Rear Diffuser for Quad Exhaust.
1 - 20 of 21 Posts
Joined
·
1,226 Posts
Splitting the exhaust like that will reduce power as the exhaust will be less efficient due to added bends in piping.
Joined
·
263 Posts
If he is going after market, it might actually reduce the number of bends as the huge stock muffler will be gone
Joined
·
1,226 Posts
Not possible with a Y pipe, which is what would be required. Single exit exhaust is always better for performance unless you're running true dual exhaust.
Joined
·
2,968 Posts
Adds weight too. I actually love the single (dual tip) exit.
Joined
·
18 Posts
I honestly the the Avante AD in Korea comes like this with the quad tip exhaust. I've seen pictures of them on lifts and the cuts are way to clean and look almost exactly like the single stock cut out we Elantra Sport owners have, just on the other side. If you look closely you can see it isn't cut but molded that way. This leads me to believe that the Avante AD comes with it or at the very least there is a company out there that makes it. And I like to have a mix of performance and looks and definitely would not mind quad tipping it. It's not like I'm gonna be going to the track. I doubt I will notice the performance loss that much.
Joined
·
228 Posts
I'd be really interested in this diffuser. I think it is an aftermarket piece though. You're right, it is molded that way as the cut is also extruded inwards. Also, I don't think you'd lose any significant performance since the stock muffler has two pipes coming out of a single muffler already. Especially if you have hollow mufflers. But some may disagree. Totally worth the look though.
Joined
·
92 Posts
can you prove your words?
not the first time I read this here... but real testing like the Motor Trend Chanel did when baching a header or comparing the 2.5 vs the 3" system over no line at all show nothing like bends killing power.
sure there is some mandrel vs crush that affect the pipe area...
Joined
·
1,226 Posts
It's exhaust 101. I shouldn't have to, but here you go:
http://kth.diva-portal.org/smash/get/diva2:515647/FULLTEXT02
"Back flow (a well-known phenomenon in pulsating flows) has been encountered
as well and it has been indicated from the weighted PDF distributions towards
zero and also from the phase-averaged signal at the pipe centerline where a
mirrored “dimple” is depicted. Additional LDV measurements (since the
hot-wire cannot sense direction of flow) were performed and back flow of a
magnitude of almost 50% of the bulk velocity was substantiated."
"Pulsating and steady turbulent flow (α = 72, De = 1.5 × 104
) was visualized
and measured quantitatively by means of TS-PIV 3 D downstream a sharp
pipe bend (γ = 0.4). The flow field at a pipe cross-section under steady
conditions exhibits two vortices which on average appear symmetrical to each
other whereas instantaneously their behavior is unsteady, oscillating between
three states, viz. a clockwise, an anti-clockwise and a symmetrical one."
"• Turbine maps at two different mass flow rates and at a pulsation frequency
of 40 Hz are plotted for the case when a sharp bend, as the one used for the
PIV measurements, is mounted upstream the turbine in order to account for
effects of the presence of curvature on the turbocharger performance. The
hysteresis loop due to the filling and emptying of the turbine under a pulse
period, was observed to expand to greater magnitudes as the mass flow rate
increased. A slight effect of the presence of the bend at the inlet of the turbine
was shown on the average quantities but a significant change was observed in
the instantaneous results with the hysteresis loop significantly damped due to
the presence of the bend."
tl;dr: Bends in exhaust pipes add turbulence which slows exhaust flow which creates backpressure which is undesirable and robs the engine of performance and is especially problematic in turbos.
http://kth.diva-portal.org/smash/get/diva2:515647/FULLTEXT02
"Back flow (a well-known phenomenon in pulsating flows) has been encountered
as well and it has been indicated from the weighted PDF distributions towards
zero and also from the phase-averaged signal at the pipe centerline where a
mirrored “dimple” is depicted. Additional LDV measurements (since the
hot-wire cannot sense direction of flow) were performed and back flow of a
magnitude of almost 50% of the bulk velocity was substantiated."
"Pulsating and steady turbulent flow (α = 72, De = 1.5 × 104
) was visualized
and measured quantitatively by means of TS-PIV 3 D downstream a sharp
pipe bend (γ = 0.4). The flow field at a pipe cross-section under steady
conditions exhibits two vortices which on average appear symmetrical to each
other whereas instantaneously their behavior is unsteady, oscillating between
three states, viz. a clockwise, an anti-clockwise and a symmetrical one."
"• Turbine maps at two different mass flow rates and at a pulsation frequency
of 40 Hz are plotted for the case when a sharp bend, as the one used for the
PIV measurements, is mounted upstream the turbine in order to account for
effects of the presence of curvature on the turbocharger performance. The
hysteresis loop due to the filling and emptying of the turbine under a pulse
period, was observed to expand to greater magnitudes as the mass flow rate
increased. A slight effect of the presence of the bend at the inlet of the turbine
was shown on the average quantities but a significant change was observed in
the instantaneous results with the hysteresis loop significantly damped due to
the presence of the bend."
tl;dr: Bends in exhaust pipes add turbulence which slows exhaust flow which creates backpressure which is undesirable and robs the engine of performance and is especially problematic in turbos.
Joined
·
92 Posts
I do understand basic fluid dynamic, energy wave, pulsing (even if I'm more familiar with frequency of valve train over the harmonic of turbine impeller).
I love the use of the hot/cold wire used since it's basically a MAF
but my point was more about concrete result on the dyno. the 620 hp w/ only header engine was doing 614hp with over 20 feet of 3" pipe with bends. this 2% would probably be the same if the 20 feet of straight pipe (inside surface pipe effect)
I love the use of the hot/cold wire used since it's basically a MAF
but my point was more about concrete result on the dyno. the 620 hp w/ only header engine was doing 614hp with over 20 feet of 3" pipe with bends. this 2% would probably be the same if the 20 feet of straight pipe (inside surface pipe effect)
Joined
·
39 Posts
Just make sure you don't overload your phase capacitor at highway speeds when your plasma injectors are at maximum flow rate or things could go sideways really quick. Sorry. Couldn't resist... ?
Joined
·
1,226 Posts
Yes, straight pipes vs. bends have been tested side by side on dynos pretty much since there have been dynos. That's how we know that straight and fewer bends means more power.
Joined
·
18 Posts
So I may have also found a solution to the quad exhaust being cut into a y and having bends. I was looking into getting a better picture of the rear diffuser so you can see that it is probably a part you can buy instead of cutting your diffuser. I ran into this Korean company that makes exhausts. They are called Jun B.L. anyways if you look at the exhaust it is a single pipe that goes straight into a muffler that then branches out to quad tip exhaust. I understand it probably doesn't do help at all and still has bends and makes a y of sorts. But it may help some people feel better.
Joined
·
228 Posts
This is what Voodoo was talking about... Adding the extra bends for the extra tips past that muffler instead of just having a simple exit out. I won't argue whether it reduces flow or not, but I think I'm gonna stick with my single side dual tips, I've grown to like them. They make sense on a car like this. That diffuser probably isn't cheap! Or it's cheap and has crappy fitment.
Joined
·
1,226 Posts
Honestly, the only way you should ever have a dual exhaust is if they are true duals - at no point should the y down into a single pipe. If you aren't running true duals but you have a dual exhaust, you've lost some power. Even on the Tiburon GTs... the guys that ran single exit exhaust instead of the factory duals always made more power than a similar set up with a dual exist exhaust. Sometimes as much as a 10hp difference.
Joined
·
12 Posts
I'd be interested in finding out, if you could look into it
BUMPPPPPP, I'd love to know as well!
Joined
·
90 Posts
Wonder if this would fit?
http://www.ebay.com.au/itm/Rear-Bumper-Diffuser-Guard-Black-For-Hyundai-Elantra-Avante-AD-2017/222427001915?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649[/URL]
1 - 20 of 21 Posts
