Hey,

Ok so I was thinking about exhausts... I have heard before, that there is no difference between a good 'true dual' exhaust and a good single exhaust that utilizes a Y pipe. Then why do people flock to the 'true' dual exhausts that are not really true since they utilize X pipes to balance flow.

Also for the Y pipe in the single exhaust, do you add the area from the smaller two pipes when determining the size of the larger single pipe.
2.5" initial piping => 4.9 area 4.9x2=9.8 9.8 area ~> 3.5" diameter

Assuming that my reasoning is correct, whats the difference between a 'true dual' that is 2.5" piping all the way back, compared to a single that is 2.5" to 3.5" single piping out the back? (besides the ability to brag considering the apparent prestige from having a true dual over a single)


Second question...
If there was restriction in the exhaust, where would it be it be less harmful? closer up around the Y pipe area, or further back near the muffler.

 

Injen does NOT have a x-pipe, so i can safely say it is a true dual exhaust.
The exhaust is just a personal thing, they make different sounds thats about it. Havin ridden in a bunch of different G's, i can only tell you that the powerband will be moved a little only when you have more mods than just an exhaust.

 

great question, anyone with knowledge please chime in, im interested to know about this as well

 

bump

 

so what system is more efficient for street driving (power down low)...stock exhaust with minor bolt ons (intake, spacer, headers, HFC) or dual exhaust with the X pipe with the same bolt ons?

 

Thanks for breaking the X/Y pipe part down, but this wasnt quite the question I had asked.

I am already familiar with all the concepts discussed here http://www.nsxprime.com/FAQ/Miscella...austtheory.htm, and I understand how the X/Y pipes are necessary to promote efficient scavenging by aligning the pulse to draw out exhaust. My question regarding the two is, whats the difference? If you were to sync/balance the exhaust pressure with the X pipe, why split it back up again? Where is the gain as opposed to a single system that is also synced via Y pipe. Also, since the dual exhaust is bridged with the X pipe to balance pressure, what makes it true?


I still want answers/discussion on my other questions, is anyone wants to take a stab at them...

 

You seem to want information only dynos would answer. Good luck getting that here.

go search and wade though the 25 billion pages of people telling others to search for dyno threads.

 

^ not necessarily. If someone is knowledgable in this regard, then they would know the 'reasons' why there are differences, and why one would perform in a certain way. I am not asking for specific answers like 2.34576 whp at 5000rpm. I want the 'reasons'... why the true dual is 'true'? what the differences are between efficiency of X/Y pipe (are there any or is it a way to charge more for more piping and parts)?

*edit* The 'reasons' would be subject to testing to be proven, but I am only asking for the theory.

 

I'm not quite sure why people go to duals. It's my understanding that one bigger pipe has more area than two smaller ones. Unless two smaller ones can keep the exhaust velocity up better than one big one. but two small ones would be only handling 1/2 of the exhaust.

 

im guessing with intake, spacers, headers, HFCs with true dual like ISMSOLUTIONS mentioned, you aren't really going to lose low end and gain a lot, like 20 hp high end especially above 5k rpm. So with the mods u mentioned it is better to go with true dual with X-pipe. Without the mods stock or single piped exhaust is a good balance for power low and high end, but u will lose some power down low if u go true dual without any cat, header mods.

 

From what I gather, there wouldnt be a difference between the two if the single exhaust goes along with my calculations earlier. The 3.5" single exhaust would handle the same amount of exhaust as the dual with two individual 2.5" pipes. I think the exhaust velocity would also be the same when set up this way.

 

3.5" exhaust is HUGE for a na application. Unless you have a big block 572!

I'm not sure you can get a Y with a 3.5" outlet anyway.

Yes, if you ran big downpipes from the Y into a 3.5" collector and ran the rest of the system 3.5", there would be a big loss of low end due the loss of exhaust velocity.

 

I consider this the norm, everyone goes the dual with X route if they do alot of engine mods. But thats assuming that the dual with X pipe would flow better than a proportionally sized single exhaust. Which brings up my question, how can we assume this?

 

each cat is 2.5" ID on our cars if remember correctly + the Y-pipe's are 2 2.5"s in and 1 2.5" out. I don't see how can u do 3.5 inc single exhaust unless u do all costum which will cost u a lot more.

 

Well thats given my calculation... since I cant measure the volume of exhaust (which I think would be more accurate) I am estimating with area... and that is approximately what it comes out to.

You can try it too...
given:
2.5" piping = 1.25" radius
Area of circle = pi x (radius)^2
-add area of both pipes, then reverse the above equation to find diameter of larger pipe.

If someone knows how this is actually calculated, please chime in.