I've ordered all the tubes + bends I think I'll need to make the exhaust manifolds for the V6 in the manta. But, I need to order the manifold flanges.
Previously I designed some manifold flanges to suit 1 3/4" primaries. However, having consulted the book Four Stroke Performance tuning and going through some sums it looks like I need to go a bit smaller on the primaries. The American company that I ordered the tube through does 1 5/8" tubing and that works out pretty much spot on, so I ordered stainless tubing, mandrel bends and collectors in that size. The collectors are 3:1 and 1 5/8" inlets and 2" outlet. So, I need to work out the external circumference of the tube + make this the circumference of the holes in the exhaust flange (Plus some clearance!) The od of the tube is:
The current cutouts in the exhaust flange are obrounds with a radius of 15mm and an external horizontal measurement of 55.5mm. Thus the circumference of that cutout is:
(I never remember the order of precedence for operations so I've just parenthesised it well) I need a couple of mm of clearance, but not 15mm! So I will instead use an obround with an overall horizontal dim of 50mm and a radius of 13.75mm
I've uploaded a quick reference drawing of the design. I should upload a DXF too as this makes life a lot easier. It's too complex to fully dimension the PDF! |

- 2010-01-30 Picked up another V6
- 2010-02-02 Starting the V6 Build