pipe design software and cone layout cad data

found these a while ago, seem easy to use , and free heres a link to the pipe design software http://www.iwt.com.au/mota.htm

and here(  http://www.conelayout.com/   )  for a free 21 day trial ,ive had it a lot longer that 21 days and it still works you just have to wait a few seconds for it to count down until you can use it 
. just cut and paste the link to your browser or write it down!

Mota, the Australian simulation software version 6:1 , now includes a utility that will enable the user to design a pipe and then print out all of the cone shapes and the respective angles to produce a complete pipe. The printouts come tabbed to align the pieces and, for instance, a tapering header pipe can be constructed , I made one with eight little cones, and the arc of the pipe is factored in, so no more hacksaw jobs. It is a good piece of software, just a pity that the sim package is elementary by modern standards but it does have its uses, and would be of benefit to serious Bantam developers.  

Trevor

That´s fantastic Trevor! Eight tapering cones forming an arc in the header pipe? Wow? I realise now we never really got into properly tuning Icarus-!. How inportant was -- is --  the inner surface of the Header Pipe? For that matter -- the whole pipe?

I mean there´s a lot of welding....

Hello John ,
                 The header is the most critical part of the pipe as far as gas flow is concerned, with average temperatures typically in excess of 600*c, gas speed is very high, any vestige of roughness will inevitably slow the flow and remove heat, further slowing gas speed. A lot of Bantams seem to favour high level pipes, but the header has to make some very tight bends to get the whole thing to serpentine it`s route through the frame, which gets the pipe fitted, but, incurs a power loss, the pressure wave gets through reasonably well but gas particles hate it, the path is too tortuous. Interestingly, most quick Bantams have conventional low level pipes, coincidence?
The best, hand crafted pipes have hammered joints, smoothing the inside as the cones are welded end to end, final finishing made with an emery flap wheel. This technique should be used for the whole system, for any projection into the internal flow will creates reflections to upset things and saps energy from the flow, which will diminish the valuable plugging return pulse .
                Another penalty of a high pipe is that hot air flowing from the pipe has to impact the barrel and impairs cooling at the point where the finning is limited, just behind the offset exhaust duct. The largest diameter of the pipe is often right alongside the carb, heat radiating from that centre section, at around 400*c, is inevitably going to heat things up in an area that, critically, needs to be cool . 
               After saying all that, the position of the various sections should remain defined so the commencement and ending of various functions are correctly phased for optimum effect, blown pipes with ill defined sections smear functions and will not function as efficiently as welded .

Cheers for now,  Trevor

Hi Trevor - out of interest what's your take on Blown header/front [pipes) and why is the junction between header and first defuser so important. ? just trying to understand a little better.

regrds Derek

Evening Derek,
                      Blown front pipes are the best you could use, nice and smooth and a constant taper . The junction then, between header and diffuser needs to be defined, and sharp, welded sections separate the reflective function with some level of timing prediction. Blown multi sections have reflective points rounded off and timing becomes variable with changing temps and flow speed . None of the factories of recent years used fully blown pipes, when ever they did a very quick return to welded proved the point .

Regards ,  Trevor