Paul,
Has anyone ever put a 13B on an outboard motor? I have a blown big
Evenrude, and was just pondering ideas.
Regards,
Norm Parmley
Not that I know of but that is a great idea. With aluminum end houses it
might weigh about the same. You would need a dry sump pump to handle
the oiling system. With a turbo it would be one spectacular out board.
How much HP was the Evenrude? New big Evenrudes are about $15,000
Paul Lamar
If memory serves me correctly, OMC spent a great deal of time and money
developing a rotary outboard. It Rocked!!!, However, I think that had
problems in two areas that prevented it from coming to market.
1. the vertical orientation created problems with lubrication
2, ecologically it was not great as in oil in the exhaust and "oil
slicks" in the water.
I occasionally have lunch with x- OMC guys and I will try to find out
more about it when we meet.
Rich Goldman
That is a possibility. The vertically orientation could cause problems
with oiling. But I don't think that is insurmountable. A dry sump pump
IMHO could do the job. Sachs built a lawn mower with a vertical engine.
All two cycles had that oil in the water problem. Somehow Mercury and
maybe OMC solved it. Two cycles out boards are still available I think.
https://www.mercurymarine.com/en/br/engines/outboard/twostroke/
Maybe not in California :-)
Paul Lamar
Part of the oil slick solution is synthetic oils that allow leaner
oil ratios.
Dale Davies
OMC 4-rotor
http://www.screamandfly.com/showthread.php?186454-OMC-s-4-Rotor-Wankel-Racing-Engine-The-Real-Story
Jim Rudholm
As told by John Sheldon
Former OMC rotary engineer
PREFACE
After the successful introduction of the 35 HP and 45 HP air
cool/charged cooled snowmobile engine, OMC started working on water
cooled/charged cooled variants of the same engine. Basically all the
parts were the same except the housings, which were water cooled.
Contrary to previous OMC, Curtis Wright and Mazda water cooled engines
which had the water flowing axially; parallel to the crankshaft; these
engines were partially circumferentially cooled. Water entered before
the spark plug, ran around the rotor housing and exited around the
exhaust port. The side housings picked up water at the entrance point
for the rotor housing, travel across the hot section of the housing and
exited at a low pressure point after the exhaust port.
Both single and dual rotor engines had been prototype and development
work had begun. The single rotor produced 50/55 HP and the 2 rotor
produced 110/120 HP. The increase in HP was due to the improved
volumetric efficiency (increased air flow) due to the lower temperatures
resulting from water-cooling.
Both these engines were configured for outboard use and were coupled to
current lower units. At one board of directors meeting the twin rotor
engine was mounted to a boat for demo rides. The tachometer was
disconnected and the engine was left running. Every one that got into
the boat turned the key to start the engine. There was no noise, no
motion, no vibration. It was impressive.
BIRTH OF THE 4 ROTOR RACE ENGINE
Charlie Strang was the head of OMC at the time. At the world
championships in Lake Havasu in 1972, Johnny Sanders won the race for
Johnson, but only because Mercury broke. It was clearly apparent Mercury
was faster than the OMC engines.
Both companies were running 100 ci 2-cycle engines, but Mercury had an
in line 6 cylinder and the OMC engines were V-4’s. The additional
cylinders of the Mercury engines allow more air flow, resulting in
additional power. The Mercury engine was producing approximately 200HP
while the OMC V-4 was producing approximately 175 HP. There wasn’t much
to do to get around this.
After the race, in October, Charlie Strang came by to chat with George
Miller. George was head of the rotary engine engineering group at the
time. He confirmed with George that the 2 rotor engine was producing
115/120 HP. He speculated with George if we stacked 2 of the twins on
top of one another, we would have an engine that produced 240 HP and we
would finally have a chance to “beat those black bastards”.
George reluctantly agreed, but pointed out to Charlie he didn’t have the
manpower to assign to the project and it most likely would take a year
or two. Charlie agreed, but said lets delay some of the other programs
and put some one on it. Besides, he said, racing will find weaknesses
and force development much faster than conventional engineering development.
As he was leaving George’s office he said “oh, by the way, I want to
race them at Parker, Az in March. So began what was referred to as HSXL;
Havasu experimental limited and was assigned the project # D706.
INITIAL DESIGN WORK
Reluctantly George assigned Mike Griffith to the program. The first
issue addressed was the crankshaft. A stationary gear is required for
each rotor and its pitch diameter is dictated by engine geometry and
can’t be changed. Because this is smaller than the eccentric diameter,
either the crankshaft or stationary gear has to be split. It was decided
to keep the stock stationary gear and use 2 –two rotor crankshafts, some
how magically held together in the middle. Mike remembered Mercedes Benz
had used a coupling on their 3 and 4 rotor engines put into their C-111
experimental cars.
After a little research, Mike found out Gleason Works had a curvic
coupling that resembles an involute gear standing on its end. OMC was
one of Gleason Works biggest customers. After a few phone calls a curvic
coupling design was developed by Gleason that would work for this
application. Because of the separating forces generated by the curvic
coupling and the fact we wanted the crankshaft to think it was one piece
(more on this later) an enormous clamping load was required to hold the
two cranks together. The solution was a thru bolt; a very special thru
bolt. It was 7/8” in diameter and was made from EDT-180. A material
having 180,000 psi minimum yield strength. The bolt was necked down
along it center section to equalize the stress in the threaded ends, due
to stress riser from the threads.
The decision was also made to have 180 degree eccentric spacing instead
of 90 degrees. This allowed the engine to be dynamically balanced
without counter weights and use 2 of the current 2 rotor crankshafts.
Rotors 1 and 4 along with 2/3 were in phase with each other. Because 2
rotors fired at the same time, the stock ignition system from the twin
rotor could be used. Each plug had its own coil, but only 2 triggers
were used.
Charlie Strang came up with the idea on mounting the engine almost
directly to the gear case eliminating the conventional mid-section and
lowering the overall height of the package; i.e. lower center of gravity
would me faster turns. Thus the so-called bucket came into being. It had
to be tall enough to keep water from spilling over when at rest or idle
and be waterproof.
It was decided to use stock snowmobile carbs and all the internal
hardware; rotors, seals, bearings, etc. This minimized the new parts
that need to be designed and produced. Remember race in March. With the
conceptual design complete, detail design started. All of the housings
had to be new as long thru bolts outside of the conventional 2 rotor
engine thru bolts were used to hold every thing together. Also, the
bottom housing of the top engine and the top housing of the bottom
engine had to be modified to allow mounting to the steering arm and the
two engine to stand on each other.
New snowmobile flywheels were cast without counter weights and using
existing 2 rotor crankshaft castings allowed the modification for the
coupling and thru bolt. The exhaust system for the 2 rotor was a steel
casting with deflectors turning the exhaust flow 90 degrees downward.
Two of these were used on the 4 rotor with the housings acting as the
water cooled box around them.
Designs were completed, parts were ordered and the first engine was
assembled. The day of reckoning came and the engine was ready for its
first dyno run. The engine produced 220 HP at 6500 RPM. Acceptable for
the first try, but disappointing none the less. This was also crankshaft
HP and the gear case absorbed approximately 15 HP. This meant the power
to the prop wasn’t much more than the V-4.
INITIAL POWER DEVELOPMENT
We knew from previous work that the exhaust restriction was
hindering power and the engine was somewhat subjective to exhaust
tuning. This is where I entered the program. It was the first of the
year and we were running out of time. The bosses decided we would work 2
– 12 hr shifts, 7 days a week. Illinois labor laws say an hourly paid
worker can only work 13 days in a row and then must have a day off. The
law didn’t apply to salaried people so Mike and I were on 12/7.
Unfortunately, Mike got sick the first week on this schedule and ended
up in the hospital. This meant I had to cover both shifts. I would go
home at 2 in the morning and return at 6. We started by removing the
butterfly in the peripheral port, enlarged the bore and venturis of the
carbs and started working on exhaust tuning.
The dynos at OMC did not have remote controls at that time so the
operator and others including myself were in the dyno rooms while the
engine was running. If anyone ever heard these engines run at the races,
multiply that time ten and that gives you an idea what it was like in
the dyno room.
After determining what exhaust length gave the best power, the challenge
was package it in the space that already existed in the original design.
Mike and his designer came up with the solution and had parts made. The
system was made from 6 aluminum casting welded together. The fear was
the enormous heat of the rotary exhaust would melt the castings. As a
result, a second water pump was added that only cooled the exhaust
system. With the additions of all these changes, power went up to 260
crankshaft HP.
The next hurtle to cross, would it survive the 9 hrs of Parker. An
engine was built and mounted on a old twin engine Molinari racing
tunnel. We took it to our Florida test base in Stuart and ran up and
down the Indian River above the locks. The engine performed well and was
cruising in excess of 100 MPH even though we weren’t pushing things. The
first day went fine without incident. About half way thru the second
day, the driver got it too high out of corner and blew it over
backwards. The water was only 10 ft deep so the motor end went to the
bottom and the front stuck out of the water. We could not see the driver
and feared he was stuck in the boat under water. Jack Leek and I were in
the chase boat and started immediately to the crash sight.
Unfortunately, we didn’t even get on plane and the engine quit.
Franticly we tried to figure out what was wrong and restart the engine.
We had run out of gas! After quickly changing tanks we rushed to the
sight. On the way there I stripped down to my skivvies ready to dive in
and rescue the driver. The day before we had seen a 12 ft alligator
lying on the shore but today he wasn’t there. All I could think on the
way to the crash site was diving into the water and having that
alligator show up.
As we got closer we saw Rich bobbing behind the boat. The front of the
boat sticking out of the water had blocked our view of him. I dove in
and grabbed Rick. He was mad as a hornet, but not hurt. Off to the
hospital for him; standard procedure for any driver that goes into the
water. My technician and I went with the chase boat and hauled the boat
back on the trailer. After taking the spark plugs out, cranking it over
to clean out the water and replacing the plugs the engine started back
up and ran just fine. We let it run for a half hour squirting oil in the
carbs every once in awhile.
Now what? A call went into Jimbo McConnell and he flew down the next day
and finished the 10 hrs of testing. We all felt pretty good about going
to Parker. While I was in Fl. Mike built two engines for the Miami press
demo and then onto Parker. The press demo went very well and the guys
headed for
Parker note; of all the pictures you see of the boats running you can
tell the Miami boat as they did not have the fuel fill caps installed yet.
THE PARKER RACE
We had two boats at Parker. The Evinrude was driven by Jimbo McConnell
and the Johnson by Tommy Posey. They were the talk of the prerace scene.
The gear case used for the initial races was a twin pinion 15/17 ratio.
This is used for max top speed. Parker was a “run what you brung” race,
outboards, inboards, jet boats, hydros, single engine, dual engines, and
even triples. It’s a river race with the boats going 6 ½ miles up the
river, turn around and come back.
The race went off as scheduled and everyone held their breath to see who
would lead the first lap. Here they came with the two rotaries side by
side; 1-2; with a 7 liter 3 point hydro chasing them. The hydro had been
clocked at 140mph the week before. Consider the world speed record for
outboards was 136 mph at the time. The driver of the hydro had bet
$1000.00 he would lead the first lap and was doing everything but
running upside down trying to catch the two rotaries. Jimbo and Tommy
coolly drove by the crowd waving as they went. A big wave went to the
Mercury camp as they flew by. Mike and I were all smiles and feeling
pretty good about all the long hours and work we had put in.
As the boats approached for the second lap, Tommy was still in first by
a big margin, but Jimbo was nowhere to be seen. We found out shortly his
engine had failed. Tommy continued to lead, but succumbed to engine
failure before the first hour was complete. We went home dejected and
waited for the guys to drive the boats back from Parker. As soon as they
returned, we tore the engines apart and found failed rotor bearings. In
reviewing the dyno sheets I found the engines were producing 265 HP on
18 gph of gas.
That’s BS Fuel Consumption [BSFC] better then most diesels. In talking
with Mike, he had adjusted each carb for max power and didn’t believe
the fuel flow meters. He went out and bought 4 new Cox certified flow
meters and repeated the run with the same result. He didn’t believe the
data but had to button up the engines to leave for Miami.
-----------------------------------------------------------------------------------------
Charged cooled. Of course the rotor bearing failed :-) Paul Lamar
---------------------------------------------------------------------------------------------------------------
End of part 1
Thanks for that, Now I will have nothing to talk about with my OMC friends
Rich Goldman
Thanks for the history lesson.
Norm Parmley
The Rotary Engine free News Letter. Powered by Linux. If you want off
the list PLEASE let me know and I will remove you. ACRE NL web site.
http://www.rotaryeng.net You Tube
http://tinyurl.com/beqqxas Copyright
1998-2016 All world wide rights reserved.