Author Topic: Pipe dream, an agressive looking performance 4-1  (Read 13018 times)

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troppo

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #50 on: March 01, 2008, 10:06:11 PM »
@736cc, the collector on that sexy pipe looks a bit off.  It should be a cone from around 3 3/8" inside diameter (specifically, collector i.d. = 2.414 x o.d. of header pipe) and fitted/molded around the header pipes, down to about 2 3/4" (specifically, i.d. = 2 x o.d. of header pipe) at the silencer end.  The collector on the pipe you're showing looks like is was made from straight pipe rather than cone.  Straight pipe will work fine as long as its wide enough (i.e. 3 3/8")

The length of the collector cone is not important (5" - 6" is a workable length)

Also, optionally, a dispersion cone inside the collector welded in between the 4 pipes speeds gases through the collector.



i can see a lot of similarities between car and bike here, so heres a silly question for you....
would a four into two into one setup be worth trying or is the four into one the best way with these bikes..
cheers
troppo

Offline Tower

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #51 on: March 01, 2008, 10:14:43 PM »
Sure 4 - 2 - 1 will work, but why the complication, when 4 - 1 is arguably the best approach?  I suppose you could get some real funky  8) designs, maybe even some good cross-over effects.
« Last Edit: March 01, 2008, 10:17:19 PM by Tower »

troppo

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #52 on: March 01, 2008, 10:19:41 PM »
it was just a thought Tower, kinda thinking aloud with all this, want to think this through to work out a good looking effective exhaust for the other bike when i build it as i`m going to do as much of the fabrication as i can myself...
for me the fun is in the creation of things as much as the finished product....
I`m going to have to copy a hell of a lot of this thread down, its great stuff
cheers
troppo

Offline kghost

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #53 on: March 01, 2008, 10:35:56 PM »
it was just a thought Tower, kinda thinking aloud with all this, want to think this through to work out a good looking effective exhaust for the other bike when i build it as i`m going to do as much of the fabrication as i can myself...
for me the fun is in the creation of things as much as the finished product....
I`m going to have to copy a hell of a lot of this thread down, its great stuff
cheers
troppo

Amen brother.

Hence the funky two into one I have under construction
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Offline CrisPDuk

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #54 on: March 02, 2008, 03:43:01 AM »
Sure 4 - 2 - 1 will work, but why the complication, when 4 - 1 is arguably the best approach?  I suppose you could get some real funky  8) designs, maybe even some good cross-over effects.

Depends what you are after, as ever the horses for courses rule applies ;)

Generally 4-2-1 systems are great for getting a good torque spread across the low to mid rev range, but tend to cause a drop in power in the high reaches.  A 4-1 system on the same engine will result in less torque across the lower range but, will allow for more power to be produced as the revs increase.  Of course other variables do come into play such as cam profiles/timing, ignition set up and fuelling.
Generally speaking, from my own experience in the automotive world 4-2-1 systems are what you want for a quick road car, but in a race car, its 4-1 every time ;D
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troppo

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #55 on: March 02, 2008, 03:56:37 AM »

Depends what you are after, as ever the horses for courses rule applies ;)

Generally 4-2-1 systems are great for getting a good torque spread across the low to mid rev range, but tend to cause a drop in power in the high reaches.  A 4-1 system on the same engine will result in less torque across the lower range but, will allow for more power to be produced as the revs increase.  Of course other variables do come into play such as cam profiles/timing, ignition set up and fuelling.
Generally speaking, from my own experience in the automotive world 4-2-1 systems are what you want for a quick road car, but in a race car, its 4-1 every time ;D

now that answers my question perfectly crispduk thanks mate, i can now see why bikes have a 4 into 1 rather than a 4 into 2 into 1
cheers
troppo

Offline Tower

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #56 on: March 02, 2008, 09:24:24 AM »
Precisely @CrisPDuk.  The argument is almost always a trade-off between rpm-range and peak power.  The more crossover points that are introduced into the design, the more resonant frequencies are formed.  This applies to number of bends as well. 

An extreme example:  Use short, overwide, straight exhaust stacks clamped together at their open end, and the bike will really scream at max power - right before it blows up. Any other rpm is less than optimal.   This is just what you want if the engine is to be run at a single rpm, say for drag racing. i.e. an 8 second burst at max/peak rpm.  Cam, timing, balance and pipes all tuned to one unsustainable high frequency (rpm).

Physics of waves determine that short range, high frequency operation means short straight pipes and very short megaphones/collectors.  Lower frequency useable rpm means longer pipes.  Broader rpm range means longer pipes, more crossovers, more bends.  But alas, as wave area (distance, interference) inceases, energy dissipates exponentially - and that's lost energy that can't be put back into making horsepower.

Offline 754

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #57 on: March 02, 2008, 09:33:35 AM »
I think it is way better to use the pipe as an example than try to create a drawing.. Harder to deal with but I am thinking the price for creating this drawing will be a lot higher than you could imagine.

You can measure the radii yourself and simply ask if they have the capability, or lay a pipe over cardboard, trace it, send to the bender, and ask them to send a sample..that will be fairly reasonable.

The Yosh header, you mention has filter clearance issues, hits the frame going on and off, eliminates the c-stand. ..sounds like a pipe not everyone can or will live with.. not a pipe I would run. How many units do you hope to sell??

 Pipe survey coming up.
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Offline Tower

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #58 on: March 02, 2008, 11:12:51 AM »
I like to use flexible 1/4" copper tubing for mockups and sheet copper for scale flanges, cones and brackets.  Gives you 6:1 scale.  Flexible copper is easily (by hand) and precisely bent or straightened, soldered or reused.   ;D

If you want to create a form shape, use thick gauge armature wire (1/8"-3/32") to create the exact curves in 3-D that the pipe follows.
« Last Edit: March 02, 2008, 11:15:36 AM by Tower »

Offline 736cc

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #59 on: March 02, 2008, 06:51:11 PM »
 What would happen if the headers were made of copper?

Offline Soos

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #60 on: March 02, 2008, 07:44:46 PM »
I don't know why...

It may become quite soft at operating temps though.
The melting point is like 1981 F. (1083 C.)
Way below the exhaust temps headers reach on any CB i've heard of.
I'm guessing the max temp these CB's see is around 1100 to 1300F at the header after hard riding.


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Offline coyotecowboy

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #61 on: March 02, 2008, 08:13:20 PM »
What would happen if the headers were made of copper?

You'd have to keep them painted black, or the copper thieves woud have 'em!!! :D
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Offline Terry in Australia

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #62 on: March 02, 2008, 08:27:13 PM »
Well I've never tried it myself, but years ago a couple of old hotrod guys were telling me about the copper pipe exhaust systems that they ran back in the 1950 and 60's, apparently the copper pipe gave the exhaust note a deep "bark" that was rather unique, and very popular at the time.

I think that copper would harden up after a few runs anyway, and (apart from the copper thieves concern) a coat of black heat paint would pretty them up, not that copper needs much protection due to it's high tolerance to corrosion. I guess you could always polish them for a truly unique look?

It certainly would be a lot easier to work than steel, if you don't have a mandrel bender handy! Cheers, Terry. ;D
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Re: Pipe dream, an agressive looking performance 4-1
« Reply #63 on: March 02, 2008, 10:17:05 PM »
Good question.  I haven't seen any myself, and the right tubing might be a little exotic to get.  But, I don't see why heavy gauge copper pipes wouldn't work.  They make pipes out of titanium alloy, so why not copper?  Copper is very conductive, so they'd probably run hotter - good for the cylinders, maybe not so good for the legs.  Copper to aluminum is quite a bit more reactive than steel to aluminum, so, an insulating carbon fibre sleeve over the exhaust port would be advisable.  The copper would very quickly loose it sheen, turn pink, and perhaps become more porous and brittle (the way burned copper wire does).  1200oF would easily do it.  Painting with super high temp ceramic paint might keep the pipes healthy, and running still a little hotter.


Offline 754

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #64 on: March 02, 2008, 10:24:32 PM »
I think the lightening on the flanges & the taper adaptor to increase pipe size  :oin the lower pic arte pretty cool...
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Offline CrisPDuk

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #65 on: March 03, 2008, 02:34:37 AM »
I think the lightening on the flanges & the taper adaptor to increase pipe size  :oin the lower pic arte pretty cool...

A lot of the early automobile exhausts were made from copper, I suspect a few of the early motorbikes had them to?
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Offline eurban

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #66 on: March 03, 2008, 05:33:03 AM »
Couple of small observations . . .Exhaust gaskets (on the 750 anyway) are copper. Stock setup basically has steel to copper to aluminum so I doubt there needs to be much worry about different metal reactions if one were to use copper for headers.   Weight will be high with copper and it might be prone to cracking tearing over time. (Didn't Proteal use copper on his 450 project for exhaust pipes?)   Should be easy to work with though.
As to the earlier comments in reference to 4-1 or 4-2-1 etc . . .Actually the stock exhausts on many (and perhaps even most) modern 4 cylinder performance bikes are of the 4-2-1 design.  These designs likely give up just a bit on top HP but help to reduce the soft spots at lower RPMs that you are going to have with a 4-1.  Today on the race track, modern engines can easily make more power than tire traction / suspension can handle so useable power trumps outright HP.  Guess what? You'll find lots of the racers using the 4-2-1 design! 
« Last Edit: March 03, 2008, 06:57:10 AM by eurban »

Offline Tower

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #67 on: March 03, 2008, 06:06:04 AM »
@eurban, most exhaust gaskets are copper sandwitch - fibre-copper-fibre.  Copper sandwitch is used to bridge expansion rates between the two surfaces.  Electrolytic reaction between copper and aluminum is definitely something to avoid.

Offline eurban

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #68 on: March 03, 2008, 06:35:41 AM »
Perhaps so, but the OEM copper exhaust "donuts" I have seen for the 750 are indeed all copper. They squeeze flat when the header flange or spiggot is tightened down.  I have never observed any dissimilar metal issues from their use. . . .Oh and here are a couple of pics of high end aftermarket performance exhaust systems for modern inline 4s .  Note the 4-2-1 design . . . . .
« Last Edit: March 03, 2008, 09:52:38 AM by eurban »

Offline Terry in Australia

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #69 on: March 03, 2008, 08:20:00 PM »
Not "dissing" Tower at all (he knows more about exhaust theory than I know about anything) but copper head gaskets are still common in race engines, so I wouldn't be all that worried about electrolytic reaction. Cheers, Terry. ;D
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Offline 754

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #70 on: March 03, 2008, 08:26:57 PM »
If those gaskets were solid copper, please explain how they get flattened out in use, without turning the exhaust flage into a pretzel? ???

That is the metallurgical question for today..
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Offline Terry in Australia

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Re: Pipe dream, an agressive looking performance 4-1
« Reply #71 on: March 04, 2008, 02:38:56 AM »
Nah, Eurby didn't say "solid" copper mate, he said "all copper", and they crush flat because in fact they're rings of thin walled copper tube. Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)