Mr. Bryant...

[1olbull]

I'll pass. The heat coming off the top pipe next to the valve cover may be OK for some but to me it looks like it very well could become a problem. Could be wrong. I'll stick it out with this.

Sonny,
From the look of your pix, it looks to me that the top pipe would not create an issue.
This is what I'd like to see for the OZ header.
BTW - nice riding boots!!!

 

[Claviger]

We’ll wait a couple months and you may be able to test it out for yourself Steve

 

[Claviger]

triple

An engine requires about 2.2 CFM per horsepower, and exhaust gas flows about 115 CFM per square inch.

Assuming 1,400 hp / 2 (since there are two exhaust pipes) means we have 700 hp per exhaust pipe. Multiply that by 2.2 cfm / horsepower and we see we need 1,440 cfm. Divide that by 115 cfm / square inch, and we need 12.5 square inches of pipe area. The area of a 4-inch round pipe is equal to (pi r (squared) = 3.14 x 2 (squared) = 12.6 square inches. So a 4-inch exhaust is just barely big enough to support 1,400 hp.


As an aside, 1,400 hp means each primary tube in the header needs to support 1400 / 8 hp = 175 hp. Doing the same calculation 175 x 2.2 / 115 = 3.3 square inches. The area of a 2-inch tube is 3.1 square inches

So I’ve been sitting here today thinking through the whole header size dilemma and I’ve run some math, that, actually matches right up with real world dyno results. First some measurements:

CES Primary Pipes = 44mm (1.732”)
CES after collector = 57mm (2,244”)

That is Outer Diameter, assuming 0.625” wall you get

1.607” ID = Primary or 2.01 Square inches
2.119” ID = Rear Section or 3.526 Square inches

Using the formula
Area x 115 = CFM for exhaust / 2.2 = HP supported for each pipe you get

105hp for each Primary - All good
184hp for the rear section - not enough...

Now if it were
2” OD Primary
2.5” OD rear section
You’d get

144hp per Primary worth of flow
231hp for rear section

The rear part math doesn’t work like this because the gases have cooled some, but it clearly shows the biggest restriction isn’t the primaries, they’re already a good bit oversized. I posit that a stock motor bike, won’t find anything from diameter increased any bigger than 44mm and 57mm but a built motor certainly might find gains from a larger pipe after the collector.

Further, I’d suggest the Carpenter pipes work as well as they do more because, on his design the 2.25” section acts like a venturi to increase gas velocity and then immediately opens into the flaring megaphone which supports the flow volume and smooths the gas flow. The choke point immediately after the collector is also known to assist in timing sound wave reflections against the exhaust valve to arrive at the right time and prevent reversion, like in a 4-2-1 instead of a 4-1.

There’s a saying “you won’t gain any power after the collector but you can certainly lose it” and I think that’s exactly what’s happening when my CES setup is 20hp behind the Brute same dyno same day same bike.

To go a small step further those flow estimates are based on straight pipe with no restriction. Considering our headers tend to look like spaghetti, they’re certainly causing some restriction, so the 1.75” primaries may actually be a bit of a restriction on a built motor, further validating 2” primaries.

Thoughts?

 

[Tal]

Very good!....Getting the very best flow with maximum results interests me as i'm sure it does with many others...especially "Mr Bryant"
I can almost hear is engineering mind grinding away from here.
I guess if it was water flowing thru there, it would be akin to seeing maximum volume with no bubbles, no slowing down and a good clean product at the end..

 

[Claviger]

Found the below on another forum, supports my theory that the megaphone is a significant contributor to the carpenter setup.


Re: Megaphone Theory 101
04-10-2011, 12:49 PM
Here is the quick and dirty, 3-minute theory on Exhaust Wave Propagation:

Some quick info
1. A positive wave or pulse is a small volume of gas ABOVE atmospheric pressure.
2. A negative wave (rarefaction or "suction") is a small volume of gas below atm. press.
3. When a wave moves into region of higher volume, a wave of opposite polarity is reflected.
4. When a wave moves into a region of lower volume, a wave of the same polarity is reflected.

The extremes of (3) and (4) would be the open end of a pipe and a flat baffle (wall).

Sequence of Events
When the piston opens the exhaust port, the blowdown cycle begins. A small pressure pulse (not a shock wave) is formed at the port/pipe interface The pulse continues to build in amplitude as additional port is uncovered. As this is happening, the pulse begins its journey through the exhaust system. Assume for this discussion that this is a simple 2-section system; straight pipe -> megaphone.

The pulse travels down the straight section and enters the megaphone. At the instant the pulse enters the megaphone, a "suction" wave is created and is reflected back toward the cylinder. This happens because the pulse "sees" an increasing area (and volume) as it enters the megaphone in the outward direction. This condition matches (3) above.

In our example, the very first fraction of an inch into the megaphone represents an increase in area (and volume) which causes a very small expansion of the pulse. This results in reflection of a "suction" or rarefaction wave. This reflecting process happens continuously as the pulse travels along the entire length of the megaphone. The bigger the change in area (diameter), the bigger the suction returned to the cylinder port, until finally, the pulse reaches the end of the megaphone. At this point, you would expect a very large returned suction wave, but if the megaphone diameter is sufficiently large at the discharge end, the pulse amplitude may be so small as to result in a very small contribution to the overall returned suction wave. Why is this? It's because the reflection happens because of the pulse wave expanding, and expansion means the pulse is decreasing in pressure amplitude. When the pulse has expanded to near atmospheric pressure, the expansion ends. There is no more pulse--and no more reflection. Most often, the pulse retains some amplitude and does return a reflection from the end of the megaphone.

Some of this is not exactly theory, as I've measured the pulses in exhaust systems using pressure transducers and an oscilloscope in thesis work and also while at Quincy Welding developing various systems.

I must apologize for my first post here turning into such a long book. I hope this helps.

Frank Volker

 

[JohnsoD]

I'll pass. The heat coming off the top pipe next to the valve cover may be OK for some but to me it looks like it very well could become a problem. Could be wrong. I'll stick it out with this.

Thanks for this post. I installed forward controls and waiting for a system from Paul B. I was happy to see actual clearance. Looks like I shouldn't have any problem. Now I need a delivery from N.Z. and a break from this winter.