jays83gsl

What's the dimensions of a 12A rotor?

steve84GS TII

About 69.5MM wide
About 105MM center to each tip.(X 3)
About 180MM total width...apex to apex

jays83gsl

****, how do you convert that to inches again? I'm on a stupid streak.

candyassmiler

25.4 mm/1 in

SparkienSuggah

ooh! are ya gonna make some aluminum rotors? i always wondered why mazda didnt make the rotors aluminum.. not EVERYTHING in this damn engine needs to be so heavy. I could beat an army of terrorists to death with this spare eccentric shaft in my room, and then go build a new motor out of it.
Or melt it down and make a couple dozen camshafts for my dads V8

Mazdax605

iTrader: (5)

Maybe they needed the rotors to be of a certain weight to keep them spinning right,or maybe aluminum isn't strong enough,or wasn't at the time they designed the engine.I would think Mazda knows a lot more about what materials are best to use in an engine than we do.

jays83gsl

No, nothing fancy. I was just curious.
I know that racing beat is making (aluminum?) housings now, but not rotors. This leads me to beleive the rotors are the way they are for a very specific reason.

vipernicus42

iTrader: (4)

I know that when you switch to a lightweight flywheel and remove more spinning mass from the engine you tend to lose low-end torque.

If the rotors, e-shaft and flywheel were all aluminum, the engine would rev INCREDIBLY quickly (cool), but would probably lack any real low-end power.

As it is, a revewier in the local newspaper wrote "You reall have to grab the bull by the horns to get any real feeling of power out of the Rx8. You have to rev it really high right off the bat, but that's okay because this engine loves to rev..."

or something like that. It's true if you think of our cars. Piston cars make torque down low but don't rev high. We have to rev higher and faster for the same effect. I'd guess that more spinning mass can "store" more energy or something (takes more to get it moving but when it does it really moves) and so making things lighter would float the opposite way (easier to get moving, so it has to move faster to have the same effect)

Only physics formula I remember:

Force = Mass x Acceleration

(I remember it because "Force equals "MA", so the greatest Force in your life is your Mother)

Heavier or faster = more "torque"?
Lighter or slower = less "torque"?

Now I don't know physics very well (I failed Physics 101 with 6%) but I know that there's someone around here who has a rotary jeep and was saying that they keep the heavier flywheel for more torque.

Jon

vipernicus42

iTrader: (4)

Stuff that's not SPINNING mass however (like side plates) is just dead weight. The less dead weight you have the higher the horsepower-to-weight ratio.

So making front, rear and intermediate plates out of aluminum makes your engine very light, but doesn't affect it's distribution of power/torque.

Jon

SparkienSuggah

amen to that.. now i know a lightweight engine would be hard to launch, but once the clutch is fully engauged, i dont see how the engine would put out less torque than a stock one. you're right about the mass of the rotors storing energy thats released when you dump the clutch, which probably makes the rotary driveable, but the mass of the engine only slows it down once the revs stabalize in gear. theroretically lighter engines should display a higher broadband torque curve simply because the torque required to accerate the engines internals is less, thus power origanally used up by the engines mass is now transmitted out of the system to the car. if it was undrivable they could just put a bigger fly on..

and piston engines have aluminum pistons.
aluminum rotors would also prevent the e-shaft from flexing at high speeds (well, the speed would have to be 50% higher) and the stationary gears from distorting at high speeds (50%) because the wobbling mass would be reduced by about 50%...
we should email racing beat and ask how their race lightened rotors affect driveability...

trochoid

iTrader: (6)

Aluminum is too soft and it's coeffcient of expansion is too great to be used as a rotor. It works as part of the block because it is contained by the tension bolts.

Piston engines gain most of thier torque from the crankshaft. Lightweight pistons, rods, and valvetrain components help reduce parasitic hp losses due to the fact that they go up and down, changing directions.