From the PRI show !

 

mmmhm aluminum....now just need more potassium or the rockets won't fire!

 

talk about heat..

 

so nice

 

wouldn't that cause issues if the rotor heats up and expands before the housing? Isn't that why Mazda went with steel rotors? Or am I wrong?

 

Its just not finished yet. Targeted weight is 6 lbs!

 

How much do the factory rotors weigh, and which engine are these for?

 

factory rotors weigh approx. 9.2 lbs (racing beat)

-Cody

 

9.2lbs according to Racing Beat, http://www.racingbeat.com/FRmazda4.htm

 

that's hot if they could get it to work without sacrificing longevity

 

Considering that Racing Beat's lightened rotors save 0.2lbs each at a cost of $2,000 for the set, these 6lbs rotors look very interesting if they are not too expensive.

 

Good for drag racing. I wonder how many runs you could do....

 

get RG in here

 

I've known these were in development but I haven't known any specifics. These don't have apex seal grooves machined in them yet. You guys will be happy to know that these are Renesis rotors!

 

Watch out your Christmas hat may fall off.

 

hmmm.....3lbs almost off the original rotors, and thats reciprocating weight, any hypothesis on how much hp or torque that could free up, or longevity issues?

 

At least 3 or 4.

You would think that if Al had decent durability that Mazda would be using it.

Has anyone gotten Al rotors to last more then about 50 hours in an RX7 yet?

 

Remember you also need lighter counterwieghts and it's even possible to get an eccentric shaft with a center bearing that weighs 1.5 lbs less than stock.

 

From the tech papers I've seen on testing, surface temps on the rotors never exceeds about 400* or so due to heat transfer into the oil system. Aluminum transfers heat better so it would be curious to see what happens. My concern would be with denting or cracking a rotor. Aluminum needs to be thicker than stell or other metals to have the same strength. The guys making these are not making any promises. They are just testing them right now and are hoping they'll work.

 

Piston motors get away with iron blocks and aluminum heads without creating leaks at the planed surfaces so it could work.


-OR- that may be a good excuse for aluminum housings.(notice stage right)

 

Lower compression option?

 

I was waiting for that from someone else.

Yea as long as you are fabricating rotors why not?

go big or go home

 

You are correct I have aluminum heads on an iron block but since they mat together on a flat deck they never really interfere with one another with differing expansion rates. With a aluminum rotor spinning inside of a steel (unsure) housing, if the aluminum expands 2x as much as the material in the rotor housing you would think when the motor is cold the tolerances in the apex seal to wall clearance would be great and than as the motor heated up it would try to out expand the rotor housing and potentially lock the motor up. The only way I would think you could do it is set of the motor so when it is up to operation temp the tolerances of the aluminum rotor are perfect inside the housing, though I dont know how the motor would run up to that point.

Just a thought, i'm not too sure there is any merit to my thoughts. Anyone with more expertize on metalurgy and rototaries care to set me straight.

John

Accepted Linear Expansion Values of Common Materials

Material a
(x10-5 °C-1)

Steel 1.24

Copper 1.76

Aluminum 2.34

 

Yea i deff agree with you. I dont know enough about rotaries to suggest how it could be done, I just know in piston motors that there are many differences in the metals used in various parts e.g head, block, pistons so maybe you could get away with it here. Again, I don't know. I was more kind of pointing out that a very logical answer to that question would be an aluminum housing, which is pictured also. Then you wouldn't have to worry about expansion rates unless for some reason different alloy compounds were used between the rotor and housing.

 

Aluminum works well for blocks, heads, and pistons...but not so well for connecting rods. They stretch out after a few dozen runs IIRC. A rotor is sort of like a piston and con rod all in one, so who knows. Seems like it would work though, I mean a rotor should be a lot stronger shape than a H-beam, right?

Has Mazda ever experimented with Al rotors, or has it been ignored due to cost, or durability concerns, or what?