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post #1 of 7 (permalink) Old 03-03-2008, 07:22 PM Thread Starter
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Exhaust system questions

I was wondering would I have to make a custom dual exhaust system?whats the pros and cons of even doing dual exhaust compare to just having a exhaust system.From what I read so far is that since its only coming out of one pipe its not even consider real dual exhaust.I was looking at the rk sport body kit and I see that people had the dual exhaust set up,I figure if I was going to go with the RK sport body kit why make it look lame with just one exhaust ya know.

2006 Chevy Cobalt LT
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post #2 of 7 (permalink) Old 03-03-2008, 08:19 PM
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I would go with single for multiple reasons.

1. Better performance with only one outlet.
2. Dual only sounds good with at least a big V6. 3.5 or bigger. Really need a V8.
3. It would look better with single, possibly a side exit.
 
post #3 of 7 (permalink) Old 03-03-2008, 08:36 PM
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Quote:
Originally Posted by burzumaske20 View Post
I was wondering would I have to make a custom dual exhaust system?whats the pros and cons of even doing dual exhaust compare to just having a exhaust system.From what I read so far is that since its only coming out of one pipe its not even consider real dual exhaust.I was looking at the rk sport body kit and I see that people had the dual exhaust set up,I figure if I was going to go with the RK sport body kit why make it look lame with just one exhaust ya know.
being the exhaust guy, i will say this now:Duals look cool on our cars, but that is pretty much it. If you dual it, it will lose the backpressure built from the restriction.. "True Duals" are created when you run one pipe per side(only done on a V-format motor) Best to go with a dual setup, but make it a functional single, simple enough to do
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post #4 of 7 (permalink) Old 03-04-2008, 09:55 AM
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Make it a dual exhaust with each side taking exhaust from two cylinders.:D

Minor mods... Wheels, de-badged & de-trimmed, stereo, grill, intake, eyelids.
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post #5 of 7 (permalink) Old 03-04-2008, 12:38 PM
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if you do a dual exit exhaust the correct way you will not lose any power, infact it is just a myth... it will not open you exhaust up any more then a single...... figure out what size pipe will best suit your cars power/induction. run that size pipe from your cat back bolt up flange... run it the stock route, straight down the middle, cut to the driver side in front of the rear axle then go over it (this is all same as stock...) then put in your Y pipe... and finish it off.

judging by your car being a 2.2 stock... the stock size piping will be fine..so you can leave all the piping from the cat to where i said to put the Y pipe in, and just cut and weld (or have some one weld) in a Y pipe and finish it out the back.

if you want it to be even louder you can also cut your resinator off and weld in a striaght section of pipe or a high flow one (like a glass pack...)

i will get pics of how to do the Y pipe and back later on when i get on a better computer that can access my photobucket.
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post #6 of 7 (permalink) Old 03-05-2008, 06:42 AM
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Originally Posted by cobaltkrazy View Post
being the exhaust guy, i will say this now:Duals look cool on our cars, but that is pretty much it. If you dual it, it will lose the backpressure built from the restriction.. "True Duals" are created when you run one pipe per side(only done on a V-format motor) Best to go with a dual setup, but make it a functional single, simple enough to do
right idea, but wrong execution. big, very old myth that backpressure is good. but, it's not so much about backpressure as it is about exhaust VELOCITY. that's the key word, get the exhaust out as quickly as possible. backpressure is your enemy, even in a na car.

personally, i don't really like the idea of 2 mufflers on a cobalt, but if you're going to do it, i would make them both functional. ever see a car with "dual" exhausts, and the exhaust is only coming out one side? looks a little silly imo.
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post #7 of 7 (permalink) Old 03-05-2008, 08:47 AM
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Exhaust.. Simple rules to follow

Building an exhaust systems is not the "black art" some may think it is, here are some simple rules for you to follow.........

FIRST - Since an engine is an air pump, much of its power making is based on how easily air can get into and out of the cylinder. Restrictions to this inward and outward flow are called pumping losses.

EXHAUST SYSTEM - The pipping that directs the engine's exhaust stream from the exhaust manifold to the tailpipe. To get there, it must first pass through the catalytic converter and the muffler and out the back of the car.

To produce the most power, your exhaust should have the least amount of restriction to the exhaust flow.

Restrictions hamper the burned exhaust gases from getting out of your engine, exhaust left in the cylinder is mixed with the fresh intake air/fuel mix. This is called charge dilution.

Charge dilution causes a loss of power, pumping losses. With greater restrictions, back pressure is generated, making the engine work a lot harder in pumping the exhaust out of the cylinders.

MUFFLER - The straight through designs (STD) are best. What that means is there is little to no restriction in exhaust gas flow. The longer the (STD) muffler the quieter it is, not more restrictive. Old school mufflers, like some glass packs, and lovered piping should be avoided. These cause back pressure, inturn causing charge dilution.

TIPS - Large tips on todays exhaust systems are for looks only. Some are resonator type tips, these restrict flow as they quiet the exhaust. You can tell them apart by looking at them. The resonator tip will have a perferated insert.

COLLECTORS - These are the 'Y' pipes exhaust makers talk about. A "y" pipe is used to split or put together exhaust/header pipes. I would not use a true Y pipe, instead use a converge collector, I say this because of restriction. A converging collector has the inlet/output pipes against each other in a straight line. They are much harder to make, but the straighter the way is for the gasses to travel the faster they will move.

PIPING - The straighter and smoother the pipe the faster the gas moves. Any bends in the pipe will slow the gasses. Types of bends are critical. Mandrel bends are best, becuase the diameter of the pipe through the bend is the same allthe way through the radius. Some bends will have a corrigated section on the inside of the bend, and that adds restriction.

HOPE THIS HELPS...

Bigger pipe diameter is not always better..... But, I'll leave that for another day....I have to work sometime ;)

Never drive or ride faster than your guardian angel can fly.
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