I’m not planning on getting rid of my dual plenum manifold or changing anything on the 90, but I had some things I wanted to try to address from when I made the first manifold . A few things that I thought could be better if I was to make another one . I wanted to add curve to the runners, increase the size of the runners, maybe do a bigger plenum, and put the inlet over on the drivers side (not the center)
So right after I made my intake using the RMR oval tubing, I saw that LPS Fab came out with a formed piece in two halves to make the oval to circle transition in a straight or curved version and for a while
Now I’ve been planning on getting those to see what I can do
Runners :





The velocity stacks. You can see I'n the above pics I have some machined ones, and that is what I planned on using. But after I welded the runners up, I realized they are 2.5 OD not 2.5 ID. So I decided to make the plenum base in a billet piece instead with all the stacks machined in rather than making 5 more individuals then welding them all together to a plate.




2nd attempt , after cutting the first one and realizing that the radius was not as big as it could be .


I don’t have an intake flange yet and I can’t find one , so I’ll have to make it I guess . So with that in mind I know what the overall height will be , I made this piece just to simulate that height so I can figure out where the runner length should be .





Pic of a comparison to illustrate the maximum length of runners I’m shooting for , this is an IE intake- just using using this weld rod to roughly measure to the plenum base from the head... The IE intake runners are already pretty long. My head flange is pretty thick since it includes the injectors, so the LPS runners and my plenum base together is way too long which means the runners need to get trimmed .



Trimming the runners and getting them all the same again is proving to be quite difficult , but hopefully I’m in the right path .




After trimming them all with the band saw . A little on the long side - but they’re not all equal . I’m struggling to come up with a way to get them all the same .
So I just made a “jig” and that’s the first thing I’ll try. There will be a lot of sanding involved to get it right.
I think maybe what I should do is make something that will sleeve over the runner and use that for making them to make the cuts . Like a clamshell style thing . I don’t know


I really think that with the combined angle of the sealing surface on the head and the engine tilt the runners need a good bit or curve , so I think this will get me in the ballpark .

Soon ill finish the base and then figure out a decent shape and design. No idea exactly what to do with that
Foil “template”





