Turbine Doc
Just Another Diesel Guy
Well I had no idea this would be such an active thread, so I changed the heading to expand to a complete exhaust Q&A.
I started discussion with X overs, but to expand and answer possibly why change exhaust at all beyond the X over?
It is well known that key to making power in a Diesel is airflow, for more in depth info on that visit Banks website, seek the tech articles/discussion link and there is some very good info about airflow.
Stock exhaust is 2.25" with many restrictions: X over, Down pipe, Cat/soot trap that plugs easily, Muffler, all of which need to be free flowing as the 6.5 just like any other Diesel likes to breathe.
After market 3" is plenty for most folks, some folks go straight pipe after the turbo no muffler (turbo itself makes a pretty good muffler) that is until you go to the ATT which can be loud at the exit even with a quality muffler on it, not loud really it announces it's presence with AUTHORITY , no "fart can ricer noises" from the outlet.
1st system I had was a Banks 3" system which was an improvement, but gave me some odd ball pressure pulses on WOT accelerations, that showed at the boost gauge, rapid pulsations of boost 1-4 psi depending on how hard I pushed it when I had my GM turbo.
I run a 0-15 psi boost gauge which is more sensitive than a 0-20/0-30+ one is, not sensitive more like a tighter span of range looked at so small changes show up as large ones because of gauge sweep range.
Anyway I shared this with Bill Heath one day, and he suggested I had a issue with my muffler, Banks then (I don't know about now) used a reverse/cross flow muffler like GM muffler, exhaust in high side on inlet-thru muffler/baffle tube-hit back wall of body-enter other tube-turning internally then out the back of the muffler low side.
He suggested I replace it with one of his, since nothing was wrong with mine other than the oddball boost which was more of a visual distraction than felt performance loss, I was hesitant, he did some light arm twisting and I relented to him,
.
Boy am I ever glad I did relent, not only was it 4" but the muffler was thru flow like a big assed straight glass pack I used to run back int the 70s, (without the glass).
Wow I gained a more throaty growl and the boost drift nuisance I had been trying to solve for 4 years went away, plus I picked up some more street grunt by seat of pant dyno, and improved acceleration time over distance at my favorite stretch of "test track" at the old shipyard access road by my house that I use to judge results of mods I make, way to go Bill :thumbsup: .
Added the ATT and now when I get in a tunnel with windows cracked it sounds like a semi rig is right behind me with the re-virb off the wall when I punch it up a little, very fun to do when next to a ricer or Prius and they freak out looking for the semi that came out of nowhere this is "fixin to" run em over. Know what a Prius sounds like if it passes you ??? Immmm Gaaaayyyyy (Thx for that joke Juff Dunham)
So from that experience my recommendation is that whatever system you choose it needs to be mandrel bent, and have a straight thru flow muffler, 3+", 4" if you plan on pushing the performance envelope to it's limits.
I like the Heath setup obviously as it is on both of my 6.5s, now if really cash strapped, another possibility for a home brew system, get an old stock system from a Stroke.
From a bone yard, 4x4 specialty shop, or muffler shop that does exhaust upgrades for Strokes, the removed stock systems on those are IIRC are 3/+3" maybe 4" stainless tube systems and would work very well for the 6.5
I started discussion with X overs, but to expand and answer possibly why change exhaust at all beyond the X over?
It is well known that key to making power in a Diesel is airflow, for more in depth info on that visit Banks website, seek the tech articles/discussion link and there is some very good info about airflow.
Stock exhaust is 2.25" with many restrictions: X over, Down pipe, Cat/soot trap that plugs easily, Muffler, all of which need to be free flowing as the 6.5 just like any other Diesel likes to breathe.
After market 3" is plenty for most folks, some folks go straight pipe after the turbo no muffler (turbo itself makes a pretty good muffler) that is until you go to the ATT which can be loud at the exit even with a quality muffler on it, not loud really it announces it's presence with AUTHORITY , no "fart can ricer noises" from the outlet.
1st system I had was a Banks 3" system which was an improvement, but gave me some odd ball pressure pulses on WOT accelerations, that showed at the boost gauge, rapid pulsations of boost 1-4 psi depending on how hard I pushed it when I had my GM turbo.
I run a 0-15 psi boost gauge which is more sensitive than a 0-20/0-30+ one is, not sensitive more like a tighter span of range looked at so small changes show up as large ones because of gauge sweep range.
Anyway I shared this with Bill Heath one day, and he suggested I had a issue with my muffler, Banks then (I don't know about now) used a reverse/cross flow muffler like GM muffler, exhaust in high side on inlet-thru muffler/baffle tube-hit back wall of body-enter other tube-turning internally then out the back of the muffler low side.
He suggested I replace it with one of his, since nothing was wrong with mine other than the oddball boost which was more of a visual distraction than felt performance loss, I was hesitant, he did some light arm twisting and I relented to him,
.Boy am I ever glad I did relent, not only was it 4" but the muffler was thru flow like a big assed straight glass pack I used to run back int the 70s, (without the glass).
Wow I gained a more throaty growl and the boost drift nuisance I had been trying to solve for 4 years went away, plus I picked up some more street grunt by seat of pant dyno, and improved acceleration time over distance at my favorite stretch of "test track" at the old shipyard access road by my house that I use to judge results of mods I make, way to go Bill :thumbsup: .
Added the ATT and now when I get in a tunnel with windows cracked it sounds like a semi rig is right behind me with the re-virb off the wall when I punch it up a little, very fun to do when next to a ricer or Prius and they freak out looking for the semi that came out of nowhere this is "fixin to" run em over. Know what a Prius sounds like if it passes you ??? Immmm Gaaaayyyyy (Thx for that joke Juff Dunham)
So from that experience my recommendation is that whatever system you choose it needs to be mandrel bent, and have a straight thru flow muffler, 3+", 4" if you plan on pushing the performance envelope to it's limits.
I like the Heath setup obviously as it is on both of my 6.5s, now if really cash strapped, another possibility for a home brew system, get an old stock system from a Stroke.
From a bone yard, 4x4 specialty shop, or muffler shop that does exhaust upgrades for Strokes, the removed stock systems on those are IIRC are 3/+3" maybe 4" stainless tube systems and would work very well for the 6.5
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