hmmm u guys are makin more of an argument of this then there needs to b. In my opinion, jus get the exhaust system u like. If it doesnt produce mass power u can always make up for that under then hood rite? second, how would u feel spendin money on a exhaust that doesnt sound how u want it to? then u would have to listen to it every single day... it would drive me nutz. im planning on gettin the racing beat dual pipe setup mainly jus cause of the look and sound ... im not really worried about the hp gain cause i dont need a 500hp beast. but thats only my opinion, if u think im totally wrong then i couldnt really care less lol

 

thank you 604, the resounding voice of logic surfaces.

this is similar to what i said about preference in loss of weight.

 

ok, I'm going to try this one more time before I give up.

When you connect a certain type of pipe to the source of the exhaust gas (the engine), that pipe becomes the primary restricting factor limiting the source's (engine) ability to flow. Hence my muffler-on-engine example.

Try harder NZ, because this example is very fitting and far from bizarre. But I will try to make it even simpler to understand, although you claim that you don't need help visualize due to your profession.
Imagine a muffler that's bolted onto the end of a header. This muffler has already restricted the engine's ability to emit exhaust gas, even by modifying the muffler tip to a 10 foot long, 5" dual at the end of this muffler is not going to help the situation. But according to your cumulative theory, oops sorry, "proven engineering" I should say, it will help the situation. We all know that it obviously won't.

And regarding weight. 1% or not, whether you can feel the difference or not, it will always be an important issue to some people. I don't understand how you can be so stubborn headed to not see how this 1% can make a contribution to the total weight reduction. According to your theory, people might as well not strip any weight off their cars. Just becuase you can't feel the before-after effects of removing a single part (whether it be the carpet, the tar, or an exhaust pipe in this case) off of your car shouldn't be the reason to stop attempting to make your car lighter.

And I'm personally getting really sick of this, as we have already had the same discussion before. And frankly, I'm also getting sick of your condecending tone. Maybe it is just me, but I always feel like you're trying to make yourself sound like a fluids god explaining things a retarded kid.

This is how stubborn you are, even after this lengthy discussion, you STILL used the same damn double 2.5" is better than single 3" example.
https://www.rx7club.com/showthread.p...hreadid=241029

This is the last pipe-flow discussion I will participate with you. I'll let you educate this forum w/ your knowledge and proven engineering.

lates,

howi

 

would you just give it a break and go put a single 5" strait pipe on your car already since you are so convinced it is better. and then once your ears bleed, and hou have an exhaust that flows beyond the ability of your engine and actualy reduces the overall power, come back and admit you were wrong. k?

 

well how much more power does a 3 inch dual make over a 3 inch single if it's the same developer?

 

With the ones I have been playing with on Non-Turbos, they are the same, just the dual is much quieter (because you can get the same flow with the duals, so you can use a more restrictive muffler).

See there are other issues as well... noise, style, exhaust velocity, and whether the system is to be used on a non-turbo with its heat and noise issues, or a turbo (which is much quieter and does not have the continuing burn that non-turbos do)

 

I think this thread is over as the questiona t hand has been answered and debated to death. I just wanted to point that out.

 

personally, I am more interested in reducing exhaust volume. I think we've kinda hit the diminishing returns wall with exhaust flow. I mean, that engine can only squeeze out so much air, and can only make so much power going from 2.5 to 3 inches. Personally if I could trade 5hp to knock off 5 of 100db of my car(hehe it would need it if it were that loud) hell yes I would do it. Could duals get me that? maybe. Probably. I don't have enough experience with exhaust and muffling though, but I could learn a lot hearing you guys duke it out over something like that instead. And it would be useful.(at least to me)

 

where did you get that from?
when did i ever say i'd go for a 5" staright?
when did i ever say bigger is better?
did you even bother reading the thread i attached (https://www.rx7club.com/showthread.p...threadid=241029)?

fyi, i have a 2.5" straight on my t2.

howi

 

You're absolutely right. Exhaust selection usually comes down to cost and noise, despite what people may claim. They get what they can afford, hoping to avoid anything that sounds bad. Forum threads titled "Which exhaust sounds best" are far more common than those titled "Which exhaust makes more power."

OK, now I see where you're heading, and you're miles off base. You're changing the length of the system! Add length to any flow system and the restriction obviously increases. But we're talking about the exhaust on a car, which runs right to the bumper. Its length does not change! We're discussing different pipe configurations, not lengths. Sorry, but this "explanation" doesn't prove anything, except that you don't fully understand the subject matter.
1% is 1%, no matter how much you talk it up. Those who claim a single exhaust gives better performance because it's lighter may be technically correct, but I'd love to see them try to actually measure that improvement.

That depends entirely on the engine's output. The power difference between 2.5" and 3" on a relatively stock engine is still very noticeable (and worthwhile), but on a highly modified engine a 2.5" exhaust will be strangling it, and changing to a 3" exhaust would have a huge effect. Power is roughly proportional to the engine's airflow, and restriction increases to the square of that airflow (as Evil correctly pointed out), so more power always needs more exhaust. That's why 3.5" systems are now gaining popularity.

 

Yes, it does depend on the engine's output. I think we can guess that the max for any street n/a rotary, though, (turbo's don't have as big of a problem with noise) 3" is about as big as anyone is going to EDIT:need (well... n/a 20b?) going to the y or otherwise. So from the Y back, we're looking at one straight 3" pipe all the way back(well, after the header that is) as being the LEAST restrictive method of getting rid of all of that hot air. Now, since you can't really street a straight pipe like that on an n/a rotary, we're going to try to make it as quiet as possible without losing power, and that is where the argument is(IMO).

EDIT: I also realize that everyone has a different definition of "streetable" but oh well...

 

hahah i kno i already made my point in this thread but i have to comment on something. When people talk about the weight difference between single or dual's. its such a minimal difference it wouldnt matter. I think it would b far more effective if the driver lost some weight instead ^_-

 

ok, dude heres the thing, if you have a racing beat or ither header that has dual pipes, then you would make a tru dual setup, with each pipe from the headers each having their own piping and muffler.

if you are running a single pipe collector like the stock one, a single setup is better and will gain you more power than having a single collector having to split into 2 pipes like the stock. I have a 2.25" single piping on mine with a port matched exhaust manifold.