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Thread: OMC’s 4-Rotor Wankel Racing Engine - The Real Story

  1. #21
    Preserving OMC Heritage LIQUID NIRVANA's Avatar
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    Quote from above: Now I'm wondering. Were the OMC rotary's aluminum housing's sandwiched between cast iron as well? And were there any problems due to the temperature differential between the intake and exhaust ports while the motor was warming up?

    My "GUESS" that OMC were in a new field & that they were trying so many different things. Combining aluminium & steel seems a bit of a nonsense but perhaps it was just a quick fix to see what would happen. All these engines were prototypes. No individual engine was the same, every single engine was unique. John has been sending me updates as things pop into his head. After all this was 35 odd years ago. I will be posting them all. These engines were way ahead of their time & probably still are. Moeller has them now & I believe they are now direct Injected. Wouldn't it be awesome if they could adapt one to an E-Tec gearcase & run it.
    I just want to see & explore one of the four that John boxed up back in 1976. These were the new era powerheads without the notorious bolt. Another thought I had was regarding the EPA. If Charlie had notified them of their (OMC) success with the emissions & fuel consumption figures would they (EPA) have banned 2 stroke outboards (as they did with the 2 stroke bikes) & effectively killed Mercury & all other 2 stroke outboard manufacturers. The EPA were certainly a law unto themselves with no thought for common sense. or so it seems.
    Things could have been very different today.
    Ken

  2. #22
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    Guys. The OMC engine was all aluminum. The side housings on the race engine were sprayed with 80 carbon steel as a wear surface only because to get the Hi-Silicon housing like what was used on the snownmobile engine took an enormously long time and were very expensive. There was no thermal problem with the engine warming up, only the loss of voumetric efficiency as I explained in the story. One note on the Mazdas. When they were introduced, gas was 35 cents a gallon and nobody cared about milage. Mazda put the engine in everything, sedans, coups, station wagons, even a pickup truck. It wasn't till 1974 with the oil embargo hit that people got conserned about milage. Your comment was correct, it almost broke Mazda and they quickly took the rotary out of everything except their sports car. It was Ford that bought a big portion of Mazda ( which they recently sold).

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    Default displacement

    The engine displacement was 129.8 ci. (2112cc). The displacement is maximum volume-minimun volume, just like any other engine; 2-cycle, 4-cycle or rotary. The argument comes as to power strokes per displaced volume. A 2-cycle and rotary has 1 power stroke per 1 revolution of the crankshft, per piston or rotor. A 4-cycle has 1 power stroke per 2 crankshaft revolutions per piston. Thus this engine competed against 2-cycles and had comparable swept volume measurments.

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    Bill:
    I remember Paul. Lets just talk about one rotor for now. The displacement of one combution pocket is as I described. Minimum volune is at top dead center. The max volume is at the point where increasing volume (induction) stops and decreasing volume starts (compression) It has nothing to due with port timing just like a 2-cycle where the ports are open during part of the cycle. If you used port timing on either rotary or 2-cycle you would be measuring effective compression ratio or displacement. Its similar to valve overlap on 4-cycle engines. Where the rotary is unique, each of the 3 faces on each rotor is doing a different part of the cycle simioustaniously. ie; when face 1 is intaking, face 2 is compressing and firing and face 3 is exhausting. Remember this is still only one rotor. Thats where the argument came that it should be 3 times one faces displacement. However, if you look at a 2-cycle, the power stroke is also forcing the intake and the compression is also exhausting so the argument against a 2-cycle is mute. Check out this web site for a animated explantion.
    static: http://www.howstuffworks.com/flash/r...-animation.swf
    Last edited by Mark75H; 05-17-2009 at 11:09 AM.

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    The argument has been and will continue on how to rate displacement. Japan wants to have 3 times the displaced volume because they tax cars on displacement; ie more displacement-more tax. The argument to measure displaced volume per crankshaft revolution is technically the most accruate, but the 4-cycle guys argue they only get 1 POWER stroke for every 2 crank revolutions, thus they argue for 2 times. I find this argument rather weak as a 2-cycle has 1 power stroke for every crank revolution and nobody ever suggested it be multiplied by 2 when comparing to a 4-cycle. Look at our outboards today. Many are now 4-cycle and yet displacement is measured the same as 2-cycles. One of the problems was advertising. Outboards and lawnmowers were the only engines sold by HP, while other engine products sold by displacement. ie 427 Chevy and a 9.9 hp outboard. Boat racing did class by displacement, but rotaries ran in the unlimited class, run what you brung.

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    1. Jimbo at Parker, first lap waving to the crowd. The wake behind him was Posey. 15:17 gearcase


    2. Tommy Posey at Provo Utah. 14:23 gearcase


    3. Tommy Posey at Miami Marine Stadium at press introduction before Parker. Note no fuel filler caps the boat rear shroud. 15:17 gearcase


    4. Tommy Posey at Provo, Utah. Look carefully, nothing in the water, he was really flying. 14:30 gearcase


    5. Very early press photo; note vertical "Johnson" 15/17 gearcase


    6. OMC Engineering boat dock. Mike Kukla (died 1975) behind engine, Harold "Mouse" Wade. Note the cut off exhaust exit and the black spacer between the 15:17 gearcase and the bucket. This was a V-4 gearcase modified for the rotary. Later in the program a new gearcase casting was made for the 14/23.


    Many thanks to John Sheldon aka 'ROTARY JOHN' on BRF for providing most of the above literature.

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    1. Jimbo at Parker, first lap waving to the crowd. The wake behind him was Posey.
    2. Posey at Provo
    3. Posey at Miami Marine stadium at press intro befor Parker. Note no fuel filler caps the bost rear shroud.
    4. Posey at Provo. Look carefully, nothing in the water, he was really flying.
    5. Very early press photo; note vertical "Johnson" 15/17 gearcase
    6. OMC Engineering boat dock. Mike Kukla (died 1975)behind engine, Harold "Mouse" Wade. 14/23 gearcase used at Provo. Note the cut off exhaust exit and the black spacer between the gearcase and the bucket. The was a V-4 gearcase modified for the rotary. Later in the program a new gearcase casting was made for the 14/23.

  8. #28
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    DYNAMOMETER Testing












    A later DYNOMOMETER SHEET showing 313 propshaft horsepower @ 10500rpm with 217 crankshaft ft Lbs of torque @ 5000rpm

    Many thanks to John Sheldon aka 'ROTARY JOHN' on BRF for providing the above literature.

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    Sam Cullis Mark75H's Avatar
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    I don't know why, but sometimes Webshots won't let me open the images full size, other times it does.

    Any way ... If Ken would be kind enough to email me the original scans, I can improve a lot of them like this:

    Attached Images Attached Images    
    Last edited by Mark75H; 05-20-2009 at 07:38 AM.
    Since 1925, about 150 different racing outboards have been made.


  10. #30
    Sam Cullis Mark75H's Avatar
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    Quote Originally Posted by Allen J. Lang View Post
    Hi Ken- Did OMC ever state what HP the engines pulled on the dyno?
    Ye Olde Desert Geezer Al

    OMC never released it during the program, but John has it in the text on this thread ... the early versions made 265+ and the later versions made 280+
    Since 1925, about 150 different racing outboards have been made.


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