Arctic cat T660

Good to see photos of Al's installation of his 660cc Turbo Arctic Cat engine in his Zenith 701. We worked very closely with Al to develop a custom Raven ReDrive around this engine and build the custom engine mount and motor mount brackets for the 701 as well. It's by far the most powerful engine we have ever tested (it even beat out our 1300cc SVS 115HP with turbo- which is saying something). That puts it above the Rotax 914. We had hoped to tool up for a run of drives for this engine which we consider to be a better choice than the Yamaha for those at altitude as it keeps sea level power with the turbo and does it at lower RPM, but the expense and limited availability of the engine in large enough numbers to justify our tool up cost has held us back. It also has solid bell housing attach points so it could be more easily adapted for a simple gearbox for use on a pusher gyro where the lower thrust line would be workable.

I may be willing to sell the two complete engines (no redrive) I currently have in stock and have been saving for my own personal machine. If anyone is interested, contact me at [email protected] or call me at 575-737-9656 cell 303-440-6234

Jeron Smith
Raven Rotorcraft/ReDrives Inc.
 
Brent
I am with you, if Snowmobiles engines are looking promising as Rotax alternatives.
 
The rotax's that we have used for years, started out in snowmobiles, lets hope that the next round of 4 stroke snowmobile engines will be as successful!
 
Arctic Cat 660T

Arctic Cat 660T

Brent

After spending last week at Sun-n-Fun airshow and getting feedback from a lot of great folks at our Seminars there on both our Rotor-Plane and our Geo/Suzuki auto engine conversions, we have decided to tool up for adapters to fit the Rotax C gearbox to these Arctic Cat 660T engines. We will then offer these two units as complete engine packages and also be able to offer adapter kits for folks who want to build up their own engine packages. We also had a number of folks interested in adapting the Geo Metro 1.0L and 1.3L engines to the C box as well so we are investigating that option as well.

It’s unfortunate that there aren’t enough units available Stateside for us to invest in a production run of our proven belt drive for this great little 660T engine. The guy flying it in the 701 is way more than happy with the performance.

We did announce at Sun-n-Fun that we are tooling up for a new lightweight belt redrive for the Geo G13BB engine that will be available in our standard 1300SVX 90HP/165lb. version as well as our 1300SVX-T 115HP/ 178lb. turbo package as well. This is the engine that is readily available in the automotive aftermarket. Guys can put together our 115HP turbo package built up around our redrive kit with turbo upgrade for 1/4 the cost of a Rotax 914! This is the powerplant for our new Rotor-Plane Hybrid STOL Cargo aircraft.

Thanks for you interest!

Jeron Smith
Raven Rotorcraft/ReDrives Inc.
575-737-9656 cell 303-440-6234
 
Brent

Haven’t checked yet to see if the taper is the same- I’m hoping that it is. The big advantage of the Artic Cat engine is a real bell housing with solid attach points. For and aft spacing may be an issue as well as the Rotax has no flywheel before the taper.

For the Geo 1.0/1.3 we would eliminate the tapered shaft entirely and couple directly from the crank to the Rubber Hardy disk with an adapter. This may turn out to be a better design for the Arctic Cat as well. One factor that is often overlooked when converting the snowmobile engines is the lack of flywheel momentum on the crankshaft once the heavy mass of the CVT drive clutch is removed. The tiny Rotax 2 stroke flywheel doesn’t add any significant mass to this combo.

Arctic Cat used only the sheet metal automatic transmission flexplate behind the tapered crank adapter. Couple that with the very low compression of a turbo engine and you will be dealing with heavy resonance spikes building up quickly in the low RPM band. It is still a big question mark as to whether the simple rubber donut coupler of the Rotax Gearbox will work properly with this particular engine package. We had to tune our proven torsional dampening system, standard on all our belt redrives, to dampen the resonance spikes for this engine. It looks like there is just enough room for that type of custom coupling inside the gearbox housing extension. We will only know what works properly when the engine is running again under full prop load on our test stand with this drive combo. Maybe we will luck out and be able to use the existing rubber coupler designed for the two stroke- but I wouldn’t bet on it.

Still need a separate adapter plate to mount the starter as well as mounting points in the correct location for aircraft use. Definitely not a bolt and play operation, but still way simpler than what I’ve seen on the Yamaha conversions to date.

Thanks again for your interest. Think you can see now why we’ve elected to complete at least some preliminary initial testing of these engine packages rather than just have others experimenting with a totally unproven combo. Adapting any gearbox from a two stroke to a 4 stroke application is something that immediately puts the word EXPERIMENTAL in bold type and should be treated with respect. Now that we have seen a number of successful conversions of small 4 strokes, and even larger Suburu engines with this gearbox, we are conservatively willing to explore a bit further in that direction if there is a customer interest in experimenting with that option.

It’s the most powerful engine package we’ve developed to date!!

Jeron Smith
Raven Rotorcraft/ReDrives Inc.
575-737-9656 cell 303-440-6234
 
(Jeron Smith Wrote:
"Still need a separate adapter plate to mount the starter as well as mounting points in the correct location for aircraft use. Definitely not a bolt and play operation, but still way simpler than what I’ve seen on the Yamaha conversions to date.")

Hello Jeron,
Can you please explain the details of why this is "way simpler" than the Yamaha conversion?
 
Arctic Cat 660T

Arctic Cat 660T

Jason

Hop up on the great build out pages for the Yamaha conversion to see all the fine quality (but complex) parts that were required to adapt the C box to the sled engine which has limited structural attach points. The Suzuki 660T engine originated in the Kei car class in Japan and therefore already has a bell housing and structural mounting points cast into the block. Easier and cleaner, less complex adaptation for the addition of a belt or gear drive.

Jeron Smith
Raven Rotorcraft/ReDrives Inc.
 
If you happen to have an E box laying around its certainly worth a try. Going the new E box route its a pretty expensive upgrade. At Raven, our philosophy is to recycle everything usable that came with the original engine. Note in the original post of this thread how we designed the starter plate for the small stock Suzuki starter into the engine mounting system on Al Shimpa's 701 installation. Keeps more of the mass near the center of the engine as well.

Jeron Smith
Ravrn ReDrives Inc.
 
Brent

Assume you are referring to the RK400 clutch unit that can be retrofitted to the Rotax box. We nixed decoupling redrive from engine as a viable option for handling torsionals as you end up popping a significant small parachute (in the form of a windmilling prop) in the event of an engine out. Not a great option.

Have also heard second hand that these clutches can slip under the right RPM band and loading and quickly overheat the rubber dampner attached to it. Remember that these 4 stroke adaptations we are talking about have a much more powerful low end torque pulse to deal with than the two stroke.

Hope this helps.

Jeron Smith
Raven Rotorcraft/ ReDrives Inc.
 
Clutch on gearbox

Clutch on gearbox

When you use the RK400 clutch, you do not use the rubber dampner, so it would be pretty hard to over heat it. Being an engine developer youself, you should know the danger of quoting 2nd hand information.

I have an RK 400 clutch on my aircraft and I can tell you that it is nothing like popping out a small parachute when the engine is at idle.



Brent

Assume you are referring to the RK400 clutch unit that can be retrofitted to the Rotax box. We nixed decoupling redrive from engine as a viable option for handling torsionals as you end up popping a significant small parachute (in the form of a windmilling prop) in the event of an engine out. Not a great option.

Have also heard second hand that these clutches can slip under the right RPM band and loading and quickly overheat the rubber dampner attached to it. Remember that these 4 stroke adaptations we are talking about have a much more powerful low end torque pulse to deal with than the two stroke.

Hope this helps.

Jeron Smith
Raven Rotorcraft/ ReDrives Inc.
 
Jason

Thanks for the clarification on the RK-400. You didn't mention whether you were flying a gyro or a fixed wing. If you were flying a gyro- there would be much less noticable drag change since with our rotorcraft we are already in the most draggy category of anything typically flying. Just about like a PPC, we have already unfurled the chute.

Regarding the rubber coupling to the RK-400, my apologies. That's exactly why I was careful to note it as second hand information. Must have been the brake material that was overheating. I'll try to find the article to get it first hand.

Thanks again.

Jeron Smith
Raven Rotorcraft/ReDrives Inc.
 
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