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

In this day of electrification, I don't see anyone investing the capital required to produce a rotary economically. The world has been machining round holes and cylinders for 120 years and have become quite proficient at it. Mazda held on as long as they could, until emission abatement cost more than a competitive 4-stroke.
With today's materials, durability is not an issue. The rotary's weakness is its surface to volume ratio, resulting in significant flame quench, causing high hydro carbons and reduced fuel efficiency.
I believe if OMC would have continued the rotary in specific application, they may still be in business. I believe the rotary would have been competitive over the complexity, size and cost of the Ficht and their latest air injection system.
Imagine a 250HP twin rotary IO w/o a dog house. or a side wider 4 rotor 500HP IO also w/o a dog house. Both with 1/2 the weight of a comparable 4-stroke.

Soooooooooo, does it fire every time a rotor lobe passes through a chamber??

As in, 3 lobes so it fires 3 times per rotor revolution?

Yes, however , the crank has made 3 revolutions for that to happen. Its's like a 2-stroke that way. If the crank revolves 3 times, the spark plug fires 3 times Thus by your way of thinking a 2-stroke should be measured X 3. The simplest way to measure displacement for ANY engine is to measure the displaced volume per each crankshaft revolution.

No argument from me.
I am just trying to wrap my head around, how it does what it does.

Not throwing stones.

I spent 3 days trying to make sense of the illustrations posted ��

I thought I understood rotaries.
Clearly I did not.

I guess the argument could be, swept volume Vs crankshaft rotation?

I like it.

Is the rotary design being used anywhere besides the bike project I posted?

I caught your comments on emissions and the bike guys are using a total loss oil system and stated that it burns so clean it doesn’t show up in the exhaust.

I still have the ‘1973 Mechanix Illustrated issue on the OMC motor and remember what caught me the most was the engineering that allowed them to stack them up and make what ever power they wanted.

Always thought was brilliant and should be a game changer.

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Originally Posted by Rotary John

Yes, however , the crank has made 3 revolutions for that to happen. Its's like a 2-stroke that way. If the crank revolves 3 times, the spark plug fires 3 times Thus by your way of thinking a 2-stroke should be measured X 3. The simplest way to measure displacement for ANY engine is to measure the displaced volume per each crankshaft revolution.

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There are a couple of company's in England making rotaries for drones and military activities. Mazda claims they will make a rotary range extender for their hybrid cars. Moller in California has put rotaries in all sorts of things and continues to look for investors to bring the engine to mass production. I have done consulting work for several company's building gen sets for the military, but none to my knowledge have gone into production.

Yrs back, I tried to find a twin turbo RX-7, but failed.

Cant remember if it was that or the 8 where they got sued over inflated HP claims.

Claimed 280 but was closer to 250/260???

Id still like to have a twin turbo 7.

We have a shop, still in Cols that has specialized in Mazda rotaries from day 1.
Just passed it the other day and they had 20+ cars sitting in front.

BTW, re-read the first 14 pages of this thread last night!
13 yrs later, it still entrtains!

Sad part is Liquid Nirvanas absence.
I spoke w/him on the phone several times back in that era.
Sent him some OMC racing posters.

I remember he was devastated when the photo hosting service he was using,locked/erased all his, hundreds of photos and yrs of work.

I remember him telling me he was just doing it for the love of the brand.

Horse power being defined as "work over time " the rotary's long combustion pressure events seems to be it's big advantage. It also doesn't have the negative inertia problem of a reciprocating engine.

Quote:

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Originally Posted by Instigator

Yrs back, I tried to find a twin turbo RX-7, but failed.

Cant remember if it was that or the 8 where they got sued over inflated HP claims.

Claimed 280 but was closer to 250/260???

Id still like to have a twin turbo 7.

We have a shop, still in Cols that has specialized in Mazda rotaries from day 1.
Just passed it the other day and they had 20+ cars sitting in front.

BTW, re-read the first 14 pages of this thread last night!
13 yrs later, it still entrtains!

Sad part is Liquid Nirvanas absence.
I spoke w/him on the phone several times back in that era.
Sent him some OMC racing posters.

I remember he was devastated when the photo hosting service he was using,locked/erased all his, hundreds of photos and yrs of work.

I remember him telling me he was just doing it for the love of the brand.

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here ya go.
Used Mazda RX-7 Turbo for Sale: 7 Cars from $26,500 - iSeeCars.com

When I was looking at them, they were $10K cars!

I currently have a 600HP ‘2002 Trans Am and a 87hp MGB.

Some day I’ll own an RX-7, but not today.

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Originally Posted by Rotary John

here ya go.
Used Mazda RX-7 Turbo for Sale: 7 Cars from $26,500 - iSeeCars.com

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Quote:

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Originally Posted by Rotary John

... The rotary's weakness is its surface to volume ratio, resulting in significant flame quench, causing high hydro carbons and reduced fuel efficiency.

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Would redesigning the Rotor's surface change the flame quench problem.

Like a concave rotor (see my poor illustration attempt to draw on the computer).

Attachment 502597

Quote:

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Originally Posted by Lake X Kid

Would redesigning the Rotor's surface change the flame quench problem.

Like a concave rotor (see my poor illustration attempt to draw on the computer).



Attachment 502597

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We all know a curved line between 2 points is longer than a straight line. Your concept just increased surface area for flame quench. The out side shape of the rotor is a mathematical shape based on the mathematical shape of the trochoid. go back to my you tube model and watch the rotor go around.

NEW - Titanium Rotary Engine Key-chain Spinning Rotor Stimulates Motor |
On SALE

https://www.screamandfly.com/attachm...3&d=1650370390

Quote:

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Originally Posted by lars strom

NEW - Titanium Rotary Engine Key-chain Spinning Rotor Stimulates Motor |
On SALE

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I bought one too.

I think my formulaic parameter puts the 2 Cycle's performance greater, than the 4 Stroke engine.

However, I do not think my comparison formula made any difference in the Rotary engine comparison - to the other combustion engines performance.

Attachment 515370

How high can a rotarys compression ratio be?