diabolical1

iTrader: (3)

you're not seeing discussion because you didn't seem to come here for one (which is fine, in general, i guess ... but kinda pointless when you REALLY think about it). you had an idea, you gave it some thought and you posted about it. again, all of that is fine.

the discussion ensued and then you proceeded to either steamroll, ignore or otherwise reject any input. no one said "hey, Jush, it's a good idea. go for it." (at least no one did so without facetiousness or a knowing smile) and it's not what you want to hear. that's pretty much it. i've been here long enough to see that experience matters and if you stick around and open your mind a bit, it's likely you will see the same.

in not so many words, you have stated that you are basically going to do what you're going to do, and again, that's fine. it's your car, your time and your life - make yourself happy. no one here is cramming anything down your throat and if someone was saying do x-y-and-z because i said so, i missed it. what i saw are people that have done what you're proposing and are saying don't waste your time because of x-y-and-z.


real life sacrifice??? really? what practical reason can you come up with for running pipe under the axle? note i said practical, not personal. aside from a handful of old Gen I race cars, i can't remember seeing anyone go that route (and that would have been circa '92) and i'm only mentioning it now to show you it's fairly common knowledge, but not many people care ... and rightfully so because if you gain say ... 15 hp from a header, then you're already at +12. you seemed to have glanced over THAT part of J9's post, so it needs to be included.

also, what about the oil pump, water pump and running a fixed wheel instead of a transmission? any thoughts on a real world solution for those parasites? yes, i am being an *** now, but it's simply to illustrate you're going to be hard-pressed to find an honest-to-god new idea with these cars.

MosesX605

Just trying to save you from yourself. You'll miss your hearing when you're older.

It may not show through my crusty exterior but I too was young, dumb and almost entirely deafened by a rotary. You'll learn.

Jush

iTrader: (2)

Wow I don't even know what to say, you guys are harsh.

I don't understand where you guys are getting the notion that I'm not open minded, but this is the internet and everyone knows everything so I'll let it be at that.

Anyways I'll post results whenever I get around to this.

Seriously, I'm open to anything, not saying I don't want a muffler, not saying I won't go over axle.

My lack of communication doesn't mean I'm not thinking about everyone's input, seriously. Any help is awesome I just need to figure out a starting point and I'm trying to start small, That's why I want to avoid the over axle and that's why I want to avoid a muffler.

Not to mention I'm cheap!

Don't call me young and dumb please even if it's true it shouldn't be relevant, I hate this arguing bs, this isn't what I came here for, Honest!

rotarygod

iTrader: (1)

Here's my unsolicited take on this. I enjoy trying things. I enjoy trying things that others say won't work. I look at failure as a learning experience although I don't intend to fail. I say if you have an idea, try it. Don't worry if others disagree with it. Yes there are some tried and true methods that work well but that's not to say that there isn't something else good left out there.

My personal favorite exhaust would be a long primary which is collected at the rear. A stock 12A has very tiny exhaust ports. Very very tiny! The downside is that a 2" standard pipe is going to be a huge velocity loss and is unnecessarily large. If you were to use a smaller primary pipe, collecting it at the back may no longer be the best option. Since I've never played with a 12A all I can recommend is to try something. I'd start simple at first. Start with a standard header and try a new one of the same length will smaller primaries. Note the change. If it's better, use the new design. If it's not, don't. Then play with the collection point. You get the idea. I'd do this before getting into more abstract ideas such as the exhaust box.

Your engine flows so little that a full muffler isn't going to hurt as long as it's a good design. A glass pack style muffler isn't recommended as a front muffler, as in a pre-silencer, but at the back it'll be fine. Especially from a stock port 12A. A Dynomax Superturbo would be a nice choice. You won't need anymore than a 2-1/4" pipe after the header collection point so either matching it in size at the muffler or going to a 2-1/2" through muffler would be fine. It wouldn't be all that loud. Keep in mind that the sooner a rotary exhaust is collected, the quieter it is. The tone is also higher. A longer header is louder and lower in tone approaching a lawnmower when fully uncollected.

j9fd3s

iTrader: (3)

not trying to be, but you have to realize that these are old cars and people have tried basically everything you can think of as mods already.

with the rotary it is very easy to arrive at an exhaust that is loud and slow, fast is a little harder, and fast and quiet is difficult.

people have run side exhaust before, and it usually is too loud. i know the volvo people do side exhaust and its fine, but the volvo engine just doesn't have anywhere near the exhaust energy that the rotary does. even the rotary race cars had to run mufflers....

actually if you want an interesting data point, the Mazdatrix people found that they made MORE power with a LONGER exhaust. https://www.mazdatrix.com/pictures/f.../ep120502f.jpg

so if you must do a side exhaust, than do a side exhaust, but don't say we didn't warn ya

Jeff20B

iTrader: (13)

That's where I'm at these days. If it wasn't for the previous failures I've built, or should I say learning experiences, I wouldn't be fast and quiet today.

mustanghammer

iTrader: (3)

The one I saw looked like a Mazdaspeed laval rock muffler. Saw it after exhaust heat caught the fiberglass body on fire!

j9fd3s

iTrader: (3)

true!

mine is unloud, and decent in the power dept, but it was also stupidly expensive, and its literally melting off the car...

mustanghammer

iTrader: (3)

Saw this Mazdatrix setup at Mid Ohio at the Runoffs. It was dead quiet and the car was REALLY fast. That car has a street ported 13B.

wankel=awesome

Mid Ohio

joshhallow

cant wait to see a video for this.

Arcolithe

and here I am trying to find the most quietest exhaust since I live in one of those high-ordinanced neighborhoods.

now that I'm running a fuel cell in the trunk I want to try this!

now that I run a fuel cell I must try this!
how heavy would the extra piping be to run two mufflers+1 silencer?

NanaimoRx-7

Update from OP?

Don't make me go out and unbolt my header from the rest of the exhaust and take a video to make this thread get a 5 star rating lol

JSmall

^^ I've been tempted to do this lately, but don't want to scare the neighbourhood haha. I need a new exhaust though hmm

Jush

iTrader: (2)

Going to take time! I'm a little discouraged atm with a few other things I must tend to.

My window stopped working so I'm going to get rid of the electric motors and swap in some crank regulators instead.



BTW to all the Americans here happy 4th of July!

NanaimoRx-7

I hate the power windows in my GSL, they don't go down all the way and they're slow. I miss the manual window regulators of the SA lol

Jush

iTrader: (2)

So as I near to the day I experiment I am constantly thinking about how this should go, and after you guys had mentioned the Megaphone idea I thought that maybe a reverse megaphone would be awesome for reducing from the collector

j9fd3s

iTrader: (3)

2.5" is big for a collector on a 12A, even the P port race cars in the 80's were using like 2 3/8" collectors.

i think you'd be happy with 2x2" pipes into a 2.25" pipe.

or actually just run 2x2" pipes and don't collect at all. you don't get any scavenging, but it seems to be lower restriction

Jush

iTrader: (2)

I've been debating fabbing my own header all together without collecting as you said.. Only problem is getting a header plate as a starting point.. Also would be more difficult to put a muffler on a dual system. Either way, is there anyone that sells header plates (Not sure on terminology)

Also the material for the header would need to be way thicker..? Which may be difficult to source.

j9fd3s

iTrader: (3)

Disassembled Road Race Header Kit for 74-85 12A - Racing Beat

Engine-to-Header Flange for 74-85 12A - Racing Beat

Collector/Megaphone Exhaust Outlet Assembly for RX7 1975-1985 - Racing Beat

Jush

iTrader: (2)

That is awesome, thank you.