OMC's 4-Rotor Wankel Racing Engine - The Real Story

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Originally Posted by Rotary John

Oh, by the way the Graupner rotary is rated at 18,00/22,000 RPM.

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Now John, if you're going to go quoting model/toy engine rev figures, you may as well tell them that a Cox .049 Killer Bee piston engine would turn 28K straight out of the box. Those OS/Graupner wankels were horrible turds when they came out, btw... I bought one. Their seal backing springs would turn to silly putty if you even thought about running one hot, and a little fussy to start even with good compression. They might be better made now, and you can still buy them today from hobby retailers. No doubt they are neat.

Their a toy with wow factor. They can be cleaned up with valves and cats injector and o2. Still no torque hAving mosquito sounding junk though. Although a 400 hp 300 lbs outboard spinning 10k turning a 10x4 pitch on a 10 foot john boAt hitting 22gps is defiantly awesome.

Ok ok I jest their cool efficient Nd have issues like everything else. Face it this emissions stuff is worse on us then anything it ever did to cars. In the 70's. Took us 40 years for a 400 hp Camarillo from the factory again. Yea their were one offs and little makes here and their. That's were we are at. Outboard or boating in general. 454 big blocks making 150 hp in 4 ton cars.

Now ow you want fun yamma or suzi need to slap a 1100 bike motor on their outboard. And let it hit 11-13k rpm

How is it considered such junk when it's done so well in many different performance motor sports? I know it's not a better engine then a piston engine overall. it's apple's to oranges but how such junk?

4 stroke bike engines dont work as an outboard as they wont pull the skin off a rice pudding
No gears in an outboard

Thanks for the support. Everyone please remember, this engine and the information is from 1972/75. Not today. So when I talk about 2-strokes we are talking about cross scavenged OMC and direct charged Mercs. OMC had 1 loop engine at the time and Merc was only in development of their V-6 looper. The only 4-stroke was the Fisher Price/Homelite.
Apex seals are no longer a problem. Several solutions are now available that virtually eliminate any problems. You also have to remember that it is the apex seal-trochoid coating that's makes it work. We hadn't fully solve this problem back in the '70 on the race engine. I had developed alternative seal in snowmobile testing, but never actually put them into the race engine. We never DNF because of apex seals, so I was hesitant to put different seals in a race engine. As far as fuel and timing goes. A rotary is very insensitive to spark timing as far as power is concerned. Remember the rotor (ala combustion) is going 1/3 the crank speed. Timing is important for emissions as seen in Mazda engines. The trailing spark plug can increase power by 8/10% while also effecting emissions. We never used dual plugs on this engine series as our experience had shown housing cracking problems. Besides at the time we really didn't need any more power. The rotary is also very tolerant to fuels. It can run on 85 Octane w/o problems. In fact at Windermere, Merc want Leek to go half's on a load of av. gas but said no as we didn't need it. It again goes back to the relatively slow, stationary flame front in this engine. As told before, for some reason we were never able to figure out, the race engine wanted to run super lean for best power. We measured BSFC of .385 at LBT but would fail rotor bearings if we ran at that level (ala Parker). We would run RBT of about .6. which was still better than the best 2-stroke of the time. I would love to put todays development into that engine and run it on todays generation boat. It ani't gona happen, but I can still dream what if.

Many thanks John
Hey if that adapter that guy in Melbourne made pops up somewhere I could see I might take on the project but then I again I might make my own for a short OMC mid/V8 lower

This is very interesting, I'm glad I got to start the day learning a little. Nearly all of what I know or think I know relates to pushing the limits of turbocharged rotaries and John is talking about an engine running at atmospheric manifold pressure... renders those fuel and timing points moot with regard to the OMC project (and any other normally aspirated rotary) due to chamber pressure differences. I'll stop comparing apples and oranges now. Thank you for your knowledge Mr. Sheldon. I'll have to take a picture of a rotor face pushed in from pressure between the chamber and seal later, you might get a chuckle out of that.

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Originally Posted by Speedfab

This is very interesting, I'm glad I got to start the day learning a little. Nearly all of what I know or think I know relates to pushing the limits of turbocharged rotaries and John is talking about an engine running at atmospheric manifold pressure... renders those fuel and timing points moot with regard to the OMC project (and any other normally aspirated rotary) due to chamber pressure differences. I'll stop comparing apples and oranges now. Thank you for your knowledge Mr. Sheldon. I'll have to take a picture of a rotor face pushed in from pressure between the chamber and seal later, you might get a chuckle out of that.

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We turbo charged a snowmobile engine once, Shut it down at 54HP @3000 rpm; overheating.

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Originally Posted by Speedfab

This is very interesting, I'm glad I got to start the day learning a little. Nearly all of what I know or think I know relates to pushing the limits of turbocharged rotaries and John is talking about an engine running at atmospheric manifold pressure... renders those fuel and timing points moot with regard to the OMC project (and any other normally aspirated rotary) due to chamber pressure differences. I'll stop comparing apples and oranges now. Thank you for your knowledge Mr. Sheldon. I'll have to take a picture of a rotor face pushed in from pressure between the chamber and seal later, you might get a chuckle out of that.

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We turbo charged a snowmobile engine once, Shut it down at 54HP @3000 rpm; overheating. I can imagine what can be done. The race engine dropped to approx. 65% volumetric when it warmed up. If I could get that 35% back plus, wow the boat wouldn't have stayed together.

Thanks for that info. Your the real mcoy with the experience and u also said that was1970s technology u would love to do it again with today's technology and see the final product. Everyone thinks these problems still exist.... the import game is hugee. And more young people and builders are into rotaries then ever.. Florida Australia and puerto rico they are flooded with rotaries and they are fasttttt... its not leaving any time soon that's for sure... I hate when people say it was a waist what you guy's accomplished, you guys did a great job. And i hope someone picks your brain enough that itwil be atattempted again. Awesome thread.

[QUOTE=Speedfab

I'll take Rotary John's real life knowledge of these things over internet armchair quarterbacks and rotary fanboys all day. I may have many years of experience with them, I may be an engineer, but he actually ENGINEERED one. Big difference. I'm not just blowing smoke, I think everyone reading this needs to realize how fortunate we are that he is actually here telling us about it. I find the whole thing fascinating.[/QUOTE]

Let me set the table and tell you of what I remember as a kid
of the Greatest Parker Race Ever!

I grew up in a family, full of mechanics.
Starting back to Barney Oilfield / Henry Ford

My Father and partner had been asked by Shelby to work with them. Joe Mondello worked down the street and went on to win the Enduro

Well we were all VIP guests of Mc Culloch oil for the race.
Jack was Robert Mc Culloch's "special projects" guru

Jack along with Ak Miller won the "Pan American" road race.

Ford, gave Miller a 25 million grant job designing the FE ford motor platform.

Jack, was amazing, build a city, move a bridge, supercharger, 2-stroke motors, promote boat racing. And a mentor

This Parker race was about winning. Ford, Chev, Mopar
had vested stakes. Win on Sunday sell on Monday !

But, to Mercury
It's about crushing you opponent !

Well life is about the little things

Like a "David vs Goliath" moment.

You don't see them often.

That's why we are still talking about it to this day.

My brother and I learned something that day !
First, we want a Rotary.
Second, we want to win that race someday.
Well, we did the latter.

And we still want a rotary
It was the little train that could !

Big Steve

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Originally Posted by Rotary John

The race engine dropped to approx. 65% volumetric when it warmed up. If I could get that 35% back plus, wow the boat wouldn't have stayed together.

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What do you think caused that? Sealing? Inlet air temps? Cooling hot spots? That's a huge hit.

Big Steve, I totally get what you mean. We must be about the same age or close. My dad was small time into boat racing, only stuff I ever saw was in Florida as far as I know. But I did get to see and hear stackers run in their heyday, along with some other neat stuff. I look back glad that I was at least born early enough to witness what to me were the great days of outboard racing.

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Originally Posted by Speedfab

What do you think caused that? Sealing? Inlet air temps? Cooling hot spots? That's a huge hit.

Big Steve, I totally get what you mean. We must be about the same age or close. My dad was small time into boat racing, only stuff I ever saw was in Florida as far as I know. But I did get to see and hear stackers run in their heyday, along with some other neat stuff. I look back glad that I was at least born early enough to witness what to me were the great days of outboard racing.

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These engines were charged cooled. Meaning the fuel/air intake charge went thru the internals of the rotor first and then into the intake cycle. The charge heated up approx. 150 F in the process and thus expanded resulting in a lower volumetric. In addition the intake path was quite tortuous resulting in further loses. This is how the rotor bearing was lubricated also, The delta T across the rotor cause the bearing to be larger on the hot side than the cold side, resulting in hugh side loading and premature failure, Mazda engines are oil cooled and can allow for direct intake to the intake cycle resulting in 100+ volumetric. If you look at the Mazda LaMans engine, it had variable length intake horns to maximize volumetric thru out the rpm range.

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Originally Posted by Big Steve 435

Let me set the table and tell you of what I remember as a kid
of the Greatest Parker Race Ever!

I grew up in a family, full of mechanics.
Starting back to Barney Oilfield / Henry Ford

My Father and partner had been asked by Shelby to work with them. Joe Mondello worked down the street and went on to win the Enduro

Well we were all VIP guests of Mc Culloch oil for the race.
Jack was Robert Mc Culloch's "special projects" guru

Jack along with Ak Miller won the "Pan American" road race.

Ford, gave Miller a 25 million grant job designing the FE ford motor platform.

Jack, was amazing, build a city, move a bridge, supercharger, 2-stroke motors, promote boat racing. And a mentor

This Parker race was about winning. Ford, Chev, Mopar
had vested stakes. Win on Sunday sell on Monday !

But, to Mercury
It's about crushing you opponent !

Well life is about the little things

Like a "David vs Goliath" moment.

You don't see them often.

That's why we are still talking about it to this day.

My brother and I learned something that day !
First, we want a Rotary.
Second, we want to win that race someday.
Well, we did the latter.

And we still want a rotary
It was the little train that could !

Big Steve

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It happened again at Provo. Merc brought all their big guns including 600HP IO's trying to compete with the rotary. They went home with there tail between their legs.

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Originally Posted by Rotary John

It happened again at Provo. Merc brought all their big guns including 600HP IO's trying to compete with the rotary. They went home with there tail between their legs.

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C'mon Johnno, you cannot be serious, one quick first lap at Parker-----what happened to the mighty ROTORY the next time round,---stopped for a drink and a sandwich did we?
6 wins out of eight starts 40 + years ago and your still celebrating ,----3of those were at backyard events with minimum opposition
Windermere was by default after the opposition broke, hells teeth I was in the first five with a 1000 BP, DRIVING SO SLOW GG SACKED ME.
Never been to Provo, but every time WILLABEE and you get into it there is conflicting memories of the event.
Mercury probably won over 1,000 races worldwide that year (' cos that's what they do ) hell of a lot more than 6.