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Thread: Rotary Engine in a BMW?

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    Administrator 20774's Avatar
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    Rotary Engine in a BMW?

    Doyle Rotary engine:

    http://www.youtube.com/watch?v=lJ1kxbtsBSU

    Now, discuss!
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    John. jstrube's Avatar
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    Seems like it would have huge frictrional losses via the rings.
    John.

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    Still Wondering mika's Avatar
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    Interesting. I am not an engineer nor do I play one on television.

    John, would the increase in friction from the rings be offset by decreased friction from other moving parts not included in the system such as valve trane?
    Pass the mustard and UP THE REVOLUTION!

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    Small road corner junkie pffog's Avatar
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    An answer to a question no one asked.
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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by pffog View Post
    An answer to a question no one asked.
    Au contraire. The basic 4 stroke cycle engine design is over 100 years old. Finding a way to produce power more economically (both in manufacture and in use) is a question that has been pursued for almost as long.

    I have no idea if this is a good video or a real breakthrough but I'll keep my eyes open for more information on this technology.
    Paul Glaves - "Big Bend", Texas U.S.A
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    Still Wondering mika's Avatar
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    Their website: http://doylerotary.com/index.php

    Popular Mechanics

    Google Search on Doyle Rotary Engine yielded some results.


    Perhaps it is better to think of it as an answer to a question we hadn't thought to ask since the wankle. Looking at the size and weight specs it has a lot of appeal. I had a RX7 some years ago and loved the thing. Many of the things were a direct result of the engine - how it delivered power, the size and weight of the power plant which allowed for the best balance / handling car I have had. Down side was a thirsty engine (in part because it begged to be driven hard) and pollution.
    Pass the mustard and UP THE REVOLUTION!

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  7. #7
    Registered User rickyd's Avatar
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    Cool post. What's old is new. A refinement of the old gnome rotary aircraft engines of the WW1 era.
    Rick

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by pffog View Post
    An answer to a question no one asked.
    I understated a few things in my earlier post. Here is what Popular Mechanics said:

    "The basic design of the four-stroke piston engine that powers all of our cars has been kicking around for about 150 years. And during that time there have been countless alternatives proposed. But apart from the occasional oddballÔÇölike the Wankel rotaryÔÇömodern engines, while certainly refined, still stick to the basic formula. Now with ever-increasing demand for greater efficiency, new and older alternative engine designs are attracting attention."
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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    Registered User der verge's Avatar
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    I am completely with the guy on youtube about 4 posts down. I am sick and tired of watching engine videos, excuse me, animations, of engines that DO NOT EXIST. If you have a genius idea, make a prototype, test it, then PROVE to me it is oh so great.

    There are definitely some unique and fresh ideas in the design, but I think much of it has not been thought through. Example: using one piston to compress the charge, then another for combustion and exhaust would make it easy to lead you to the idea of lower engine temperatures. But that is not true. A set quantity of fuel has a set amount of BTU in it, regardless of the engine type it is used in. Lower engine temperatures are more a function of engine cooling design than combustion design. Also, why use two cylinders and pistons to complete the four stroke process, when it can be done with one cylinder, and one piston? Machining and assembly costs.......

    I think this design would create a very smooth engine. More rotating mass for better balance, and to help suck up any unwanted vibrations. Throttle response would suck though. Instead of moving the pistons, rods, and crank, we now have to rotate the entire engine block. Higher rotating mass= less response, and MORE fuel will be used to have to rotate the engine. We now also need a large adapter to go from the block to the driven device, instead of straight to the crank.

    Wait!!!! How in the hell do you mount an engine that itself is always moving?????
    By the crankshaft. The same one we will be blocking on one end by the adapter piece that runs the pto for our transmission/flywheel/etc?

    I could keep going........yep, genius!
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    Registered User mneblett's Avatar
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    I see at least four significant concerns with this design:

    1. The single combustion chamber has to receive, ignite and transfer gases to an expansion cylinder 6 times with every revolution. This begs several questions:

    a. Is the engine substantially limited in useful rpm range? 6 combustion cycles every revolution allows only a very short time for:

    -- air to be transferred from a compression cylinder,

    -- fuel to be injected *and* distributed about the combustion chamber (doesn't have to be uniformly distributed, but will still require some not-ignorable time),

    -- recharging the coil (or other pulse generator) and initiating a spark (even assuming the spark would be timed to be delivered just prior to the compression cylinder port closing, further constraining the fuel injection/distribution time),

    -- generate sufficient fuel burn before the next expansion cylinder reaches the exhaust port, and

    -- transfer the combustion gases to the expansion cylinder before (or overlapping) the next intake port opening.

    At 60 degree cylinder separation (as opposed to the 720 degrees enjoyed by an individual cylinder in a conventional engine), I'm hard pressed to believe this engine could spin at a usefully-high rpm before one or more of the above elements becomes flow and/or combustion rate limiting.

    b. Cooling -- I didn't see (maybe I missed) any provision for cooling of:

    (i) the combustion chamber region in the core of the stationary crankshaft, and it appears that providing adequate cooling in such a constrained environment would be quite a challenge (the cooling passages can only enter/leave through the ends of the crankshaft). Without some means of cooling, that single combustion chamber firing off several times each revolution would erode/meltdown/destroy that region in short order;

    (ii) the expansion cylinders or the internal volume of the engine case to which the expansion cylinders (and to a lesser extent, the compression cylinders) will be rejecting heat.

    c. Efficiency -- Quite a bit of energy can be expected to be lost from the initial combustion in the fixed-single combustion chamber and the (likely mach-limited) flow of hot gases into the expansion cylinder (setting aside transfer port wall erosion concerns for the moment). I don't see how the amount of mechanical energy/work produced from each expansion cylinder could begin to come close to the corresponding conventional cylinder's conversion of the fuel chemical energy -- in other words, lower efficiency at producing torque per pound of fuel consumed.

    2. While the masses of the components may be uniformly distributed and/or counterbalancing (something of which I'm not convinced, as this is an eccentric engine), the fact remains that power production is always at the same place and same side of the engine -- roughly in the region 60-90 degrees after the combustion gas transfer port. A constant pounding from one direction is not a great idea for either smooth running or long bearing life.

    3. I don't begin to believe the mass estimates (65 lb for a 2.3L Doyle vs. 250 lb for a 2.3L 4-banger).

    Long ago and far, far away, I worked with the Navy's nuclear power design office. Every year, someone would come along with a "new and better" submarine propulsion plant design which would make the Navy's plants look like the Hindenburg in a race against an SR-71, and try to get Congress to fund the design. The number one, most consistent problem with these "better" designs was the amazing amount of necessary supporting equipment -- and much more importantly -- shielding material required for protection of the crew that would be left out. In other words, great designs for about thirty seconds of use (if that long).

    In the case of the Doyle engine, I see no cooling, no oil pump, etc. I also don't see how 2.3L spread across 6 cylinders and pistons could possible be significantly lighter than 2.3L spread across 4 cylinders and pistons -- particularly where (i) the 4-cylinder's cylinders are integrated into a common block, and (ii) there's an entire bank of *additional* compression cylinders which *doubles* the total cylinder weight.

    4. I also don't believe the emissions reduction claims. Modern 4's burn very cleanly; I can't see how they could match a 4's emissions performance. First, I strongly doubt they could maintain the combusion temperature in the single combustion chamber as low as they state without a *lot* of cooling in that region or substantially "retarded" (and power-robbing) timing. And while they say they can use "off the shelf" 2011 RX-8 sliding seals, they don't say how they would cure the problem of inherently higher emissions of even the latest rotary seals.

    I suppose that's enough for now -- this horse is dead enough.
    Last edited by mneblett; 11-27-2012 at 08:53 PM.
    Mark Neblett
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  11. #11
    Registered User lkchris's Avatar
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    Quote Originally Posted by PGlaves View Post
    Now with ever-increasing demand for greater efficiency, new and older alternative engine designs are attracting attention."
    And in addition lots of new ideas for the "traditional" engine configurations are coming online as well.

    Direct injection
    Turbocharging everything

    My diesel has piezoelectric fuel injectors that squirt 5 times per power cycle, the system developing ~25,000 psi.

    I've got variable pitch blades in the turbo ... like your propeller airplane.

    The old standby variable length intake manifold runners.

    This engine makes more than 1 hp per cubic inch, which not so long ago was a seldom-reached goal for a gas engine let alone a diesel.

    "Valvetronic" is an old standby now, too, helping to reduce efficiency losses caused by throttle plates on gasoline engines. BMW a leader with this.

    The S1000RR engine at 190+ hp is making over 3 hp per cubic inch and doesn't really have that much in the way of electronic goodies. That would be 1050 hp out of yer 350 chebbie.

    There's really not much out there to suggest that any new basic designs are coming soon but there sure are more opportunities in working with the design that's prevailed all this time.
    Kent Christensen
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  12. #12
    Caribbean Druid
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    Suzuki produced and sold the rotary-engined RE-5 bike in 1975-1976. Heavy, complex and it produced a lot of engine heat. It never sold well and was discontinued after two years.

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    On the other hand, the Norton rotary won the 1992 Senior TT at the Isle of Man.
    Karl
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  14. #14
    Small road corner junkie pffog's Avatar
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    Quote Originally Posted by dwestly View Post
    Suzuki produced and sold the rotary-engined RE-5 bike in 1975-1976. Heavy, complex and it produced a lot of engine heat. It never sold well and was discontinued after two years.
    You forgot weird looking. I own one of each year.
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  15. #15
    Registered User lkchris's Avatar
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    Of course neither the Suzuki nor the Norton were the same version of "rotary" as this latest adventure.

    In the old days it was quite possible and maybe even fairly common for a "machinist" to come up with viable new concepts--see Henry Ford--but these days there is just so much knowledge to be gained in engineering schools and, I think, an equal amount of "desire" there that it seems less likely to happen. The guy with this new radial is an admirable exception, then, but I'd still suspect he's got lots to learn.
    Kent Christensen
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