I wouldn't call it bullet proof 100,000 mile reliable but it DEFF would work for this kind of test. It's only a red apples to green apples comparison and would never pass scientific scrutiny but would be good enough for rational comparisons sake.

 

The problem isn't that the REW rotors can't physically fit in the Renesis. They can. They don't have the wedge shaped side seals which the Renesis NEEDS and there are no cutoff seals. The side seals are also slightly farther out on the Renesis rotors to clear the earlier port opening which will pose support issues with a REW rotor. The REW rotors have been installed and run in a Renesis. It works for a while but longevity isn't there and by that I don't mean 100K+ miles. Try a fraction of that! You WILL lose the motor! There's no if. It's when. It's about as "bulletproof" as a wet paper bag with a stick of dynomite in it.

A rotor needs to be machined with Renesis specific seal grooves if it is to be used in a Renesis block. No exceptions.

 

Offtopic but just for fun.


What would be the pros and cons of a titanium rotor?

 

I am not a metal person but, are there any metals out there that can be combined for light weight and strength and still be relatively cheap to make? Throw one out there for the fun and it would be very expensive but, any kind of CF out there that can fit the bill? Carbon has the highest heat resistance of anything, only tungsten boils higher but carbon melts higher. I am just blurting out but a renesis made almost totally of CF would be cool, expensive, and basically crazy. If it could ever be done, would be the ultimate rotary. Understandably, there would have to be metal parts at contact points but, if there could be CF inserts such as housings, gears, and all. It would probably catch on fire and burn up though LOL just a thought as to what might work and all on this. Would be nice though if the 8 weighed in at about 2500 instead of 3000 though.

 

High grade aluminum doesnt dent and crack like the typical common crap we see. I have used better grades like 7075 alum. in place of 6061, and its not even comparable.....6061(99% of parts you see) will just bend and crack where 7075 wont even flex. I think a 7075 rotor with a good hard anodize would be ideal, it wouldnt corrode as easily.

And to the guy above...carbon could possibly work, but its fragile. Its pretty easy to snap if the conditions are right. I have seen carbon pistons before, but then again I have seen wood pistons.

 

Pros: lighter than steel, heavier than aluminum, cheaper than a diamond rotor.

Cons: wears very fast, very expensive, hard to repair, very expensive.

 

I just thought I would ask as CF has com a long way in the car industry. Carbon itself is very durable as far as heat is concerned but, I am not familar with how the rotor is made. I do know that it is not a simple task to make one and out of the capabilities that I am currently aware of. I am just thinking of the top of my head. I make wire and the carbon brushes we use on our annealers last for months with high heat and high current running through them. They are not quite the same as pure CF but, they are very durable and we run these machines 24/7 for the most part. Just a thought but know there are major complications with the idea and will take lots of time to see if it could even be done.

 

I don't know the ability to machine into carbon but you could probably make a rotor out of some sort of carbon material and process. Wouldn't be cheap though. If you think $1000 for a racing beat lightened rotor is expensive your head would spin at the price of something like that. Think another zero plus.

 

RG how do you know all this stuff?

 

Carbon fibre wouldn't work because it's bonded together will epoxy resin, carbon is NOT the same as carbon fibre parts.

 

It should just take a standard endmill that has been turned down to .032, thats a fairly simple process...I ran into that same issue on other project, thats the easy way. The .140 deep is cake of course. The 7075 aluminum will machine alot cleaner for ya, and will be nearly indestructable.

 

I didnt think carbon fiber as used to make hoods ect. would work but carbon itself as in the same carbon as used to make motor brushes. Still, would have no idea how to adapt that to the engine as carbon is very brittle and, the heat would probably make it bond with other elements in the air while running and would just eat it away. It was just a thought off the top of my head at the time. Would have to look at the periodic table again to see what else may be a contender.

 

yea, woven carbon wouldnt be the way to go, you need a carbon composite...I have seen it work already in piston engine.

 

Another thing i was wondering, why are they trying to lighten it SO much? Over 3 Ilbs lighter??? How did they come up with that particular number? Would seem to me that the difficulty in building these to work correctly would increase the more weight you tried to take out of them. Wouldn't building rotors weighing 1 pound less (than stock) yeild considerable gains while being less difficult to make work than rotors weighing 3 pound less? Guess what im saying is why such a drastic drop in weight when we dont even know what a .5 pound drop would yeild?

 

somebody knows what a .2lb drop in weight yields. you can send them to racing beat and they will lighten your rotors for you.

6lbs is a nice number. lofty goals that seem crazy push R&D. if they shoot for 6 and get 7. they still have a ridiculously nice product provided they price it correctly.

i think its possible to make 6lb alum rotors. i just am not sure on the durability of said rotors.

 

Yes, that's exactly why Mazda wisely went with a combo of steel rotors and aluminum housing in our Renesis - can't seize the engine even with extreme heat.

 

They'd still be better with all steel as far as that goes...

It seems to be a common thought that when the material a chamber is made out of "expands," that the chamber gets bigger when the opposite is true. When the rotor housings expand, the room inside shrinks. Think about heating up a metal ring... as it gets hotter, it's going to get "fatter." The outside diameter increases, and the inside diameter decreases.

Of course I'm not an expert, and I could be mistaken... Maybe somebody that knows more about metallurgy can chime in and school me on this matter?

 

The current rotor are iron. They are using aluminum. Aluminum being roughly 48% lighter than iron. This is where the major weight loss is coming from.

One would have to do some serious engineering to drop 3lbs off a rotor is using iron for construction.

 

Aluminum expands more, and faster, than steel, therefore the anti-sieze capability of the current engine. Heat migrates, so it's not the equal expansion you cite.

 

Sure, one side of the engine is hot, one is cold...

I still fail to see how an aluminum housing + iron rotor is more resistant to seizing than an all iron rotary is. As you say, aluminum expands more; in an ideal world we'd have 0 expansion to deal with.

 

If you were truly a "Rotary Enthusiast" you would already know all of this.

I hate to be a "search guy" but this has all been well discussed/supported before.

 

Well if you could point me to one that would be fantastic, because my good friend Google has failed me on this issue. Or you could just provide a brief explanation since you seem to have an understanding of it.

Anyway, expansion rates and seizing aside, it doesn't really matter as an overheated rotary is most likely trash due to warped rotor housings anyway.

 

True, but at least you would keep moving, as opposed to a seized piston motor. Anyway:

"In addition to the enhanced reliability by virtue of the complete removal of this reciprocating stress on internal parts, the engine is constructed with an iron rotor within a housing made of aluminium, which has greater thermal expansion. This ensures that even a severely overheated Wankel engine cannot seize, as would likely occur in an overheated piston engine. This is a substantial safety benefit in aircraft use since no valves can burn out.

A further advantage of the Wankel engine for use in aircraft is the fact that a Wankel engine can have a smaller frontal area than a piston engine of equivalent power. The simplicity of design and smaller size of the Wankel engine also allows for savings in construction costs, compared to piston engines of comparable power output.

Of perhaps the most importance is that Wankel engines are almost immune to catastrophic failure. A Wankel that loses compression, cooling or oil pressure will lose a large amount of power, and will die over a short period of time; however, it will usually continue to produce some power during that time. Piston engines under the same circumstances are prone to seizing or breaking parts that almost certainly results in complete internal destruction of the engine and instant loss of power. For this reason Wankel engines are very well suited to aircraft. However, a Wankel is extremely susceptible to damage from pre-ignition, also known as detonation or "pinging."

 

I know someone will probably respond to that by saying that they do in fact fail catastropically but I've only seen that happen to engines using forced induction at high relatively high power levels. I have seen many engines that were only running on one rotor allowing them to limp around.

 

Any engine producing massive amounts of power can fail abruptly and catastrophically... but ridiculous amounts of boost aside, rotary engines generally keep limping along.

However, I still fail to see how the thermal expansion differential between the aluminum housing and the iron rotor is an advantage in this regard though... just because Wikipedia says it's so doesn't make it true. If somebody can explain the theory behind that assertion I would appreciate it, but if not it really doesn't matter