bryant

I HAVE A 87N/A . WHICH DO YOU GUYS THINK IS BETTER &WHY?

wpgrexx

i have an 86 na with dual exhaust, i don't care about noise level or pollution(sorry to those who do), I wanted the most gains, research said this will give me the most gains

bcty

sorry i love the look of a single.. i think it would be louder than dual but maybe not as much power.. well then true dual.. i say go single!!

dingo

i would say go dual... now someone correct me if i'm wrong, but i've heard that rotory engines don't like back pressure, and the more free flowing exhaust improves performance

rxspd

ok here it goes.
Most power gain: True dual exhaust, no cats, straight exhaust going straight from manifolds or headers to mufflers.
Sound rating:very loud
2nd:Straight single exhaust, no cats straight exhaust from manifold or headers to muffler
Sound rating:Super loud
3rd:single exhaust from y pipe, saves weight over dual from y- pipe, but not as powerfull as true dual or single from manifold.
Sound rating:loud
4th, dual exhaust from y-pipe, heavier, no more power than single from y-pipe.but two mufflers to quiet it down.
Sound rating:quieter

If i was you, i would get up a muffler shop to build me a true dual exhaust from the manifolds, with nothing in it, but mufflers in the end, Make sure to get mufflers with removable silencers, so you can quiet it down some.

Jason

rico05

Single flows the best for cat back, dual from the cat back is quiter, dual from the block back is the best.

autocrash

I was just gonna ask that... (the loudness bit.... ) I think that if I stay N/A for much longer I will be getting a true dual....

TeamWireRacing

I find it strange that a true dual system gets recommended more than a single system, yet when I see any of the fastest ITS RX7s racing, they are all using a single 3" system from a Y-pipe off the back of a Mazda Motorsports header. In many cases the entire system is done in stainless. Speedsource, ISC (Mike VanSteenburg), SDJ, SAS Racing. All these engine builders equip their motors with a single exhaust. I can't believe that they would all be wrong, since they are all equipped with dynos for testing the various configurations.

Disclaimer: My experience is strictly in a racing format. Your street mileage may vary.

JOTALUV1

I THINK THE 2ND GEN RX-7'S WERE MADE DUAL FOR A REASON. I THINK A 2ND GEN WITH 1 MUFFLER IS UGLY AS HELL. BUT HEY WHATEVER FLOATS YOUR BOAT THATS JUST MY OPINION.

banzaitoyota

I'm with TEAM WIRE RACING on this one. But hey, I'm in it for the cones!!

95R2-89TII Ground Zero

I like the look of the dual better, but supposedly the single has better breathability and more hp.

banzaitoyota

MUST NOT KILL THE CONES!!!!!!!!

UniqueTII

I like the look of the dual, but if I could find a reasonably priced bumper cover that has one opening, I'd go single in an instant.

RylAssassin

I have an 88 N/A and im goin single. I did all the research i could and i narrowed it down and asked myself am i doing this for max power or looks and i decided on max power. Two reasons from my research
1) Single is lighter
2) From the research i did i found single exaust can achieve more hp of corse going with no cats in the exaust.

Bill Harrison

Without a doubt a dual exhaust will flow more than a single unless you are talking MONSTROUS exhaust pipe sizes on the single. A 3" single exhaust has a total area of 7.065 square inches (Area=Pi*radius(Squared)), and a 2 1/2" dual has an area of 9.812 square inches - an improvement of 38%. Even a 3 1/2" single only has an area of 9.616 square inches, less than a 2 1/2" dual. And if you went to 3" dual exhaust, the area would jump up to 14.3 square inches, more than a 4" single! So without a doubt you get more flow potential from a dual exhaust. The only drawback I can see is the extra weight, but, in my opinion since our cars HAVE dual exhausts (which by the way MOST other guys with different types of cars STRIVE for.... ), I just find they look tacky with a single. Now that part is opinion, the first part is fact

BDoty311

I have a question. Dont people use true dual because they have 2 pipes going from both sides of the engine. But the 13B only has 1 pipe going from 1 side of the engine. What would the point be of having 2 pipes going to 1 side of the engine??

Sorry if this is confusing, worded it the best i could.

TeamWireRacing

Bill H is correct in that a true dual exhaust has more area of exhaust pipe. The problem may be that the rotary may not be able to use all that area, so it probably acts as a negative more than a positive.

A trend that is showing in some of the race cars I see, and an idea that I have experimented in my mind about, is to run the dual 2" pipes from the Motorsport header, then Y them into a single 3" pipe. Sounds pretty conventional, huh? Well, the key is to create a "merge collector" prior to going to the 3" pipe. A merge collector is a necked-down piece of pipe, say down to 2.25 or 2.5", just before expanding it to the 3".

This accomplishes a couple of things. First, it acts as a venturi for the gases and will actually speed them up coming out of the header. Second, it creates a scavenging effect as the sped-up gases create a low pressure area behind the pulses to aid the next pulse coming down the tube. Third, it combines the gases from each header tube in the 3" pipe, and the gases will "heat each other up". And we all know that hot gases move more quickly than cooler gases.

I guess my concerns with a dual system would be that a) the gases are never encouraged to speed up, they just get pushed along, b) there is no scavenging effect whatsoever, and c) the additional weight from 2 mufflers instead of one, plus the extra piping to make it work.

I would like to see someone do a back-to-back set of dyno runs and post the results. It may clear up a few misconceptions and save people some money too!

benhart21

Aesthetically, I'd go double, but the price doesn't justify the gains to me. Why spend $570-719 on a N1 Dual when you could get something like the Corksport single(if they've built more yet) for $280. Give me the single and the $ I saved can go towards other mods.

Go faster first, look better later is what I say. Then again, my car is there for beating and wringing as much fun out of it as possible, not to sit there and look pretty. Maybe that's why I go through tires so quickly.....?

picazo505

i think that the dual look better on the fc

benhart21

All depends on your view of form vs. function

jspecracer7

I've had both single and dual on my old FC. I think that the single made it look SO much better.

NEED4SPEED'88

I personally think that a single exhaust system would perform much better for a few reasons.... 1) a single exhaust is much lighter 2) it would flow more exhaust through by pressure 3) a single exhaust would improve torque and hp. Dual exhaust is pretty pointless unless you have complete power, delivering enough exhaust to flow though a single piping then branching off through the Y pipe, then through two mufflers. You also have to think about a Mazda Rx 7... it is considered a sports car, of course, what else of making the car look a little more sporty with dual exhaust! The cars that are more sporty often come with alot of cosmetics... too make them appear fast and , but of course the sporty look. I would recomend a single exhaust system!

banzaitoyota

Hey Chris, Have you seen SAS's single exhaust system?
Its supposed to be very nice.

TeamWireRacing

No, I haven't seen it yet, but Carl does very nice work and I'm sure it's a quality piece.

I have seen the ISC version and it's pretty nice as well. Mike has seen as many as 10 or more HP from the exhaust alone on an already prepped engine. Several of my friends and customers are running it with good success. Fully stainless and a bit pricey, but probably worth it if your looking for that final 10 or so HP.

SoloIIdrift

This makes alot of sense, does anyone have a pic of this style exhaust, or even a paintshop diagram.

Would this exhaust be streetable? It sounds like a race-only exhaust.

so Mazdacomp header, then dual pipes running down into one collector near the rear of the car 3 inch, and then a normal cat-back single exhaust hooked up (also 3 inch)?

So basically only one muffler, sounds like it'd be pretty loud.