just want to doulbe check on this im gonna be using a set of early fd s6 rotors on my 87 t2 eshaft and rotating assembly . should be fine right?

 

Yea that is fine so long as you are using S5 or S6 counter weights.

 

see i didnt know that lol . whats the diffrence? ill look at em tommarow then . thanks

 

I believe FD rotors are already clearanced but don't quote me on that. *edit* Just checked and i cant find anything on it.
other than that they are pretty much the same other than small differences.
Same reason you can use either S5 or S6 flywheel on both rotating assemblies.

 

iirc you just need a S5 or S6 flywheel, s5 or s6 front counterweight and matching front needle bearings, and of course S6 rotors. the S6 needle bearings are wider than S4

 

they're basically the same as s5 turbo rotors, just use the s5 counterweights

 

Out of all the replies in this thread, this is the only one that is correct.

 

umm so this means i have to use a s5 flywheel? i have my s4 t2 clutch . how am i gonna be able to tell the diffrence **** i dont think i even have a s5 counter weight just s4 and s6 ones wtf

 

Don't take this the wrong way, but should you be building your own motor if you don't know this stuff?

You'd need either an FD or s5 T2 flywheel, yes. You can use any 87-91 turbo clutch.

You can tell the difference in s4, s5, and s6 front counterweights easily. Mazdatrix has a writeup to differentiate between s4 and s5/6 rear auto counterweights as well. Stock flywheels are easily ID'd by the model number cast into the back.

 

I'm guessing the only reason you're using s5 rotors for more power, you could of just used s4 NA rotors and make even more power with less boost.

Rotary > Pistons

 

well i built my first one fine but im still lerning about this counter weight stuff thats about it . lets hope i find out . so i can use a stock fd flywheel? i have atleast 5 of those and a s6 front counter wieght right? if so i have all that

 

what was wrong with my post?

i went the opposite direction and put S4 9.4CR rotors in an FD engine. All i used was the S4 front counterweight, S4 flywheel, and had to use the S4 torrington bearings since the S6 bearings where wider and wouldnt fit in the S4 counterweight race

 

man... if you cant check the PN to see if they're the same dont bother. just put down the tools and take the parts to a reputable rotary shop. if you cant do some self learning on basic part interchange how can you hope to figure out how more complex parts of the engine build will work?

 

You can use an FD stock flywheel on any 89-95 turbo engine/rotors.

You cannot use an s6 front counterweight without converting over to s6 or rx8 stat gears, and using the larger diameter needle bearings/thrust parts. You can however use an s5 front counterweight with no issues.

 

thanks alot man . lol now i gotta hunt for the s5 front counterweight and ill be fine .as to everyone else sorry i havnt been to the shop today yet to check part numbers so please keep those rude comments to yourself

 

they're only rude if this hadn't been posted dozens of times before. how many times have i pulled apart engines that were a mix of parts that never should have been used in an engine? more times than i care to remember.

we all want to think we're experts but if you can't take a little criticism then they may be correct.

the basics:

the shell of an engine does not matter, so long as the series remains constant, rotor housings can be substituted but also should be kept within the same series.
rotating assemblies should also be kept all within the same series, this consists of: rotors, front counterweight and rear counterweight(stock flywheel or auto counterweight).
e-shaft series does not matter, so long as it is '86+ 13B.
turbo stat gears are hardened(grey finish under the gear surface), non turbo stat gears are not hardened(polished finish under the gear surface). non turbo stat gears can be used up to about 350whp, turbo gears should be used beyond that.

 

I took apart an FD rebuild last year with s4 t2 rotors. It had not been rebalanced or lightened in any way.

 

but it's only a problem if the counterweights were not used.

we're probably going to see more high compression builds in the future as people continue to blow up turbo rotors. but high compression also has a new set of issues with higher boost levels.

to keep the engines more current i haven't been dissuaded by upping compression ratios, it just takes a slightly different approach.

 

They weren't. It had s4 rotors and stock FD counterweighting.

What? I said it had S4 T2 rotors...8.5:1.

 

Literally just printed this to keep in my binder of notes. Simple/obvious information but still a nice quick guide to reference. Thanks

 

i put my fc e shaft next to a fd one i think the fd one was a tiny bit taller pretty sure it was

 

no, it wasn't.

 

I can see the reason why Rotary Engine has such bad name now ... so many XperTZ ~~

*hey look! thiz rotor looks newer must be better ! S4 wat? who carez they all da same anywayz duh of cuz u use newer, newer iz alwayz better!*

 

 

this is not just a rotary engine building issue, its a engine building issue in general. i've taken apart all kinds of "built" engines and 70% or more of the time they're a complete hash of mix matched scrapyard parts slapped together. People generally think saying a rebuilt engine will get a car sold or look more appealing, it usually scares me away from used cars.