787B

FB = single

FC = dual

FD = single


Why did mazda put a dual exhaust on the FC?? And then go with a single exhaust for the FD which is a higher performance car??

Does this show that single is better??

I think so!!!!! Maybe that is because I am getting my single system installed in a week though.

Felix Wankel

Lets hit the strip and see whats better....

(Both my FB and FC have duals )

Scott 89t2

single flows better, dual looks better.

mazdaspeed7

Dual isnt necessarily better than single. Its all in the way its designed. I good single exhaust will be be better than a ****-poor dual exhaust, and a good dual exhaust will be better than a ****-poor single. The single exhaust can make more peak power, but the powerband over which it is the most efficient is smaller than a dual setup. That is why you see single more in racing and dual more on the fast street cars.

Icemark

One word why there is a single on the FD:

Weight.

Cost and power were not as much of an issue as it was on the FC, so Mazda could use more engineering time and materials to shave the weight on the FD.

NZConvertible

I'd add another reason: space. Designing a car is all about compromise; Mazda decided tp free up room by fitting a single. Look for room for a dual under an FD; it ain't there!
And I've said it before and I'll say it again. For turbos and NAs with a merged header, dual has the potential to flow more than a single, if you use nice big pipes. Dual 2.5", using the same type of mufflers, will outflow a single 3".

supergoat

Dude, no one cares you are going single; you don't have to try and defend yourself.

mazdaspeed7

Of course, the dual 2.5" pipes have almost DOUBLE the volume of a single 3" pipe. That is NOT a legit comparison. Why dont you compare dual 2.5" pipes to a single 3.5" They have the same volume(yes I calculated it, the exact pipe diamter for single is 3.545" to have the same volume as 2 2.5" pipes). Im using the pipes as 2 dimensionsl to simplify this some. The volume would be the cross sectional area, and the perimeter would be the surface area.

dual 2.5" pipes have the same volume as a single 3.5" pipe. But, the dual 2.5" pipes have 43% MORE surface area than the single 3.5" pipe. The air along the sirface of the pipe flows much slower than that at the center of the pipe. So, even though the dual 2.5" pipes have the same volume, they simply cannot flow as much air as the single 3.5" because there is more air along the surface of the pipe.

BTW, a merged header defeats the purpose of having 2 pipes, b/c when you split them, you create A LOT of turbulence, which also slows down the airflow.

RXTC7

I agree with all of the above. Weight and space wee probably 2 major points of the FD having single. Dude be happy with your decision and stay with it. I like my dual exhaust because that is the way the FC looks the best to me. Also I like the sound of dual better to. Whatever floats your boat.

RXTC7

what about 2 3" pipes. How big would the single need to be to match that?

mazdaspeed7

Who was that directed at? If it was me, I have no need to defend myself. I could care less of what other people think of my decisions. I was simply trying to clear up misconceptions people had.

mazdaspeed7

4.242"

TwinCam13BT

Ask god why he gave humans 2 nostils....

Duals are the best in the world. Period.

(Ok, maybe Im a little biased since I have the RB turbo back)

NZConvertible

Not a legit comparison? You've missed the point. Why use one pipe when you can fit two? Mazda engineered the car to fit two mufflers. Why waste that?
You're dead right about the 3.5" pipe, but 3.5" stuff is alot more expensive than 3" (dunno why, lack of demand probably) and the larger radiuses of the bends make tidy installs trickier. But there's nothing stopping you doing it.

mazdaspeed7

My point was you were comparing 2 pipes to a single pipe only a little bigger. Of course the 2 pipes are going to flow more, any 5 yr old could have told you that. Why not compare 2 pipes to a single pipe that has the same volume inside the pipe at the 2 pipes?

If dual is so good, why do ALL of the road racers use tuned single systems? Because they make more power, period. https://www.rx7club.com/forum/showth...hlight=exhaust Go read that thread, it should help you inderstand a little better why dual is NOT necessarily better than single.

RETed

FD was all about lightness (weight).



-Ted

10TH_ANNIV_T2

Like I said before in the other threads, STYLING is probably the primary driving reason the FC has duals. From all of the other threads you should know by now that it is possible to optimize either design if cost is not an issue. Since cost is an issue for most, typically there is a compromise-- whether it's Mazda for styling or packaging reasons, a racer for performance or weight, or a consumer for sound and appearance.

Now, about a 10th Anniv not being worth any more than a regular 88T2....

MikeL

I don't know which is better, single or dual but, I do know these things:

The largest pipe diameter is needed near the engine. Farther towards the rear, the pipe diameter can be reduced and should be, to help with noise.

A car company looks at every dollar. If there are to be 100,000 cars made, a $10 cost increase in an exhaust system means an extra $1M increase in the cost of the model run.

Mike

Wankel7

Dude, I thought it was a dual design so people can get these HUGE 4.5 inch diameter N1 Dual exhaust tips.

At least that is what I think

I love my N1 Duals

James

MaxRX7

who says "duals are so great" ?

Felix Wankel

I like my duals because they are QUIET. **** the power difference. I don't want some obnoxious *** car that can't even break a 14 (been there already with my GXL).

I'll keep my cars quiet and let the *** whooping commence

Flobb

The FC is the stlye era of the RX-7. (they all have nice style though) I say this because of the fact it was the only generation with a convertible. The stock duals are for looks.
True dual will get you the most power, but that applys to N/A's.

mazdaspeed7

That is not correct. True dual gives a broader powerband than most single systems, but a tuned single system can have more peak power. Theres not much tuning you can do to a true dual other than an x-pipe/h-pipe. And that makes the powerband very pronounced and very narrow.

True dual is seen a lot because it needs no tuning out of the box, and still makes impressive power. But if you look at the people who go all out in search of every last ounce of power then can possibly get out of an engine, they all have tuned single systems. Road racers define this category. Ask ITSrotary7 and FPrep2ndGenRX7 or any of the other road racers if they run dual or single exhaust and why. They will say single b/c it makes more power.

RX7_Racing2001

this is a great looking tip.HAHAHA

AcmeSkater

lol, that pic was funny. Doesn't a dual make more back-pressure?? maybe not, im not sure, but if it does then it would be better than a single on a N/A due to the 5th and 6th ports. But as i said I don't know if it does. someone let me know??