your opinion on dual exhaust

I have a 2004 silverado with a 6.0 gas. I have been toying with the idea of dual exhaust. I want a little tone but nothing loud. Does putting duals on have any effect on gas milage or horsepower, by making it better or worse? Thanks

2004 may be new enough that would interfere with the messages to the computer may give out incorrect info May have to have it tweaked to match the lesser back pressure that a dual system would have.

I dont know about these newer HEI,EFI,computer
controled vehicles,But My'70 F100/302 got 3-4 more
mph and a noticable increase in power.After a few
years,the glasspac mufflers have 'burned out' and
are sounding REALLY NICE!!

As long as you split behind the cat you can do what
ever you want. Some of the best sounding I ever
built were split behind the converter, and then two
36 inch glass packs to, two tail pipes. I would
like to add duels to my Chevy, but I don t have
excess to a pipe bender anymore.(It has factory
duels into one muffler to a single tail pipe) More
noise than anything else.

Well look at it this way. You have an O2 sensor in your exhaust sending mixture/temp readings back to your computer so it can make the required adjustments to fuel. If you have true duals are you going to put one in each pipe? If only in one pipe are you assured that 4 cylinders will cause the sensor to send an accurate message? 2 hooked together? If you leave the "Y" pipe on with it's single sensor then duals will affect nothing but the sound. My guess is just leave it alone. It's not a hot rod and nothing is any more annoying than a loud pick-up truck. I have to assume you are not in high school anymore?

B-maniac you made me smile! When I was in highschool I always had the loudest trucks. Now I cant stand the noisy damn things! No I havent been in highschool for 12 years now. It has factory duals to the muffler about half way back. All sensors are before the factory muffler. I would remove factory muffler and go fron there back. I just dont wanna loose any MPG or horsepower out of the deal.

Glad you have a sense of humor. Just trying to make a point. Only one that can answer the mileage/power question is someone with the same truck / same mods and more honesty than ego. Let us know how it works out either way. RB

Had a 05" 2500 hd with the 6.0 in it. Replaced the factory muffler with a Magnaflow cross flow muffler 2 in and 2 out with 3" pipes coming out behind the rear tires at 45 degree angle. Sounded really good, not too noisy and definitely not annoying. That paired with a cold air intake system I noticed a little bit of power increase and maybe a mpg or two increase.

(quoted from post at 21:18:45 02/26/12) 2004 may be new enough that would interfere with the messages to the computer may give out incorrect info May have to have it tweaked to match the lesser back pressure that a dual system would have.

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I don't know for sure on a Chevy but most modern vehicles have 2 sets of O2 sensors, before the cats and behind. The only thing the ones behind do is verify that the catalytic converters are working.

People connect resistors of a certain value across the wires to those rear sensors to fool the computer into thinking the cats are still working all the time and remove them. Search for "MIL eliminators" I would be shocked if you can't them for your truck.

Dual exhaust won't do you much good unless you're going to modify the engine big time. Seems like I read somewhere that a single 2" exhaust is good for up to somewhere around 300HP but I might be off on that figure. I don't know if they were talking about a straight pipe or muffler and cat included. I do remember it was a higher horsepower figure than I thought it should be.

Going by someone else's seat of the pants experience is dangerous and expensive. You don't really know if you've improved power unless you dyno it before and after. You don't know what it will do with the mileage figure unless you keep accurate mileage records for several thousand miles before or after. And like others have said, you have the computer and it's sensors to deal with. Jim

If the existing exhaust is limiting the airflow through a spark ignition engine, then opening up the exhauste with a bigger pipe or duals can help but BUT ONLY AT FULL THROTTLE.

(quoted from post at 00:01:54 02/27/12) Dual exhaust won't do you much good unless you're going to modify the engine big time. Seems like I read somewhere that a single 2" exhaust is good for up to somewhere around 300HP but I might be off on that figure. I don't know if they were talking about a straight pipe or muffler and cat included. I do remember it was a higher horsepower figure than I thought it should be.

Going by someone else's seat of the pants experience is dangerous and expensive. You don't really know if you've improved power unless you dyno it before and after. You don't know what it will do with the mileage figure unless you keep accurate mileage records for several thousand miles before or after. And like others have said, you have the computer and it's sensors to deal with. Jim

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h, come on now! Just the loud noise alone is enough to convince these guys that they are making more power. :evil:

OK to be honest.....if you are going to boost HP/Toque/Mileage past the current conditions your would have to go from the heads back. Guess what? GM took care of that! After market systems will give boost to the point that unless you are going to go past 500K it will never pay for itself. You have to make an engine work less to produce HP to gain a great deal of improvement.

You will find that a lot of people claim great improvement after spending a great deal of money but it is only a claim!!!!!

Rick

got a 2000 that prior owner rigged with dual 3" pipes into muffler, dual 3" pipes out. Also have 2001 w/factory exhaust system. Both 6.0. Difference is can't keep exhaust pipes on duals & have to wear earplugs on trips. Unless you think hearing aids are cool, don't change anything. Any difference in horsepower or mileage is purely imaginary.

Daul exhuast will add horse power and if you add a seperate muffler and converter, it should even be quiter. Is it legal in Iowa to make that type of madification. Tennessee allows it in my county. We don't even get annual inspection. I believe that Iowa has a tighter view of exhaust. The O2 sensor measures the percentage of Oxygen, and along with other sensors determines how much air the engine recieves to fuel. The percentage of oxygen to exhaust gas from haf the engine should be the same as from the total exhaust, Though I would only put the O2 sensor on one side. If you, however, must be inspected annually and they visually inspect this stuff, I wouldn't bother doing it, as you will be changing it out to get your sticker. I'll share a cool story. New Hampshire required that a rusted through hole is a failure. They salt the roads. I had a very old pick up, that because of it's age beats the emission rules, but had plenty of rust holes. Just before I would go to get my inspection, I would sling drywall compound all over the rust holes. I always got the sticker, though the next rain would wash away all the "body compound". Because the local mechanic knew I did sheetrock, it looked like I was just a messy one. Maybe he knew, maybe he didn't, but I got my sticker.

Can you go to a larger diameter single pipe instead of duals to save weight and cost?

Unless you are towing or run at high rpm a lot of time a dual exhaust won't save enough fuel to pay for itself.

My experience was for short trips the mufflers on dual exhausts rusted out much faster than on single exhausts.

Engine is an air pump. Air in, air out. restrict either, you restrict
performance.

1. I have seen GM and Ram P/U trucks at least back to '05,
maybe as far back as '98 on the Ram that have separate exhaust
systems initially on each side of their V8 engines. Those
systems each contain a cat. conv. Then they join and exit one
tail pipe and muffler.

2. On velocity of air out, obviously rpm of the engine for a given
set of conditions has it's limitations.

3. Type of flow has it's effects, i.e. laminar vs turbulent.
Laminar is straight line and has the least contact with the walls
of the pipe hence the least resistance, hence breathing of the
engine is best. Turbulent on the other hand puts the air to
circulating and it moves down the pipe, slowing it down and
scrubbing the sides over and over; both limiting flow.

4. Used to be (mid 70's for a benchmark) 1 7/8 tail pipes were
what you got with your small block V8. Dual exhausts helped
that by doubling the area of the outlet.

5. I think Ram started it but doesn't matter, especially with
diesel trucks. Check out the size of the exhaust in today's
trucks and there is a marked difference in size between these
and yesteryear....yes part of it is hp increase, but that's only part
of it.

6. On 1 pipe vs 2, other than just to get your brain rattled by the
noise, area of the pipe is 22/7 (pi) x radius squared. So the
diameter of a single pipe doesn't have to go up all that much to
equal the area of a pair of smaller pipes. Additionally, the flow
in that single pipe is much less restricted due to the reduction of
the surface area of the pipe that the air has to pass by, and
hence be slowed by.

7. Now I will give you the fact that a flow through muffler
(glass/steel pack) will offer less resistance to flow, that normally
are used with after market dual exhausts, than a poorly
designed conventional muffler, but there are those out there that
are quiet and minimally restrictive.

Lots of reference books out there to support what I said. Not my
words, words of mathematicians, physicists, propulsion
engineers, and equipment designers.

My 2c,
Mark

You want to draw attention to yourself with a noisy exhaust
system.

Are you just looking fo a good sound?
My B.I.L. has a Dodge Dakota with a V-8 and he was determined to put a "glasspack" on it.
He bought the glasspack and I put it on for him and to be honest, I did not expect much.
Lo and behold this thing has about as good a sound as any real dual V-8 I"ve ever heard.
We then put one of those split systems so he has dual pipes out the back.
I swear if you didn"t look, you would certainly think it had true duals.
We"re both products of the 50s and never did get over the "delicious" sound of a mellow dual exhaust system.
BTW, putting true dual mufflers on will INCREASE
the noise, not reduce it!
Its all about the increased time between "impulses".

I never understoon why a fellow would remove the oem stainless steel exhaust system which would last a lifetime and replace it with a steel dual exhaust that he might get 75K miles out of.

That"s why all dem Harley riders rum dem window rattlin" straight pipes!?
Never could undestand why the cops give the guy with a nice sounding set of duals on his car or truck a hard time and ignore all dem Harley guys?!
Makes no sense to me at all!
Also proves my point about the bigger space between exhaust pulses increases the loudness.

Same reason animal right activists and cops pick on joe average instead. An animal rights activist spray painting a bikers animal skin jacket or a cop buggIng a biker , neither are tolerated.

An "H" pipe connecting the two sides of a dual exhaust ahead of the mufflers will reduce noise and reduce back pressure.

Me neither, and on a brand new truck.....maybe had a rattled brain from listening to too many loud exhausts.

Mark

Make a recording of loud pipes, then play it in your truck with the windows closed.Motor cycle noise would be best.