303cc sachs wankel in a minimax

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charles

Well-Known Member
i got another minimax 103 the other day, and i"ve just rebuilt a 303cc wankel, it came out of a snowmobile. im going to try it in the minimax. its 20 hp @5500 rpms. i really think they have more hp than that.

Cy V

Well-Known Member
20HP isn't enough to pull a mini max.

charles

Well-Known Member
i know, im going to mount the motor on my test wagon roller and put an adjustable prop on it and check the pull thrust before mounting it on the minimax.the minimax weights 172 lbs with no motor. these wankles were put in artic cat panthers snowmobiles and they are prized for there pulling power , they are used by ski lodges (now) to pack fresh snow trails 3 foot high that other snowmobiles cant handle.and pulling 600 to 800 lbs of fire wood on a sled with no problem. i really think this motor is 35 to 40 hp or more.it weighs 32lbs with exhaust and i can cut more weight off of it .it will also run of off kerosene that i thought was kool.its in new condition now.it will run off of points or electronic ign i installed.that 20 hp was rated in 1972 .ratings back then were different than now.

Hot Wings

Well-Known Member
HBA Supporter
Log Member
it will also run of off kerosene
That's interesting! I have one setting in a box in the back room that I had planed to experiment with using Jet-A someday. Any more details would be appreciated. What kind of modifications are needed?

challenger_II

Well-Known Member
If you research the older Sport Aviation magazines, you will see that the Fichtel-Sachs 303 has been converted before. From the performance specs that were listed, it would pull about as good as a Cuyuna 215cc.

Now, if you can manage to keep the Apex seals in it, you might consider setting it up with a 4:1 drive, more carb, and turning it at a higher rpm, to get your power.

Where did you find the parts to overhaul the engine?

WonderousMountain

Well-Known Member
He made them, the parts that is.

Porting is where you get extra power from a rotary. Problem is they will run at high RPM, for a lot of power and then they won't all of a sudden. For this reason the majority of these motors were given smaller than optimal ports, and some form of governing. If you can keep the Rpm's to a sane level, it should be possible to increase performance without aquiring instability.

It's true about old time motor ratings. I had a Geo Metro 3cyl that was rated at 10hp. Same ones people get 80 out of in air-conversions.

Wonderous Mountain

charles

Well-Known Member
hot wings pm me or e- mail me on re-build ..cost is about $67.00 for carb kit,$97.00 for apex seals springs , side seal springs and corner springs .\$20.00 for engine front and back seals. the apex seals don't go bad just the springs.these parts are ordered from different company's.challengertwo,if you loose compression in any rotor and have 60 to 70 lbs ,take the engine down and replace all engine springs before the apex seals spin in place and ruin the rotor.wonderous mountain, dude you are smart! the parts are made to fit from mazda parts.i did find out i got more rpms with electronic ign and quicker acceleration. small world, i drive a GEO METRO. i rebuilt it; it gets 47mpg in city i brought it running in bad shape, one exhaust vale was broke in half and one piston skirt was cracked from the factory from pushing the piston on the crankshaft counter weights.made on Friday afternoon.but still ran 60mph on two pistons.these motors also have a plug on the side of the intake manifold for hydrogen or propane or natural gas and it goes in a piped system to 1/4'' from each intake vale.this plug has to be drilled pulled out and taped.

charles

Well-Known Member
look at this 38 hp wankel engine offered for the military made in UK . weights 24 lbs.. ::UAV Engines Ltd: AR741 - 38 bhp:: ;. its less ccs than the 303. and air cooled !

slociviccoupe

Well-Known Member
another thought is convert a mazda 13b to single rotor. plenty of readily available parts out there to do so.

Vigilant1

Well-Known Member
another thought is convert a mazda 13b to single rotor. plenty of readily available parts out there to do so.
Yes, there are folks doing it. Richard Sohn has been working on his single rotor for years, it's running now. With PSRU, exhaust, coolant, radiators, etc I think it weighs a tad over 200 lbs and I think he plans to get about 90 HP out of it. That's output that should be good, continuous "we can do this all day" HP (decreasing, of course with altitude in this normally aspirated engine).

The single-rotor is competitive with piston-engines on HP/weight, but it will unavoidably have a lower HP/weight than a twin rotor due to required counterweights and scaling effects. Still, since no one is making an affordable 100HP Wankel twin rotor, the single-rotor 13B will be a good alternative. It would also be a strong candidate for turbocharging/turbonormalizing, the Wankels do very well with some boost.

slociviccoupe

Well-Known Member
kinda neat what axiro is doing with the kart engine rotary for aircraft use. decreasing hp rating my 10hp supposedly different bearings, and a redrive that looks to be rotax.

but what is really cool is how the engine has side ports and p port. and uses a valve to switch what ports it runs on by throttle setting and engine rpm. not much is mentioned in the add for the engine but seems it is run premixed with oil for lubrication. and looks like they are now stacking these little rotary's

wwest

Member
Has no one considered a Wankel rotary engine with an Atkinson cycle? Wouldn't a rotationally displaced inlet port lower the compression stroke pressure while maintaining the power stroke equal?