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Rotary Engines: Would it work in a boat?

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Old 10-09-2003, 05:35 PM
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Default Rotary Engines: Would it work in a boat?

The R26B engine that won the 1991 LeMans was normally aspirated and had four rotors and three sequential spark plugs per rotor. The capacity is 2622 cc actual, rated by FIA formula at 4708 cc. It produced 700 bhp at 9000 rpm and 62 mkg torque at 6500 rpm (448 lb-ft). Fuel was electronically injected and consumption was 51.881 liters per 100 km at an average speed of 213.58 kph (excluding pit stops). The air intakes had continuously variable geometry controlled by the engine electronics. The transmission had 5 speeds (full synchromesh) from a Porsche design gearbox and a limited slip differential.


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Old 10-09-2003, 05:43 PM
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Default Re: Rotary Engines: Would it work in a boat?

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Originally posted by PhantomChaos
The R26B engine that won the 1991 LeMans was normally aspirated and had four rotors and three sequential spark plugs per rotor. The capacity is 2622 cc actual, rated by FIA formula at 4708 cc. It produced 700 bhp at 9000 rpm and 62 mkg torque at 6500 rpm (448 lb-ft). Fuel was electronically injected and consumption was 51.881 liters per 100 km at an average speed of 213.58 kph (excluding pit stops). The air intakes had continuously variable geometry controlled by the engine electronics. The transmission had 5 speeds (full synchromesh) from a Porsche design gearbox and a limited slip differential.


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You know this begs the question.......
Who cares? It ain't no big block.
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Old 10-09-2003, 05:46 PM
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I don't think the imput shaft of the drive would like 9000 rpm very much. Besides,the torque curve on a rotory is very tight, not really condusive to a one speed transmission.
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Old 10-09-2003, 05:47 PM
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Let see here...my bigblock makes 600hp @ 5500 and 650lbft @ 4000. So will it work? Yes. Will it live? No. Will it be fast? Depends on how heavy the boat is. That engine has to be 1/3 the weight of my big motor. It also costs 10 times as much.
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Old 10-09-2003, 06:09 PM
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I think you speed should be in MPH not kilo's[ i hope ] cause 213.58 kilo's per hour is not very fast, my old porsche turbo will run 260kph,
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Old 10-09-2003, 06:49 PM
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tehre is a company here on LI (in glencove) called rotary marine. And guess what???? they make rotary engines for boats.
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Old 10-09-2003, 07:05 PM
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They make 260hp supercharged 13b's puder. In a small boat, say 18 or less, it would be fun, where the torque isnt needed as much. I would be up to try it sometime.
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Old 10-09-2003, 07:16 PM
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I had three Rx 7's in the 80's and you cannot kill those engines. I think the concept for continuous propulsion is better than a reciprocating engine unfortunately good old cylinders are so prevalent that apart from Mazda there is no major companies doing serious R&D on those engines, and the cylinder culture is entrenched and here to stay.

Like airpacker said though they are very high reving engines. they take A TON of gas if you compare same cubic inches and run VERY VERY hot.

So on paper I would think they are better but no market no manufacturer.
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Old 10-09-2003, 07:42 PM
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Seems to me that one of the small jet boat manufacturers used a Wankle in their boat for a while. Used a TON of gas even when compared to a comparable two stroke motor. Jet pumps are not as susseptable to rpm's as an outdrive is, therefore the best application for a rotary engine might be a jet boat????
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Old 10-09-2003, 08:20 PM
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Rotary's are, in effect, a lot like a 2-stroke in that they are "port timed". This means that they can't be "cammed" for different desirable torque curves, they must be ported like a 2-stroke and this is somethng that can't be reversed.

They can, however, be ported for a broad torque curve and supercharged for massive amounts of power from a lightweight package.

Durability? Reliability? It all comes down to two things:
1) "oversize" rotors are EXPENSIVE and oversizing the double-trochoidal "cylinder walls" can only be done with specialized equipment.
2) Seals, Seals, Seals. Seals are used instead of rings. Seal wear is accelerated in a pressure-fed motor, and seal life is not as long as we would like to see it.

There have been one or two wankel aircraft motors certified, but I am think I remember hearing that they are no longer produced. Seal dependability was one of the issues.

Aircraft motors run at constant load. Boat motors run at constant load. Cars run at very light load except under acceleration.

I like rotaries. There's a guy putting them in jetskis and having pretty good results (close to 300hp).

As far as input shaft speed, hook em to a surface drive on a light boat. That'd be cool.

For a marine application, the variable timing and such would be a nightmare. Bolt a blower on it, fuel inject it, and rip.
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