Was at a talk with a friend about her exhaust.
Shes got an long-block installed with manifolds on her engine, since she wanted those for stock appearance.
We were discussing about what she plans to do next, and happened to measure her downpipes.
When they are equally positioned, both ends level with transmission crossmember, the drivers side is 8.7 inches longer.
Now, if we install X- or H-pipe, its not really at the crosspoint, or at any "multiple" ( 31.2" vs 22.5" total lengths for downpipes). Pipes are 2.5".
Got me thinking, that wouldnt Y-pipe be equal to x-pipe? With that kind of length difference, it would be easy to play that length difference to be equal if taking the shorter side to other side of drive-shaft; then using merge y-collector with 2x2.5" inlets to 3.5" outlet ( since 3.5" diameter pipe is really close to two 2.5" diameter pipes), and running it down with that pipe?
You see where im heading for? We are talking approx. 400hp V8- X/H-pipe with unequal length before joint, or joining equal length pipes to Y-merge collector and running it out with single 3.5". Not positively sure when wondering that the all-so-loved x-pipe would be the best option..
Exhaust tech ( unequal length )
Moderator: Team
Re: Exhaust tech ( unequal length )
I was once told to figure out the hottest spot on the exhaust after the collector and connect the H-pipe there.
There will be hot spots following the length of the pipe. Where they are depends on exhaust diameter and exhaust wavelength which is dependent on engine character and rpm.
The hot spot is the place where most of the exhaust pulses share space and time..... most of the time.
You can figure out where the first hot spot is, or second, by painting or adhering something across of the length of the pipe and drive the car in the conditions where you want it to work the best.
I thought, cool. and stuck it where I had room, and where I thought it looked right.
There will be hot spots following the length of the pipe. Where they are depends on exhaust diameter and exhaust wavelength which is dependent on engine character and rpm.
The hot spot is the place where most of the exhaust pulses share space and time..... most of the time.
You can figure out where the first hot spot is, or second, by painting or adhering something across of the length of the pipe and drive the car in the conditions where you want it to work the best.
I thought, cool. and stuck it where I had room, and where I thought it looked right.
Magnús Aðalvíkingur Finnbjörnsson
Re: Exhaust tech ( unequal length )
Some years back, I was calling the shots on a custom exhaust system for a Big Block dually. I had the 3" (overkill!) left bank pipe swept across and run parallel with the right one back to the mufflers. I used stripes of several temperatures of Tempilac (e.g. https://www.coleparmer.com/p/tempilaq-t ... ints/66925 ) to find the hot spots, which, sure enough, were staggered down the pipes by the left's crossover length, ~ 2'.
To connect them, I had ~ 2-1/2" openings cut in the facing sides of the pipes, boxed in the pipes with top and bottom plates and sealed off the ends just beyond the 'windows', with filler plates. This effectively resulted in an hourglass cross section 'H' pipe connected between the hot spots.
To compare with/without effects, I also had a cable-operated 'throttle plate' fitted in it. Open vs. closed had a significant but hard to describe effect on sound but didn't really move the needle on the butt dyno. Since it was just mild steel, before long the plate rotted out and I just had the shaft holes welded shut.
To connect them, I had ~ 2-1/2" openings cut in the facing sides of the pipes, boxed in the pipes with top and bottom plates and sealed off the ends just beyond the 'windows', with filler plates. This effectively resulted in an hourglass cross section 'H' pipe connected between the hot spots.
To compare with/without effects, I also had a cable-operated 'throttle plate' fitted in it. Open vs. closed had a significant but hard to describe effect on sound but didn't really move the needle on the butt dyno. Since it was just mild steel, before long the plate rotted out and I just had the shaft holes welded shut.
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.