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The manifold can be cut in half at the plenum and ported.
But the dumping of the flow from the throttlebody into the plenum is the worst offender and saps flow 20CFM.
So first you need to diffuse the flow into the plenum.

Erland

thankyou Erland for the reply. is there a known design that i can mod the manifold with a diffuser that works? im very interested in this. Or can you please suggest a design? If the manifold will be split, i can put anything inside of it before welding it back up. Or can you do this for me?

Also, does a 59mm throttle body create enough flow, or is the 63mm one better? thankyou

The inlet should be from the bottom of the plenum instead of from the top.
As it is now there is a huge expansion and flow loss whwn entering the plenum.
How big modifcations are you allowed to make?

Erland

Really I can't mod it at all but if it looks standard it'll be fine

How about the B234F intake? I know i dont fit, but how does it flow?

it has to be the b230f lh2.4 type manifold unfortunatly. Also the b234 has oval tubes, the b230 has round.

I wrote top and bottom but I meant from the side.
Instead from the long side the flow should go in from the short side.
Flow should always go into a cavity surrounded by walls and not into a big space without diffusing walls.
Welding a bigger inlet hole and using a larger throttle or mowing the throttle out with a diffuser between throttle and plenum would help.
The B230K manifold has the same problem vith the throttle in from the bottom.
Moving the throttle to the front of that manifold makes it much better.

Erland

Thanks erland I understand now , inside how would you shape a defuser ? Thanks

B230K, do you mean B230E, K-Jet manifold?

The one I have is the lh2.4 type the f?

Erland wrote B230K, must have meant B230E intake, sorry for the confusion.

oh sorry i got confused aswell lol! thanks


if i was just to put a simple cone inside of the air way, say 55mm wide and 55mm tall, is that what you mean? split up the air flow, or make like 4 different sections?

thankyou!

Yes I meant E but I thought of K-jet.

Erland

A diffusor converts the kinetic energy in a duct back to pressure.¨
So if atmospheric pressure is 1 bar getting 1 bar in the plenum is 100% efficiency.
A short diffusor is maximum 2 diameters long and can have 8 degrees taper per side, 16 degrees included.
So för a 55mm throttle the 16 degree taper didffusor can be a maximum of 110mm:s.
If I am calculating correctly the diffusor exit can be 30mm bigger in the end of the diffusor.
Tapering from 55 to 85 mm:s.
This lowers the velocity into the plenum to less than half and helps with pressure recovery.
That means cutting off the throttle body end of the manifold and building atapered cone between the throttle body and plenum.

Erland

thankyou again for the reply Erland. im not sure what you mean exactly, do you mean put a cone in the inlet with 85mm-55mm that is 30mm high? if so that can be done fairly easily!

thankyou again!