the runners are the same diameter as the ports in my head and the runners are a little longer than i wanted but it had to clear the standard exhaust manifold,it will be interesting to see how it goes, im sure i will be making another as im not all that happy with the design anyway.

It will be finished by the middle of next week and fitted next weekend.

want to make and sell those?

I'm interested in one that is just the plenum with no injector bosses ( using propane )

why not use sr20 60 mm throttlebodies? they're cheap and plentiful.

if i were to make 1 change to the design, make the plenum then cut it in half lengthwise and clean up the insides of the runners then weld it back together then put the throttle body flange on, yeah you add a big long weld, but you get cleaner runner entry.

Something else for you to consider if you end up making another manifold. The thickness of the throttle body mounting flange should be a bit thicker because they tend to leak very easily between the throttle body and the face of the flange. It only takes a small bit of distortion to create a vacuum leak between the two faces. My guess is the problem might be amplified if you are going to add boost to the manifold.
Good luck with it and let us know how everything turns out.

that manifold will flow better than any poxy piece of emissions controlled factory junk.

good runner size there too, a great length and diameter. by my rough calcs by looking at that, you should have peak torque at about 3800rpm.

the throttlebody is a great size too, people get so obsessed with this part but it really make 5/8ths of fukcall difference to your driveability, but really helps midrange and topend power.

injector position is good - facing the back of the valve - and as close to it as possible is always a good idea as it minimises flow reversion thru the vacuum created by the other cylinders.

i like it. two thumbs up from me.

this is mine

seeing that manifold got me to thinking... just how hard would it be...

the materials aren't very expensive. I wonder if i need more than a band saw, drill press and welder to pull it off.

i think that if the intake and exhaust flange are made of 1 piece of stock and cut apart to keep the heat transfer down then it makes a good start for a exhaust/turbo...

what about using runners the same length but with a radius bend so that the plenum is up a little higher, would give more room for a turbo.

or just low mount your turbo and make it easier on yourself...