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Yes I have heard of it before. The engine company has been making rotaries for many years; primarily drone engines. I suspect the bike will be a flash in the pan (cost) and if it dominates will be banned. I seem to recall a similar situation.Quote:
Originally Posted by Instigator
If I remember the 3.5 L V-8 weighed around 235# and produced 450HP. The rotary powerhead was just over 2 L, weighed around 130 # and produced around 300 HP. Knowing what I know today and with todays materials, I believe the same rotary could produce 450 HP weighing less than 100#. Problem is no one today is interested in boat racing to invest the monies required.Quote:
Originally Posted by powerabout
The designer ran Norton Motorcycles successful, multi race winning rotary bike program.
Norton went belly up and new owners finished driving them in the dirt.
One of my classic bike mags had a great, in-depth, multi page story on the new bike/motor.
It is cooled through the crank and he made the rotors wider instead of larger diameter like Mazda did.
He thought that was a mistake on their part.
He is getting 220 hp+ from 700 CC’s.
Agreed on seeing how deep new owners pockets are.
Quote:
Originally Posted by Rotary John
Mazda made the rotors narrower because of emissions. With a W/E ratio of around 4; (rotor width/eccentric value) is the most efficient to reduce the surface to volume ratio; ie. Hydrocarbon emissions. In addition, Mazda used side ports and the intake area in not dependent on rotor width. Thus a narrower rotor gave proportionately more intake are per displacement.
Norton uses a peripheral port directly into the rotor hsg. and making them wider allows a larger intake port (more intake area) w/o changing port timing. They weren't worried about emissions on a race bike.
Would dfi on a rotary make a big improvement in emissions to try to get the fuel away from all that surface area?Quote:
Originally Posted by Rotary John
Direct injection has been tried and helps some on the intake side, but you still have the fuel quench problem on the combustion side. At some point, alternatives to the rotary due to the cost to achieve emission results are more economical. I believe the future of the rotary is as a range extender in electric vehicles, size, weight, lack of vibration. The engine could be optimized to run at a specific RPM driving a generator or specialized uses where power to weight/size are critical.
John, as always, thank you for the education on this subject.
so what we need is a ceramic rotor so it becomes an adiabatic engine, no heat loss?Quote:
Originally Posted by Rotary John
:iagree:Quote:
Originally Posted by Mark75H
How do you quantify cubic-inches/liters for a Rotary engine?Quote:
Originally Posted by Rotary John
A) One rotor has 3 combustion surfaces/heads. Therefore, (per each rotor) 3 x combustion chamber area = cubic-inches/liters.
B) One rotor/combustion chamber. Therefore, each rotor is only designated as only having 1 combustion head. 1 x combustion chamber area = cubic-inches/liters.
I am wrong to think the rotor engine should be classified as example A. Giving the rotor engine & the conventional combustion piston engine equal footing in engine size comparison.
Example B, seems to me, to give the rotary engine an unfair advantage in racing classification against piston engines.
https://external-content.duckduckgo....jpg&f=1&nofb=1
https://external-content.duckduckgo....png&f=1&nofb=1
Agreed.
I followed IMSA car road racing in the ‘80’s and Mazda ruled GTU which is Grand Touring Under 3.0 liters.
Many competitors complained that Mazda was given an unfair, +50% displacement capacity due to the unfair way a rotary was classified.
Love the motors and tech but please…..
Quote:
Originally Posted by Lake X Kid
At the time of the rotary race engine, they were competing against 2 strokes. A 2 stroke engine has one power pulse per crankshaft revolution; so does a rotary. A 2 stroke completes all phases, intake, compression, power and exhaust for each revolution of the crankshaft; so does a rotary. Thus if compared to a 2 stroke the displace should be measured for 1 revolution of the crank. It's the 4 stroke that's the oddball. It takes 2 complete revolution of the crank to complete all 4 phases. I don't recall anyone ever saying a 2 stroke should be measured for 2 crank revolutions as a 4 stroke. A 4 stroke displacement has always been measured displaced volume per crank revolution, same as a 2 stroke and a rotary. The argument only comes up when the rotary dominates. Kinda like Andy Granitily's turbine. Kinda like when the big boys banned the 2 stroke in thunder boat racing. The establishment hates being beat. Enough for tonight, I'm going to the shower and bed.
I count 3 ignition events per crank revolution. One for each rotor face. Thus the total swept volume of all 3 faces equals displacement. Seems like basic trig to me?
You don't count too well. The rotor turns at 1/3 the speed of the crank. There is ONLY ONE spark plug fire for each rotation of the crank.Quote:
Originally Posted by 2us70
Wankel animation - YouTube
Remind me not to ask you to balance my cheque book.Quote:
Originally Posted by 2us70
Next thing John somebody will mention the usual.
Ha, looks like you beat me to the punch. I'm getting slow.
That clarifies a lot, thanks RJ.Quote:
Originally Posted by Rotary John
The real difference in the rotary is each of the 4 cycles consumes approx 270 degrees of crank rotation. A 2 stroke by contrast consumes approx. 90 degrees for each cycle and a 4 stroke approx 180 degrees. ( forget about overlap and exact port timing). This is the reason the rotary has such high power density. Displace ment is measured max volume - min. volume x the number of cylinders or rotors. I you want equality give a fixed amount of fuel and run what you brung. Audi did that with their turbo diesels.
James: I'm surprised Jackie hasn't jumped in and claim it should be 8 times because he raced a V-8 four stroke.Quote:
Originally Posted by techteam
Not that I matter in this equation but…, I still don’t get it John.
4 stroke to two, I do.
Rotary to everything else, I still don’t.
One crankshaft revolution what do we have correct?
One crankshaft revolution: One spark plug fire, one power stroke. one intake, one compression, one exhaust; just like a 2 stroke. The difference is these events happed simultaneously in a rotary, while they happen sequentially in a 2 stroke. You have to also remember the rotary is a 4 cycle. It has a positive exhaust cycle where a 2 stroke exhaust is dependent on blow down and the incoming fresh charge to force the spent charge out the exhaust port. Same is true for the rotary intake, compression and power cycles.Quote:
Originally Posted by Instigator
I think were the punters get confused is which part is counted as a revolution?
See above for crank as explained by John.
So the crankshaft in overdriven 3 to 1 from the rotor? Does this have an effect on torque at the crankshaft output end? Also what are the revs seen by both the rotor and crank in operation? My only experience with a rotary was driving my brother-inlaw's Mazda RX-3 many years ago.
You have said it correctly but should read the rotor turns at 1/3 crank RPM. The torque on the crank is determined by the eccentric of the shaft and the combustion pressure on the rotor and is independent of the rotor RPM. However, because the shaft has to turn approx. 270 Degrees before the exhaust port opens, the force on the eccentric lasts longer than a piston engine. Hope this makes sense.
The OMC race engine ran between 7000/8000 RPM crankshaft meaning the rotor turned 1/3 of that; 2333/2667 RPM. Before someone asks again, the final version of the race engine produced between 265/280 prop shaft HP at those RPM's. (1974)
The rotor engine’s rotational components seem to be more conducive to generating crankshaft rotation, then the action of converting piston’s linear motion into crankshaft rotation. High RPMs would seem not to be a major obstacle (in spite of an eccentric non-circular rotor motion, and the rotor’s larger circumference turning the smaller diameter crankshaft should supply ample torque.
However, being the rotor engine has a more favorable geometry of internal moving parts, why does it not dominate the boat & car market? Is the rotor engine’s weak link(s) due to … cooling issues, seal problems, combustion efficiency – in comparison to piston engines, or …?
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.
Quote:
Originally Posted by Rotary John
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.
here ya go.Quote:
Originally Posted by Instigator
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.
Quote:
Originally Posted by Rotary John
Quote:
Originally Posted by Rotary John
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
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.Quote:
Originally Posted by Lake X Kid
NEW - Titanium Rotary Engine Key-chain Spinning Rotor Stimulates Motor |
On SALE
https://www.screamandfly.com/attachm...3&d=1650370390
Quote:
Originally Posted by lars strom
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?