Transaxle X Engine

[Graffy]

Im new to the UTV world but not new to the fabrication world. Me and my friend have been focusing on designing and building a rallye-type setup with a custom chassis and a single seater. With suspension design at a good point, we want to start work on the chassis; however, there is one big hiccup in the way, and that is the powertrain. We've been going back and forth on this for quite some time now and realized that we cant find any great options. We want the engine to be behind the driver and mounted between the seat and the rear axle with a transaxle setup. We aren't going to need any power for the front wheels, as this is an RWD application (Toyota MR2 style setup). It also needs quite a small engine; I would love for it to be 100+ hp and possibly be turbocharged down the line, but power isn't a huge deal right now. Right now its a battle between a UTV engine X trans or a bike engine with a diff.

Although crotch rocket engines are super cool, they aren't built for high-torque applications, and a differential setup for one can range up to $6k, which is pretty ridiculous for our initial budget. (We are not going chain-driven as we have bad experience in that area.).

That's what leads us to UTV x Snowmobile drivetrains. I was initially surprised to find out how much power they have and realized it could be a great option with how they are designed for high torque applications. It is a difficult situation to find a good setup. 

The transaxle needs to be either a manual or a sequential setup. And although there are some great engine options, with my limited knowledge in the UTV world, I have yet to find a transaxle that fits or works well with those engines.

So my questions are this: Does anyone know of a good combo or might be able to lead me down a direction? Could it be damaging to an AWD transmission if nothing is connected to the front output shaft and only the rear diff?