Exhaust question...

[BulletTrain]

Ok, this ain't gonna be the same old "which exhaust is best" question. I actually have a fresh question regarding exhaust. At least I ain't seen it posted yet.

Here's the deal. You see a lot of folks replace their 4-2 exhaust with 4-2-1 systems on bikes. This idea seems strange to me. All my hot roddin' has been with cars. It seems that the thing to do on a car that comes with single exhaust is to install a true dual system.

Now, my question. Do the 4-2-1 systems make more power than a comparible 4-2 aftermarket system on a bike? Or, is it some other factor(s) that makes bikers go with the 4-2-1 single can system? Hell, for all I know, proper single systems on cars might actually be better. That's whay I am akin' this question. To have my azz ejumakated...

 

[L4G4RT0]

Main factor: weight... am I correct? or not? hummm... it's just a guess

 

[BulletTrain]

I thought about the weight savings, but if you have to choke the engine when exhaling to lose the weight, it'd have to be enough of a weight reduction to outweigh (pun intended   ) the hp loss from restrictive breathing. Kinda like removing one lung to lose weight to make you run faster. Sure, you're lighter, but you can't breath like you could with two lungs...

Of course, this is assuming that the 4-2-1 system actually is more restrictive than a 4-2 system. Maybe they use different diameter tubing throughout the system to make it flow like a 4-2. That's why I'm asking my question. I don't know these things.  

 

[vincebusa]

I thought about the weight savings, but if you have to choke the engine when exhaling to lose the weight, it'd have to be enough of a weight reduction to outweigh (pun intended   ) the hp loss from restrictive breathing. Kinda like removing one lung to lose weight to make you run faster. Sure, you're lighter, but you can't breath like you could with two lungs...

Of course, this is assuming that the 4-2-1 system actually is more restrictive than a 4-2 system. Maybe they use different diameter tubing throughout the system to make it flow like a 4-2. That's why I'm asking my question. I don't know these things.  

ohh yaaa haaa never thouh of that..

 

[vincent]

I know that my busa felt as though it was a bit more powerful when I went to a single can system, but that could be in my mind. JC would know?

 

[BulletTrain]

Hey vincent, just out of curiousity, which single can system did you go with?

 

[BulletTrain]

Oh, and since we're on the subject, is there a sound difference between 4-2-1 and 4-2 systems, given the same kinda can(s) of course?

 

[BusaFever]

BT,
I know that on the RC51, going from the stock dual cans to a single sacrificed some Mid-range HP & Torque. But that is a V-twin engine, not a HUGE I-4 like our babys have. But one would think that it suffered somewhat...

 

[BulletTrain]

BT,
 I know that on the RC51, going from the stock dual cans to a single sacrificed some Mid-range HP & Torque.  But that is a V-twin engine, not a HUGE I-4 like our babys have.  But one would think that it suffered somewhat...

Thanks for the comments. Was the loss measured by dyno? Or how?

 

[BusaFever]

Soley dyno charts....

and butt dynos, of course. :bounce:

 

[BusaFever]

If you want to see the results, check out rc51.org

 

[BulletTrain]

'K, thanks.

 

[Revlis]

Not an expert opinion but I have noticed that just about every 4-2-1 system out there makes just about the same sort of noises.  The 4-2 systems seem to give a deeper more resonant less screachy noise.

As for the Single pipe choking the engine?  Nah man, the Full systems have nice fat pipes from header to exhaust tip, little Baffeling, more than enough for proper exhalation.   The big bonus with going to a full System is real power gains and a good 20-25 pound weight loss if you go for a full Ti system.  
  Myself?  I am thinking slip ons for now, then full system down the road if I decide I need more power.  Then I can sell the slip on on ebay for a fairly decent price and only be out a couple of Hundred...  I have also heard that Carbon, Stainless, Titanium, and Aluminium cans produce different types of noise...with the Carbon cans giving the best bass...remember "I heard"  Haven't lined them up yet and had a listen...

 

[BusaFever]

Agreed Rev,

With my old bike, the singles and the duals made very close to the same hp. Virtually the same in many cases. Just the dual had noticeably more mid-range grunt than the single.

This is something that I have been searching for info on for the busa. Anyone got any single vs dual dyno runs?

 

[rubbersidedown]

stock stuff is very restrictive BT (emissions stan an all that)
the bike breathes better with aftermarket . Just like the first K&N ya dropped on that holley 650 dubl pumper . or ya turned over yer air cleaner lid to let it breathe . Cars and bikes have to exhaust and the straighter the line the better(most of the time) so on yer v8 you throw on some 3 in exhaust on each side and pump it straight out the rear . Its all about creating better VOLUMETRIC EFFICIENCY right . After markets are bigger, lighter , breath better etc etc. why a 4 2 1 instead of a 4 2 2 . Its for a few reasons , like you want some cross over , but not a bunch , if a header on a bike has a crossover between 2 and 3 it will pull a little better outa the lower rpms . I could go on an on BT , but I'd just bore the shid outa ya.....one of the drag racers will be along shortly Im sume with better reasoning than mine....

hav good 1...RSD.