Hey what's up guys. I got a guy who just put in his fully built R motor. I don't know the components, but he's got in mind a comptech 4-2-1 header so i pointed him in the direction of HT and told him he should get the JDM 4-1 or DC JDM 4-1. (bang for your buck and also 2.5" > 2" collector sizes) Anyway, he then begins talking about putting on a dual exhaust. I already suggested one thing about the header so all I can hope for is for him to come to HT. My question is, are there any dyno plots or sites that proves that dual exhaust on our cars are worse off? I'm sure it is. TIA.

 

Dual exhaust needs a Y-pipe to split exhaustflow, which causes turbulence and restricts exhaust flow. Plus, two mufflers dont flow as good as one muffler. In my opinion, it just looks gross on an integra as well.

No matter what, it wont be as good or better than a single exhaust pipe.

 

that's what i'm thinking as well!! i wish to God that my buddy doesn't put on a dual exhaust.

edit: any proof on sites or dyno plots?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92TypeR &raquo;</TD></TR><TR><TD CLASS="quote">No matter what, it wont be as good or better than a single exhaust pipe.</TD></TR></TABLE>

From a pure power standpoint, I'm not necessarily sure that's true. No one has a ever tested a properly designed dual exhaust on an ITR, but I'd be interested to see the results. I envision something similar to the E30 M3's setup, where the header never actually "collects" into 1, and two smaller-diameter pipes are run to individual mufflers (although the M3 uses a single muffler). I think the two major hindrances would be the packaging constraints (trying to fit two pipes where one used to run), and the effects of the additional weight on the car's polar moment of inertia (as well as it's overall performance). Regardless, I would very much like to see more research put into this.

 

Just make sure he gets lighted tips for each of the exhaust outlets.

BTW -- a dual 2 1/2" exhaust w/crossover worked very well in my friends 340 Cuda.

 

I would like to see a dyno plot of a "true" dual exhaust. I am talking about where the header goes from 4-2 (not down to 1). Then runs two pipes all of the way out the back. Sounds interesting...

 

dual exhaust looks better on a domestic Muslce car.. It looks ****** gay on hondas

 

i'm not worried about the aethetics of it. i am asking about performance gains or loesses. thanks for your opinion though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rated_r &raquo;</TD></TR><TR><TD CLASS="quote">dual exhaust looks better on a domestic Muslce car.. It looks ****** gay on hondas</TD></TR></TABLE>

What about Accords ??? u think it looks gay on them too ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Padawan &raquo;</TD></TR><TR><TD CLASS="quote">

From a pure power standpoint, I'm not necessarily sure that's true. No one has a ever tested a properly designed dual exhaust on an ITR, but I'd be interested to see the results. I envision something similar to the E30 M3's setup, where the header never actually "collects" into 1, and two smaller-diameter pipes are run to individual mufflers (although the M3 uses a single muffler). I think the two major hindrances would be the packaging constraints (trying to fit two pipes where one used to run), and the effects of the additional weight on the car's polar moment of inertia (as well as it's overall performance). Regardless, I would very much like to see more research put into this.</TD></TR></TABLE>

interesting idea.. essentially have a 4-2-1 header that never makes it to that last 1 and has a b-pipe attached to each "2" portion.. basically having 2 2-1 headers that attach at the same point on the motor..

i'd LOVE to test this out.. if only i had the loot to get SMSP to make it..

i'm not a physics guru enough to understand the question you posed regarding the polar moment of inertia.. could you explain that idea a little more?

 

A photo of typical E30 M3 exhaust manifolds (engines are either 2.3L or 2.5L I4's):


borrowed from e30m3performance.com

and a underside shot of a typical E30 M3 exhaust setup (note dual cats. and cross-overs):



As for the polar moment issue, the basic concept is that the farther an object's mass is moved from its axis, the more difficult it becomes to rotate that object about its axis. In this case, the concern would be that adding additional mass (the second muffler and additional piping) far from the car's center would likely negatively affect its handling dynamics. As a real world example, I recall reading that this was a major factor in Toyota's decision to locate the Celica's muffler before the rear suspension rather than in the more conventional location near the bumper.

 

Pada:

It is an interesting idea. Maybe someone will build on someday, maybe not. I don't have the tools (mand. bender) to try it myself and I certainly aint going to buy pre bent pieces just to test

 

more weight and just odd looking and money to be invested elsewere.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">more weight and just odd looking and money to be invested elsewere.</TD></TR></TABLE>

That's not what he asked.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">My question is, are there any dyno plots or sites that proves that dual exhaust on our cars are worse off?</TD></TR></TABLE>

That was his original question.

However, if you were talking about the idea of dual exhausts in a 4cyl in general, I wouldn't be so quick to dismiss an idea just because it isn't common in the honda world.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dave-ROR &raquo;</TD></TR><TR><TD CLASS="quote">

That's not what he asked.

That was his original question.

However, if you were talking about the idea of dual exhausts in a 4cyl in general, I wouldn't be so quick to dismiss an idea just because it isn't common in the honda world.</TD></TR></TABLE>

my answer more directed towards "downfall of dual exhausts?".. no i do not have dynos of dual vs single, mabye s2000 be somwhat of comparison..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">

my answer more directed towards "downfall of dual exhausts?".. no i do not have dynos of dual vs single, mabye s2000 be somwhat of comparison.. </TD></TR></TABLE>

S2000 is not a true dual exhaust though. Just like the Accords. So it would be valid to compare against what's currently available (to my knowledge) for "dual" exhausts for DC2s. However, a true dual design may, or may not, provide a worthwhile increase in power.

 

maybe a s2k dyno plot would help, but the fact that it's a different motor it would still be up in the air for the B-series motor.

 

i see.. so you're talking like m3 shown in the picture, from exhaust manifold to exhaust itself.. that would be intersting to see.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dave-ROR &raquo;</TD></TR><TR><TD CLASS="quote">I wouldn't be so quick to dismiss an idea just because it isn't common in the honda world.</TD></TR></TABLE>

I agree. Despite the major disadvantages that I mentioned (and there are no doubt others), there is one possible benefit that I could foresee. While I have very little knowledge of the dynamics of exhaust gases, I think there is the possibility that such a setup could allow a greater overall combined diameter while still maintaining optimal exhaust gas velocity.

For example, two 2" pipes would provide 6.28 sq.in. of cross-sectional area (a rough calculation using OD) while a single traditional 2.5" setup would provide 4.9 sq.in. That's approximately 28% greater area. As I said, the major assumption on my part is that the smaller individual pipes would allow gas velocity to be more favorable than it would be with a larger single pipe setup, and perhaps this isn't the case. Hopefully, someone with greater knowledge of this subject can provide his/her input as well.

 

Do aftermarket E30 exhaust pipes maintain the factory dual nature? Or are some single, larger diameter pipes?

I think a good test would be to see if the single piped exhaust setups on the E30's fair better than the aftermarket dual pipes. I know the engine dynamics of the B series is different compared to the S14 motor, but the general feel for the power gains or losses can be seen by the above comparison.

 

Remember
it would take two 2 1/4' inch exhausts (ruffly) to get the same area as one 3'inch single exhaust.

 

A dual exhaust starting from the head will increase the scavenging effects of the pulses of exhaust gas as they travel down the exhaust. Dividing the cylinders up at the head also decreases the chance of a non exhausting cylinder's closed exhaust valve from getting blasted with hot gases creating a further loss of power. Exhaust valves need time to cool to keep the incoming charge cool.

Cosmetics aside, splitting the exhaust in say the B pipe would not gain you much if anything at all.

As for the polar moment of interia mumbo jumbo...well said.

 

Although S2Ks have a "dual" exit, I believe the only aftermarket exhausts that help gain any real power are single. Like the Spoon exhaust for the S2K. Most of the aftermarket dual exhaust for the S2K don't gain any #'s, they are just lighter than stock. So even on an S2K the single is better.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOSPOWND &raquo;</TD></TR><TR><TD CLASS="quote">Although S2Ks have a "dual" exit, I believe the only aftermarket exhausts that help gain any real power are single. Like the Spoon exhaust for the S2K. Most of the aftermarket dual exhaust for the S2K don't gain any #'s, they are just lighter than stock. So even on an S2K the single is better.</TD></TR></TABLE>

Yes, but that's still just a dual exit exist and not a true dual system

 

Nice pics!