needing exhaust advice

ran83 · 05-23-2013, 10:44 PM

So i did a full custom exhaust my self to my factory 12a. I whent with a header based off of racing beats basic model, running into 2 3/4 pipe with a high flow cat into a off brand
N/a "turbo" muffler.... Heres the problem ..... It sounds terrible on top end. Below 4000 rpm it sounds like a veast but on the top end i have way too much rasp or rattle- ish sound. Kinda sounds like a cross between a lawn mower and a pissed off bumple bee in a tuna can.... Now before any one jumps in my ass i know that the muffler is gonna be the first thing brought up but do know people using similar set ups with same muffler on piston motors and they sound great.... But if it needs to go then so bee it but would i be better off doing away with the cat and doing a resignator or should i rethink everything and go a new rout.... Any suggestions. I have money and or tools benders welder and knowledge at my disposal...looking at like $350 to work with...

GySgtFrank · 05-24-2013, 12:02 AM

The exhaust on a rotary is totally different than for piston engines. The exhaust gasses are much hotter and flowing a lot faster. Which is why the normal thinking for piston engines doesn't work.

My suggestion would be to add a resonator or muffler inline ahead of your final muffler. You didn't mention what gauge pipe you used. The rotary requires a heavy gauge pipe, typically 14 gauge, or the high energy exhaust pulses will cause the pipe to "ring" making it sound "tinny/raspy". This is why the Racing Beat system is so heavy.

On muffler choices you do not want to use anything that has glass packing materials. The heat of the exhaust will burn/blow it out in short order. Again the Racing Beat mufflers are made for this. Some turbo style mufflers will also work, but they will be loud because they do not slow down the exhaust very much. You just have to check out the construction of the muffler first. Another route some have used is to build their own muffler using stainless steel wool as packing inside the case.

Hope this helps.

t_g_farrell · 05-24-2013, 07:36 AM

RB makes the best bolt on solution, but its pricey. The street port long primary is the best.
They are well made and last so picking up a used one is an option, I got mine for $400.00.

You can read the tech articles on their site to gain a better understanding.

http://www.racingbeat.com/mazda/perf...y-exhaust.html

ran83 · 05-24-2013, 02:29 PM

Yeah gunny i think i am gonna havr to gi with a new muffker. But i am running 14 gage stainless Nd believe me it is plenty heavy lol.... I seem to thing doing away with the high flow cat and switching for a reignator will be my besst option along with something racing beat has ro offer.

one320fc · 05-24-2013, 02:47 PM

I am currently building my 12As exhaust, its not running yet so not sure how its going to sound but I bought a chamberd muffler hope it makes it more reasonable sounding!

GySgtFrank · 05-24-2013, 07:04 PM

Quote:

Originally Posted by one320fc

I am currently building my 12As exhaust, its not running yet so not sure how its going to sound but I bought a chamberd muffler hope it makes it more reasonable sounding!

I went the same build it yourself route as well. Used the Spin-Tech mufflers, no packing, basically similar in design to the chambered. They sound good, not tinny or raspy with a nice snarl. Problem is they are almost objectionably loud. When I get a round tuit I plan on trying some of the self adjusting baffles from Rocky Mountain Performance.

http://www.rocky-mountain-performance.com/

They're mainly for motorcycles, but I figured it can't hurt at this point to give them a try. SS mufflers are pricey and I'm stubborn, not to mention cheap.

Rot · 11-21-2013, 10:42 PM

Again, racing beat is the best in exhaust for your 12A there's some set-ups to choose from, the best for performance is the road race combination is a true dual exhaust system, the only problem; is expensive!

eprx7 · 11-25-2013, 10:23 PM

I will also go with the racing beat option. I have been using the racing beat dual pie header and the street port dual exhaust with the 2 presilencers. I have used the exhaust over 6 years. I don't drive the car much on the street but if I go on a long drive i will put ear plugs in because it does drone at highway speeds, but my car is also gutted which makes it a little echoy. I use it as a autox car and a track day car mostly, and it has held up well to the heat of the constant high rpms at the track. so if you only have $350 to spend try looking for a used exhaust. they do come up every now and then.

05-23-2013, 10:44 PM	#1
ran83 Rotary Fan in Training Join Date: Apr 2013 Posts: 72 Rep Power: 13	needing exhaust advice So i did a full custom exhaust my self to my factory 12a. I whent with a header based off of racing beats basic model, running into 2 3/4 pipe with a high flow cat into a off brand N/a "turbo" muffler.... Heres the problem ..... It sounds terrible on top end. Below 4000 rpm it sounds like a veast but on the top end i have way too much rasp or rattle- ish sound. Kinda sounds like a cross between a lawn mower and a pissed off bumple bee in a tuna can.... Now before any one jumps in my ass i know that the muffler is gonna be the first thing brought up but do know people using similar set ups with same muffler on piston motors and they sound great.... But if it needs to go then so bee it but would i be better off doing away with the cat and doing a resignator or should i rethink everything and go a new rout.... Any suggestions. I have money and or tools benders welder and knowledge at my disposal...looking at like $350 to work with...

05-24-2013, 12:02 AM	#2
GySgtFrank Professional Stick Poker Join Date: Feb 2011 Location: Stafford, Ks. Posts: 1,011 Rep Power: 16	The exhaust on a rotary is totally different than for piston engines. The exhaust gasses are much hotter and flowing a lot faster. Which is why the normal thinking for piston engines doesn't work. My suggestion would be to add a resonator or muffler inline ahead of your final muffler. You didn't mention what gauge pipe you used. The rotary requires a heavy gauge pipe, typically 14 gauge, or the high energy exhaust pulses will cause the pipe to "ring" making it sound "tinny/raspy". This is why the Racing Beat system is so heavy. On muffler choices you do not want to use anything that has glass packing materials. The heat of the exhaust will burn/blow it out in short order. Again the Racing Beat mufflers are made for this. Some turbo style mufflers will also work, but they will be loud because they do not slow down the exhaust very much. You just have to check out the construction of the muffler first. Another route some have used is to build their own muffler using stainless steel wool as packing inside the case. Hope this helps. __________________ 1988 N/A SE 2+2, dead stock and staying that way. 1979 SA22C stock? Not so much. http://rotarycarclub.com/rotary_foru...ad.php?t=15585

05-24-2013, 07:36 AM	#3
t_g_farrell Waffles - hmmm good Join Date: Aug 2008 Location: Huntersville, NC Posts: 757 Rep Power: 0	RB makes the best bolt on solution, but its pricey. The street port long primary is the best. They are well made and last so picking up a used one is an option, I got mine for $400.00. You can read the tech articles on their site to gain a better understanding. http://www.racingbeat.com/mazda/perf...y-exhaust.html __________________ 1980 GS stockport, Fat Nikki, RB Dual Facetfuel pumps, Holley regulator, RB Street port exhaust, 2GDFIS, MR2 MK I electric fans, 2G strut bar, relayed fans, lights and fuel pump, LEDs Project Fat Nikki Budget 12A rebuild Video setup < $30.00

05-24-2013, 02:47 PM	#5
one320fc one Apex @ a time Join Date: Feb 2008 Location: Culpeper VA Posts: 272 Rep Power: 18	I am currently building my 12As exhaust, its not running yet so not sure how its going to sound but I bought a chamberd muffler hope it makes it more reasonable sounding! __________________ 1983 Limited Edition SOLD 1977 Mazda REPU I will work on it one day I sware!! 1987 T2 um after the repu is done?? 2013 Chrysler 200 DD 2009 Dodge Journey 94 Volvo 850 N/A The slowest car I have EVER owned!!!

11-25-2013, 10:23 PM	#8
eprx7 Rotary Fan in Training Join Date: Sep 2008 Location: Copley, Oh Posts: 38 Rep Power: 0	I will also go with the racing beat option. I have been using the racing beat dual pie header and the street port dual exhaust with the 2 presilencers. I have used the exhaust over 6 years. I don't drive the car much on the street but if I go on a long drive i will put ear plugs in because it does drone at highway speeds, but my car is also gutted which makes it a little echoy. I use it as a autox car and a track day car mostly, and it has held up well to the heat of the constant high rpms at the track. so if you only have $350 to spend try looking for a used exhaust. they do come up every now and then. __________________ 1979 SA F Prepared solo/ Track day car 12a w/Weber carb,RB header and exhaust, Ground Control coilovers, camber/caster plates GforceEng.panhard rod w/ tri-link,Panasports wheels w/Hoosier slicks.

05-24-2013, 02:29 PM	#4
ran83 Rotary Fan in Training Join Date: Apr 2013 Posts: 72 Rep Power: 13	Yeah gunny i think i am gonna havr to gi with a new muffker. But i am running 14 gage stainless Nd believe me it is plenty heavy lol.... I seem to thing doing away with the high flow cat and switching for a reignator will be my besst option along with something racing beat has ro offer.

11-21-2013, 10:42 PM	#7
Rot The Newbie Join Date: Aug 2012 Posts: 13 Rep Power: 0	Again, racing beat is the best in exhaust for your 12A there's some set-ups to choose from, the best for performance is the road race combination is a true dual exhaust system, the only problem; is expensive!