My name is Kevin, I attend the University of Central Florida. Our SAE (Society of Automotive Engineers) is working on a baja car for competition this year up in Monrtreal Canada. We are starting the design phase.
We are given a a 10hp engine and regulated to 3600rpm and we basically build an entire baja car out of it.

Gears vs Chain - What we are discussing/researching now is how to transfer the power from the enine to the gear box and then to the wheels. In years past we have used a CVT from the engine to the gear box. In the gear box we have used sun gears to reduce the rpm. And then run a chain to the rear axel to spin the wheels. We have thought about using a chain inside the gear box aswell, aswell as using gears in both the gear box and from the gear box to the wheels. Keep in mind this vehicle does have to go deep water and float across. What we really need to know are pro's/con's to using chains or gears to transfer the power.

CVT - the particular CVT we are running operates best at 4800rpm, we are restricted to 3600. So we have to mod it in some way for optimun performance. I don't know any specifics on the CVT, but if you know how to mod one for performance, we would be very interested in hearing from you.

I know many more details would be needed for our specific application, but if there are any generalities, we'd be very interested in hearing. Keep in mind this is only a 10hp engine.

Thank for your time.
Thankyou in Advance.

 

A chain will have slightly less power loss than gears. An O-ring style chain can take underwater abuse, for a while anyway, due to having grease sealed in the rollers by the O-rings. A chain drive also gives the ability to more easily change the drive ratio. If it can be in an enclosed guard/housing, us a non-O-ring chain for the least drag and put enough oil in to keep it well lubed.

A downside of the chain is the need to fully guard it so nothing can get in and jamb it or knock it off the sprockets. A chain needs to be properly tensioned, so there needs to be either an idler or adjustment range built in.

Is it really a CVT or just a centrifugal clutch? If it is a CVT, is it a two variable pulley and belt type? More info would help. I was going to reference snowmobile and snowblower drives, but remembered you are in Fla and may not spend a lot of time around the white stuff.

If the drive works best at 4800, could you gear up the motor output before driving the transmission? I don't know if the efficiency increase on the trans would outweigh the loss in gearing up the motor output.

Send over more info and I'll see if I have any other thoughts.

 

Hey, thanks.
I'm gonna talk to the guys tom. morning i think, and collect some more info.

But for now...

It is an actual CVT (contuous varying transmission) with one belt and 2 discs. Motor spins one, and the other goes into the gear box. I'm next to positive that it is an o-ring style chain. The chain on previous years has been enclosed, as well as the CVT (and gear box obviously)

We've had previous baja's, in the past we've ran the CVT from engine to gear box, used sun gears inside gear box, and ran it to the axels by a chain. We're looking into different options. But we're not sure which will work best.

It is the CVT that runs best at 4800rpm, and if we adjust our engine to rev higher...we basically get disqualified. They regulate us pretty harshly as far as the engine goes.

Let me give you our site...
http://www.ucfmotorsports.cecs.ucf.edu/pics.html

there's some pictures on there, but you can't see much.

Really appreciate all the help. I think what our delemma basically comes down to is, will gears or chain give us the more power. And as for the CVT, we need to figure out which weights to swap into it to put our peak power at 3600rpm as opposed to the configured 4800rpm.