I'm wondering if it would be more beneficial to:

1. Machine S4 TII rotors to lighten/balance them to the wieght of 89+ rotors.

or

2. Machine S5 or RE/REW rotors to lower compression, and have them balanced (which would make them lighter as well)?

Which would be the stronger rotor?

I realize 9:1 is a good compromise, but I like doing extremes. With my setup, I will be running very high PRs, and like the relative safeguard of lower CR rotors.

 

if you go with option number one, what do you machine from the rotor to get the wieght down? i dont really know how you would find out short of experimenting.
option number 2 is kinda the same, i have seen a few rotors with dents in the face, if you take material off the face will it collapse?
the problem you have is wieght vs strength, maybe if you are going for max power you want stock 87 rotors, over potentially weak lightened ones. it kinda depends on what you are building the engine for. if you want something like the racing beat bonneville motors that last for 3 passes, i would say go for lightened 89+ rotors and leave the comperession alone. if you want one for your street car that has to last 100k miles i would say so for the low compression ones.

mike

 

i say leave the rotors alone unless you absolutely insist, and then only machine for lightness, don't mess w/ the compression ratio.

 

Now why would you want to do that?&nbsp Machining means taking out metal; taking out metal means less strength.&nbsp I can understand is this is an NA enigine, but you can always turn up the boost on a turbo one.

The Japan tuners who run ungodly amounts of boost all run Zenki FC3S rotors - why?&nbsp Cause the heavier casting resists detonation better.&nbsp Ever seen an FD rotor dent due to detonation?&nbsp It's surprisingly easy to do...


-Ted

 

I see your point Ted.

The only reason I would consider lightening is for high RPM use (9k). I'm sure balancing, clearancing, and stationary gears would take care of the issues, but if possible I would like it to be "seemless" at high rpm .

I was also under the impression that S5+ rotors were stronger because they have been milled/machined. This is just what I read on this forum, and half the hearsay on this forum is bullshit.

Why can't we just have forged rotors?

Anyways, thanks.

 

It would be cool I we had so titanium rotors avilable those would kick ***! strong and light no rust but expensive as hell. and don't ask me where to get them because this is just a rambule so don't kill me.

 

Titanium is NOT a good material for ROTORS (or Pistons) because it has a VERY HIGH coeficient of thermal expansion (ie it expands ALOT when Heated) Much higher even than aluminum

 

wood rotors

 

Tree bark is pretty good at withstanding high temperatures.

 

Mazda Comp sells the lightened rotors. I have a set..sorry, not selling.

The material that is removed is from the sides of the rotors...not from the face.

Again, Mazda Comp sells them, lightened and balanced.

 

Roger Mandeville, who road raced for Mazda from about 77-91, still builds "real road race RXs"($200k) for one of his tube frame cars. He runs 24hr races with stock 91 rotors, stock stationary gears and the gears are not even locked in the rotors! He has no problems with the 10k plus revs. and no problems with the gears wearing. I just had him balance and lighten my rotors, shaft, and counter weights. Mandeville Autotech is the name of his shop and he is in Spartenburg, SC. Very impressive shop!!!!

Forgot to say he didnt lighten the rotors, just took a little off of the shaft and balanced it all.

 

Balsa wood apex seals

 

Well they'd probably not have any problems with chattering


Hmm maybe I'll whittle up a seat and see how long they last. Should I even bother putting compression seals in the engine, or do you think it'd run long enough to need coolant?

I know... while I'm at it I'll resurrect some trashed rotor housings by using JB Weld and a big drum sander to smooth it down...