Twin rotor Peripheral port

[Grizzly]

Out of intrest How would you expect a Billet Rotor to wear? I\'m not to clued up on Metals but would it hold its shape ok for example Apex grooves or Side seal grooves?

I always though a set of rotors made from somthing lighter than cast iron would be good in a Rotary but Mazda must have made them like that for a reason??

[Grizzly]

for really high revs you need different bearings than white metal.
workheads on grinding machines have main drive spindle normally using phosphur bronze bearings with oil grooves in the inside bores for good lubrication, some spidles can spin well over 30 000rpm,
just think of a turbo , main shaft on a loose fit (sloppy) phosphur bronze bearing, these will spin at 150 000 rpm but need the oil big time/

Yeh i have just read Glenns post on Aus Board and the bearing load was brought up. I wounder if you could get round it by upping the Oil presure? or cross drilling the Crank??

[Grizzly]

Glenn they don\'t mess about on Ausrotary do they.......

[Glenn Butcher]

Glenn they don\'t mess about on Ausrotary do they.......

Some very clued up guys on there.  The really treasured information is kept close to heart of course.

I have heard of quite a few people doing things like grinding the sides of the rotors down around the apex seal area to help with high revs and big boost etc. - I\'m not sure if that is also done in NA engines?  Obviously only to a point - as again I believe that the rotors tend to wobble about at high rpm.

A lot of the high revving stuff was covered in that thread, mainly came down to there being a need for less rotating mass to reduce stress on the shaft - so lighter rotors (maybe a different material?), stronger e-shaft (again maybe a different material), supporting centre bearing would help, better lubrication, and again other materials to help with harmonic issues.

Thinking about it though, all the stuff we are playing around with on the RX engines is all around 10+ years old, apart from the RX-8 bits.  So in theory, there should be better materials available now - cost less to produce now etc.

If and only IF! Mazda would attempt Le Mans again with a full on Factory Based effort with millions of $$$ - it will be just individuals trying to make the engine better - more of less using the standard parts.


Guys like you Stuart could have a head start on Mazda if you start playing around with these things - maybe try some other materials??? chat to your boss!

[shaunwil]

Are rotors made of cast iron ?? Couldn\'t you make them out of forged alumiunium, machine them and then nitritide them to give them a good hard surface ?

Do F1 use carbon fibre bits in engines ? Could you do the same with a rotor ?

With Turbo technology now what would stop people using roller bearings for the e-shaft to be able to get the rpms up ?

Couldn\'t you have a step down before the clutch and flywheel to reduce the spinning mass after the engine, if it only saw the original rpm then it wouldn\'t be a problem ?

This thread is really interesting read

Shaun

[iaint]

Are rotors made of cast iron ?? Couldn\'t you make them out of forged alumiunium, machine them and then nitritide them to give them a good hard surface ?

Do F1 use carbon fibre bits in engines ? Could you do the same with a rotor ?

Forged ali would have a vastly different expansion porperty than iron (or steel) - it\'d expand far more for a given temp rise:

Linear Expansion Coeficient (10^6 K^-1):

Fe (Iron): 11.8
Al (Ali): 23.1

Ali may be light but it\'s very soft in comparison and not good for hot environments where tolerances must be tight.

[RotorHeid]

Jim Downing :god  (Amercian RXracer) designed his own "in house" ali alloy rotors and  running with success.
that\'s what I heard long ago.

[shaunwil]

But isn\'t the housing aluminium nitrided ? Wouldn\'t that mean you would get more constant expansion and contraction between the housing and the rotor ? You would still have the apex seals in the original materials but you reduce the overall mass of the rotor.

Whats the difference with titanium, could that be the material of choice ?

Shaun

[stuart wizy]

titananium is mega mega expensive, ive machined small pins and shafts bolts etc for a guy who was building a racing bike to lighten anything possible.
Its amazing material u know, holding a piece of 50 mm dia bar, feels a lot lighter than ali and is the strongest material available.
I dont know how it copes with heat, ie warpage and expansion.
the f1 guys use titanium con rods and cranks, thats why they get the revs.

like shaun says ali rotors should work well with nitride coating to protect from combustion temps, you would need to fit apex seal slots to the rotors though made from steel or the apex tips would wear an ali slot out in no time.

[stuart wizy]

glen holroyds rotors are the most acurrate in the world.
they got the queens award for technological achievement for making milling and grinding machines that mill and grind a pair of screw rotors with 5 micron clearence between the pair.
the rotor milling and grinding machines made by holroyds are used all over the world, but there not interested in making wankel rotors!!
they make rotors for trane ,compair ,atlas copco, ingersoll rand, used in  most of the air conditioning units and air compressors worldwide, also for superchargers, fuel pumps etc. its a massive firm with production cells worldwide.
have mazda not got the rights to the wankel, is it not illegal to reproduce mazda parts?
If not, there could be a nice little project coming on here, I need to get the real tech boffins who design the machines ,from holroyds design team in on this!!!

[Grizzly]

Forged ali would have a vastly different expansion porperty than iron (or steel) - it\'d expand far more for a given temp rise:

Linear Expansion Coeficient (10^6 K^-1):

Fe (Iron): 11.8
Al (Ali): 23.1

Ali may be light but it\'s very soft in comparison and not good for hot environments where tolerances must be tight.

Is the Housing that the Rotors spin in not alloy?

Does anyone have any more info on Jim Downing\'s Rotors?

[Grizzly]

But isn\'t the housing aluminium nitrided ? Wouldn\'t that mean you would get more constant expansion and contraction between the housing and the rotor ? You would still have the apex seals in the original materials but you reduce the overall mass of the rotor.

Whats the difference with titanium, could that be the material of choice ?

Shaun

Shawn, the Rotor housing is chrome plated and the Iron Plates are Nitrided. I understand one of the problems Mazda had with there Race engines was the Rotor Expanded quicker than the Cooled Alloy Housing so it was possable to make contact with the End plate in a race or prolonged load.

It does beg the question, if it was as easy as changing the meterial the rotor was being made from why use Cast steel that is heavy and quite hard to work? I\'m guessing they did it to keep the Groove shape (Eg. a Seal moving in and out all the time with little lubrication), I supose Cast iron would resist wear better than say Alloy??

Also i was thinking about the centrifugal force thing, at first i thought a Lighter alloy would be better, but Then i thought what if Mazda made the Rotors from cast for a reason?? eg. to add more weight to the Rotating assembly there for making it smoother.... Or a stock Rotary drive better... But at the end of the day its proberly more like it did the job and was alot cheaper to produce??

[stuart wizy]

the hardest thing to machine on a billet rotor would be the oil galeries inside.
The rest is turning and milling, to get a patern made to make cast ali rotors with the same oil galeries as a std rotor is pretty dam hard to do.
I think the only way to make them is from billet ali, with large holes drilled through the rotor ,to feed the rotor gear, ie- similar to the original cast rotor oilways but drilled.
Then you need some sort of steel inserts fitted to the rotor for side seals, apex seals and corer seals, these inserts need to be fixed to the ali rotor somehow.
I thought of machining the middle of the rotor out completely the same way that the racing beat rotor has been, but instead of 2mm deep, go full depth of the rotor, this could then be pressed and fitted onto an ali middle section with bores, oil grooves, gear all re machined in the inner ali section of the rotor,
this way u can still use the original apex grooves side seal grooves and corner seal bores, and save a **** load of weight with the inside of the rotor being ali.

[Grizzly]

but are we not getting back to the Expansion problem??

Could they not be forged? or is this just very expencive way of making a rotor?

I would be intrested to see how Jim Downing has made his??

[Grizzly]

MMMM i see what you mean about the Oil ways inside the rotor.