rotax 80hp vs 100hp auto conversion

[n85ae]

I've never been sorry I put an IO-240B in my airplane, and with regard to
what it spins at most of the time? I typically fly along at 2200 rpm's, and if
I want to go VNE & faster I firewall it and let it wrap up to 2700-2800. Low
power gets me 120'ish, and depending on weather and weight I get 1'000
to 2'000 fpm climb.

I can also throttle it down to 1500, and lumber along burning no fuel, and
it's happy going slow.

I've seen several auto conversions, and while I've seen some nice machine
work every once has been undergoing constant maintenance. Or working
on solutions to "problems" which seems the bane of their existance.

The Corvair motors seem nice, but I spent too many days reading the KR
guys postings about broken cranks, etc. That seems a risky business to
me.

If I built another one, Rotax, Lycoming, and Continental would be the only
motors I'd be looking at.

Jeff

[n85ae]

Of course I use to work on Allison T-56's, so of course there are exceptions
to the rule ... They are good solid motors also ...

Jeff

[dynomike]

I fly behind a Subaru that has never given me a lick of trouble and takes me all over the northwest united states at three and a half gallons an hour .rotax is an awesome engine ,as well as Lycoming and conys,but there is lots of great engines out there.ill be buying a sonex in the near future and it will most likely have an aerovee which I guess you could consider an autoconversion,to each his own the airplanes that make you happy ..I love all airplanes!

[mscotter]

Forgive my ignorance Tim, as I know nothing about snowmobiles. Grew up in Delaware, now live in North Carolina. Have seen a couple snowmobiles in my life, but never been anywhere where they're commonplace. What are the typical snowmobile engines that are used for aircraft use and what modifications are involved?

[Esser]

Almost every rotax two stroke began it's life as a snowmobile engine or a snowmobile engine design.

[av8rps]

Jeff, I can appreciate your feelings about the IO-240, as that is the engine I was thinking about when I said earlier that some engines provide better climb or cruise than the 912. So I can understand liking it on your Kitfox. I've always liked that airframe engine combination.

The only downside of that engine in a Kitfox is when you put the airplane on amphib floats...as then all that great performance goes away. I know that factually as two friends put their great performing Model 5 and Model 6 IO-240 Kitfoxes on amphibs, and both were surprised by the poor performance. They tried a lot of things to improve it to no avail.

So why would that happen? My opinion is that it was caused by their 1250+ lb empty weight on the amphibs causing too high of a wing loading, even though they had gobs of power on tap, I believe there is a point of no return with our small 132 sq ft wing, where it is just expected to lift too many pounds per square foot, so it consequent results in poor aircraft performance. That's the same reason I believe extra engine weight is less damaging on a Piper or Cessna; they typically will have 170+ sq ft of wing, so there are more square feet of wing area to absorb more of that heavy engine weight.

Just my opinion...

[jtpitkin06]

Conversion motors do not necessarily need continuous fiddling to keep running. My Corvair has electronic ignition, hydraulic lifters and a single certified MA3-SPA carburetor... None require periodic adjustments.

When it came time to start it for the first time I hit the starter, the prop turned about six blades and it fired right off.

This motor was derived from one designed to run with little or no maintenance and dang near out of oil.

I also had a blast doing the conversion.

[Paul Z]

If I had an 80 hp, I'd do the Zipper kit upgrade. With new cylinders & Pistons they say it will put out 104 hp on the lower compression set up. Google zipper Rotax very impressive.

[896tr]

John, what horse power do you expect from your Corvair conversion?
The shop that did the valves on my Subaru turbo guarantied I would get 140+ hp. He builds drift cars and likes to build "Subaru Sleepers".
Steve

[jtpitkin06]

John, what horse power do you expect from your Corvair conversion?
The shop that did the valves on my Subaru turbo guarantied I would get 140+ hp. He builds drift cars and likes to build "Subaru Sleepers".
Steve

My Corvair engine has run on a test stand which measures torque and RPM. The engine puts out 100 hp at 3200 RPM. It is direct drive swinging a 66 inch warp drive prop so there is no point in going beyond that. As with all engines you get a choice of longevity, price and power... Pick two. Some Corvair builders have gone the big bore route and opted for 120 hp. I elected to stay with stock displacement.
I chose longevity and price. Total cost was $6000. That includes the prop and spinner.
JP