Jeff20B

Yep, it was orange with black on the ribs giving an interesting striped appearance.



FedEx could do it, but their prices may be more. I'll have to box up the plates and gears and weigh it. The discount may bring the total to below USPS.



I already have one decent GSL-SE intermediate sitting here. The other can be had without costing an arm and a leg. The two gears may be a little more difficult as I'd like to use ones with good looking bearings. All the ones around here have a slight bit of copper showing. Some is ok if it's not shiney because it means it has self clearanced, but since the shaft will be different, I'd prefer no copper showing or new bearings.



Well, I know all the rotors will be the lightest 12A '83-'85 type, and since I have at least three sets from which to choose, I can probably come up with all four having the same letter or maybe one + or -. It would suck if they had a spread like A+B, B+C, C+D. I'd have to tear into a fourth core and it would be even worse if it had D+E. That's the worst scenario other than maybe finding a bunch of water damage or broken apex seals.



I'm hoping to get four C rotors because those are presumebly in the middle of the production run weight allowances. They're probably the most compatible with non-factory matched front and rear counterweight set as will be the case with Jeff Bruce's custom rear counterweight. I assume he knows the weight offset of S3 12A rotors.



Since this engine won't be reved to the outer limits, having everything dynamically balanced probably won't be necessary. That'll save some money. Using stock Mazda apex seals will limit this thing to below 8500RPM.



Ok, I think it will consist of these parts:

GSL-SE front cover

GSL-SE OMP routed to the rotor housings or carbs (some 12As had oil injectors)

S4 NA waterpump

S5 front plate with oil pump cavity modification and doubled up coolant seals

S5 or S6 oil pump

Peripheral ported 12A rotor housings

2 GSL-SE intermediate plates for the motor mount studs at the bottom, modded by Jeff Bruce

Y casting middle intermediate

Y or R5 rear plate (17 or 18 tension bolt holes; I'd prefer 18)

dual weber 48IDA

Two racing Beat 12A headers reshaped to fit.

RB dual pipe center section. Two rotors phased 180° on each pipe.

Two free flowing mufflers 4x9x18 to fit side by side in stock muffler location.

Fuel cell with 3/8 send and high volume low pressure fuel pump.



Oh yeah, about the exhaust, I don't think I've mentioned it yet. I wanted pipe sizes for maximum velocity in the RPM this engine will operate. Like a good compromise between low RPM and high RPM since it will be a street driven vehicle. Too many people go to 3" or larger and lose velocity. It's ok with a turbo since most of the exhaust energy is spent pushing the turbo, but since this will be NA, I didn't want to go that large.



I figure with 12A sized exhaust ports, I could get away with the Racing Beat 2" OD pipe with one pipe per phased 180° rotor pair, like the RB single pipe system. I know the RB single pipe system works fine for a streetported 13B in a 1st gen (or in my case, an RX-4 hehe) with the relatively quiet (and relatively restrictive) Primaflow muffler. Since I know a p-port doesn't like a restrictive exhaust, and the low end isn't going to be as strong as a street port regardless of pipe size, all rotor counts being equal (heh), two unrestrictive narrow oval mufflers placed side by side should fit in the stock muffler location. The RB muffler is 8" round and 18" long. I found two aftermarket mufflers 4x9x18". Side by side, they should fit up into the muffler location since it's sorta square up there, and won't be any wider than 8". They'll stick down an extra inch, but I don't think that'll be a problem. The length will be the same as RB (I think stock is longer.. meh). I'll get the offset style so they enter at the top and exit at the bottom much like the stock or Primaflow. The tips should fit under the bumper no problem.



The noise will be whatever a p-ported 12A will normally sound like with a header, single pipe system; one RB presilencer, and an unrestrictive, straight through (though offset) muffler will produce, but times two. It should be plenty loud enough to hear the wonderful 'true' 4 rotor sound coming through, and unrestricted enough for the p-port to breath properly.



You know, if I was doing a 4 rotor 13B, I'd most likely need to use 2 1/4" or 2 1/2" pipe on each rotor pair and I wouldn't be able to get away with the RB dual pipe center section. Not to mention the extra length of the engine, relocation of the front sway bar, not enough 13B parts laying around etc. Besides, a GSL-SE with 12A rotors in it just sounds kinda funny/interesting. We could tell people who ask that it's got 12A rotors in it. Then laugh when it smokes 'em.

z-beater

Another great post Jeff! I laughed at the "only 8500" comment.



I do have a couple of comments about the exhaust though...



When I did my exhaust(turbo) I used a Sprint car silencer and a magnaflow race muffler. It was a little too loud for my taste but later I found out that my problem was a HUGE exhaust leak. Since then I put another maganflow muffler in there.



I agree I would stay away from a baffled muffler. And the maganflow that I have might be a viable option. They run 100 a piece. Just an option for you



I also heard that RB presilencers were really restrictive. I have never done any research myself and this is all hearsay. I am sure that you can do your own investigations. Just what I have heard...

Jeff20B

Yeah, I think Magnaflow is the brand of muffler I found in 4x9x18. The RB presilencers are straight through with an ID the same size as their pipes. It looks like a sort of mesh sleeve of thousands of holes with stainless steel wool between the sleeve and the outer shell. Doesn't look restrictive to me, but then again, I don't know how the pulese are changed as they enter the presilencer.



The presilencers by themselves don't do a whole lot of actual quieting. The exhaust is basically the same dB level before and after. It's just reduced in the upper frequencies. I'm hoping the Magnaflow ovals will have enough muffling for the street. If they don't, I may have to install two narrow cylindrical mufflers parallel to each presilencer.



One thing I'm counting on for helping to reduce total noise but retain flow will be in the natural quieting effect from blending two rotors phased 180° apart. If you've ever heard the RB single pipe system vs a dual pipe system, the noise difference is significant. Even with the same muffler and porting. The dual pipe system is way louder even though it has two presilncers. Why? Because the pulses are kept seperate for a very long time. The single pipe system, on the other hand, has a short primary header and joines together a lot sooner. The quietest (and most restrictive) is the stock manifold where the pulse are joined right after they leave the engine.



Think of a woofer box with two woofers in it. If you happen to hook up one of them wrong, the bass is basically terminated because they are canceling each other out. That's basically what's happening with the stock manifold and the short primary header, to a lesser extent. Keep the pulses seperate for a long time or never join them at all, and you've got a much louder exhaust system.



It's my goal to keep this 4 rotor exhaust system quiet enough to drive on the street without making it so restrictive that p-ports wouldn't work. It'll go like this: rotors 1 and 2, which are phased 180° like stock, will go into one header and then into one pipe of the RB dual pipe center section; rotors 3 and 4 will go into the other header and into the other pipe of the RB center setion. Both will go up and over the rear axle and into two oval mufflers.



If there is not enough room to fit two 2" pipes up and over the rearend, I may have to consider joining both together right after the center section into a 3" pipe. That would reduce velocity and increase backpressure. I'd really rather not do that if I could avoid it.



I'd prefere to add an H pipe or an X pipe at some point in the system, location to be determined for best sound, to keep the whole system from sounding like two 12As reving up together. That was kind of the goal in getting a 90° shaft from the beginning.



What if I added an H pipe right before they go over the rear end? That way the 90° phase offset between the two pairs of rotors won't affect the blending/noise cancellation like it possibly would if I were to add the H pipe further forward in the system; like say right before the center section where the header collectors (Y pipes) are. Yeah, I wouldn't want the H pipe to interfere with the noise reduction effect of the Y pipes at the ends of the headers.



Thoughts?

Jeff20B

I just found the Magnaflow muffler. What if we got two of these and placed them side by side? Think they'd fit in the stock muffler location? Think they'd be quiet enough for the street?



http://www.magnaflow.com/02product/shopexd...main&id=431

z-beater

Jeff, that is interesting on the exhaust and I can tell that you really thought that plan out before deciding. As mentioned you said that it is important to keep the restriction to a minimum. It is hard since the rotary is so loud in NA form.



I ran a RB header to a stock muffer quite some time ago. There were no cats in the system. It was kind of loud IMO. I am sure that with the addition of a silencer or two things would have been different.



That being said I would think that there is some way that you could create a system that provides less restriction and is still quiet.



Here is my reccomedation:



Same header setup as you mentioned

run true duals and two small silencers midway(under the passengers seat). There is a nice little bum there for the stock cat that would house two small silencers nicely.

Then place you h pipe

and finally two small magnaflow mufflers out the back.



I have not taken measurements where your mufflers would sit so I cannot comment if they would work.



Also my magnaflow race muffler is of similar design as the RB one. SS body with a perforated mesh on the inside. Only difference is that the inlet/outlet is 3.5" Sorry, I must have been mistaken.

Jeff20B

When you say to run true duals and two small silencers midway(under the passengers seat), are you tralking about dual pipes and two of RB's short presilencers parallel under the passenger seat? If so, I think the RB dual pipe center section would work better because the presilencers are the long type and we already know it is a bolt-in affair. Or perhaps I misunderstood what you said.

Rxmfn7

Ive just read every page of this thread.. and I have a few questions. I may have missed it in my quick skimming of the pages, but is there a shop where I can call and buy a complete 4-rotor engine? And if so, what is the price?

z-beater

Can I see a link to the RB product...I think that you are on the same page as me but I don't think that I am on the same page as you...

Jeff20B

Rxmfn7, Pineapple Racing may have a 4 rotor just sitting on the shelf ready to be installed in something. Look them up on the internet for phone number, email, location etc.



Z, the RB dual pipe center section is here. They call it the 'street port center section'. Heh, ok. http://www.racingbeat.com/resultset....rtNumber=16398

z-beater

ohhhhh, that is really cool! Yeah my vote is for that!