"H" before catback... does it really do anything?

[SRT-MIKE]

Looking at the stock catback, the straight pipe sections going though the muffler have several large perforations that cause the exhaust from both tubes to mix inside the can. How would the addition of an "H" or "X" before the muffler have much of an effect, since the exhausts are mixed in the muffler anyway?

Thanks in advance for any insight.

 

[Django]

Since no one else with any real proficiency has answered....

It's supposed to relieve more backpressure if memory serves...

Probably HUGE hp gains, too.............

D

 

[Prof]

I agree with Django...I would estimate hp gains at maybe in between 5, or about a buck two eighty per each hp.

 

[SRT-MIKE]

Hey guys, thanks for the input.

What I'm looking for is a better sound, certainly not hp gains. But if both pipes dump exhaust into the same muffler though the perforations, would this not have the same backpressure reduction effect than an "H"?

I mean, an exhaust pulse from one pipe would be shared between both pipes inside the can, right?

 

[AWDisuzu]

h pipes are used on v8 engines because the firing order is uneven between banks and the h pipe equalizes the exhaust puffs. this is not the case on out engines, as each bank of 5 cylinders fires as a 5 cylinder engine. an H pipe on a v10 will cause the exhaust "puffs" to collide and may not be the most beneficial for hp.

 

[SRT-MIKE]

h pipes are used on v8 engines because the firing order is uneven between banks and the h pipe equalizes the exhaust puffs. this is not the case on out engines, as each bank of 5 cylinders fires as a 5 cylinder engine. an H pipe on a v10 will cause the exhaust "puffs" to collide and may not be the most beneficial for hp.

Wow... very interesting, I had no idea.
I bet some in here will not like these news...

Thanks for the info, AWDisuzu.

 

[SrtBrad]

h pipes are used on v8 engines because the firing order is uneven between banks and the h pipe equalizes the exhaust puffs. this is not the case on out engines, as each bank of 5 cylinders fires as a 5 cylinder engine. an H pipe on a v10 will cause the exhaust "puffs" to collide and may not be the most beneficial for hp.

Mike continues to amaze me in his knowledge of these trucks. Are you sure you're not a disgruntled Viper Tech.

 

[AWDisuzu]

if I were disgruntled, I'd tell all 'yall to buy something else lol

 

[SRT10VENOMOUS]

hey cool update had no idea as well.. just thought it was the thing to do as did most ppl on here im sure

 

[HOT RAM]

Just a thought..................if an "X" pipe cross-over HURT HP,why do most people GAIN HP when going to a MagnaFlow from stock ? ( in case you don't know,the MagnaFlow has an internal X)
If you look at it,the stock muffler is wide open and straight through.

I think one of the reasons the MagnaFlow sounds so good is due to that internal crossover.

I ran mine with no cats and stock muffler and it sounds horrible.With just an "H" pipe (simplest type of crossover) it sounds MUCH better.

The only way that I know we can find out for sure would be to dyno test each combination.Otherwise we are all just speculating and guessing.

One FACT that I can put out there.............for whatever reason, the crossover DEFINITELY improves the sound (stock muffler,no cats)!!!!!!!!! Whether or not it would provide any additional improvement to a MagnaFlow equipped truck or not I can only guess.My guess is it will also help the sound on these systems.

For me,the sound quality was more important than a tiny bit of horsepower lost (IF there is any lost)

 

[Prof]

I think the slight increase is a combination of things but primarily the reduction in back pressure.

 

[rottenronnie]

Ford largely gets credit for the H pipe back in the 60s.. It's function was to lower noise and add torque. It worked well enough that manufacturers incorporated it into the exhaust systems of their performance vehicles of the time. It worked, even with that peculiar Ford firing order!

 

[HOT RAM]

I think the slight increase is a combination of things but primarily the reduction in back pressure.

I am curious as to where this reduction would come from being that both mufflers are straight-through ? I doubt it would come from the 3" tail pipes on the MagnaFlow. Less bends ? Maybe the passageways are bigger in the MagnaFlow muffler ?

 

[rottenronnie]

I am curious as to where this reduction would come from being that both mufflers are straight-through ? I doubt it would come from the 3" tail pipes on the MagnaFlow. Less bends ? Maybe the passageways are bigger in the MagnaFlow muffler ?

Years ago, when I asked this question to an engineer/exhaust guru, the answer was something like this:

"Because the exhaust pipes are now connected and the exhaust gas pulses alternate back and forth between each side, the pressure inside of the dormant side is slightly reduced by the draw of the exhaust pulse passing by the connector. This creates less resistance for the upcoming pulse on the soon to be active side".

I guess that is why it was/is important to have the pipes connected before the mufflers for this action to be the most effective.

Ron

 

[SRT-MIKE]

Just a thought..................if an "X" pipe cross-over HURT HP,why do most people GAIN HP when going to a MagnaFlow from stock ? ( in case you don't know,the MagnaFlow has an internal X)
If you look at it,the stock muffler is wide open and straight through.

I think one of the reasons the MagnaFlow sounds so good is due to that internal crossover.

I ran mine with no cats and stock muffler and it sounds horrible.With just an "H" pipe (simplest type of crossover) it sounds MUCH better.

The only way that I know we can find out for sure would be to dyno test each combination.Otherwise we are all just speculating and guessing.

One FACT that I can put out there.............for whatever reason, the crossover DEFINITELY improves the sound (stock muffler,no cats)!!!!!!!!! Whether or not it would provide any additional improvement to a MagnaFlow equipped truck or not I can only guess.My guess is it will also help the sound on these systems.

For me,the sound quality was more important than a tiny bit of horsepower lost (IF there is any lost)

My Magnaflow muffler just had two straight pipes, no "X".
However I think it is worth a try to put that H just in front of the stock catback, you convinced me on the sound quality thing.

 

[HOT RAM]

My Magnaflow muffler just had two straight pipes, no "X".
However I think it is worth a try to put that H just in front of the stock catback, you convinced me on the sound quality thing.

It is on the inside of the muffler

 

[Prof]

It is on the inside of the muffler

And the restriction goes to 2.5 inches in the cross! (I've been lead to believe.)