Bunch of Bananas Manifold

[Jamie]

Thank you for the suggestions and, Ken, the offer of your manifold. On balance, I think that I shall buy a manifold plate and have a go at fabricating something. If that fails, I shall approach a professional.

Regards,

Jamie.

[Greig Smith]

Jamie, I made a complete manifold for our blown single seater from pre-bent tube. from memory the smallest I could get was 30mm.

We had some manifold plates laser cut and I made a mandrel for squaring off the ends of the pipe to suit the 2 sizes of cutouts in the plate. The mandrel was nothing more than 2 chunks of heavy flat bar welded together and ground to size. I then clamped the  pre-formed bends in the vice, heated one end up red hot & bashed the mandrel into it to square off the tube. For the inlets I just welded an additional bit of flat bar onto the mandrel, ground to size again & took a second go at some of the pipes to make the rectangular inlet shape. From there I laid out the basic shape by working out the angles necessary to get the pipe straight alongside the car with an angled offset motor. Once I had that, I transferred it to a steel work table and offered up the pipes to a flange.


Bit by bit I filed and trimmed and fiddled and fettled until I had the pipes fitting tightly against each other. I then tack welded them to the plate with my MIG and passed it across to a very talented mate with a TIG who stitched it all together for me. Despite careful planning, miniscule gaps and being bolted to a head, it ended up with a slight warp. The manifold plates are too thin to skim, so I bolted it to a heavy plate I use for building manifolds & heated the pipes up properly with a huge propane torch, then when it was good & hot, I walloped the back of the heavy plate with a large hammer to 'shock' the red hot steel. left it overnight and the following morning the manifold flange was perfectly straight and the #1 pipe now has a tiny bump just where it intersects #3. That's where the warp went. Dad is still shaking his head about that one.

I made a mistake in that I should have jointed 1+4 & 2+3... sigh, but by that stage the bonnet was cut and I wasn't going to start patching that. It's a blown car so a bit of overlap isn't the end of the world here & besides, it's a nice looking piece & everything fits perfectly.

I have to build another one for our green single seater as the bunch of bananas on that are something Dad was given before I was born and they have cracked badly now, being copper pipes brazed to a steel plate. This one will be easier as it's a simple branch with riser pipes for twin SU's

Aye
Greig

[Jamie]

Greig,

That is really helpful, Greig. Thank you. Your manifold certainly looks good and suits the car well.

Regards,

Jamie.

[David.H]

 looks like a mini Vanwall exhaust!