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Discussion Starter · #1 ·
I plan to install a stock 6 cyl dual ehaust on my I4. Would that allow for more exhaust to escape from the engine than the stoch single exhaust? I don't want to think of 2 exhaust > 1 exhaust, which in turn equals more exhaust to escape from the engine, which equals a little better performance. This is just something that flew over my head.
 

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In short yes - you'll be able to breath a bit better at high rpm's (more HP) but you'll lose some low-end torque. Real world - you won't notice any real performance gain - you'll just have a twin outlet exhaust.
 

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[quote author=Ceace link=topic=85674.msg1622451#msg1622451 date=1186605246]
I plan to install a stock 6 cyl dual ehaust on my I4. Would that allow for more exhaust to escape from the engine than the stoch single exhaust? I don't want to think of 2 exhaust > 1 exhaust, which in turn equals more exhaust to escape from the engine, which equals a little better performance. This is just something that flew over my head.
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Hi Ceace. :wavey: The quick and dirty answer is: No, it really will not improve performance at all. If you want to do it because you like the looks, go for it. But don't do it because you think it will unleash some hidden horsepower, because it won't.

The choke points in the exhaust system of todays new cars are the catalytic converters. If you open up the exhaust rear of the converters (which is essentially what you will be doing by adding a dual exhaust aft of the converters), you are not opening up the choke point, and it is of no help.

Think of the analogy of widening a river downstream of a dam. Since the dam (the catalytic converters) is what is holding back the water (the exhaust flow), widening the river (a bigger exhaust) after the dam accomplishes nothing. Very simplified analogy, but relatively accurate.

Of course, it is a little more complicated than the short answer, but you get the idea.

Good luck! :cheers:
 

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[quote author=cos link=topic=85674.msg1623857#msg1623857 date=1186632531]
Your "choke point" theory has some validity but there are certainly many "cat-back" systems that allow better breathing and increase HP and Torque as has been proven countless time on dynos everywhere.

E.g. http://www.rockcrawler.com/techreports/dynomax_xj/page2.asp
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Hi cos. :wavey: Certainly not trying to start an argument with you, as you are a good and valued forum member.

However, Ceace has an I-4, and you will notice that those dyno results are usually for 6 and 8 cylinder engines, which push out much more exhaust than a 4 cylinder engine, and can benefit from better exhaust breathing and scavenging.

Even your link, where they are testing a large 6 cylinder Jeep engine, shows a supposed average gain of only 5.72 HP. Certainly negligible. And the gain on a smaller four cylinder, if any percentage wise, would be less to none.

A non-high performance four cylinder engine (the Fusion 4 is certainly non-high performance) will see no tangible benefit from a dual exhaust system (without other modifications, high flow catalytic converters, etc).

Good luck. :cheers:
 

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bbf2530,

Agreed! :D We're on the same page!

I did like the gain of 5.72 hp and 7.1 ft-lbs on the Jeep - quite a "bang for the buck" for what's essentially a $45 DynoMax muffler (stock piping is 2.25"). One of my buddies has a Jeep Comanche 4.0 with a CAI, hi-flo cat and a Flowmaster. It has 210K miles (he's the original owner), the engine and trans are original and the truck runs the same 1/4 mile time it did 15 yrs ago!
 

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I agree you're not likely to see much gain. The I4 Fusion has about 20lbs for every HP, so adding the 20lbs of the heavier duel exhaust is actually going to decrease performance by the equivalent of 1 HP due to the weight. So if it adds less than 1hp to the engine it will be a net loss.
 

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Discussion Starter · #8 ·
This is something I am doing solely for looks. I love duals. I plan to get a CAI later, so that is what I plan on doing for performance. :) And, hopefully tunes if they become affordable for me.
 

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[quote author=Ceace link=topic=85674.msg1624554#msg1624554 date=1186665309]
This is something I am doing solely for looks. I love duals. I plan to get a CAI later, so that is what I plan on doing for performance. :) And, hopefully tunes if they become affordable for me.
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Hi Ceace. :wavey: A dual exhaust would be a good cosmetic upgrade to your car. It will look great.

Good luck! :cheers:
 

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Hey Cease...have at it!!! U'll notice abit more 'git up & go'...I did...but the Dual Look is IT!!
 
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