OHV headers on SOHC

[Roert42]

There longer the headers the better it sounds.

 

[MSGia]

There longer the headers the better it sounds.

I’m not considering long tube headers, I’m just talking about the difference between cast iron oe manifold and headers. Here’s the one I’m looking at:

I was then going to use the stock cats (well, a replacement because mine broke off) and then weld up some sort of X pipe (and ditch the reverse Y pipe) and also a glasspack style muffler.

 

[RonD]

Think Pipe Organ and what the pipes look like to makes the "notes" played
The same "air" enters each pipe organs tube, but the diameter and length of that tube produces a different note
Same air, different note...................

Forget the header part, that is a design for scavenged power, not sound, so picked by best performance at the RPM range you want

After the header, is where you can tailor the sound, larger diameter straighter pipes will hold the lower frequencies better
Going over the axle use a longer curve verses a sharp curve if you like the lower sound
So go 2.5" or even 3" after header
Obviously Cats and muffler need the larger diameter as well

Mufflers job is to lower the volume of exhaust which means limiting the lower frequencies which travel farther than high fequencies
i.e. you can hear the sub-woofers beat from 4 cars back in a line up but can't hear the song part, lol, its not just because the sub is cranked its because low frequencies just travel farther, longer waves of sound

 

[funguy26]

I was able to find the dyno graph for the 2 runs:

View attachment 90905

What was interesting is that you could feel that torque bump just before 3500 rpm with the JBA, so the "butt dyno" said they produced more power, but in fact they were just catching up to the stock manifolds at that point.

the power difference is within the "noise" HP is 1.92 TQ is 1.17 that air could have just change how the engine give power, the dyno is shelf could be the one that change the number.

 

[rubydist]

@funguy26 - you are missing the point. All the way up to 3500 rpm the "headers" curve is significantly lower than the "stock" curve. That difference is not in the noise. Yes, the peaks are very close to each other.