You have a lot more to deal with than just the engine.
There is the cooling system the gear box and the prop.
The big question is how much HP do you need?

Or.................

What airplane are you building?

Paul Lamar


Paul,
You may have misread my email. I am not looking for an 80lb. rotary engine,
My intent was to configure a Renesis engine with components to achieve a
total weight of 210 lbs. excluding the prop and mount. My reasoning is as
follows:
    Base engine wt.- 109 lbs. (based on the image on your website)
    
    Aluminum flywheel - 7 lbs.

    PSRU - 35 lbs.

    Starter - 7 lbs.

    Alternator - 7 lbs.

    Hydraulic pump - 9 lbs.

    Exhaust system - 17 lbs.

    Radiator, oil cooler, Oil filter, Oil tank, and fluids - 21.5 lbs.

As opposed to the Mistral G200 engine, based on 1300 cc Mazda engine,
weighing 291 lbs. My comment was that it was achievable, without
extraordinary measures, to build an aircraft engine, without turbo charger,
of equal or more hp and have it weigh 80lbs. less.

The aircraft I intend to build is of my own design. I cannot adequately
describe it to you in an email, however I can say it looks remarkably like
an Eclipse 400 with a tractor engine in the front rather than a jet on the
back.

I need an engine that is small, light weight and produces approximately 150
to 190 hp.

Thank you for your reply.

I value your advice.

Doug


Yes I did. Sorry Doug.

P-port the RX8 engine and you are sure to get 190 HP with
a simple and light weight intake system. 190 HP can be had
at 7500 RPM with out the p-port but you will need to "port" the
engine and get the intake manifold exactly right.

Why the 9 pound Hydraulic pump? The 109 pound engine has the engine oil pump
in it.

The exhaust system can be much lighter if you use .035 thick Inconel.
Inconel is .3 pound per cubic inch. So a square in of .035 thick sheet would
weigh
.01 pound.

Paul


Paul,
Thank you for the tip on the exhaust system.

I am aware that I can achieve my specifications with a P-port engine,
however, the side port Renesis engines appear to have greater fuel
efficiency and more power with the same displacement. The Renesis engine
appears to be the superior engine and a little additional power without a
weight penalty and fewer emissions. More power with the same weight is fine
with me.

Do you know of anyone who is casting high quality aluminum alloy end and
intermediate pieces for the post 2007 Renesis engine?

The hydraulic pump is added to power the hydraulic flight control system
which is controlled via digitally controlled hydraulic valves. The system
will be operated with a redundant digital flight control system. The system
will have the following advantages:
The airplane design has a v-tail so the ruddervators will be operated
collectively and independently with stop and speed limitations. A system
with hydraulic actuators a digital flight control system should be safer,
lighter and without the slop of a mechanical system.
The design has rather long thin wings which would make it prone to adverse
yaw. Ailerons independently controlled by actuators will reduce or eliminate
this tendency.

As a third level of redundancy, the valves could be controlled with a direct
analog setup from the control stick to the valves.
The Eltings

That is just appearances. The advantage, if any of the RX8 engine over the 13B
is a slightly higher compression ratio. The side EXHAUST port RX8 engine helps
the low power, low speed fuel consumption by recirculating the raw unburned fuel
but that also applies to an RX8 P-port engine.

RX8 engine P-ports have higher volumetric efficiency than RX8 side intake ports and that
helps, not hurts the fuel consumption in the aircraft power level range.

Here is the curve for a LeMans  P-port engine and you can see the BSFC is a minimum
at 6000 RPM. Intake pipe length and diameter are everything.


Paul Lamar