Grizzly

Is there any diffrence between a S5 Turbo 2 Rotor and a S6 Fd rotor?

Its just i need to replace one and i have a good S5 one knocking about and woundered if it could be used?

TonyD89

iTrader: (10)

I was told there isn't. I needed a S5 TII rotor and found a member selling two FD rotors. I compared them when they arrived and I cant find a difference.

He also said the FD rotors are hardened at the apex seal area to reduce wear. An added plus if true. Regardles they are in excellent shape. I am very satisfied.

For what it's worth, the surface finish on the FD's is better than the TII's. I don't know if it makes any difference though.

__dave__

i dunno about them being hardened, but they're compatible.

just pay attention to what weight stamp you have.

Grizzly

Where will i find that?

TonyD89

iTrader: (10)

I plan on balancing. Soon actually.

My $.02, balancing is a must for a performance engine wether it be piston or rotary. Matching weights or not. I took the hardened apex area claim with a grain of salt. They do not appear to have as big of a burr from wear along the top of the groove though. But then again, I don't know their milage.

diabolical1

iTrader: (3)

usually on the gear-side of the rotor. you'll be looking for a letter between A and E.

BLUE TII

iTrader: (9)

The 3rd gen rotor does have a bearing with a deeper oil groove.

I believe the 2nd gen rotors also have the hardened apex seal slots- though they could have changed the process.

There is probably more difference between the rotors off the machine at Mazda that leaves grooves on them VS the machine that leaves a smooth finish and I have seen people mix those.

KeloidJonesJr.

iTrader: (8)

I know someone on here has a 20B using a custom e-shaft with 3 S5 NA rotors.

TonyD89

iTrader: (10)

I have asked about this many times. Both of the last two factory stock engines I've taken apart had a rough machined front rotor and a smooth (I would say ground) rear rotor. One was a NA an the other was a TII. Both had rear rotor apex seal failure.

Being a machinist, I wondered why? My best guess is that the rough rotors were machined to close to go through the finishing process or Mazda tried to save costs. I don't know. The rough one looks like it was machined with a single point tool. The smooth one looks ground.

Anyone with more info?

RotaryEvolution

iTrader: (30)

i have noticed the rough surface rotors before also but i couldn't figure out why they did it that way. my best guess is they had runs of rotors and simply assembled many engines with 1 of each to get rid of their stock of crappy machined rotors, i cannot see any benefit to having one with a rough surface and one without. i'm sure some engineer would give some "highly educated" answer about this but i will never believe there is a benefit to it even though the rear rotor does see more heat than the front rotor.


balancing is uneccessary unless you plan on pushing past 10k RPMs, waste of money IMO unless you are building a drag car with a scatter shield.

BLUE TII

iTrader: (9)

i have noticed the rough surface rotors before also but i couldn't figure out why they did it that way. my best guess is they had runs of rotors and simply assembled many engines with 1 of each to get rid of their stock of crappy machined rotors

except I have seen the '86-88 rotors and the '89-92 rotors (different castings) both smooth and ribbed.

GUITARJUNKIE28

balancing is good for n/a's...you actually have to spin those things fast to make power.

but when was the last time you saw a turbo engine peak past 7500, or mid 8k's with a bp?

if you've got more than 400 hp, it wouldn't hurt.