Revmaster’s New R-2300 Engine, 85 Hp for $8K

[rogerh12]

I was on Revmasters site today, and they are offering a new 2331 cc long stroke engine for less than $ 8,000. It is said to have larger fins on the heads to improve cooling and weighs 170 lbs dry. Probably has an install weight of 190 lbs, but lots of bang for the buck. It also developes it's cruise power at a lower rpm to allow longer props to be used, which is needed on the kitfox. Here are the specs:

R-2300
SPECIFICATIONS
HP Rating: 85 @ 3200
Continuous HP: 80 @ 3000
Fuel minimum octane: Aviation grade 91/98 – 100LL
Conforming to ASTM D910
Oil: multi-grade 20/50
Bore: 94mm
Stroke: 84mm 4 main bearings
Displacement: 2331cc
Firing order: 1 – 4 – 3 – 2
Compression ratio: 8:1
Spark plugs: 12 X 3/4 reach DCPR7E
Carburetion: RevFlow 36mm
Ignition: Quad CDI 8 coils
Timing: BTDC 25 degrees
Dual alternator: 20 amp each
Battery: 12V min. 20 amp
Crank flange: SAE #1 4-3/8″ bolt circle
Dry weight: 170 lbs.

OPERATING LIMITS
Max rpm: 4200
Cruise rpm: 3000 +/- 200
Idle rpm: 900 +/- 50
Oil temp min: 130 degrees F
Oil temp max: 220 degrees F (measured at sump)
Oil pressure min: 10 lbs/1000 rpm
Oil pressure max: 80 psi
CHT cruise: 350 – 375 degrees F
CHT climb: 450 degrees F
EGT full rich: 1250 degrees F
EGT max; 1400 degrees F





Enjoy
Roger

[inzersv]

Roger12,
I have to ask this because I am not well versed in the science of prop length. Why does the Kitfox need a longer prop? I have been reading this forum for some time now and I keep seeing posts about longer prop length for various configurations. Are you talking about the Rotax in particular or engines in general. I don't understand.

[rogerh12]

Stan;

Any prop maker will tell you that prop selection is a black art, and even the experts can’t always predict what prop length and pitch will work best with any particular plane. However, in general, if you are using the kitfox round cowling, you have a lot of frontal area to interfere with the prop blast. The outer 1/3 of the prop does most of the work anyway, so for best results you want this area to be as far away from the front and sides of the plane as can be reasonable done (without hitting the ground of course). This allows for a clean exit of the prop blast from the rear of the blade.

Also, for climb, a long prop with flatter pitch lets the engine turn up more and develop better static trust at take off and in a steep climb.

Fast turning -High pitch angle props are typically not as efficient as longer slower moving props when it comes to actually transferring engine power into usable propulsion. So that is something to keep in mind as well.

Clear as mud?

Hope this helps
Roger

[DBVZ]

I don't know how black the art is, but I got into a big thing about prop length when I was looking at the Kitfox Speedster with the VW engine still on Barnstormers.

The prop mfg's have formula for tip speed, at a given length and RPM - you do not want to be very close to mach 1. 80% or perhaps 85% is about it or you lose to much efficiency. So that is determined by the peak power and cruise power RPM of the engine, and the blade length.

They also have power formula for the pitch, RPM, number of blades, and blade length of the prop. You can't turn a prop at the peak power RPM, if you have more blades and a steeper pitch than the engine power will turn at that speed. So you add more blades, you need a shallower pitch or shorter blades. A pusher has more options in this regard than a tractor, for the reasons Roger mentioned about the engine frontal area. You can't put more than 3 blades in front of a Kitfox and have the length be efficient, but you can behind a Predator or a Cozy.

And then fixed pitch you must compromise more than in-flight adjustable, since you can not change the pitch to adjust the RPM into peak power at any time in any conditions.

[t j]

To over simlify prop theory. The longer the prop and the slower you can turn it, the more effecient it is.

[Esser]

I don't know how black the art is, but

A good place to start with how to figure out your tip speed is here: http://www.epi-eng.com/propeller_tec..._propeller.htm

Interesting website. We talked about this a bit in the engine area of the site and it made me realize how little I know about props. Bottom line is it a very complex subject with many opinions.

[mr bill]

Longer props reduce disc loading of the prop (increased swept area). This equates to better acceleration and climb.

[rogerh12]

Props aside and back to the motor. Revmaster states they can produce 82 HP at 2950 rpm continuous, which sure ani't bad. Wow, that is about 400 rpm less than what I figured you would have to spin the motor to get 82 HP out of it. Should make for a good cruise speed and perhaps this motor could even be used on a float plane?


They also say that it comes with dual CDI ignition with 8-coil spark to 8 spark plugs, dual 20-amp alternators, oil cooler.

If this were a Johnny come lately company, I would not believe the engine specs, but Revamaster has been around for decades, so.... I got kinda believe it can do what they say it can. Sweet looking motor too:

[inzersv]

Thanks guys for the responses. I want to keep this part of the thread going, so I am going to start it in the prop thread. And I agree, it is a sweet looking engine.