heynoman

iTrader: (5)

Hi just wondering if it can be done use 12a rotor housings and rotating assembly with 13bmsp side housings forgive me if this has been asked before I've searched and found nothing . however I did see that mazdatrix did manage to build and 13b rew/msp hybrid engine with the use of GSL-SE 13b rotor housings. So I figure the same can be done with a 12a now before anyone here ask why I would want to do such a thing the real question is why not . i have all the parts to put it together but since I have other engines to build at the moment i don't what to start doing any prep work till I see how others feel about it . Please let me know how you all feel about this thanks

Aaron Cake

iTrader: (1)

No.

To elaborate, the 12A rotors don't have their seals in the correct location to account for the MSP side exhaust ports.

There are probably also some issues with bearing configuration at the front mounting 12A stationaries on MSP irons.

heynoman

iTrader: (5)

Sorry Aaron but you are going to have to be more specific . Are you referring to the side seals being closer to the msp exhaust port if I were to use a 12a rotor ?if so what problems will I run into short term . As far as the stationary gear goes I was planning on using a modified rx8 gears .

Aaron Cake

iTrader: (1)

I do not know specifically if the side seals of a 12A rotor will foul on the exhaust ports. I believe they will if one compares the location of side seals on a 12A rotor to the Renesis rotor. On the Renesis, they move in at least a few MM.

The Renesis rotor also has a 3rd oil seal, the cutoff seal, which prevents carbon fouling of the two inner O-rings.

heynoman

iTrader: (5)

Im positive the side seals will eventually foul as it will be subjected to carbon build up and heat from direct exhaust exposure. It also runs the risk of jamming up and breaking if I don't modify the ports since the edges are really sharp and the seal is not supported as it passed over . I under stand the risk of fouling the oil control rings but how long will it take 1k 5k 10k miles? More ? Less? I think building the engine is completely possible but not with out its drawbacks which is not a problem to me since it will be completely experimental . I really appreciate your input thank you .

diabolical1

iTrader: (3)

of course you can build it, but at the risk of sounding like the foot in your nuts, what is there to experiment with? in other words, what are you trying to prove and to whom?

you could possibly have the rotors modified to suit, but that would only be one of the several pieces of custom (and likely quite expensive) work you will NEED to have done for a successful attempt at the build.

heynoman

iTrader: (5)

Its not about proving anything I just happen to have enough parts lying around to attempt the build . I started this thread to see if anyone can find a good reason for me not to even attempt. I understand that it is not as simple as just slapping a few parts together and I understand that I am going to have to do quite a bit of modifications and that im going to have to use quite a few custom parts I'm not worried about any of those things . I think at this point I just going to jump into it and see exactly why it won't work and what issues I run into that I can't work around . The experiment is to see if I can get the 12a parts to work with the 13b msp parts . Thank you for replying

diabolical1

iTrader: (3)

okay, it may just come down to semantics, but that's kind of what i was getting at. Mazda already gave you all the reasons in the world why you should not attempt it and those reasons are all the modifications they made to MSP rotors that make them different from the older ones (side seal location, the oil seal scrapers, apex seal size, etc.). you could possibly find ways to circumvent some of it (Ito's port modification, 1 piece apexes) but you'll be totally on your own for finding a way to protect the oil seals from the exhaust, and then of course, there's the manifolds, oil pan and a few other things here and there.

if it's just a matter of you wanting to put your parts together and see what happens and when, then go for it. i'd be curious, even if only for the before and after photos.

BLUE TII

iTrader: (9)

No, won't work.

The problem is that for the 13B-MSP Mazda moved the side seals ends closer to the edge of the rotor so they could move the port's opening line closer to 0 deg and make up the rest of the timing to 0 deg with the rotor bevel.

If you put 12A rotors/seals in the 13B-MSP side housings the leading end of side seal will fall into the port on the opening line and crash into the closing line breaking the seals.

Yes, you can make it work.

You could machine the 12A's rotor's corner seal to capture the leading ends of longer side seals so the side seal cannot drop into the port further than the corner seal.

Or you could weld the 13B-MSP side housing's port's opening line so it opens later and re-machine the side housing flat.

Here is old 12A and 13B side seal position relative to rotor edge/corner seal (notice it is about 1/2 way up the corner seal.


Here is 13B-MSP side seal position relative to rotor edge/corner seal (notice it is above the 1/2 way point of the corner seal.


Here is the mod you can do to corner seals to keep the leading edge of the side seal from dropping into the port.


Here is 13B-MSP port opening line.


Here is old 12A/13B port opening line ported to max early opening in order to keep leading edge of side seal from falling into port (~24 deg ABDC).

heynoman

iTrader: (5)

True one of my biggest worries is the oil seals burning up and It is true that mazda did set up a lot of reason so that I wouldn't attempt . But I'm very curious to I will keep you posted as soon as I start working on it once again thank you for all your input

heynoman

iTrader: (5)

I thought about running a modified corner seal just like the one you have picture but I've ran large street port where the side seal run pass the edge and it will be easier to port a smooth transition for the side seal to ride on and there will be no edge for it to snag on . The side seals space difference is almost exactly double the distance for the 12a compared to the 13b msp I think I measure 2.75mm further in from the edge at the widest point near the corner and 1.5mm difference in the center . I think at this point I will start working on it and keep you guys posted . Thank you