Multi Cyl into one exp chamber

[Powerabout]

Ok I know you can have 2 cyl into a single chamber as per seadoo's and ski doo's
but can you put 4 or 6 cylinders?

[OUTBOARDER]

4 into 1 makin 200hp http://www.youtube.com/watch?v=Ceeyrmn2Pj4

[Powerabout]

Thanks for the find.
but 2 1000cc sled engines joined is almost double that ( with pipes that is and emission compliant)

[Fastjeff57]

Pretty sure you have to have pairs and multiples of pairs. In this case, 3 into 6 would work.

Jeff

[Powerabout]

Pretty sure you have to have pairs and multiples of pairs. In this case, 3 into 6 would work.

Jeff
there are plenty of seadoo things with 3 into 1.
I found a couple of bike threads with people looking for data to build 3 into 1 for the old Kawa's and Suzuki's. All they said was less peak power than 3 singles
Maybe 4 into 1 only works with a megaphone as OMC set a world record with?
I guess 77 140's have a 4 into one megaphone.
I guess there is very little data on 4 cyl as there are not many ( less GP 500 bikes with 4 pipes and tons of HP)

[Revengable]

Due to the increased size of the common header(for volume) the pulses at the exhaust port are weaker....But with enough time and $$$ (testing) they will work.

[Fastjeff57]

.."there are plenty of seadoo things with 3 into 1."

Correct. I shouldn't have used the word "pairs". But the pulses must be in a proper sequence, and 6 into 4 chambers is not.

Not

[Powerabout]

.."there are plenty of seadoo things with 3 into 1."

Correct. I shouldn't have used the word "pairs". But the pulses must be in a proper sequence, and 6 into 4 chambers is not.

Not
Would you run 4 pipes into one then into the divergent cone or 4 pipes into the cone so look like a 4 stroke header collector?

[Fastjeff57]

Absolutely. A zillion V-8 race car engines use that setup.

Jeff

[Powerabout]

Absolutely. A zillion V-8 race car engines use that setup.

Jeff
If it was a zillion v8 two stroke race cars I would have some data to work with hence the question.

[Fastjeff57]

Okay, okay! So they're FOUR strokes, but the principle is the same.

Jeff

[Powerabout]

Okay, okay! So they're FOUR strokes, but the principle is the same.

Jeff
Not so sure about that...a collector drags the gas out better than 1 pipe would but we know a single pipe on a 2 stroke makes more power for other reasons
Much better blow down on a 2 stroke than a 4 so less of an issue.

[Fastjeff57]

Acoustically speaking--and this is what it's all about--the action is similar.

Jeff

[Powerabout]

Acoustically speaking--and this is what it's all about--the action is similar.

Jeff
I'm not with you..
a 4 stroke collector creates a low pressure to pull the adjacent cylinder down and after that who cares
pulling the exhaust out of a 2 stroke is not a problem its pushing it back in thats the art of it, not something you need to do with a 4 stroke

[Fastjeff57]

ACOUSTICS--that's the thing here. Two or four stroke, exhaust pulses are being used to draw exhaust out (and air in). Be it an expansion chamber, megaphones, or the simplest form (drag car headers) the acoustic principle is the same.

Jeff

[Powerabout]

ACOUSTICS--that's the thing here. Two or four stroke, exhaust pulses are being used to draw exhaust out (and air in). Be it an expansion chamber, megaphones, or the simplest form (drag car headers) the acoustic principle is the same.

Jeff
ok yes, its all about sound waves

[champ20B]

ok yes, its all about sound waves

My brother's Polaris 1200cc jet ski is a two cycle (3 cylinder) engine with 135hp. It has ONE expansion chamber! I replaced the brain box and rebuilt the three carbs on this engine.

[Powerabout]

My brother's Polaris 1200cc jet ski is a two cycle (3 cylinder) engine with 135hp. It has ONE expansion chamber! I replaced the brain box and rebuilt the three carbs on this engine.
Nothing special, that makes a2.4ltr 270hp?

[champ20B]

Nothing special, that makes a2.4ltr 170hp?

No, 1200cc is about 75 cubic inches. That is a (1.2) liter w/135 horses.

At 2.4 liters that would equate to 270bhp if one looks at it for relative power per displacement. That's pretty impressive for a standard production engine! But it is an odd cylinder # with one chamber. I have heard that three cyls don't usually need a chamber because of the pulses from each other makes up the needed resonation. It appears that there was an engineer that thought differently.

[Revengable]

58572

The tri-Y type headers are an attempt at equal distances..

[Powerabout]

800 etec sled twin is 175hp I think buts thats with a ex valves and single chamber, sea doos have less power, no ex valves so more inline with an outboard but the jet still makes life easier for them.

[Fastjeff57]

Back --WAY back--when I was building custom expansion chambers, a guy brought me his 440 Yamaha with one request: Make that sucker fly! It seems he had a neighbor's hot Artic Cat was just a bit faster, and that was intolerable!

The Yammy had a two into one expansion chamber (factory) that ended in a huge muffler. I made him two chambers for it with stinger mufflers, and I made them for top end power only. The result was it was a dog getting "on plane" (so to speak), but when that sucker hit the power band---whooh doggie! He blew that guy's cowling off, but it took a ton of spring work on the clutch to get it to rev a lot higher before ratioing up.

I also built a triple set of chambers for a guy with a "water Buffalo" (750 Suzuki) road bike that he made into a chopper. It was a real challenge to get all three nestled in there without them dragging on the road, but... Sounded insane as he roared off!

Ah, memories...

Jeff