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

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Originally Posted by whipper

Theres a guy who has finally figured out all the flaws with these rotorys and has been experimenting with the combustion flaws and spark. It looks like there going to give it another go. This time looks promising that the stroke can have a much better compression and combustion making them way more efficient. Ernie Brink http://www.youtube.com/watch?v=m3pCLjHZmhM

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As with most shade tree mechanics, this one doesn't have a clue what he's talking about. The leading spark plug hole is positioned where the pressures are equal on either side of the apex seal. and if it has a trailing plug, it has a shooting hole which is smaller than the apex seal. In fact the original Wankel didn't have any spark plug holes as the plug was in the rotor face. The leading pocket has been used for years, but his contention that it aids rotation is crap. Combustion pressure acting thru the center against the eccentric is what gives it torque. It would be like saying an offset combustion chamber on a piston engine would give more power because it puts combustion pressure on the good side of the crank throw.

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Originally Posted by jackiewilson

Tell me again how you measure the ROTORY Johnno , if I remember rightly this was always a bone of contention, I also loved to buck the establishment, and the best feeling in the world was to Stuff it to the factories.

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Its measured just like the 2-strokes; displaced volume per crank revolution.

I thought 2 strokes were measured piston displaced volume times number of cylinders/pistons?

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Originally Posted by Mark75H

I thought 2 strokes were measured piston displaced volume times number of cylinders/pistons?

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And just what is displaced volume????

Where exactly in the rotation cycle are the starting and end points for measuring the individual chamber displacement and compression ratios?

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Originally Posted by 2us70

Where exactly in the rotation cycle are the starting and end points for measuring the individual chamber displacement and compression ratios?

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Min vol is at TDC; max vol happens when the crank is at 90 degrees; dis placed vol = max - min

And that happens 3 times per revolution per rotor right? So each rotor equals a 3 cyl motor? A 4 rotor is like running a 12 cylinder 2 stroke.

So Johnno, the question still remains,how do you measure the capacity or can you even measure it to compare to any other motor. Me, I'm a simple minded chap with only a basic maths understanding but a modicum of common sense, I can add and subtract (still) and even I can see with the minimum amount of movement the Wankel SHOULD BE A WINNER but a hundred years on nobody has taken up the cudgel and produced a cost effective " profitable " piece of propulsion , whilst Every other form of motor from two stroke to jet and all points between continue to develop.
like I said before Johnno-----THE DAMN THING IS FATALLY FLAWED. FIND THE FLAW YOU HAVE A WINNER.

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Originally Posted by jackiewilson

So Johnno, the question still remains,how do you measure the capacity or can you even measure it to compare to any other motor. Me, I'm a simple minded chap with only a basic maths understanding but a modicum of common sense, I can add and subtract (still) and even I can see with the minimum amount of movement the Wankel SHOULD BE A WINNER but a hundred years on nobody has taken up the cudgel and produced a cost effective " profitable " piece of propulsion , whilst Every other form of motor from two stroke to jet and all points between continue to develop.
like I said before Johnno-----THE DAMN THING IS FATALLY FLAWED. FIND THE FLAW YOU HAVE A WINNER.

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didnt Mazda spend a bit and clean up in LeMans once?

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Originally Posted by 2us70

And that happens 3 times per revolution per rotor right? So each rotor equals a 3 cyl motor? A 4 rotor is like running a 12 cylinder 2 stroke.

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NO! It only happens once per revolution. That's the point. It displaces its "displaced volume " ONCE per revolution on the crank. Search Wankel if you need to see how one works.

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Originally Posted by powerabout

didnt Mazda spend a bit and clean up in LeMans once?

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Yes> They ran a 4-rotor engine and won Lemans. They were so dominant, they were banned. Boy does that sound familiar.http://ts1.mm.bing.net/th?id=HN.6080...=10_30&pid=1.7

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Originally Posted by jackiewilson

So Johnno, the question still remains,how do you measure the capacity or can you even measure it to compare to any other motor. Me, I'm a simple minded chap with only a basic maths understanding but a modicum of common sense, I can add and subtract (still) and even I can see with the minimum amount of movement the Wankel SHOULD BE A WINNER but a hundred years on nobody has taken up the cudgel and produced a cost effective " profitable " piece of propulsion , whilst Every other form of motor from two stroke to jet and all points between continue to develop.
like I said before Johnno-----THE DAMN THING IS FATALLY FLAWED. FIND THE FLAW YOU HAVE A WINNER.

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Oh Jackie: I guess I'll never teach you. You can't "measure" a rotary engine displacement without knowing some basic geometry. Then its simple to calculate. Displacement arguments also come about because a 4-stroke engine requires 2 complete revolutions of the crank to complete 1 cycle. A 2-stroke or Wankel completes its cycle with one revolution of the crank. Only recently has there been any discussion on how to compare 2-stroke and 4- stroke displacement. Its always been bore area x stroke; regardless of how many times the crank goes around. It gets down to politics and taxes on how you rate displacement. You are correct on one inherent flaw and that is large surface to volume ration. This leads to surface quenching of the charge and HC emissions. However, the opposite is true of NOx. The slow flame propagation results in inherently lower NOx emissions. Now with that said, When was the last time you saw emission testing required on race engines? As I said politics and taxes.

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Originally Posted by Rotary John

Min vol is at TDC; max vol happens when the crank is at 90 degrees; dis placed vol = max - min

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This where my common sense thinking says to me---if max volume is at 90degrees, What happens in the other 270degrees----doesn't that count?
Displaced volume= max- min, why would you bother to include. - min, is minimum still counted, ' cos if it's not, why bother to put it there anyway, unless it's to blind me with science.
just my simple mind trying to understand what I should not be anywhere near in the first place.

Any way you slice it a four rotor rotary produces 12 power pulses per revolution right? A 4 cyl two stroke produces 4 power pulses per rev and a four stroke makes only 2. This would appear to account for the power advantage of the rotary and also its fuel economy disadvantage.

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Originally Posted by 2us70

Any way you slice it a four rotor rotary produces 12 power pulses per revolution right? A 4 cyl two stroke produces 4 power pulses per rev and a four stroke makes only 2. This would appear to account for the power advantage of the rotary and also its fuel economy disadvantage.

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you cant have it both ways bsfc is how you measure it
4 stroke outboard heavier less torque and why would you buy one? How come a v6 DI 2 stroke firing twice as often competes with one?