new exhaust technolgy??

[Paul Rig]

I noticed a exhaust mod. Ive never seen before on a 4into1


Where small diameter tubes link cylinders 1 and 4 , and 2 and 3.
Just wondering what purpose or thoughts people have about this.

[David Redszus]

The BMW 2002 has linked exhaust pipes 1 &4, 2 & 3, for about 45 years.

[enigma57]

Look to be small diameter balance pipes. Might help smooth out idle and low speed running? Can't hurt, might help.

Best regards,

Harry

[Paul Rig]

alright maybe not new. still interesting, I hadn't seen it before

[enigma57]

4-cyl. firing order if building 4 into 2 into 1 exhaust system usually join 1 & 4 and 2 & 3 before joining all of them together downstream. Interesting that on this engine, they would do a 4 into 1 system and add small balance tubes to link primary tubes from those same cylinders. Thanks for posting. You reminded me of something I have been thinking about doing on my own car.

Happy Motoring,

Harry

[Paul Rig]

I find it interesting for the same reasons.
But I wonder why its set up how it is ... ie the staggered setup of the cross overs.

[engineguyBill]

I'm thinking it is the same principle/theory as Tri-Y headers or 'H' pipe in the exhaust system. Tends to tone-down the pulses within the system.

[ptuomov]

How about getting the expected/desired sound that the marketing department has specified?

[hoffman900]

These have been used on sportbikes for the better part of 15-20 years now.

Neels had a good reply here:
viewtopic.php?f=1&t=40737

[peejay]

There was a company that was installing balance pipes like that on Mazda rotary headers a few years back.

An interesting comment I heard from someone who was experimenting with them.

Are you sure that the balance pipe is connecting the two? Or that it is fully open and there isn't an orifice or two in there?

Might be balancing resonance between the two pipes... Might be a pair of Helmholz resonators and no connection at all. Or maybe there's an orifice in the middle, or the opening from the header pipe to the tube isn't fully open...

[MadBill]

Per the principle of Ockham's razor*, the tubes are probably just tubes.
*Paraphrased: "Among competing hypotheses, the one with the fewest assumptions should be selected."

[af2]

Per the principle of Ockham's razor*, the tubes are probably just tubes.
*Paraphrased: "Among competing hypotheses, the one with the fewest assumptions should be selected."

Or they are keeping the exhaust from ripping off the flange? By tying them together.

[peejay]

Meaning no connection at all, it's just a dead ended pipe...

I do wonder about the idea of using a resonance tube with an orifice in it, that might mean it works at lower RPM in order to kill an antinode, but at higher RPM it becomes less relevant.

Or maybe I've been breathing too many 2-stroke enhanced exhaust fumes!

[af2]

Meaning no connection at all, it's just a dead ended pipe...

Or maybe I've been breathing too many 2-stroke enhanced exhaust fumes!

YEP and I am also in the enhanced 2 stroke stage....LOL But they run good!!!!

[hoffman900]

Per the principle of Ockham's razor*, the tubes are probably just tubes.
*Paraphrased: "Among competing hypotheses, the one with the fewest assumptions should be selected."

See Neels' post about a test Akrapovic system.. tubes with a 30mm i.d. and a 15mm hole from the primary tube.