Hows it going everyone. been doin a lotta research tryna figure out if my rotors are gsl-se 3mm rotors or 3mm milled s5 NA/Turbo rotors. Anyone know any physical appearance differences between the gsl-se and s5 rotors?

I know s5 rotors have machined dishes on the rotor and the lines run parallel to the side seals. Just dont know if gsl-se rotors have this same appearance.

The rotors I have are stamped C and have machined lines parallel to the side seals

Any help is appreciated ill try and get some pics up later today. thanks!

-Marvin

 

http://www.mazdatrix.com/faq/rotorwgt.htm

2 lbs difference in the 2 suspects. That should be easy to check.

 

Gslse rotors and S4 rotors have a cast look in the combustion dish, S5 turbo or NA have machine lines in the dish running in a line from rotor tip to rotor tip. Do not read this as a line going from rotor tip to rotor tip. The lines just go the length of the dish.

 

sick awesome guys thanks!. so i narrowed it down to either s5 turbo or s5 n/a rotors. they both weigh about the same.

Im guessing the only way to distinguish between s5 turbo and s5 n/a rotors is by the depth of the dish? I dont have a s5 n/a to compare..so does anyone have any pics of the depth difference?

Thanks again guys.

 

depth of dish = compression..... if you haven't thought of that yet you really really really need to figure that out. Are you going low boost / high compression or high boost / low compression?

 

yeah i know that i want to use the 9.0:1 s5 turbo rotors instead of the 9.7:1 s5 n/a rotors. The problem is that i got these 3mm rotors in a motor i bought and dont know if it is s5 n/a or s5 turbo.

And i can only tell the difference if i had a s5 n/a and s5 turbo rotor side by side to compare the depth of each dish. Just wondering if anyone had pictures of the two side by side?

 

Most likely.... and this is speculating.... if it's 3mm they are most likely turbo. There is little to no benefit of enlarging the apex seals in a N/A motor, in my mind.

 

What estimated results would be seen running 3mm milled n/a s5 rotors on a s5 tII engine?

 

People run 3mm for a few reasons.

First, mill out rotors that would otherwise be trash becuse the apex kerf is out of spec.

2nd, looking to get increased durability thicker = stronger, harder to crack.

3rd, stronger when running carbon apex seal

4th, 3mm carbon for really high rmp's like on an NA bridge that sustains 7-10k in a race.

The bad,

More weight, harder for the spring to do its job, more centrepedal force pushing into the housing. Slightly less of a seal at low rpm's (not so much with carbon)

On an NA the only reason to go 3mm that I can think of would be to use carbon seals or to get more life out of rotors that are out of spec aka one could do both at the same time.

 

lay an old 2mm apex seal on it's side over the pocket on the rotor and using a slide micrometer measure the pocket depth.


S5/FD turbo rotor pocket depth = 12.72mm minus apex seal width of 1.95mm = 10.77mm actual pocket depth. (9.0:1 CR, machined pocket)
S4 turbo rotor pocket depth = 14.02mm minus apex seal width of 1.95mm = 12.07mm actual pocket depth (8.5:1 CR, cast pocket)
S4 non turbo rotor pocket depth = 11.70mm minus apex seal width of 1.95mm = 9.75mm actual pocket depth (9.4:1 CR, cast pocket)


looks like i don't have any S5 non turbo rotors or GSL-SE rotors to measure, glad i checked this as i found a set of FD rotors and another set of S4 TII rotors i didn't even know i had.. GSL-SE rotors should theoretically have the same dimension pocket as the series 4 non turbo pocket depth and have the same cast pocket but the telltale 3mm OEM apex seal slot(could have been milled however, rotor weight is the ONLY way to tell these 2 apart). series 5 and 6 have machined compression pockets.

so there you go, your way to determine rotors from various series with a basic method which i haven't seen anyone post to date aside from weight which is less accurate.

series 5 non turbo will have the lowest figure beyond anything on that list so it should stick out like a sore thumb. according to the differences the pocket should measure right around 8.75-9.00mm deep.

those are rough figures and will vary by about .2mm across the board(noted various readings but took averages) but should not borderline into another series' territory.

 

forgot about my display model which conveniently had a blown S5 non turbo rotor.

S5 non turbo rotor pocket depth = 10.55mm minus apex seal width of 1.95mm = 8.60mm actual pocket depth (9.7:1 CR, machined pocket)

 

Roll pins! Count the roll pins around the rotor gear. GSL-SE will have less than S4/S5.

 

good point to finish off this segment on how to determine your rotor series and model!

all later model 13B rotors have 12 stat gear pins
GSL-SE rotors have 9 stat gear pins

 

For s4/5 na/turbo:

S4: If you look at the opposite side of the rotors gear side (open side) next to the bearing you will see a "I" for one/front rotor or a II/2 for rear rotor and a T for Turbo.

S5: If you see a "1" or "2" then it might be an s5 rotor. Again if you see a T its a Turbo rotor.

there are some pics
first is s4 na
second is s4 turbo
and third is s5 na
and forth is s5 turbo, this one is kinda blurry


hope that helps

 

interesting that i haven't heard of the casting marks on the inner veins before, learn something new everyday with these engines.

all the turbo rotors i did find the "T" stamp but the "I" and "II" markings usually were erratic and sometimes no markings whatsoever on the early S4 n/a rotors. i suppose it would be best to use several methods to determine the rotors to be sure. the pocket depths on the cast S4 rotors can vary a bit from one spot to another but with the cast pocket and the large variance between the turbo and non turbo rotor depths it's quite easy to know for sure.

you can usually tell which is the front and which is the rear rotor by the lip formed on the apex seal slot against the rotation of the engine. i wouldn't flip rotor positions because then you will quickly widen the "V" shape of the rotor slots as they wear.

i just dislike the weight method unless you have your scale calibrated and have several rotors to compare figures against.

 

This is a good thread. I vote archive.

 

awesome info! you guys helped out a lot thanks guys. this should be archived!!

 

Measured everything and counted the roll pins also like what you guys suggested. turns out the rotors are s5 turbo milled for 3mm apex seals ^____^ . thanks for the help guys

 

no worries, i've been looking for a better way of determining the rotors and to get some hard data down on paper anyways as i had a stack of rotors to clean up that i hadn't marked at all when i tossed them on the shelf.

as a kicker i'll post some pics of the old deuce 6mm carbon seal/dual side seal rotors tomorrow as i may as well clean those up while i'm at it, not something you see everyday. gives me a break from the monotony from time to time to do something different for a day.

 

40 year old antiques, pay attention to the apex and side seal slot(s):





and the 6mm carbon seals in all their glory next to our current 2mm stock seals:



it would be interesting to build that engine using 6mm ceramic seals and nitrite the endplates as well as anneal the gears, would be a viable long running engine compared to the carbon seal motors that lasted ~30k on average. but i doubt anyone wants to dump $5k into an original twin dizzy deuce engine.

 

geezus.. those are fat *** apex seals LOOL. and dual side seals? pretty coool.

 

how do you guys think mazda cuts the side seal groves? how would they get a narrow deep cut like that? what kind of tool?

 

something similar to current CNC machines. what kind of bits, i can only guess.

 

Going back to when Mazda first started making the 2 mm seal, they probably milled them in a horizontal machine using a slitting style cutter. Modern machinery could end mill the slot but for mass production, probably not cost effective.

I've heard of forum members having the slots in RX8 rotors opened to 2mm and 13b opened to 3mm using wire EDM. Awesome choice if you have the availability.

I imagine the guys doing it for a living are milling them. Either end mill or slitting saw/keyway cutter. I bet the latter is most popular.

 

have you guys ever herd about running the heavier rotor as the rear rotor?