Hey guys,
I looked around but did not see a definitive answer on this so I figured I would ask. Does a true dual exhaust give more or less power than a larger single exhaust? Currently I have a Apexi N1 EVO and I was thinking of trying to get my hands on a Injen true dual system. I know if I keep my current exhaust I need to replace that factory y-pipe, but what is the consensus here? replace the y pipe or get the true dual exhaust?

Thanks,
Shaun

 

if ur n/a, u probably wont feel a difference
maybe ud gain more with a true dual if u were FI'd...

 

I like dual exhaust on a V-motor. Consider the 2.5-inch dual exhaust vs a 3-inch single exhaust. Which can move a greater volume of air? The dual exhaust of course.

Which will give you the best increase in peak horsepower is impossible to guess.

 

True Dual exhaust will usually weigh more, and in some cases will lose low-end power. Like everyone says, unless you got a turbo/blower you're not going to see a gain really.

On a side note: i like the look of a true-dual, i can't stand the factory style muffler. By that i mean a muffler turned sideways with two outlets. You've got a RWD car, so show off the pumpkin. But thats me.

 

yeah, I can see both points. I do love the way my Apexi sounds, but the injen just looks awesome. I am sure it sounds good too. I would like to buy one used, so I can put it on my car, and decide which one I like better.. maybe I will start exhaust shopping... (once my account is unlocked)

 

Yeah Injen has two true duals, i think theres the SES and the Track edition. I heard the track one has slightly larger piping and has a H-pipe with the 'burnt' exhaust tips. i've seen a few clips floating around on youtube.

edit: i've heard the SES true dual in person on the dyno. it's LOUD. i like the look but don't care for the sound that much. but to each his own.

 

ok, I just listened to some sound clips from the injen exhaust on youtube and it sounds awful. My apexi sounds so much better. I guess I will stick with it or get a JIC.

Thanks,
Shaun

 

Theres two JIC's. Theres the Type1 (single) and then theres the Type2 (stock like muffler).

heres a clip of someone on the forum that almost made me wana buy the Type2.

http://vids.myspace.com/index.cfm?fu...oID=1235820234

 

that sounds similar to my Apexi Evo N1. It sounds like stock, only louder. It is probably one of the higher pitched exhausts, but thats what I like about it.

 

So I ran a few #'s for pipe flow to come up with the pressure drop from a few different set-ups...I had to make some big assumptions, but think it gives a good general feel for real life:

assumptions:
-10ft straight pipe
-Max exhuast flow = (1/2)*(3.5L)*(7,000 RPM) of air at standard conditions (I know exhaust flow isn't at Ambient pressures and temp, but it gets fairly close once it's at the exhaust tips...this is the assumption with the largest amount of error)



so, for peak HP at 7,000 RPMs, you'd most likley want the dual 3" exhuast. But you have to remember that there's much more going on to this...in the best of all worlds, you want to have high velcoties and low pressure drop.

high velocities - this helps scavenging effects of the cylinder...as the exhuast air exits the cylinder, it has a certain amount of momentum (mass*velocity). the more momentum it has, the larger % of exhuast will actually exit the cylinder before the exhuast valve closes....this will increase burning effeiceny on the next combustion stroke since it will have less residual exhuast in the mix. (in general, this effects mid range power)

low pressure drop - pressure drop is bascially resistance...the more resistance in the exuast system the more the engine has to work at pushing the exhaust out. (in general, this effects top end power)


In the end, you want to find an exhuast system that has a good balance - I went with AMM's 2.5" single exhaust b/c it'll greatly increase peak HP over the OE exhaust, while not giving up the mid range power b/c the exhaust velocities are still high enough. Plus the single exhuast is much lighter

 

You also gotta keep in mind that any TD exhaust will change the sound of the Z. All the y-pipe/ single exhausts retains some of the stock note i.e. Nismo/Fuji. But I agree with everyone here and if you want the look and sound of a TD, then go for it. But on a NA car you wont feel that much of a difference.

 

You're also a chemical engineer?

Nice simulations complete with reynolds #!!

I'd really like to see some more simulations, maybe you can PM me with what you used to do the calculations

The tricky thing is to make this simulation even better, you really need to account for the very high temperature (and consequently higher pressure) near the headers, and the huge temperature gradient as that high pressure gas expands towards the tips and cools.

 

I'm a Mechanical Engineer...the equations that I used can be found in the website I added to the bottom portion of the table (engineeringtoolbox.com)

I work on the thermal/combustion side of engineering, and am currently gaining experience in CFD (computational fluid dynamics)...at some point I'd like to try modeling the whole exhuast or intake system - but work is so busy, it's hard enough to find time just to install new mods on the Z

-Peter

 

Which did you order?

 

Excellent choice.

 

i was thinking of aams 2.5 true dual. But i still here stillen has the most power as far as exhuast systems are concerned but more weight

 

Maybe its just the supra owner in me ... but 4" single all the way back

 

LoL They have 4.5 - 5" now.

But for the OP, I would suggest any single exhaust. They sound too damn good.

 

not sure if that's true...it's hard to compare HP/TQ gains from what different companies advertise. from just looking at the designs, I would think AAM's exhaust would make more power - it's more or less a straight shot out the back w/ a few small bends.

AAM

STILLEN

-Peter

 

i hope you did not see the OLD injen setup..the one with the angle tips...that was awful... the new injen does soudn hella nice and loud...

i have heard of the N1 apexi and if you think its better then i think you heard the old discontinued injen design...which i have seen many on youtube and streetfire
Unless you want it quiet the newer injen design actually have one of the best sounds.
As far as gains, true duals do give you more power n/a... the loss of low end power is due to the not having an h/X pipe..the newer injen i think comes with it and the olderones dont...but this was easily fabricated...