jimcol711

clearly, there would be issues with passing emissions, but wouldnt it be sweet if someone paired a set of comptech headers with true dual exhast pipes all the way out the back of the car..i mean, its like our exhaust (and many others like us) goes from the manifolds (or headers) to 1 pipe, then splits back out to 2....how about each pipe stayes seperate from the manifold all the way back to the exhaust tip...wouldnt it be relatively simple to get some pipe to fit up to the headers and then meet some comptech or hks mufflers on the back end??? how much added performance would something like this offer???

peiqinglong

I've always been curious about this...what kind of gains can we expect with a true dual exhaust? I recall this arguement brought up before and someone had mentioned something about how the supra was originally going to have a true dual exhaust, but the engineers scraped the project because they realized that higher gains can be realized with just a single exhaust.

Nashua_Night_Hawk

That would a great project, but does it work!... You need to have 2 cat converters and 2 pre-mufller and 2 mufflers ... but the lack of space is your biggest problem...

I would love to see the CLS dyno or raced on no-headers/ race headers no-cat no mufflers!!

Red Nj-s

yea well a supra cant have a "true" dual exhaust, its an inline 6, we can though, but it would be hard as hell because out engines are transverse mounted

peiqinglong

Okay...so what would be the advantage of having a true dual exhaust?

sidemarker

isnt the gs300 also an inline 6 and it has a true dual exhaust?

sidemarker

maevonee

im taking off my silence resonator tommorow. lets see how it sounds. im getting it cut off and welding the empty space with another pipe ...any comments?

Rescuer

yeah, it's going to be a very loud droning noise and you will get sick of it.

do NOT do it. sure it sounds like perfect bassy sound, but it's quite loud.

Klamalama

This topic has been of particular interest to Taurus SHO folks. Some have tried them with varying sucess. Please note that the two separate exhaust pipes will still need an interconnecting "H" pipe between them.

Anyway, you can check out some of the discussion on the subject at:

http://www.shotimes.com/SHO4exhaust.html

http://www.shotimes.com/SHO4exhausttedb.html

http://www.shotimes.com/SHO4exhaustjohnh.html

http://www.shotimes.com/SHO4exhaustvadim.html

http://labwww.csv.cmich.edu/luke/auto/SHO/duals/

NOMAD

Don't forget that "Scavenging" is also very important for exhausts.

Basically the pulses of each cylinder pushing out gas all combine with each other and work together to "pull" gasses out of the engine. That's why headers are effective... they optimize the pulses of gas and create a very smooth and efficient flow of gasses. Many top headers use decreasing and increasing pipe diameters to utilize and speed or slow the gasses as needed to create the perfect flow of pulsing gasses.

With that said... If you have a true dual exhaust you'll only have three cylinders pulsing and combining to push gasses out of each pipe. First off, the pulses would not be timed correctly to create a smooth flow. Second, the headers would have to be researched and made exactly for a three cylinder each set-up. Thirdly, you'd still have to have a connecting pipe like Klamalama said... I can't remember why but i did read it at one time

Pappy

What about all this back pressure bull I've been hearing about. If you do this, don't you eliminate that pressure that is supposed to be important? Could someone please explain this to me. Thanks.

peiqinglong

Okay...so what is the advantage of having a true dual exhaust?

Zapata

We don't need a dual exhaust............we need to take what we have now and make a larger single exhaust. 3 inch pipe back to a single muffler would be easiest and see the most gains. A dual would be too much money for most people on this board. Look at the M3....i-6 with a quad exhaust....but look at the engineering in that thing!

jimcol711

too much money?? how much could it possibly cost for 25 feet of 3" pipe, and 2 mufflers?? then just cut and weld as needed...obviously, this wouldnt be smog legal (no cats) and probably loud as hell but it would be relatively cheap...and pretty easy for anyone with any experience in pipe bending and welding

peiqinglong

I was talking to Arnold (blxmj...spelled something like that) and a few others in a chat room, the true dual exhaust on the CL would actually cause us to lose back pressure and the benefits for it are not worth it. True dual exhaust is better on a turbo car because it needs less restrictions...but then even most turbo cars don't even use it.

NOMAD

Raw material cost is not the point. Anyone can weld up a bunch of pipe but it has to be ENGINEERED correctly or you'll experience little to no gains and possibly setbacks.

The deal with backpressure is this:
Backpressure is good to get rid of. Your engine will breath easier and end up at a better level of performance... you could call it the base level of performance before it is choked up by small pipes.
The deal though is that you still need to keep the velocity of the exhaust gasses up. This gets the gasses out of the pipe and cylinders. When one cylinder opens to exhaust the gasses on a properly engineered setup will be "sucked out" by the vaccuum created by the other cylinders flowing out of the tube.
(example: if you blow a leafblower down one side of a Y shaped tube, say the right side top, the left side tube will on the Y will develop a vaccuum suction on it. it's Bernoulli's principle)

If you look at how headers are made it's a bunch of Y tubes connected. This creates the scavenging or flow velocity out the exhaust.

If you go any larger than say 2 3/4" to 3" you will not decrease backpressure any more but you will decrease velocity of the gasses. The gass will beging to ripple and eddy inside the pipe, creating high and low pressure areas... slowing velocity and keeping gasses from exiting the cylinders correctly.

This is why the basic rule of thumb is not to have piping larger than 2 1/2 for 4cyl... 3" on N/A V6 cars (yes VTEC included)... and for Turbo cars that have a lot higher velocity of exhaust gas can run 3" and bigger if needed.

Bottom line: Good pipe diameter and low-flow mufflers decrease backpressure and maintain velocity.
Duals can be used IF ENGINEERED precicely.

That's my knowledge... feel free to disagree.

Nashua_Night_Hawk

What about no Headers at all or simply a down pipe headers no Cat no mufflers

Zapata

Yeah cause it isn't as simple as welding pipes together. You would want to make sure that the pressure is equal on both sides etc.,

Single exhaust is the way to go.

JRock

Only cars I've ever seen true duals on are Mustangs or old muscle cars.
Waste of time for a CL.

JasonT

Yes it can be done, Yes it would be loud, Yes it wouldn't be that expensive. However, on a N/A engine, you do not want to increase the pipe anymore then 3". It's nice to say duals would be cool, but there's a limit to this. An engine needs backpressure. If you lose too much you will loose low end power. Some cars like Mustangs do have true dual's but the pipe isn't 3" all the way back. It more like 2 1/2, or 2 1/4 pipe with 3" tips. You could do it on a CL-S using smaller pipe like 2" without loosing too much backpresure, but by then it just for looks, cause a pair of good muffles would give you better performance. Now on a car with forced induction(NOS, Turbo, SC), or BIG engines V10 Bigblock V8's, that's when the bigger pipes, or true duals would come into play.

Klamalama

As I understand it, the interconnecting pipe is to get the other 3 cylinders to help out on the scavenging, as you described perfectly.

1SICKLEX

Yes, it does, WTF is a fake dual exhaust?

Just buy a dual exhaust car.

bnavarro

I took out the resonator in my car and increased the size of the catback pipe to 2 1/4. Sounds a little loud, but i can put silencers in my mufflers. As for the dual exhaust subject, i'm not too familar with it.

peiqinglong

Fake dual exhaust is what our car is. A true dual exhaust is where there is two pipes that leave out from either the downpipe or header into individual exhaust.

t-rd

For you CL guys who didn't know, it's already been done on an Accord V6! And it did not work right. I heard from a long time member about 2 years down at TX. The guy had split the exhaust pipes into 2 separate ones, I'm not sure about the cat and oxygen sensors. The fact was that it ran really rough because the engine got out of tune!! Hence the exhaust scavenging and various other issues that many talked about. The exhaust resonance and pulses were messed up I believe. If your pockets are deep enough, go ahead a try it! I won't be surprised if it doesn't work right.