Hey guys, Im going to be making a custom intake manifold in the future... have been doing alot of research for quite awhile and have almost finalized the design and worked out how im going to make it but one bit im stuck on is the intake runners...
A degree of taper is beneficial as it accelerates the air towards the valve (think ive decided on 2.5' taper each side, 5' total) but uh how do I make the runners...
Its going to be a sheetmetal alloy manifold and ive seen on some they have rectangle tapered runners which im guessing just started life as Square runners which they cut in half then cut the taper into it and re-weld... yep thats easy enough except taht my Head has circle intake ports...
I cant do the same with a pipe can I? as once you cut a bit out it wont meet up properly again? Or should I use rectangle runners and just merge them into circle shape near the end?
Would it be a matter of cutting it out from a piece of sheet and rolling it into a pipe/cone.
But what makes matters worse is my runners might not be a straight line (not decided yet) and may have a bend in them and I cant even begin to think how to do it with a bend in the mix?? :S
Tappered Ports?
Started by
_Viper_
, Feb 19 2011 06:20 PM
4 replies to this topic
#2
wot179
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#3
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Posted 19 February 2011 - 06:36 PM
#4
_TorYoda_
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Posted 19 February 2011 - 10:25 PM
Start with a pipe of the length you require that has a cross sectional area of the plenum end of the runner. If you wish to make curved runners begin with a curved pipe. Calculate the area of the smaller end you require and work out the circumference. Subtract the difference of the plenum end circumference to the cylinder head end of your runner. Mark out the difference on the head end of the tube and slice a wedge from it, the point beginning close to the plenum end. From this point some patience and skill with a hammer will be needed as you close the wedge and tack the edges together. A vice can also be a lot of help. The tube will become oval as you close the wedge cut from it. Once the edges are matched and secured/welded you can then form the tubes to a more rounded shape with a suitable hammer and anvil. If you wish to do this with a curved tube you need to remove the wedge from either the upper centerline or lower to retain the curve. A shot bag is very useful for final shaping of curved runners. When your tubes are formed to your liking it is then a simple matter to shape the small end to match your round port and the larger end square or rectangular to match the plenum area. Aluminium being softer is quite easy to work in this manner. Steel ones are more difficult to shape but it can be done.
I have made numerous types of manifolds using this method and the end results are quite neat. I normally position the welds on the underside... this keeps the weld out of sight and eliminates the need to remove it for cosmetic appearances. Keep in mind a longer runner with a shallow taper will create better mid range torque with a wider power band. The opposite will result, with a short runner of a steep taper giving minimal low end power with an extremely narrow and agressive power band in the upper RPM.
Good luck with the project!
I have made numerous types of manifolds using this method and the end results are quite neat. I normally position the welds on the underside... this keeps the weld out of sight and eliminates the need to remove it for cosmetic appearances. Keep in mind a longer runner with a shallow taper will create better mid range torque with a wider power band. The opposite will result, with a short runner of a steep taper giving minimal low end power with an extremely narrow and agressive power band in the upper RPM.
Good luck with the project!
#5
_Viper_
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Posted 20 February 2011 - 09:23 AM
Cheers Toryoda, I didnt think it would work out because would make it oval... but like ya said guess ya just need to reshape it back to circle... I also assumed you would have to cut a slot from the top and bottom which would of made it worse but 1 slot will make it alot easier 
Ill give it a shot thanks
Ill give it a shot thanks
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