single vs duals

[BLKDODGE04]

getting ready to have my exhaust done on my truck next week. is there any performance gains in running true duals vs one pipe? ive heard of an x pipe helping out maybe? not sure. piping size suggestions?

 

[Hemi450hp]

A single 3" will flow more than enough for the 4.7. I dont think the benefits of true duals on your truck would outweigh the extra cost.

 

[BLKDODGE04]

i was wondering if i should run duals and get rid of the factory y? kinda wanted duals coming out the back... just run one pipe back and have it y off to 2 pipes then?

 

[BLKDODGE04]

money isnt really an issue, my fater in law will be doing it so ill be getting it cheap im sure.

 

[smiley]

I think if you do X pipe you will like the gains and not lose torque but I have been told by my shop that two 2.5 pipes will flow as well as 3 in single. The X will allow for scavenging as well. I always wished to make mine dual 2.5 with x pipe and dual in dual out muffler. I have debated between muffler with x pipe inside too. I do not want my truck to be louder than stock so I have never done it.

 

[BLKDODGE04]

what exactly does that mean? allow for scavenging? i was thinkin running true dual 2.5 with an x pipe and magnaflow mufflers...

 

[Catchin Zs]

Just go with an aftermarket y pipe, true duals are pretty expensive.

 

[BLKDODGE04]

Just go with an aftermarket y pipe, true duals are pretty expensive.

not for me my father in law runs an exhaust shop. all i gotta pay for is the pipe! i had true 2.5 duals put on my chevy for about 125 bucks i think. it was cheap.

 

[Catchin Zs]

Oh well then you are set! Others should chime in on the flow aspect..

 

[BLKDODGE04]

just figured id ask, ive learned a hell of a lot in this forum. probably gonna have it done tuesday or wednesday so just wanted to know what the best setup would be. ive read that an x pipe is better than an h pipe and the x will mellow the tone out a little...

 

[KGBIGCOUNTRY]

The runner length of the pipes will be offest to make the x work to its full potential. The driver side exhaust is going to have a lobger run to the x then the passenger side so they wont be pulsing at the same time.

 

[Belgiquebasterd]

Read this if you wan't to get really confused

Auto Exhaust Science

Been looking into exhaust a bit since I'm planning on changing my exhaust on my truck, this is what I understood:

2 things go down the exhaust, the exhaust gas flow and pressure waves.

Concerning exhaust gas flow you need to find the 'middle road' inbetween exhaust gas velocity and exhaust gas flow, smaller tubes increase gas velocity at low rpm but hurt gas flow at high rpm. Bigger tubes decrease gas velocity at low rpm but higher gas flow is possible at high rpm.

Concerning pressure waves, positive pressure waves travel down the tubes at the speed of sound, whenever they reach a change in pipe (end of primaries, end of secondaries, x pipe, h pipe) they collapse and send a negative pressure wave up the pipes. The trick is to position these changes in pipes that the returning negative pressure wave arrives at the valve exactly when the cam is in the overlap degrees. Both valves are open and the negative pressure sucks in more mixture. There are programs than can calculate these distances.

Disclaimer : this is how I understood all the articles I've read, not by any means am I sure if everything I've written here is correct. Please correct me if I'm wrong!

 

[Belgiquebasterd]

The runner length of the pipes will be offest to make the x work to its full potential. The driver side exhaust is going to have a longer run to the x then the passenger side so they wont be pulsing at the same time.

How can they pulse at the same time, if I'm not mistaken only 1 cylinder fires at a time ?

 

[KGBIGCOUNTRY]

1 does pulse at a time now picture the gasses coming from port #1 on the driver side, as it runs down the pipe and goes into the x ints gonna slam into the gasses from port # 4 on the passenger side causing them to get out of sync. Not really worth overthinking it, just simple enough to leave the mid pipes as is and run a y into one. If you want a dual out run a single in/ dual out muffler and call it a day IMO unless your trying to squeeze all the HP out of a setup. If your doing that then your talking headers, mid pipes, muffler selection ect.

 

[Belgiquebasterd]

1 does pulse at a time now picture the gasses coming from port #1 on the driver side, as it runs down the pipe and goes into the x ints gonna slam into the gasses from port # 4 on the passenger side causing them to get out of sync. Not really worth overthinking it, just simple enough to leave the mid pipes as is and run a y into one. If you want a dual out run a single in/ dual out muffler and call it a day IMO unless your trying to squeeze all the HP out of a setup. If your doing that then your talking headers, mid pipes, muffler selection ect.

A bit off topic and way overkill for this application I agree, but do like a good discussion on this topic Not really following what you mean though, is it because the 1 is in front of the engine and 4 in the back that the difference in length would cause the clashing pulses (since the cylinder fires at a different time)? Been reading up a lot on headers and exhaust but never found a reference to the passenger side pipes having to be different length than driver side.

 

[nitto]

I got true duels done to my truck about 2 weeks ago and dont really notice that much gain on power or anything

 

[KGBIGCOUNTRY]

Chris what im reffering to is yes the headers run the same length, but then the driver side pipe runs along the crossmember then can either met into the passenger side pipe or run beside it (not straight back). On the old school true dual cars from front to back the pipes were the same length. Let me change it up some for ya. We both know this does not happen but for ease of the descussing say cylinders 1 and 2 fire at the same time, so both front cylinders just to give a frame of reference. The gasses will reach the end of said pipe or to the x,y straight on the passenger side on cylinder 2 before the longer run on driver side 1 reaches it. For the scavanging effect to work you want the gasses to be flowing together to where they are not clashing at the cross over (x pipe). All that being said its way to overkill for the first question. Our N/A motors pusing what we are is fine with longtubes, a good Y pipe. There has been guys who change there whole setup numerious times and only thing that changes is the exhaust note, not total ET at the track or MPH through the traps. For the OP's labor rate being free and just has to fit 2 pipes around the crossmember, fuel tank, driveshaft, rear, schackles, spare tire then clear the bumper and put in 2 mufflers while he is there might be worth it. Me personaly just see double the work and double the price of parts IMO.

 

[suzukiquadrider]

duals look sweet on a gasser to say the least. If you had a CTD it would be a single IMO

 

[chefred112]

it sounds like your leanin towards true duals....since you're a 4.7 i would lean towards an H pipe instead of X pipe..it is more conducive for tq...

 

[chefred112]

I got true duels done to my truck about 2 weeks ago and dont really notice that much gain on power or anything

it's like a building block..you are preparing for future modding...as you add stuff like headers or maybe even heads or cam, it's nice knowing that you don't have to change your exhaust for more flow because you'll already have it...