Dual Exhaust Confiuration Differences

[TITANUP04]

As I read through the posts (both past and present) concerning dual exhaust, I notice that most everyone uses a single muffler configuration either a single in/dual out with a y-pipe or a dual in dual out. My truck has an independent pipe and muffler for each manifold. I am using 2 Flowmaster 40 series mufflers and 2” pipe. The guy at the custom exhaust shop where I had my truck done at referred to this as a true dual, and cautioned against using anything much bigger than 2” pipe in this config saying it could start to decrease low end torque. He charged the same for this configuration as for a single muffler, so by the time I paid for the dual and my 3” stainless steel tips, I was out the door for about $400. I love the sound, and the performance seems fine, but after seeing how many people are using the single muffler configurations, I am just curious as to whether there is some big disadvantage to using the “true dual” configuration. How do the different configurations compare in HP gains and sound? Thanks in advance for any insight you can give.

[Sammy Sandbag]

I would have liked to go true dual, but that would have tacked on at least another $100 for very minimal improvements in performance, if any. Looks like you got a great deal, I'd like to see some picts and hear some sound bytes. BTW, you aren't the first with this set-up. I don't recall the name, but a TitanTalk member has a similar set up.

[smoketitan]

wow you got a great deal on a true dual set up. I would think the true dual would be better

[Tony]

The factory pipe is 3" dia (7.069 sq-in)
How did the mechanic justify reducing the combined cross sectional area of the pipe by 11% (6.283 sq-in)?
With big name cat-backs offering 2.5" dia dual pipes, I would have expected twin 2.25" dia pipes appropriate for a more free-flowing system without causing drone-resonance issues or loss in torque.

[GETSOMZ28]

Got any pics of the install? I would think the true duals would give the best performance out of all the combinations. This is the route I will go it I ever get around to upgrading my exhaust.

I would think a 2.25-2.5 would be the ideal pipes to use for a dual setup, though at these power levels a 2" pipe may work just as well. Only one way to tell...dyno it!

[hawkeye680]

I think you are thinking of "Kevin" Sammy.

[pagerdaddy]

Originally Posted by sammy sandbag

I don't recall the name, but a TitanTalk member has a similar set up.

Could you per chance be referring to mine, Mr. ...., uh, what was your
name again, was it Sammy? Kevin posted pics of a true dual also, with
a different brand of muffler.

Here's mine:

Flowmaster Dual Pipes

[LikeaRock14]

Originally Posted by Tony

The factory pipe is 3" dia (7.069 sq-in)
How did the mechanic justify reducing the combined cross sectional area of the pipe by 11% (6.283 sq-in)?
With big name cat-backs offering 2.5" dia dual pipes, I would have expected twin 2.25" dia pipes appropriate for a more free-flowing system without causing drone-resonance issues or loss in torque.

Although IMO 2" is a bit small even for a V8, remember that you're also replacing the stock 55 gallon drum of a muffler w/ a much freer flowing one. It's not just pipe size alone that helps you unleash potential power, the muffler has a lot to do with it too obviously. I/e scavenging effects, chambered/strraight through, etc. Bigger isn't always better. It's more important to use the correct pipe diameter while retaining decent exhaust velocity throughout
Too large a pipe diameter, the velocity of the exhaust won't be able to flow effieciently (in a matter of words, due to the extra flow space), and ytou can let a certain amount of abckpressure back up your exhaust.

Although I do agree, 2.25" is the ideal system IMO for any engine under 350 hp., or in some applications it can differ. 2.25" retains maximum flow capability while not going too small to make the exhaust rap and pop a bit more.

[juma]

Originally Posted by Tony

The factory pipe is 3" dia (7.069 sq-in)
How did the mechanic justify reducing the combined cross sectional area of the pipe by 11% (6.283 sq-in)?
With big name cat-backs offering 2.5" dia dual pipes, I would have expected twin 2.25" dia pipes appropriate for a more free-flowing system without causing drone-resonance issues or loss in torque.

where it counts the most, between the Y and the Muff, the stocker is 2.5 inch. the 3 inch tailpipe doesn't matter as much because the exhaust gas has cooled and reduced volume by then. the actual matchup is 4.9 square inches with the 2.5 inch single versus the 6.28 square inch of the dual 2 inch. I've seen these work fine in the past. I would have added a x-crossover and this would be pretty close to optimal for keeping exhaust velocity up. Another thing that would have been a plus is to have the second cat/resonator replaced with a 2.5 inch or 3 inch pipe its entire length as some are doing now. that would have made a nice long collector, similar to those on headers and provided a lot of carrying capacity for a high volume part of the exhaust. juma

[TITANUP04]

Originally Posted by Tony

The factory pipe is 3" dia (7.069 sq-in)
How did the mechanic justify reducing the combined cross sectional area of the pipe by 11% (6.283 sq-in)?
With big name cat-backs offering 2.5" dia dual pipes, I would have expected twin 2.25" dia pipes appropriate for a more free-flowing system without causing drone-resonance issues or loss in torque.

I guess the thought behind the 2” exhaust on the true dual as it was explained to me, goes like this: on the stock Titan, you have exhaust from 8 cylinders ending up in one pipeand flowing through one muffler. Once the true dual is in place, each pipe is only handling exhaust from four cylinders, so you don’t require as big a diameter. Truth be told, he probably just had more 2” pipe in the shop than anything else. The more I research this, the more I think that once you get to a 2” diameter pipe, anything bigger is just a matter of preference. I think that unless you are drag racing, the differences are pretty minimal. Just to see where I am at, I am going to try to get the truck on a dyno in the next couple weeks. I will post the results when I get them.

[juma]

Originally Posted by TITANUP04

I guess the thought behind the 2” exhaust on the true dual as it was explained to me, goes like this: on the stock Titan, you have exhaust from 8 cylinders ending up in one pipeand flowing through one muffler. Once the true dual is in place, each pipe is only handling exhaust from four cylinders, so you don’t require as big a diameter. Truth be told, he probably just had more 2” pipe in the shop than anything else. The more I research this, the more I think that once you get to a 2” diameter pipe, anything bigger is just a matter of preference. I think that unless you are drag racing, the differences are pretty minimal. Just to see where I am at, I am going to try to get the truck on a dyno in the next couple weeks. I will post the results when I get them.

the kicker is that on every other revolution you have two cylinders firing on one side and near the same time. This makes one side have more backpressure and slows your acceleration time. furthermore, the side is usually the driver's side and you have a long exhaust pipe to pump through. this is why a H- pipe or X-pipe crossover get you more power because it allows that temporary overpressure in one side to bleed off to the other exhaust pipe. juma