Can RX8 Rotors be used in series5 or 6 Rx7 13B's
 

I know i heard somewhere that the RX8 rotors's corner seals are a bit differant in material, can it still be used in a 13B, series 5 or so, the reason i would want to use the rx8 rotors is it has higher compression and is lighter and newer technology. i am thinking of building a peripheral port motor later with rx8's rotors

Then there is a place here who does the same ceramic coating technology as used by NASA, they coat parts, which reduce temp etc and longer life of parts.
It is also the same as what Mazda used in the 787B which had ceramic coated housing surfaces and rotors.

any comments?


Philip

SA

for info my 8 now has 85000 miles on and stil going 100%, no lights, no start problems, nothing

I've seen comments here and there that the Renesis rotors are fine for previous 13Bs. Don't recall specifically about Series5 one way or the other.

Probably someone like Paul from Mazmart would be perfect for answering your question.

Nope, it doesnt work

oh and it will be great if u can use the SEarch function on the of the site.

Yes they work in 13B engines. I would have the apex seal grooves milled out to accept the deeper 13B apex seals though. You will not need the cutoff seals either. Don't forget to use the corresponding counterweights. Keep in mind though that no one has made more power with Renesis rotors in 13B engines than the 9.7:1 compression RX-7 n/a rotors have made.

Thanks

I thought the higher compression and lower weight would have made a differance.

I dont want to turbo, NA only.

I am thinking of getting reliability up as well, surely the 8's rotors is better designed looking at oil passages / bearing etc. or is it all the same i dont know how it compares.

I can also say, my 8 is fully synthetic (engine, gearbox and diff) Royal Purple and not looking back, it is now 35000km already (22000miles) in all i have 85000miles on!

Philip

If you are building a nonturbo 13B, just stick with the 9.7:1 n/a RX-7 rotors. They'll be just fine. You won't see a benefit from running the Renesis rotors but you also won't have the shorter apex seals to worry about when crossing the exhaust ports.

it wont work without some mod

RacingBeat has the info on their site.

Yes they will. You need to use the Renesis counterweights for obvious reasons and the Renesis eccentric shaft. The 13B eccentric shaft will physically work but the oil passages to the rotor bearings are different by a couple thousandths of an inch. The bearing to eccentric shaft clearance is also slightly different. It's not enough to see with the naked eye and will probably be fine but why risk it? There are people that have just dropped them in and run them though. There is no "mod work". Just careful attention to the parts used. If you intend to keep the RX-8 apex seals, it is recommended not to port the 13B exhaust ports any wider. If you do port them wider then you need to mill the rotors to accept the 13B apex seals too. You do not need to run the blowby rings on the Renesis rotors when using them in the 13B. You should also use the 13B corner seals as they don't tear up the 13B housings as bad as the Renesis corner seals do. These seals can work with the Renesis apex seals even though the cutout is deeper but may as well use 13B apex seals too. Since the side seals in a 13B don't cross over a hot exhaust port, you can also use longer side seals that are cut to fit so you have better sealing. It's not hard to make Renesis rotors work in a 13B. You just need to know what you are doing. The S5 n/a rotors make more power though so what's the point?

Thanks RG

the reason i also thought of it is the RX8 rotors are much cheaper than any other rotary rotor (strange)
so if i build a well ported na motor, then why not use newer and cheaper rx8 rotors.
The series 5 motor i have is actually a turbo model, but i think the compression is not much less than the na, about 8,.. i think.
I wont port wider on the exhaust side, going peripheral port did cross my mind though.

thanks for the comments, i will look at the racing beat site as well.

i guess they made the apex seals short to save weight (centrifugal force) for the higher revving.


I did search in beginning but didnt get much, but i remember that some time i did see a thread on the corner seals eating plates, that thread i couldnt find, so i asked.

i am also only running a gprs connection from my cell phone to the pc, firstly it is very slow, secondly we pay a big fee per megabtye, yes per meg. if i am on for a few hours downloading all the time it becomes very expensive.



thanks

The Renesis rotors are about $900 per pair and the 13B rotors are about $1200 per pair so there definitely is a price difference. However the 13B rotors have taller apex seals which are stronger if you are running the 2 piece seals (you should!). I personally don't like the idea of running the Renesis apex seals over the peripheral exhaust port even though I know the strength differences between them and the stock 13B 3 piece seals. I would mill out the Renesis rotors to the proper depth for 13B seals but unfortunately this is such a fine process to do that you will probably end up making the seal gaps slightly wider in the process. May as well machine them out to 3mm then. By the time you do this, they are no cheaper than the 13B rotors and remember you still need to buy counterweights and another eccentric shaft.

You "should" also use the the Renesis stationary gears with the Renesis assembly as well. When you look at the price list for Renesis parts, you'll see 2 part numbers. One for the auto engine and one for the 6 speed. The difference is in the bearings. The 6 speed engines get better bearings than the autos so choose your parts wisely.

Very interesting, i see what you mean, it is a catch 22

so RG if i want to build a peripheral port NA motor, what would be the best for power and reliability. It looks to me to basically have the renesis motor but with say s5 or so housings which are peripheral ported, and the s5 2 piece seals fitted (made to fit) otherwise the stationary gears, shaft and weights must be new which will be a lot of money.

or just take my s5 motor, make it p/port, use decent seals. (and use royal purple oil) and a for away, much cheaper i guess.

For a peripheral port n/a engine, stick to a 13B. Get ahold of some Turbo II end and intermediate housings so you can fill their intake ports. I wouldn't personally use 6 port housings as a base for a p-port engine. If you can make your own p-ports, copy the factory timing specs. Paul Yaw has them on his website. Otherwise the RB housings work great. Use the 89-91 n/a rotors. Then use your preference in seals. It's a pretty simple combination but proven to work very well.