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Guys, the pressure balance pipe that goes between the header pipes on the inline fours..... Why is it so different in design ? I know that the black art of header and mid pipe design will always be argued but I still don't get it. Povic will join pipes 2 & 3, Yosh does not. In this months issue of Super street bike Yosh titanium joins pipes 2 & 3 as well as 1 & 4 . This is allot like our OEM set up in design. What gives here ? Is the joining of the pipes just for the high end consumer. If so a little piece of pipe cost how much ? I have been told that balance pipes help make MORE HP and torque, but yet it would seem that most do not follow this principle? I have been trying to keep my head out of it and keep it simple in the terms of cost per pony and stick with the simple question what pipe makes the most power and torque through out the range for my bike(simple Right). Also with Yosh pipes, If the titanium header get joined pipes, why not the stainless steel ? In pipe comparisons on the same dyno with the same bike there must be a clear winner in design. It would seem to me that even the manufactures can't make up their minds. I for one, have always dealt in absolutes and this messes with my mind. It would seem that every time I open a magazine this one thing changes. Some one fix me up please. What have I missed

* Last updated by: Romans on 7/19/2009 @ 8:10 AM *

Balance Tie-In 4-in-1 Is one design.

No credit to the person who came up with the 4-in-1 design, but that is another story.

You more or less have the standard collector style. The rest like you said is a black art. If you do not think the R&D is not in that stock 14 exhaust, I would like to see the bean count on how many cans were rejected by design.

I want to see how something as simple as a hole in a pipe will stop the pop. You are fighting lighting fast 14.7psi making bed. Pop the low wave goodbye.

So, will the action/reaction work on that open hole? I could drill all over the place and the dyno is going to change no matter how tiny; go and mess with the air waves adding all the variables like; heat and meet 14.7 is keep looking.

Don't matter if the pipe is 4 into 1/4 into 2 into 1 into 2/_______ Fill in the blank combo is spin the dyno wheel, Pat Say Jack. I would like to buy a valve, Pat. OK, lets see Vanna Walk her rear end over dare is, Awwwwww, No sorry, HP is not a vowel. Wear where use from again?

OK, Lettuce move on to our next contestant is tell us who you are and wear out are you from is speak the same language as your buddy over here?

Photos taken from: The American Stock Car/ William Burt/2001

* Last updated by: Hub on 7/19/2009 @ 11:12 AM *

This is my knowledge of car exhaust, but I'm fairly sure it applies here. Short version; The larger your header tubes the more air they can flow. Great for top end. But if they are to big you'll loose bottom end because the exhaust pulses loose some velocity. So to make up for that you build/buy a set of equal length tuned headers. The pulse of the exhaust going down the tube creates a vacuum. So the next cylinder firing benefits because that vacuum helps pull the next firing cylinders exhaust out as well. So you can run a smaller diameter tubed header, to help with the bottom end, but it thinks it's a large tube, to help with top end, because the tuned system pulls more air out due to the vacuum effect. Our bikes don't have enough space to do this right. You've seen the strange shape of real tuned headers on cars, see Hub's picture of one of Smoky Yarnic's design above. So to help mimic a true tuned exhaust they put in the balance tubes. So in theory, you still have your smaller diameter tubes to help the low end. But it opens a larger pathway, by joining two header tubes, to help with the top end.

* Last updated by: Philhnnss on 7/19/2009 @ 11:27 AM *

So to help mimic a true tuned exhaust they put in the balance tubes. So in theory, you still have your smaller diameter tubes to help the low end. But it opens a larger pathway, by joining two header tubes, to help with the top end.

Soooo .... A pipe with the balance tubes installed is, in theory a better pipe because it covers both ends of the spectrum(low & high) right ? And if this is so, why are these pipe manufactures giving us such a wide range in designs? So what I get from this is, A copy of the OEM, in design with the R&D in the pipe diameter would be the best pipe available. Yes ? Or No ? My story is simple. At the time I was told that Akrapovic made the most Hp & torque throughout the entire range. So thats what I bought. But if you look at that New yosh I am willing to bet that it would be the top pipe. The only reason I am guessing this is because they have joined 1 & 4 , 2 & 3. Same design as OEM. Phil & Hub your statements support this theory. Yes ?

Large diameter pipe causes the air to slow down. Velocity suffers and when it slows, you know 14.7 is heading back in.

We have a war going on with 14.7psi. What is the pressure in the exhaust pipe when the engine is dead? 14.7psi. What happens when we push a low pressure out is say half the air is 8lbs? Say, 7 plus 7 is 14. Say, 8lbs.; give or take is half of 14.7? Do we see our war game on the valve close and open?

How much back pressure will 14.7 take in time and in more or less, the larger the pipe, the slower the one air goes, the faster the other takes is that sound wave. Each cylinder is a snowflake of a pressure wave. Say, a compression reading on one cylinder is 187psi, and the cylinder next to it pushes the compression needle to 178.

No matter the argument, I cannot smooth the walls any less porous for the rings, the gap is the same; the cc chamber is the same; we compile all that even up on each cylinder and each compression is not the same. Would I now equal length the same length for 2 different compressions? Would they not burn or move the air speed differently where equal length is out the window is not equal compression?

On the critical air speed, what I've read that makes sense is that you want no more than a 9° bend out of the header from exhaust valve. You want the straightest direction possible for as long as possible, or a bend will slow down the flow. Imagine the short curve out of the pipe we are looking at. The radiator will not let that bend move out farther in a straight line.

Smarty pants also receives no credit for the PAIR system along with his 4-in-1. Smokey knew about fresh air entering the exhaust pipe, so he drilled tiny holes under the exhaust so no one would see the theory that if you let fresh air back in, you reburn the unspent, keep 14.7 from reentering too fast is push more heat flow = Keep the spent moving.

Pipe Tie-in on Phil's post, I have to disagree with what I have read, is that if you tie-in both sides, you have a better short track exhaust. If you have them duals/separate and open, they are more for Daytona or Taladega.

When I changed from a 4-in-1, I could feel the duals were a much smoother in combination. The difference is slight, mind you, so it is more what that balance the tie-in represents; is a better air blend. What I found out between the two combo'z; are that the single pipe pops less. That guess would be the unspents are combined in a short area, where as, the dual separates into a larger area of mass. So, rich is 4-in-1. Lean are duals? One test ride does not qualify my theory. But to change very few things as one muffler is little to nil and note the change in popping. You have received the raw data. You can come to your own conclusion. I am 'butt' the messenger.

http://www.youtube.com/watch?v=mhpjw6iqFaA&feature=fvw We are down to trick looks. Cool sounds? Give me a fender washer and a wheel bearing... I got year muffler, fell ear.

Like Hub said exhaust theory is one of the black art's. But if top end horsepower is your goal, an overly large diameter header pipe is what you would want. I think the balance tubes used on the OEM and the Yoshi is an attempt at compromise between a true large tube header and a small tube header. Now if they actually did find a PERFECT compromise that will pack the top end horsepower of large tube set. And the bottom end of a small tube style, I'd have to see it to believe it. Because even though we are talking exhaust in general, it's really apples to oranges. Not saying it's impossible. But not very likely I.M.O. I'd try to get Kerry's or Brock's take on it.

And sorry Hub if I didn't make myself more clear to the point you disagreed. Because I thought that was what I was saying. Large tubes for Daytona for top end and small tubes for a short track for more bottom end. And try to find a compromise of the two for the streets, I.E. the balance tubes.