Equal-length headers on boats

[traquer]

Anyone seen one done? I had a dream last night that I had a DCB built and tig welded up my own titanium headers in an 8-to-1 config and ripped across the lake at 180mph. It was a good dream lol

This is what it would sound like if done well. I think it helps HP too besides the noise.

 

[Bajastu]

It's common in the jet boat scene. Lots of off-road guys build jet boats and add in an equal length 8-1 header.

 

[FENDERFAB]

Very popular in the jet boat world.

Danny Giannini as well as Johnny Branch have built many of them

 

[FENDERFAB]

Few more

Photo Gallery - HDR Industries- 8-1 Jet Boat Header -

HDR Industries- 8-1 Jet Boat Header

www.stainlessheaders.com

 

[rivermobster]

Just configuring a set and bolting em up it one thing.

Figuring out the Exact harmonics needed would be quite another.

AI could come on handy here.

 

[traquer]

Just configuring a set and bolting em up it one thing.

Figuring out the Exact harmonics needed would be quite another.

AI could come on handy here.

Yes! That's the rabbit hole I started going down on.. They all sound good, that yellow jet boat above too. But if you do it just right, that shit will sing you a melody lol!

 

[RiverDave]

I believe most headers are equal length?

I read a ton of see journals when I was a kid regarding the harmonics of intake manifolds, exhaust manifolds, cams.. learned about vtec and how they have by passes in the intake manifolds to shorten the length for higher rpms and different cam grinds.. vs variable cam timing to kind of accomplish something similar..

I believe it was Mercedes that did an f- car with variable length intake and exhaust..

There were some two stroke outboards a long time ago that would vary the length of the megaphones based on rpm..

Very cool
Stuff

 

[FENDERFAB]

Some of the 8 into 1 setups are built for rotary firing order, so the tubes are sequential with each other based upon the firing order of the engine if that makes sense. Some are not.

I personally have never built a set so i cant comment on the advantage/disadvantage of either setup.

Here is some more photos

 

[rivermobster]

I believe most headers are equal length?

I read a ton of see journals when I was a kid regarding the harmonics of intake manifolds, exhaust manifolds, cams.. learned about vtec and how they have by passes in the intake manifolds to shorten the length for higher rpms and different cam grinds.. vs variable cam timing to kind of accomplish something similar..

I believe it was Mercedes that did an f- car with variable length intake and exhaust..

There were some two stroke outboards a long time ago that would vary the length of the megaphones based on rpm..

Very cool
Stuff

Variables length intakes, in the car manufacturer world, have been around for three decades at least.

Equal length headers are not Always optimum.

The goal is to have the exhaust pulse, as it enters the collector, to suck out the exhaust pulse right behind it.

So it's all about timing and what RPM you want it to be Most effective at.

AI would be Very helpful with this.

 

[Sleek-Jet]

Jeezus... That Mustang sounds like an F1 car, freaking awesome.

 

[coolchange]

There’s a difference in those 8-1. Some are rotary timed, others not.
I’m old school, I like 180 deg.

 

[jetboatperformance]

Theres a young guy named Johnny Branch that does a lot of this in my world https://www.instagram.com/branchengineering/?hl=en

 

[traquer]

Jeezus... That Mustang sounds like an F1 car, freaking awesome.

Lol yup it's insane. Imagine that noise in a twin cat blowing by you on the water at 100mph!!

I wonder what would happen to the sound if there was water being injected into the headers though. Might dampen it but should still be epic.

 

[traquer]

There’s a difference in those 8-1. Some are rotary timed, others not.
I’m old school, I like 180 deg.

I love the 180 too, with a nasty cam!

I'm assuming the rotary is what gives it the smooth scream? The sound waves keep adding up instead of cancelling each other out it seems

 

[traquer]

I believe most headers are equal length?

I read a ton of see journals when I was a kid regarding the harmonics of intake manifolds, exhaust manifolds, cams.. learned about vtec and how they have by passes in the intake manifolds to shorten the length for higher rpms and different cam grinds.. vs variable cam timing to kind of accomplish something similar..

I believe it was Mercedes that did an f- car with variable length intake and exhaust..

There were some two stroke outboards a long time ago that would vary the length of the megaphones based on rpm..

Very cool
Stuff

There's equal length, and then there's the way they get piped into the collectors. But I don't think most equal-length headers are perfectly equal or optimized for sound as much as they are power.

Crazy I've never once seen a jet boat with this 8-1 setup, must be an East coast thing? Or maybe I just never paid attention before this. Hidden away in an I/O it'd be sick to just hear that noise and not know how it's being made and what the engine is until you see it up close.

 

[Bajastu]

There's equal length, and then there's the way they get piped into the collectors. But I don't think most equal-length headers are perfectly equal or optimized for sound as much as they are power.

Crazy I've never once seen a jet boat with this 8-1 setup, must be an East coast thing? Or maybe I just never paid attention before this. Hidden away in an I/O it'd be sick to just hear that noise and not know how it's being made and what the engine is until you see it up close.

All of the jet boats mentioned above with 8-1/ 180* headers are in SoCal / Central valey

 

[Bajastu]

Proper tuned 8 into1 180* LS power

 

[Clank123]

Maybe it is a jetbote thing, never seen a set on a vdrive.
Not sure, but some of those sets it seems the collector is too small.
It should at least match the total diameter of two collectors?
Like to see some dyno numbers.
If you’re gonna do an 8 into 1 it otta be at least 180 degree design.
Mid 60’s Nordskog we did years ago
Always liked the look.

 

[chvynhra]

Another

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[coolchange]

I love the 180 too, with a nasty cam!

I'm assuming the rotary is what gives it the smooth scream? The sound waves keep adding up instead of cancelling each other out it seems

My brother is building a mid engine corvair. 377 with webers, 110 lobe centers and 180 degree headers.
Ya that ain’t no ‘Vair lol.

 

[lbhsbz]

Maybe it is a jetbote thing, never seen a set on a vdrive.
Not sure, but some of those sets it seems the collector is too small.
It should at least match the total diameter of two collectors?
Like to see some dyno numbers.
If you’re gonna do an 8 into 1 it otta be at least 180 degree design.
Mid 60’s Nordskog we did years ago
Always liked the look.
View attachment 1387739

If they are timed right, the collector should be about 125-140% of the primary diameter. I worked with a guy for a few years that was chasing the second order harmonic on the Honda K20 platform….in the end, he was making north of 430hp with a N/A 2.2L…at around 8500-9000rpms. He had an intake and header for 8500, and another for 9000, both had the runner lengths optimized for a small RPM range. I would see him adding 1/8” or taking away 1/8” at a time to intakes and headers and then heading back to the dyno the next week. Thousands of hours in development.

In a certain RPM range, the header lengths and collector size/design can be tuned so that as one pulse leaves the collector is draws a vacuum on the next cylinder’s primary….that’s the sweet spot. The header is only part of the equation though.

 

[River Dirt 2]

I believe most headers are equal length?

I read a ton of see journals when I was a kid regarding the harmonics of intake manifolds, exhaust manifolds, cams.. learned about vtec and how they have by passes in the intake manifolds to shorten the length for higher rpms and different cam grinds.. vs variable cam timing to kind of accomplish something similar..

I believe it was Mercedes that did an f- car with variable length intake and exhaust..

There were some two stroke outboards a long time ago that would vary the length of the megaphones based on rpm..

Very cool
Stuff

If you haven’t already you might like to read about the new C8 corvette ZO6 motor, flat plane crank, DOHC and the intake manifold is amazing.

https://www.motortrend.com/how-to/chevy-lt6-engine/

 

[mash on it]

If they are timed right, the collector should be about 125-140% of the primary diameter. I worked with a guy for a few years that was chasing the second order harmonic on the Honda K20 platform….in the end, he was making north of 430hp with a N/A 2.2L…at around 8500-9000rpms. He had an intake and header for 8500, and another for 9000, both had the runner lengths optimized for a small RPM range. I would see him adding 1/8” or taking away 1/8” at a time to intakes and headers and then heading back to the dyno the next week. Thousands of hours in development.

In a certain RPM range, the header lengths and collector size/design can be tuned so that as one pulse leaves the collector is draws a vacuum on the next cylinder’s primary….that’s the sweet spot. The header is only part of the equation though.

What is the possible HP gain between the two?
2 HP?
20 HP?
More?

Just curious if the juice is worth the squeeze.

Dan'l

 

[outboard_256]

I wish I could find the video but I once saw this video from a car show/booth. They take 2 different brand headers for the same car on a table. They cover 3 holes with tissue paper leaving one open. They take compressed air and shoot it into the open hole. First brand of headers the tissue paper doesn't move at all. Doesn't matter what holes you cover and which one you shoot the air in. When they do the next brand of headers they cover the 3 holes and shoot air into the open one the tissue would get sucked down the header. But only one tissue out of the 3 would get sucked down. And if you changed holes the tissue pipe would change. So it was setup to suck down the next hole in the firing order. And it wasn't a little vacumm in the tube, the tissue would get sucked down instantly like you had a shop vac on the other side. Really opened my eye's that not all headers are the same. And visually the 2 headers didn't look that different from the outside. These were not equal length headers.

 

[Bajastu]

What is the possible HP gain between the two?
2 HP?
20 HP?
More?

Just curious if the juice is worth the squeeze.

Dan'l

It's a very minimal high RPM increase. I'd say less than 10 top-end HP change between the two. Most guys building these know the firing order, primary size, and collector size needed to build the headers. But I highly doubt that they have them on a flow bench of some sort to scientifically get the timing, primary length, and collector length down pat. Most of the time, outside of and open engine compartment boat, engine compartment space places the biggest factor on the design of the headers. An 8 into 1 collector is not a small item to package into the engine compartment yet alone the web of primaries.

My tube chassis F100 may see a 8 into 1 / 180* header if I feel like spending the time to fabricate one. I’m just weighing out the pros and cons of it. Added interior heat vs the most awesome sound made by an engine.

 

[Guest06]

Proper tuned 8 into1 180* LS power

i think the only truck to ever sound better was the Duralast truck in the late 99’s early 2000’s.

 

[Guest06]

I wish I could find the video but I once saw this video from a car show/booth. They take 2 different brand headers for the same car on a table. They cover 3 holes with tissue paper leaving one open. They take compressed air and shoot it into the open hole. First brand of headers the tissue paper doesn't move at all. Doesn't matter what holes you cover and which one you shoot the air in. When they do the next brand of headers they cover the 3 holes and shoot air into the open one the tissue would get sucked down the header. But only one tissue out of the 3 would get sucked down. And if you changed holes the tissue pipe would change. So it was setup to suck down the next hole in the firing order. And it wasn't a little vacumm in the tube, the tissue would get sucked down instantly like you had a shop vac on the other side. Really opened my eye's that not all headers are the same. And visually the 2 headers didn't look that different from the outside. These were not equal length headers.

Called scavenging, the right header guy can make plenty of free hp with the right headers. The ones done under the Tom Face name at Scotty’s Mufflers in San Bernardino for my buggy scavenged and sounded amazingly for a merged set vs a 180° header.

 

[Bajastu]

Called scavenging, the right header guy can make plenty of free hp with the right headers. The ones done under the Tom Face name at Scotty’s Mufflers in San Bernardino for my buggy scavenged and sounded amazingly for a merged set vs a 180° header.

I had him build a bad ass header for my turbo 2332 VW 15+ years ago. Are they still in buisness?

 

[Guest06]

I had him build a bad ass header for my turbo 2332 VW 15+ years ago. Are they still in buisness?

Yea same location and all. Tripod as you may remember him as from the GD days. If you’re looking to have him do something i have his info still.