Sponge Bob Square Pants

Hear hear!

geargrabber

the eccentric snaps at higher rpm due to the rotors trying to break it, right???---its not from just the eccentric shafts own inertia is it??....

it is a pipe dream, but im gonna try damnit =)

Kenku

Actually, there's a rules change; the engines have to last the whole weekend. Testing, practice, qualifying, and the race. Needless to say, there's a few bugs that some people have to work out. Still, they're still going up to 18k-ish.



So actually, here's a funny thought I had on how to make a stupidly high-RPM rotary. Reliability levels would be... ah, well, plan on rebuilding after every race weekend. Or maybe more often.

The big trick is that there'd be very very few parts that are as sold by Mazda.

Eccentric shaft flex is an issue. Well, have a multi-part eccentric shaft. Not only that, but a stationary gear on either side of the rotor... so for a two-rotor, we're talking 4 stationary gears. Also have the stationary and ring gears custom milled from... well, I'll just say "some exotic alloy" because that's simplest. Each rotor has oil fed to it independently of the other; dry sump of course. And since this is going to be rebuilt really often anyway, needle bearings used not only on the stationary gear bearings but on the rotor bearings.

Rotors are obviously going to have to be modified to have needle bearings and a second ring gear; starting from Renesis ones or something. See how much more material can come out at the same time, or maybe just make new ones from scratch. Making them from scratch might just be a better idea. Seals would be custom; 1-1.5mm, one piece (for reasons I'm getting to) and either carbon or ceramic. Longevity is a non-issue, so going this small can probably be gotten away with. They might have to be taller though... again for reasons I'm getting into.

Now... ports. There's a finite limit to how much port area you can get out of a peripheral port without forcing yourself to have inefficient port timing. This applies to intake and exhaust both, obviously. So you don't rely on peripheral ports alone. You combine the largest peripheral ports you can (say, to pull numbers out of thin air, leaving 5mm of rotor housing for the seals to ride on at the edge) with a "street" port on both the intake and exhaust side, like the Renesis exhaust. These ports leave *just* enough side housing for the seals to ride on; there's no limitations due to hitting water jackets, as the water jacket location is figured out after the ports are designed. Like I said before the seals might have to be taller... this is so they don't bend lengthwise and get chewed up by the peripheral ports.

There's a few other details that I'm not bothering with, or that would come up in testing. This is just the more "revolutionary" stuff.

So what's all that get us? I honestly have no ******* clue how far that would spin, or what kind of power you could make. I don't think that it would be possible to spin it fast enough to start it at all with any normal starter... blocking off all but one side exhaust and intake port per rotor might do it, but I could see it needing something like a jet aircraft auxillary power unit to get it going (okay, that's also a funny mental image) It would *COST*... uh... well, lots. Anyone want to speculate how much it would cost to get... oh, just look at one part... a fully developed ceramic apex seal of vastly different dimensions than normal? And the fact that it would need to be rebuilt constantly is another factor.

But, hey, it's just an idea I had. Anyone want to fund it?

geargrabber

how about you start a machine shop and do all the work yourself? I am.

My first machine is going to be a fadel 20x40 vmc. So with that and some tooling im going to fug around with making performance parts for the rotory.

billet titanium rotors
custom pp sleves for max port area

custom intake manifold, so the pp would have low-mid and high end power.

Sponge Bob Square Pants

A custom intake manifold (assuming you mean with variable length intake runners) does not make a HUGE difference, but it does help. It would just allow the engine to have "decent" low end power, but it would also limit the high end, but don't get me wrong that would still be amazing.

neit_jnf

iTrader: (17)

I read that stock Renesis were tested up to 17k rpm without issues. Also there are some tuners in Australia using Renesis E-shaft, rotors and fixed gears in regular 13B housings and reving them to 13,000 with no other mods except some porting and getting great results

drago86

Whered you read that? got any links, or the name of the publication?

daveo

Mazda once did a display tes for the 13B, a stock moor was ran at full throtte, with no load, at 25,000 rpm (think of the stationary gear stress), the idea was to start it, stand back, and run it till it blows up.

The engine ran for 4 days and 4 nights, the project manager cancelled the project as it was consuming 2 much fuel...

Dont get me wrong, running an engine with a load is of course an entirely different game, but if it can rev that high (without an apex seal going through the side, or the eshaft going to bits), surely race engines could be built to go 20k rpm, even if they only last a race or 2.

Also my dad had a sock RX4, 12 a, went to 13000 RPMS easily when he was drag-racing his brother in law, who had a 327 powered v8 monaro.. guess who won..

the point is that 12A was still going 2 years later as a daily driver, and only broke down once when the fuel filter clogged...

geargrabber

holy crap, 25,000 rpm?? i love it.

good info!

spongey: not variable length, just more manifold being opened up... say three runners per pp. only one would open for low, two for mid and all three for high end power... get it?

Sponge Bob Square Pants

I understand, very interesting.
I haven't heard of it implemented before on a rotary, have you?

geargrabber

nope never seen an intake setup like that before anywhere... have you? actually it has been implemented .. the rotating sleeves on the normally aspritated 2nd gens... mine is going to have butterfly valves actuated by solenoids, slamming them open and closed at different engine speed for max VE.

Kenku

Well, aside from the bridgeport mill that we got in the fall... Still working on getting that wired up though; we don't have 3-phase power.

Why don't I do all the work myself? Because I won't be able to make as good of seals as Ianetti unless I specialize in it and ditch the idea of making motors. Or I won't be able to make as good of stationary gears as a machine shop that does gears could unless I spend enough time specializing in it that I can't make motors.

As for your idea of narrowing port volume... the plumbing and fabrication on that gets tricky really fast. Toyota did do that idea with their TVIS setup, but it didn't work all that well.

The 2nd gens don't just change the port area, but also the timing. Don't forget about timing because it's a lot bigger factor than area.

Personally, I'm just building a peripheral port motor and living with the powerband not working at low RPM. And by low, I do mean low... look up data on peripheral port engines and see what the VE numbers are looking like across the whole band.

daveo

A true racind engine would not follow the designs of mazda, but would be a true wrankel design, where the rotorts spin at the same speed as the eshaft... true rotart motion it was called

does anyone have any links to the designs for this?

I read somewhere that this design was concidered unusble for road cars, as to change the spark plugs u had to take apart the engine.. but for a true race engine who cares...

daveo

A true racind engine would not follow the designs of mazda, but would be a true wrankel design, where the rotorts spin at the same speed as the eshaft... true rotart motion it was called

does anyone have any links to the designs for this?

I read somewhere that this design was concidered unusble for road cars, as to change the spark plugs u had to take apart the engine.. but for a true race engine who cares...

geargrabber

is that bridgeport mill a 2 1/2 axis cnc retrofit??? or just a handle turning mill?

(i've run both... once you go cnc, you wont look back to manual mills for production, except for maybe simple second operation)

what did you pay for it?? you can pick up a small 3 axis cnc mill for about 5 grand at auctions.

port timing is important, i forgot about that...so you're saying even the smallest pp couldn't possibly have good usable low end compareable to the n/a's??

projekt

might wanna learn to spell rotary before you make all these trick parts

and i love all the misinformation being thrown about by 'my father's friend has a 50K rpm rotary'

geargrabber

projekt, about spelling, i see where i mispelled rotary, sorry i was in the moment and didn't check my spelling.

and oh yeah, stop exaggerating and elaborate a bit more.


.

Kenku

The bridgeport is hand-turned, yeah... nothing too fancy. We got it from a guy who runs a company in Michigan and had just finished converting over to all CNC stuff; we sold him all our MGA parts. The mill was $500; needs a little work and we need tools, but at *THAT* price.

Getting it home was a bitch and a half though... and no forklift at home to get it off the trailer. Heh heh...


As for the pp timing, that's not what I'm saying at all! I'm just saying that valving a peripheral port so that you can close parts of it for better low-end volumetric efficiency isn't simple. If you were trying to do something like that, a combination peripheral and side intake port might be best. The problem with peripheral ports isn't really even VE at low RPM, it's how they behave at part throttle / low load. So again, valved combination of side and peripheral have benefits.

Oh, I see what you're referring to; my comment at the end. Well, I *could* make a peripheral port motor that would work best at lowish RPM... but I don't really *want* to. I like the powerband of some of the MFR ports.

geargrabber

ooooh ic, i have a cool pp design that is going to rock! ........low, mid, and high end power.

ill ad you to my buddy list and show you some pics when i get them done... you gonna love it!

SPiN Racing

Hiya all,

Hate to say it Kenku but its been done and If I remember correctly talked about maybe on the old version of the forum.. but if not I am fairly sure Evil Aviator or myself may have posted about it in the past..
A Certain engine builder/Race car designer in St. Pete Florida.. (PM if you REALLY wanna know.. I just dont want them bugged) Has or HAD a engine that was in his hill climb car.. 4WD, 4WS based on a 13B.

The engine is based on a 1974 13B's Steel housings.. (IE:Largest 4-ports) with perif Rotor housings. The Primaries were healthy street ported.. the Secondaries are large Bridge.. and then there are the Perif housings.

THe intake was a tubular design that ran up to a progressive linkage 6 Barrel manifold for the custom Bosch fuel injection. The linkage was set up so that all the barrels were closed.. and the primaries open first.. then secondaries.. then terciaries(sp).. The 3rd set of barrels went to the PP housings..

The engine had the requisite high rpm treatment..

Locked Hardened rotor gears
C-Clip Bearings
Clearanced eccentric shaft
Dry Sump/modified high flow stock oil pump.. (Above I believe he said 9K the oil system goes into bypass even with the comp regulator and shim.. so he ran the oil pump off a shaft to a external pulley he changed till he got 110PSI at 14K rpm.. plus he did the dry sump.. and all the oil re-routing to make it oil correctly.
Oil Jets in the Apex groves (carb jets into milled holes below springs etc to allow metered oil to cool apex seals and lubricate them)
Carbon seals
They ran the oil to gas pre-mix at some silly amount I didnt really comprehend cause it was nearly half and half IIRC.. and it smoked resultantly like a badly tuned weed eater.. (More BTUs.. and More sealing in the combustion chamber=More Powah... just dont get too much and detonate)
14K redline
All this resulted in many wins in the Chimney rock hill climb.. and eventual exhaust restrictions to the point that it was soo choked that it was no-longer competitive.

The Idea is Out there.. FEW have done it.. It DOES make INSANE power.. If you have the savvy to pull it off. Better get a stand alone. he he he.. and have some time to play with that bridgeport..

Evil may have the pics of the engine more handy than I do.. as I would have to power up the server and sift through gobs of crap.. or find the original prints...(Plus I am at work ATM)

I myself PLAN to make one like that one of these days when I can justify making a engine that isnt legal in any racing.. And is only there to scare the street people.. he he he Right now just finishing building the EP engine..

SPiN Racing

Hiya all,

Hate to say it Kenku but its been done and If I remember correctly talked about maybe on the old version of the forum.. but if not I am fairly sure Evil Aviator or myself may have posted about it in the past..
A Certain engine builder/Race car designer in St. Pete Florida.. (PM if you REALLY wanna know.. I just dont want them bugged) Has or HAD a engine that was in his hill climb car.. 4WD, 4WS based on a 13B.

The engine is based on a 1974 13B's Steel housings.. (IE:Largest 4-ports) with perif Rotor housings. The Primaries were healthy street ported.. the Secondaries are large Bridge.. and then there are the Perif housings.

THe intake was a tubular design that ran up to a progressive linkage 6 Barrel manifold for the custom Bosch fuel injection. The linkage was set up so that all the barrels were closed.. and the primaries open first.. then secondaries.. then terciaries(sp).. The 3rd set of barrels went to the PP housings..

The engine had the requisite high rpm treatment..

Locked Hardened rotor gears
C-Clip Bearings
Clearanced eccentric shaft
Dry Sump/modified high flow stock oil pump.. (Above I believe he said 9K the oil system goes into bypass even with the comp regulator and shim.. so he ran the oil pump off a shaft to a external pulley he changed till he got 110PSI at 14K rpm.. plus he did the dry sump.. and all the oil re-routing to make it oil correctly.
Oil Jets in the Apex groves (carb jets into milled holes below springs etc to allow metered oil to cool apex seals and lubricate them)
Carbon seals
They ran the oil to gas pre-mix at some silly amount I didnt really comprehend cause it was nearly half and half IIRC.. and it smoked resultantly like a badly tuned weed eater.. (More BTUs.. and More sealing in the combustion chamber=More Powah... just dont get too much and detonate)
14K redline
All this resulted in many wins in the Chimney rock hill climb.. and eventual exhaust restrictions to the point that it was soo choked that it was no-longer competitive.

The Idea is Out there.. FEW have done it.. It DOES make INSANE power.. If you have the savvy to pull it off. Better get a stand alone. he he he.. and have some time to play with that bridgeport..

Evil may have the pics of the engine more handy than I do.. as I would have to power up the server and sift through gobs of crap.. or find the original prints...(Plus I am at work ATM)

I myself PLAN to make one like that one of these days when I can justify making a engine that isnt legal in any racing.. And is only there to scare the street people.. he he he Right now just finishing building the EP engine..

Kenku

Well, that's getting there. That's really cool, I have to say... way out there. The idea I posted is wilder, but... a lot of custom fabrication, obviously, and a lot of R&D to get all the new parts working right.

I always love hearing about examples of people trying for the bleeding edge of what rotaries can do. 340hp (half of the 26B) for a 2-rotor is regarded by most as absolutely ridiculous, but I want to see that figure beaten... and not by a small margin!

You're right about legality for racing series though... but I have to wonder. Midwestern Council has almost no rules for building a rotary car in GT-1 as far as I can tell, and the weight breaks are such that in theory, maybe a 3-rotor car built to this ridiculous extreme could be competitive with the V8 boys. But that's Midwestern Council, and I'm willing to bet that SCCA has more restrictive rules. Only other place that comes to mind is NHRA or something.

Again, I have to make the disclaimer that I have no intention of making the "experiment in absurd RPMs" motor right now; just something that popped into my head.

That sounds pretty cool, and power across the whole RPM range is something to be sought for street motors. I started tinkering in my head with an idea to get something like that... modified 6 port side housings, and small pports, with a composite intake manifold made from scratch using lost-foam. Had all the runner lengths figured out, and ditto for internal geometries, but I came to the funny realization that I wanted to get the car running *SOON* so... shelving that and just going "conventional" pport.

Thinking about it, I did read a book that had some experimental port configurations that NSU tried. A couple of them had two different peripheral ports... one fairly simple one was just two circles one on top of another, but another was a circle surrounded by a larger semi-circle. I always wondered how you'd make a manifold for that one.

j9fd3s

iTrader: (3)

the nsu wankel spider engines have 2 pp's. one teeny little port running right off the primary of the carb with really mild port timing. and then one larger port with more radical timing running off the secondary or the carb. the carb bolts right on the rotor housing.

something like that wouldnt be too hard to do at all

pip12434

There is a machinest here in WA that will make rotors to spin over 20K. He was on the LeMans team in 1980 (Bling ) . He said that the rotors are good for 30K but using a 93-95 crank 20K is limits. The rotors weigh 1/3 of stock. To tool his CNC right to make a set will run $60,000 and about $1K per rotor to machine. Friend 'o' mine is considering these for a SEMA car (what's the point, it's inside the engine??). As far as the flywheel & clutch giving up, thats' what balancing and scatter shields are for. If you're worried about porting and lack of fuel/air then put a hair-dryer (turbo) on the motor and force it in. Stand-alone can do almost anything these days. The same friend has a 13bt w/557 bhp at the wheels and a 10.5K redline (guess work) using a T78/tec3/Ionetti-seals/heavy porting in an 85 SE. All of this on a stock e-shaft but with treated stationarys. He hopes to run 11s or even 10s in a daily driver. We're waiting for the rear end to give (get a ford 8.8 or 9in).
Everything is possible if that money is right......
I have a 12a (stock) with a dellorto that i take to 9K daily with no troubles, however it will not idle with my jets and i get 11mpg.
That's my 2cent on the subject......

Dave

geargrabber

pip12434, what material are the cnc'd rotors?

60 grand? what in the hell for? programming?, but 1K per rotor sounds right...(too cheap even, if you consider the market-- racing beat sells stock "cnc" lightened rotors for about that price) http://www.racingbeat.com/resultset....rtNumber=10007


I am going to buy some round stock of grade 6 Ti, if that doesnt work i am going to use the proper grade of steel.

-mike