You could use the RB aluminum end housings to get a 110 pound 2
rotor long block. With 250 HP the thing will climb like a jet. Just
watch the Vne. Only problem is the RB end housings are about 15K.
What is the expense of building a one rotor that is still somewhat
experimental even compared to the 2 rotor, and you do not have the
vibration problem Richard described.

Dale Davies

Dale, the 750 is only rated for 140 hp by the designer. Also, a 250
hp engine would exclude the craft from the light sport category, a
major reason for the popularity of the design, no medical required
and easier to get the light sport ticket. The Zenith CH-801 would be
the choice if light sport isn't a criteria. C. Smith



There is no limit on engine power for an aircraft to be eligible as
light sport. If you can make a two-rotor engine with cooling and
propeller reduction unit under 200 pounds, I say go for it. The only
power limit for light sport is that the completed aircraft can't
exceed 120 kt at full power at sea level. You can assure this with
proper choice of carburetor or EFI.

David Josephson




There's also the option to set a maximum continuous RPM in the POH at
cruise as some LSAs have done.  If you choose to firewall them, against
the max RPM requirements in the POH, then you can bust the 120 kt limit
in level flight but that is an unapproved operation.  There are some who
feel that this is cheating but the practice is approved by the authorities.

All aircraft have a Vne but you are free to bust that limit too if you
choose.  It's your butt that you're putting in the sling.  Ask Jimmy
Leeward about that, oh wait, you can't.  He found out about the results
of that violation the hard way.  It's sad that so many others died to
illustrate a lesson that was already learned by the death of so many
others before.

The LSA regulations do not set a maximum HP or climb performance. If
you have more power available than you can use continuously you are free
to apply said power in climb phase so long as you don't bust any of the
other velocity limits of the air frame you are flying.

Most common air cooled aircraft engine applications have a climb power
setting that is time limited to a few minutes lest one overheat the poor
little boing boing engine.  I've normally seen this referred to as the
climb power setting.  There's no reason why you can't use all 250 HP
that your rotary can make in the climb as long as you throttle back to
the maximum continuous RPM in cruise flight.

Weight and balance is more of a consideration than maximum horsepower.
Staying within the 1320 Lb max take off limit while still having a
usable payload will put a limit on how much engine you can carry in an LSA.

  Mark LaPierre

I can’t quote chapter and verse here but if you are a private pilot you need an endorsement to fly high performance aircraft (200 hp or more).  Assuming the above is correct and you can have an LSA with more than 200 hp as long as it meets the cruise restriction I still find it difficult to believe that a Light Sport pilot could get a high performance endorsement.  That’s something you might want to get an official opinion on.  High performance and light sport seem mutually exclusive to me and if I were to go by the spirit of the Light Sport rule high performance is not included in it.  That however is just my opinion and may be wrong.

Will Aldridge