2 into 1

[Nero-92]

Anybody have any experience of using a 2 into 1 exhaust system on the 916 engine my own bike is an s4 monster if so what system did you use and where there any other mods to be carried out e.g remap air filter.

[DucHead]

No experience, although plenty of info could be found on a search.

However no matter what else you do remapping the air filter is a must. 

[zooom]

2 into 1 systems (when all the stars are in alignment properly)generally in most cases will give you some more grunt low and mid, but will ultimately rob you of some top end...just something worth considering FWIW....YMMV of course

[NorDog]

2 into 1 systems (when all the stars are in alignment properly)generally in most cases will give you some more grunt low and mid, but will ultimately rob you of some top end...just something worth considering FWIW....YMMV of course

That seems like a great trade off for me.  I rarely really uncork my S4RS on the top end.

[brad black]

i'd say it's the other way around.  example being aprilia milles - the performance 2-2 systems gave more midrange than top end improvement.  also 999 with full systems and 1098 - both these systems have long single pipes after the collector.  compared to a 998 the 999 has a midrange hole, and the 1098 has a huge hole.  allegedly the zard 1098 system, which is like a 916/998 system with two pipes in and out of the collector, fills this hole.

my guzzi sport 1100i lost midrange when i made a 2-1 collector for the 2-2 full system i made.  it definitely changed the way it felt, as it came on hard at the top end like it never did with the 2-2.

i think eraldo ferracci's answer as to why they ran a 2-2 system on the 750 sport race bike in the late 80's was "midrange".  earlier bikes - bevels, pantahs, never had real flowing collectors, just H pipes, so the 2-2 didn't work like a real one does.

the only example of a 2-1 on a wsbk on a twin was the bike edwards won 2002 with.  all others ran 2-2, ducati started with a 2-1 on the prototype 748/851 in 1986, but it raced with 2-2 from 1988, as did the aprilia.

[Curmudgeon]

i think eraldo ferracci's answer as to why they ran a 2-2 system on the 750 sport race bike in the late 80's was "midrange".  earlier bikes - bevels, pantahs, never had real flowing collectors, just H pipes, so the 2-2 didn't work like a real one does.

No idea about what Eraldo did or what 750 Sport you reference but early Pantahs and TT2 bikes ran great on a 2-into-1 with equal length headers into a single reverse cone megaphone on the left. I had a very light stainless one on my 600 which had a flat power band and loved to rev from 3K to 9K+. Adamo also raced all his this way with a Malossi or NCR 2-into-1 system. The factory did the same. Glorious music too. Reno and Adamo used a shorter, fatter megaphone for the really fast tracks. Maybe the cams were different than the 750 Sport you mention?

Short clip, but this one sounds like mine. 

[brad black]

yes, i know all those bikes ran 2-1, and i'm sure they run great.  but as far as i'm aware no one has tried one with a proper 2-2 and published the results.  just because everyone does it doesn't make it right.  i've seen quite a lot of dyno charts, many of my own making, where a 2-1 has a midrange hole.

[Curmudgeon]

Hmmm... To get back on topic, I doubt an injected 4-valve would benefit particularly from a 2-into-1, other than perhaps the "music". With the original 2-valve Pantahs however, I believe there was a real scavenging benefit and the length and shape of the megaphone seriously influenced the torque and where the peak power was produced. They were "tuned". All this is "old school" but it worked wonders with my 600 SL.

Incidentally, as you are Australian, my road system was Australian and the man who produced it was both a craftsman and knew what he was doing. For the road with my Dellortos jetted to perfection, it was a delight. The NCR system I had just made more noise and moved the power band up 1,500 RPM, most likely due to the shorter length and volume and shorter rear cone. Never had a dyno though other than the seat-of-the-pants variety. 

My only experience with a 2-into-2 was the Conti boat anchor stock system with the crossover you mentioned. Crossovers in that period were used primarily to smooth out the power pulses but my 2-into-1 was oddly smoother. That stock system was choked of course.

What 750 engine was in the Sport you mentioned? If Eraldo got it to run better with a 2-into-2, I'd not question him as Eraldo had a lot of R&D background while still in Italy. He chipped my early 851 and I used the cans he designed but passed on his jewelry-like, $$$ superbike heads!  That 851 was a real weapon and at least for me on the street, didn't need any MORE "go". Real sneaky-fast bastard too. On backroads though, the tuned 600 SL was more grins.

Memories fade over time but I vaguely recall that Pridmore used a 2-into-1 on the BMW Superbikes he constructed. Those were 2-valve engines naturally. Reg had access to a dyno. He's still around. You could ask him.

Regards

[Nero-92]

Folks it the sound I'm after but I don't want to lose the mid range grunt that the s4 has as that's the way I ride the bike I very rarely would rev the bike above 7500 so what you are saying is if I do fit a 2 into 1 system I'll lose that mid range grunt so don't fit it.

[Curmudgeon]

Folks it the sound I'm after but I don't want to lose the mid range grunt that the s4 has as that's the way I ride the bike I very rarely would rev the bike above 7500 so what you are saying is if I do fit a 2 into 1 system I'll lose that mid range grunt so don't fit it.

No idea what resources you have in Ireland. It should be possible to tune for exactly what you want. Only money. Contact Larry Ferracci and see what he says. http://www.ferracci.com/contact.php