Rotary In 914, would It Work Options

[zeekman914]

Daryl Drummond of Drummund Enterprises; I had to dig the card out. I have heard he does a lot of Formula Mazda stuff. You are right, he does a lot of turbo engines and the supercharged isn't one of his, but is helping the guy out. I don't know if I would say the supercharger is a step back, as there are benefits to the supercharger, too; it wouldn't be my choice, but it does make instant power. We plan on going by Daryl's shop next week; we have to soon, as he is moving North to a new shop. Once the electrical and dyno cell are operational, I heard he's outta here. (IMG:style_emoticons/default/sad.gif)

[Mueller]

supercharger is perfect for a rotary...the compression sucks big time in a wankle, the supercharger will help that right off the bat.....a perfect system would be supercharger at low rpm with a turbo for high rpms (IMG:style_emoticons/default/smile.gif)

[zeekman914]

that would just make it too complicated for me! although it probably would work!

[airsix]

that would just make it too complicated for me! although it probably would work!

Yeah, but complicated is a relative thing. Road and Track a few years back did a piece on a big pumper truck that has (no I'm not kidding) a

Twin turbo
Supercharged
2-stroke
overhead valve (yes, ohv 2-stroke) (IMG:style_emoticons/default/blink.gif)
diesel

-Ben M.

[redshift]

this is why a lot of times the /4 cars dominate the auto-x courses (IMG:style_emoticons/default/smile.gif)

I can't imagine anyone driving these things much different than me... all kinds of things can kick a 914s ass.. but in certain situations..

If you are finding the upper revs often, you are moving. I just use 1st to get into the middle of second.

Wuudddnn! Wuuuuuuuuuuuuud! Wuuuuuuuuuuuuuuuuuuuuud! <-- 914 sound, yo.



M

[Bleyseng]

Love driving a turbo2 Mazda, its more like WwuuuuuuuuUUUUUUU(9000rpms)shift, wwwWWUUUUUUUUUUUU(holyshit)shift.......hehehe
would be wicked in a 914.

[zeekman914]

There is no such thing as a 2-stroke having valves, it uses a completly differnt system for fuel dilivery and exaust. It uses ports -like the rotary- to run and the valves would have to be really light weight becuase the 2-stroke engine does 2 operation in one stroke (up and down) when the 4-stroke does 1 operation for every stroke. And from what i hear Madzatrix ain't that special either. This Daryl does racing rotarys. Gets flown all over the US to help diagnois racing rotorys. And gets payed big bucks to do it.

[WaltGGB]

There is no such thing as a 2-stroke having valves, it uses a completly differnt system for fuel dilivery and exaust.

2 Stroke Detroit Diesels, which have been around for years. Have normal type OHV on exhaust side only. Intake ports are down in cylinder wall.

Walt

[soloracer]

supercharger is perfect for a rotary...the compression sucks big time in a wankle, the supercharger will help that right off the bat.....a perfect system would be supercharger at low rpm with a turbo for high rpms (IMG:style_emoticons/default/smile.gif)

I agree that the supercharger/turbo combination (which has been done) for a rotary would be an attractive package. Pretty complex to set up though.

[lapuwali]

There is no such thing as a 2-stroke having valves, it uses a completly differnt system for fuel dilivery and exaust. It uses ports -like the rotary- to run and the valves would have to be really light weight becuase the 2-stroke engine does 2 operation in one stroke (up and down) when the 4-stroke does 1 operation for every stroke.

Not at all true.

If you ran the camshaft(s) at crank speed instead of 1/2 crank speed and changed the ignition system to suit, you'd have an engine that had a power stroke on every down stroke. You'd have serious problems with getting enough mixture into the cylinder w/o all of it going out the exhaust (Toyota and Chrysler used a positive displacement blower in their engines to make up for this).

The fact that the common two-stroke design is to use in-wall ports and run the intake into the crankcase hardly means that's the ONLY way to do it.

Also, nearly every two-stroke engine made now for non-industrial purposes has reed-valves on the intake. Many also have a valve on the exhaust to change port timing. These devices have been used for 30 years or more, now, and no one refers to the engines as anything but two-strokes. Disc valves were also used in place of reeds for awhile. These were shutters in the intake stream timed to only allow induction into the crankcase in a particular time window. They were a bit for flexible in their timing adjustments, and certainly less restrictive than reeds, but both do the same thing conceptually. Both are certainly valves.

Very few poppet valve'd spark-ignition two-strokes have made it past the research stage, since they have all the complexity of four-strokes and many of the emissions problems of two-strokes. However, quite a few poppet valve'd two-stroke DIESELS (which the original quote was referring to) have made it into produciton, since a diesel inducts only air, and the fuel is injected directly into the cylinder under very high pressure after the exhaust valve has closed, just before the piston reaches TDC, thus solving many of the emissions concerns. Many of these engines are turbocharged for more volumetric efficiency, and forced induction very difficult to do with conventional piston-port or reed-valved two-strokes.

[reverie]

Regarding the original question, people have put 12A and 13B rotary engines in Volkswagens with good results. The ones in VWs are not turbo'd or supercharged, because running a carb and high-flow exhaust gives plenty of hp and the acceleration is fantastic, the Type I VW transmission (reinforced) will be at its limit, and there's already lots of heat (that cooling issue again) to deal with. Also, the aftermarket-turbo and supercharged rotaries seem to require a lot of initial adjustments and tuning, and that's no fun when the car is needed as a daily driver. I would suggest starting with a reliable carb'd setup and see how happy you are with that, before deciding to use forced induction.

[lapuwali]

One reason carbs are favored is the OEM injection setups on most of the RX-7s were evil. Very complex pneumatic systems with a zillion vacuum hoses and electric solenoid valves. They frequently don't work in the RX-7, let alone in an engine swap. Aftermarket EFI can do a great job, but they're a lot more expensive than a single Weber and manifold. You'd have a hard time even getting Megasquirt to be as cheap as a carb setup on these engines.

The big downside to rotaries is that rebuilding one yourself is almost entirely out of the question, and there are only a couple of shops in the country that can do a proper rebuild on one.

I knew a guy in STL with a tube-framed AX car with a Spridget fiberglass body on it, powered by a supercharged 13B. Rumored to make about 400hp.

[airsix]

There is no such thing as a 2-stroke having valves

That's what I used to think too. Then I learned that was one more to add to the list of things I've been wrong about. (IMG:style_emoticons/default/wink.gif)

-Ben M.

[soloracer]

<snip>
The big downside to rotaries is that rebuilding one yourself is almost entirely out of the question, and there are only a couple of shops in the country that can do a proper rebuild on one.

I knew a guy in STL with a tube-framed AX car with a Spridget fiberglass body on it, powered by a supercharged 13B. Rumored to make about 400hp.

Not true at all. Rebuilding a rotary engine is actually less complicated than a piston engine. Once you know what you are doing that is. If your rotors are assembled with their seals you can button up the keg of a rotary engine in less than an hour. Try that with a piston engine. I have friends who rebuild them all the time in their garage and this was a major consideration in what engine to put in my 914. For about $1000 in parts I can have my 3 rotor back on the road if she blows.

[lapuwali]

Not true at all. Rebuilding a rotary engine is actually less complicated than a piston engine.

I was under the impression that a very common problem was the endplates were no longer flat, and fixing that required machine work that wasn't likely to be handled by the corner machinists. If it's just a case of replacing the apex seals, that's certainly easy. Perhaps I was just drinking too much of Mazdatrix' kool-aid...

[reverie]

Just to clarify my earlier post, it's my impression that "engine heat" per se is not a problem with normally-aspirated rotary engines.. the problem is the exhaust heat, and the need to route the exhaust system well away from lines containing fuel or other flammables, and also well away from painted body panels and such. And doing that while constructing an exhaust system that meets street-legal decibel levels.

I'm not sure whether "engine heat" is a problem with turbo'd rotaries, but I know a gal with a supercharged carb'd 12A RX-7 (Code Blue 2 on rx7club.com, she's very fast) and she hasn't reported any heat-related problems in the 2 months she's had that setup.
But that might be too much power for a reinforced VW Type I trans.. (IMG:style_emoticons/default/burnout.gif)

[zeekman914]

OK maybe i will, exept the fact that I am wrong partly, maybe, kinda. I asked my dad about the detroit diesels and he said that the engine used a blower to force the exuast out. The valves were just to stop and start the process. anyway I think that eventually I will try to put a rotary in the 914. I found this old water cooled flat four that I will clean up and hopefully trade for a 13B at John's wreckers. If he doesn't want to trade i will throw in some torque converters and transmissions from my auto shop that we will never use. (IMG:style_emoticons/default/crest.gif)