Turbo manifold design.

[Pat Ford]

and don't use strainless steel. it tends to get sticky and galled when hot and moving

Previously, you (justin ivan) wrote:
{ If you are insistent on running a single flange then you should enlarge the 
{ hole and use a washer as it was suggested.
{ 
{ 
{ >From: Jörgen Karlsson <jurg at pp.sbbs.se>
{ >Reply-To: diy_efi at diy-efi.org
{ >To: <diy_efi at diy-efi.org>
{ >Subject: RE: Turbo manifold design.
{ >Date: Wed, 10 Jan 2001 17:38:21 +0100
{ >
{ >Justin Ivan wrote:
{ >
{ > > Not sure if I agree with everyting that you are saying. When the
{ > > flange is a
{ > > single piece, essential all (really just a large portion) of the
{ > > expansion
{ > > takes place at the ends of the flange, the material in between 
{ >constrains
{ > > the flange from expanding towards the center. When the flange is
{ > > separated,
{ > > each port can expand in 2 directions, therefore has more flexibility.
{ > > If someone can debunk this please do.
{ >
{ >If the manifold had looked like an ordinary V8 header I wouldn't have
{ >anything against using separate flanges, it would be far better then using
{ >one large flange. An ordinary header usually has pretty long runners in 
{ >thin
{ >material that are pretty flexible.
{ >
{ >In my case the distance between the ports are 86mm and the runners are
{ >routed the shortest possible way to the runner next to it, turbo exhaust
{ >manifolds must also be made from a bit heavier tubes then ordinary headers.
{ >To prevent cracking I used high quality tube bends and welded it with
{ >electrodes made for the specific material.
{ >
{ >This makes my manifold very strong, to make the ends of it flex 2mm 
{ >requires
{ >a lot of force. A lot more force then I would trust the manifold studs 
{ >with.
{ >
{ >When we use separate flanges the temperature of the tubes in the exhaust
{ >manifold decides how long the manifold will be. From room temperature to
{ >700ºC the manifold will grow 4mm.
{ >
{ >If we use one long flange that is bolted to the head, the temperature of 
{ >the
{ >flange will decide the length of the manifold. Since one side of this 
{ >flange
{ >is bolted to the engine that I guess are 200ºC around the ports, one side
{ >are welded to the runners and 80% of its surface are exposed to the air I
{ >would guess that it will have a temperature somewhere in the middle of the
{ >200º engine and the 700ºrunners. Hopefully closer to the engine 
{ >temperature.
{ >I think that the flange temperature will be around 250-350ºC. Since the 
{ >1/2"
{ >thick flange will be a lot stronger then the red hot runners of the 
{ >manifold
{ >it will not be affected much by the runners will to grow 4mm when the 
{ >flange
{ >only has grown 1-2mm, the runners will hopefully take the beating without
{ >cracking to often.
{ >
{ >Since the cylinderhead will grow with temperature too the flange and the
{ >head will hopefully grow about the same amount.
{ >
{ >
{ >Jörgen
{ >
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--
Pat Ford                           email: pford at qnx.com
QNX Software Systems, Ltd.           WWW: http://www.qnx.com
(613) 591-0931      (voice)         mail: 175 Terence Matthews          
(613) 591-3579      (fax)                 Kanata, Ontario, Canada K2M 1W8

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