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Truckin' on a budget
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Discussion Starter #1
I am mostly looking for performance but dont want it to sound gay. On a 4.3 vortec is it better to use a sly pipe or do true duals It has gibson headers and 3" pipes so should i get the duals for this setup or stick with the y pipe
 

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Project: Sabriel
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12,507 Posts
uh. you DONT want true duals on a 4.3L. and 3" pipes are WAY too big. you should have 2.25" or 2.5" MAX on there. yank everything from the heads back off, put on an SLP y-pipe, a good cat, a good muffler, and some 2.5" piping.
 

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Truckin' on a budget
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1,847 Posts
Discussion Starter #3
yeah im not sure if it is 3" that was just a guess i dont have the truck yet but the guy seems to know alot so it probly is 2.5 and i dont know what muffler it is i cant remember but it does have a high flow cat also why dont you want true duals. is it because of the backpressure thing i can never understand lol
 

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Project: Sabriel
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12,507 Posts
yeah, cuz of the backpressure, and the fact that a 4.3L just doesnt need duals to run right. pull everything off from behind the headers, and sell it to some bum. does it already have duals on it, or were you thinking of putting duals on?
 

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Truckin' on a budget
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Discussion Starter #5
no it has the y pipe i was just wondering if i should get duals for improvement but im just not gonna mess with it
 

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footbraker
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1,236 Posts
A single 3" pipe will outflow a pair of 2" duals because it has a bigger cross section than both 2" pipes put together.
 

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Project: Sabriel
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12,507 Posts
yeah, but a 3" pipe is simply too big for S-10's. id use 2.25" for duals, or a single 2.5" pipe for a single.
 

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footbraker
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MuddyS10 said:
yeah, but a 3" pipe is simply too big for S-10's. id use 2.25" for duals, or a single 2.5" pipe for a single.
Didn't mean to imply he should use a 3" exhaust, just pointing out the facts.
 

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footbraker
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1,236 Posts
Cross section of exh.
single 3"-7.07 sq. in.
single 2.5"- 4.91 sq. in.
dual 2.25"- 7.95 sq. in
dual 2"- 6.28 sq. in.
 

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Project: Sabriel
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12,507 Posts
oh yeah, i agree with you. i had duals with 2.5" piping, and when i get my Blazer done, it'll probably be a single 2.5" pipe, with a dual-out muffler, turndowns.
 

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S-Clusive's Jester
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3,085 Posts
i would go single in single out with dual tip.
 

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I have a single in dual out 2.50/2x2.25 and it's ok. It's a Spintech.
It's coming off though. I need to get something that doesn't ring
in the cab and I'm getting kinda old for the noise. I think I'll go
with a Hooker Maxflox muff in 3", and I was reading over at the Full
Size Chevy site that there is exhaust pipe out there in 2.75. Now I
don't know if this true, but it would seem that would be the best
of both worlds for me. I only need 1# to 2# back pressure..

If I can find this 2 3/4" pipe I'll have the expanded for the 3" muff
at the in and out of the muff and run 2 3/4" single pipe out back..

Sorry bout whoring yer thread.
 

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1,329 Posts
Stock exhaust systems are intended to work in a wide range of driving conditions and generally are not very efficient. Car manufacturers compromise performance for other considerations, such as ease of production and cost.
Typically a single log-type manifold on each cylinder bank connects through a "Y" pipe into a single catalytic converter and muffler, with an overall pipe diameter of 2" or even less. OK for a grocery-getter, but not when you're looking for low-end power, mid-range acceleration, top speed potential, and yes, even better fuel economy.
Anything that causes turbulence or back-pressure in your exhaust system reduces the power that intake or engine modifications can create.
Stock manifolds contribute heavily to turbulence because all the exhaust dumps directly into a single tube. Tubular designs separate each cylinder's exhaust pulse, reducing the possibility that spent gases will flow back into an adjacent cylinder and contaminate the incoming fuel and air mixture. This is especially crucial when you're running a cam with more overlap.Simultaneously, tubular headers reduce back-pressure, allowing more fuel and air to enter the cylinder's intake stroke. Both these factors add up to more combustion efficiency, i.e., more power to the wheels. Headers will give you a noticeable performance gain; even when connected to an otherwise stock exhaust system. But it only makes good sense to look at all the components from front to back. Certainly, restricting the headers in a single pipe system defeats the reduced back-pressure you're trying to achieve.

One of the most critical decisions to make when you're building a performance exhaust system is pipe size. Bigger is not always better ,it's very important that the pipe diameter be sized to the application and that it remains the same from the collector to the end of the tailpipe. Changing the diameter up or down within the system will "confuse" the exhaust by creating turbulence and excessive backpressure.

Basically, as a rule of thumb, if your intended use is strictly street, for cruising and maybe as an everyday driver, then 2.5" will be adequate,,,,,,,,,, unless you have 500 HP or more! For the strip, if you have a power plant rated around 425 or more realistic horsepower, then the 3" system would be the way to go. Powerplants with few horses just will not benefit from the larger 3" exhaust although 3" tailpipes showing from behind the rear wheel or under the bumper will make quite an impression.

If you're not sure of the horsepower rating of your powerplant, but have raced at the dragstrip, then any 1/4 mile ET's in the 12.40 - 12.70 range or quicker would benefit from the larger 3" exhaust versus a good 2.5" mandrel bent system.


A common misconception is that the larger the diameter, the better the system. But bigger isn't always better. Systems that are too large in diameter can actually hurt performance. As a general rule, switching to a performance system that is 1/4" to 1/2" inch larger than stock will provide you with the best horsepower increases. To determine which pipe diameters will be best for your system, decide what RPM range your engine will operate at, most of the time. Smaller diameter pipes will produce low- to mid-RPM torque. Larger diameters produce mid- to high-RPM torque.


Bigger isn't always better. Systems that are too large in diameter can actually hurt performance. Improved flow is what you need. Having large diameter pipes isn't what's cool. Going fast and making horsepower is.
 

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Project: Sabriel
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this guy has got to be a mechanic.....:bow:
 

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footbraker
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What's the typical diameter reduction of muff. shop bends? Also assuming your talking about dual exhaust and not single pipes in above post.
 
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