I did a little searching, couldn't really find anything mentioning it, but I was wondering why our motors are forged in iron over, say, aluminum?? Can AL not handle the forces put out in our case?

 

always wondered that too,
ever since I disassembled the 13b in my FC...
I was amazed at how heavy the housing are.
an all aluminum 13b would be much much lighter.

 

i think it's cheaper for one, racing beat sells irons that are made out of high grade aluminum. a little pricey but i think they are like half the weight.

 

never really thought about the cost diffrence...I thought it might have something to do with thermodynamics, expansion rates of the metals and what not but then again I could be very very wrong

 

^

Or very right. I am willing to lean on the thermodynamics

 

I checked out the RB stuff, thanks for the info, never noticed them there before.

As for thermodynamics, I think that the expansion rates, comparatively, are negligible. After doing a little research looking at piston engines, the trade-off comes in the form of energy lost in the form of heat due to aluminum's tendency to absorb and release heat MUCH better than iron, so the engine bay would get a bit warmer as well.

It's unfortunate that they are so pricey, as I would love to use them if the total cost of a conversion (for irons only, it seems) would be around $3k, which isn't worth the 50lbs or so I'd save.

 

I have heard that one of the reasons the rotor housings can warp when overheated is due to the differences in expansion rates between the housings and irons. I don't know if that's true, but it sounds plausible.

 

Aluminum wears rapidly.

 

Agreed, but then why not also make the housings out of aluminum. If specific heat is an issue, perhaps have a layer of iron on the inside?

That all depends on what kind of aluminum you use. Aircraft-grade aluminum would tend to argue with you...

 

Exactly. I suspect it is mainly a cost-related issue for Mazda. The rotary engine is pretty light as it is.

And aluminum does not wear rapidly if properly treated. Supposedly RB's side plates have superior wear characteristics to the stock irons.

I would love to build a custom 3- or 4-rotor engine using RB's aluminum side plates. But that would be impossibly expensive.