Rexx

and here is an 1100 hp version.

http://www.youtube.com/watch?v=N-cT6mra1Pw&NR=1

Quad rotor at over 1600 hp..

http://www.youtube.com/watch?v=0BGGBU2Lpyo

alexgr8

don’t take this wrong but rotaries are the wrong engine for boats . They cant produce the torque needed to push a 8000+lb boat. Maybe a little fishing boat to beat your friends to the whole. They also cant handle the long run times. I am new to boating but can only guess that you cant push that type of rpm threw a drive without a trans or gear box witch robs torque of our already limited rotary even a 20b 3rotor cant make the needed torque.

Before you go yelling at me let me tell you some of my background. I tune and build turbo efi systems. Mostly imports including some wankles. We have a 2.0 liter Mitsubishi Evo in the shop that makes over 1000hp at the wheels. This car has also ran a traction limited 170mph ¼ pass already. So I am no stranger to forced induction. We also have some friends from PR that have ran 7.10 ¼ mile in a Toyota Starlet with a 13b. So I know what the power potential of these motors when running 60-70psi of boost and methanol.

Rexx

Sorry...couple more links.

http://www.youtube.com/watch?v=PVPTDOQ2394&NR=1

Red Bellies Racing:
http://www.redbelliesracing.com.au/circuit_racer.htm

The red bellies one only does 120-135 mph, but that is set up for circuit racing....1400 hp is 1400 hp!!!...so has the ability to get a boat spooled up very fast.

Rexx

No offense taken. Even the last post of that guy Jason didn't hurt my one feeling. Discussions like this is how we all share ideas and get smarter.

Now I agree, the low end torque is not there until the motor builds boost. However, the prop will be very shallow pitch to allow it run at 9000 RPM anyway. Props slip too unlike car tires that need good traction to launch. Another thing to consider, a 8000 lb boat will no longer be an 8000 boat with the weight savings of a few rotaries in the back. My feeling is two quad rotors or three triple rotors would do the job just fine on a 38 ft boat. And there will be enough combined torque with several rotors to get it on plane and then, watch out when the boost and RPMs build.

The comment about a drive coming apart...depends if it is balanced, gears polished to reduce heat and develop a dry lube sump much like the #6 drives have...and run lower viscosity oil. High torque, like the V8s with superchargers, are the killer of drives...hence why #6s use two vertical shafts to distribute the torque, yet keep the bevel gear sizes small to reduce hub drag.

My point of the rotary discussion is it is lower cost and weight savings for a complete setup. Simply cannot beat the power density of the rotary unless talking about expensive turbine engines. One can use a smaller bravo because it is running higher RPMs which BBCs don't like. Also, the rotaries built with ceramic seals, lightened rotors..well, when the engine is built the correct way, it will last very long time. When a rotary is screaming at 9000 RPM, the inside rotor is only orbiting 3000 RPM because of the stationary gear to rotor involute gear ratio of 3:1.

One of the greatest things about a rotary is its longevity under high load conditions. They use them in aviation for that reason. I have also had great success being the first guy to design/build a kit for putting these into jetskis (in 2002). The guy who bought my first prototype kit years ago can be seen here in his jetboat (stock port, naturally aspirated):

http://www.youtube.com/watch?v=nWludxGdbD8

I developed a second generation kit (new castings, more compact design) and couple of these are out there already. Since then, I hung up my hat on jetskis and now in the big boat seen. I've also worked on torpedo powerplants and underwater submersibles...I'm no stranger to marine propulsion.

Problem I have with integrating rotaries into boats is lack of time. Being a busy helicopter propulsion engineer and just having a new baby girl does not allow me much free time compared to 8 years ago when I did the rotary powered jetski.

Lastly, several people have already done this successfully....so why all the doubt??

JasonSmith

A Bravo as it is right now would last about 5 minutes at 9000rpm.
Those rotarys are cute & all but if they were all that great for heavy boats we would have seen them by now.

alexgr8

They will run for long periods at low power level. Ceramic seals will not hold that kind of power at all. Seals have came a long way in the last few years with exotic seals. At these power levels you are in or around 40-70psi of boost 1000-+ hp they do not hold up. Trust me we deal with some of the fastest rotary guys in the world. Even the turbos of today ,ball bearing with billet wheels will not last at these psi levels. for long term.

I am all about replacement for displacement we have bin doing it for years. The supra 3+liter 6clyinder motors in the last two vids can and have made near 2000hp. All these setups are powerful light and great for drag racing. Pushing them to there limits is not what you would want in a watercraft. Forget about a aerospace situation.

As for the drive=no way. The other end of our shop is building manual transmission. Gears are something we know well. Balancing is not the problem. You have right angle ring and pinion style gear sets. They will not like that type of rpm. Most rotarys power band is 8-11k at these power levels. Even with treating gear sets REM etc and balancing you will kill drives and I mean fast like 1st time out. The second you come out of the water and the prop hits water again at 11k its time to call for a tow. There is no throttle man or rev limiter that will stop this from happening.

The real killer is also fuel. Do you know that meth burns at 2.5 times of gas. You would need to cary so much fuel the weight savings would go out the window. And NO you can not even make 600hp with these rotarys on pump.

marylandmark

I took it as the motor is 9K RPM, not the drive.

What gears in the Bravo?

JasonSmith

Who knows? At 9000rpm they would be broken gears. I, like many others can't make a set live at 5000 RPM.

alexgr8

again gear box needed

Rexx

Again, it has already been done at 9000 rpms. Do the research before raising the "it can't be done" flag. By the way, have you blown up a drive at 9000 rpm? Wondering where all this experience comes from. Oil lubed Bearings and gears of turbine engines run thousands of hours at 22,000 rpms