Side-valved Two strokes for angels.

[Urquiola]

Attached please find the Power and torque chart for the 294 cc per chamber Aixro XR-50
Kart Wankel Rotary engine, Aixro has a version for ultralight and parapente delivering 40 HP in continuous. Also is the comment in the book by Hege 'Norton Rotaries', about the way Norton solved the fuel economy and added power in their Sachs-based Wankel, a 'Plenum chamber' acting as 'Intercooler', reducing mix temperature at intake port from over 100º C to a mere 50º C, this greatly enhances BMEP; for road use, a Reed-Valve device in intake, preventing blow-back of mix into intake ducts adds a lot. Blessings +

 

[PMD]

When it comes to burning gasoline, IMHO a Felix Wankel design is what I would vastly prefer. BUT: when it comes to getting the most efficiency, reliability, utility, etc. these questions were all answered by Hugo Junkers (geez, the Germans seem to be all over this stuff!!!) had the answers 85 years ago. A 2xx series Jumo is STILL the most efficient piston engine ever to have been installed in an airframe. 2 stroke cycle, piston port, opposed piston diesel (thank you, Rudolf). No valves and valve train, no cylinder head at all, integral gear train (so ANY propeller RPM can be accommodated).

 

[Niels]

It is maybe realistic for me to see and hear a V twin two stroke with 44 mm bores and 66 mm strokes before I leave.
It is fun to try anyway.
The pistons will be from a Stihl chainsaw and the conrods from a Slowakian 50ccm moped.

 

[Niels]

Rotax 912-915 is the yardstick.
An inverted Two-stroke V2 with 100m bore and 150mm stroke can deliver 80 to 120 horsepower at 40 rps without undue stress and is shown superimposed on a 912 to same scale

 

[blane.c]

Well side valve with flat head would be better and lighter. In-line instead of V engine might be slightly heavier but would be more streamlined so ... tit for tat and personally liking the tat ... the in-line, it will look better in many designs. Superimpose a flat head inline over the 912 and see.

 

[Armilite]

Rotax 912-915 is the yardstick.
An inverted Two-stroke V2 with 100m bore and 150mm stroke can deliver 80 to 120 horsepower at 40 rps without undue stress and is shown superimposed on a 912 to same scale
View attachment 106624

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Your (4) Engines:
912 80hp@5800rpm 1211.6cc! <--- Boom 670 at 6500rpm Turbo 9 lbs = 124.9hp!
912 100hp@5800rpm 1211.6cc! <--- Boom 670 at 6500rpm Turbo 9 lbs = 124.9hp!
914T 115hp@5800rpm 1211.6cc! <--- Boom 670 at 6500rpm Turbo 9 lbs = 124.9hp!
915T 140hp@5800rpm 1352.7cc! <-- Boom 670 at 6750rpm Turbo 9 lbs = 145.9hp!

Rotax Rick 670 92hp@6350rpm using 669cc!

A 670 669cc at 6500rpm with a Turbo 9 lbs = 124.9hp!

---------------------------- 618UL was turned 6750rpm!

A 670 669cc at 6750rpm with a Turbo 7 lbs = 140.5hp!

A 670 669cc at 6750rpm with a Turbo 9 lbs = 145.9hp!

A 670 669cc at 6750rpm with a Turbo 11 lbs = 163.4hp!

 

[Niels]

A longitudinal size comparison of a V2 twostroke doing same job as a Rotax 912

 

[rmeyers]

Are you going to use crankcase compression for starting and low power?

 

[cheapracer]

Your bare bones engine without a single ancillary superimposed over a fully equipped Rotax, claiming it's doing the same job, is a nonsensical lie.

 

[Niels]

Are you going to use crankcase compression for starting and low power?

Two pistons in V90 configuration will together pump more or less the same as a single piston.
A single piston pumps air more or less corresponding to a mean effective pressure of 10 bar.
That means that if turbo is not well we still l have air for 40 to 50 horsepower.With a chainsaw carburettor we can have a robust system if we keep the big ends lubricated and happy.
When everything is OK we will need the turbo to deliver a pressure ratio of say 1.4 and this is not rocket science I think.
The snowmobile people are turboing much more

 

[Niels]

Two pictures showing a 160 horsepower 2000 rpm

 

[Niels]

And a 80 horsepower 2400