This is important to me because I found out that I have S4 rotors in my 89GXL.. My meckanic must have put them in on the last rebuild. Wierd but they do way 10lbs not 9.5 like the S5...Anyways the S4 N/A run 9.4 compression ratio and are .5 lbs lighter. Whats the major power difference say if you swaped just the rotors? Can someone inteligently give me thier educated opinion ??? Im using them for my streetported motor

 

Yes I can give you my opinion.
You cant swap rotors unless you swap flywheels and counterwieght. So you can exchange s4 to s5 and back by swapping 2 rotors 1 flywheel 1 front counterweight.
This applies to TIIs too.
sky

 

So I have to give up my new 12lb flywheel?

 

I just rebuilt my engine, and when i went to pick up my flywheel and counterweight, i was told that the fly wheel is the same for s4 and s5

 

Yes, you'll have to give it up (just send it to me just kidding, you can keep the flywheel, the rear counterweight will balance the assembly provided that your rebuilder knows that the front counterweight, rotors and rear counterweight must all be S4 or S5 - you can't mix and match.

S4 and S5 flywheels are not the same - here's a good link for stock flywheel info: http://www.mazdatrix.com/faq/flywheel.htm

Henrik
87TII

 

What? I have S4 rotors but S5 flywheel and counterweight...This setup was on before and was working fine?

 

They may bolt up the same (not sure) but the series 4 is heavier than the s5. 24 vs 22 lbs on the N/A if I remember right.

 

hey von are you sure that you are measuring the rotors on a very accurate scale? Cuz a lot of scales would see 9.5lbs and just round it up to 10lbs.
And on a side note, what do you have to do counterweight wise when you have your rotors lightend? Do they have to be lightend and balanced?

 

I dought it. Its bullshit. I have S4 rotors and a S5 flywheel and counterweight.

Even if the thing was inacurate the rotors are clearly S4 because of the desine. Thiers no mistaking it for S5. You dont even have to weigh them. Pluss I weighd a S5 and it was slightly less than both of the S4 by .5 lb

So I guess I will have no problem using the S4 rotors with S5 flywheel.... Remember its a S5 engine. Not S4. Just with S4 rotors. I dont think weight has anything to do with it as long as I have the S5 flywheel and counterwieght

 

what do you plan on taking your motor to? rpm wise.... if your gonna be taking it anything above 9000 rpms i would try to make sure you got everything correct ( weights and stuff ) you may also want to upgrade to s6 stat gears or racing beat hardened ones to be safe would suck to spin a bearing.... or at least modify the stock one to a 3 window bearing for more oil flow....

 

9,500 rpms. Im not worried about all that crap. I see alot of people on stock streetport rebuilds that spin higher with no problems. They probly wear out thier engine faster but its still as fast as hell and fun to drive.

 

With S4 rotors and a lightweight flywheel; you'd want a S4 automatic's counterweight.

Power difference comes from the rotor's compression, not so much the weight (which has more to do with shaft-flex and rev-speed). The reason TII's have more power, is because their total compression (rotor comp. + boost) is higher than an N/A.

All other things equal;
An N/A with XY compression rotors will be as fast as a TII with X compression rotors and YPSI. (Not the actual formula, but it should be simple enough to understand)

Hope I'm not spreading misinformation; but that's the way I was always taught.

 

then can someone tell me why My car with S4 rotors and S5 flywheel revs just fine with no vibrations at all???

 

shaft-flex with low horsepower isn't much of a problem. Just because it WORKS doesn't make it work RIGHT.

 

Low horsepower meaning 160rwp? So will it be a problem with my streetport?

Before I was reving to 8500 rpms no problems with the shaft or anything.

 

And my engine is already put together. What do you sugest I do with my new 700 doller flywheel? Thats pretty fucked up if I have to give it away even though I see absolutely no harm being done to my engine at 8500 rpms?

By the way. When I took this engine apart thier was no chatter marks what so ever. Shaft flex would cause chatter marks. So obviously thier was no flex going on at 8500 rpms!!!! Can you guys please explain the short term / long term effects of using this flywheel with my S4 rotors ?

Like tell me what im sopose to feel if anything wile reving that high and what damage it should be causing even though I didnt see anything...

THnx for all the input but this really isnt getting me anywere. IM in a predictament and dont know if this is bad or not.

 

ok... lets say this..... replace your flywheel and counter weights now.... or have to take out your motor and replace all the bearings and e shaft and even your housings and rotors.....

 

You can run that flywheel. Your main bearings wont last more than 30K miles. The motor that was in my car was a S4 block(I didnt know for sure until I got it apart), but I was runnign a S5 flywheel for 20K miles. There was excessive wear on the top and bottom of the bearings, but the sides were normal. The bearings were about .01" beyond the max after 20K miles.

IF its an aftermarket flywheel, the counterweight should be seperate. If so, just get a S4 rear counterweight and not worry about it again.

BTW, every point increase in compression is worth 4% more power. So the .3 of a point decrease in compression(9.4 vs 9.7) is worth about 1.3% less total power. At most, youre losing 2-3 hp.

 

von, did you take your engine apart or did autotech? I'd like to come check it out if you're still in the process. shoot me an email to increasingcircles@yahoo.com

 

Thnx Mazdaspeed7. Im only looking to put 30k on it anyways since the way I drive it...WIll a S4 counterweight fit on the aftermarket Centerforce flywheel???

FCdemon , sorry its all put together now. I put it back together myself although autoteck did show me what to do and help clean and measure parts. Very easy. Taking it apart is easier but they actually did it. I took my old T11 motor apart. Streight forowerd.

And by the way. I called centerforce and they said that thier aluminum flywheel is high 70s SFI rating aluminum wich they say is better than most brands. ALso they said it will handle 13,000 rpms. He said im good for 9500 easy. Dont think this is the right thread but whatever.

Importboi22 ? Did you hear me when I said that my engine was fine and dandy when I took it out runing S5 flywheel and S4 rotors ? I was looking for an ansewer like mazdaspeed7s. Thnx it maks sense but what bearings are you talking about ??? I never replaced any bearings during the rebuild. We kept the stationary gear inside and kept the pilot bearing as well for they both have very few miles on them.

 

Are you talking about the needle bearings ?

 

im talking about the front and rear stationary gears, just a good precation to use s6 ones cuz there factory hardened and your going to be taking the motor to some high extremes.... the only reason im saying what im saying is ive eaten 2 motors due to VERY TINY things... i know the rotary motor is very sensitive to certain things, and if the motor is out its about 10 times easier to double check a few things to be safe...you should play it safe and take out the front stat gear and double check the wear specs just to be safe.... itll take a few minutes while the motor is out. If you already did that... THEN WHAT THE HELL ARE YOU WAITING FOR get that baby running!!! good luck with your car i hope you got a kick *** NA ask mazdaspeed7 he knows i love NA powered cars maybe you can come down to corona sometime so i can check your car

 

check as in look at and take a ride in and crap lol

 

Well **** I didnt do any of that stationary stuff. All well. Everything had 28k miles on it anyways so hopefully its within spec. Dont really care if its not. Hopefully it will last me till 7 stock. Ill be thier again.