Rotary Engine?

[HyperDonzi]

Sleepless, I wondered about a rotary engine in a boat. the 13b used in the 3rd gen. Mazda Rx-7's can make 500hp per liter (1.3l) with twin turbos. Why arent thses ever seen in a boat or better yet, a 5.7l rotary. well, i will try to sleep now.

[Formula Jr]

Cause wankel sounds alittle too much like wanker? I guess you have to have followed the history of this engine design. It nearly killed Mazda. In the end, the rings barely worked and no body cared to update their repair tooling to deal with the engine design. The rx-7 is, or was, the the last strong hold. There was also a short lived motorcycle based on this engine. - "The water buffalo suzk" Its an interesting design that never had the materials, or infrastructure to make it work. Ultimately, it isn't an efficient engine as a two stroke. Lots of wasted gas and emissions . If it was better in design than piston engines you can bet that someone would have put it in a racing machine in the last 20 years -- not so................

[ALLAN BROWN]

That's the trouble with you damned kids! When Charlie Strang was Prez of OMC, he made rotary outboards that MURDERED the two-cycle competition. If my memory serves me, they were called CCC engines. Problem was, they could never agree on how to measure displacement (still can't, see above post). I predict that you will see a rebirth of the Wanker in the very near future.

[Forrest]

I remember that OMC Wankel outboard, it was short lived and kick ass! Like Jr. says, the Wankel engine ain't too efficient . . . and that's because there is so much surface area in the combustion chamber - way more surface area than in a piston engine. All that extra surface area conducts away combustion heat mostly to the cooling system, which in turn, is not converted into mechanical energy.

[CDMA]

It is being done.

http://www.rotarypowermarine.com

The guy's shop is literally 3 blocks from my school and my roomate works for him.

The website pretty much tells it all. They are pretty pricy though.
From a design standpoint they are really interesting.

Chris

[McGary911]

I've always thought that Wankels were pretty interesting. A friend of mine was a wankel nut, even had a case\rotor on his coffee table for a centerpiece. They are indeed pretty dirty emission wise, probably not as bad as a 2 stroke tho. That is the reason that each chamber has 2 spark plugs, first for the burn\compression, second for the emissions clean up. The rotor seals were the weakest link in the earlier motors, that's for sure. If you followed the SCCA in the past 15 years, you would have seen armies of RX-7's racing.
I think one of the coolest things were the motors' abilty to take high rpms. There was a buzzer that went off at about 6500 rpm, but that isnt because the engine couldnt safely spin to 10,000. The engine could spin it, but the water pump would cavitate and not keep up, so the rpm buzzer\limit was a function of cooling, not valves\springs\reciprocating mass ala V-8. I've GOT to get back to work......

[MOP]

Rotary Marine Corp of Glen Cove NY is marketing a rotory through Mack Boring. A 350lbs. unit in either 175hp or 240hp. That is less than half the wieght of a V8 should be a Butt Kicker!

[HyperDonzi]

They are also smaller.