Porting Intake Manifold

[toddyp]

I known this forum revolves mainly around the turbo vehicles so I hope I don't get flamed.

I am currently running a nizpro manifold on my N/A vehicle with the butterflies sill in place inside of the lower half of the manifold. In the near future I am looking at installing more aggressive cams , 4.1 diff gears and a stall converter. I am also thinking of opening the lower half of the manifold up removing the butterflies somewhat similar to what has been done in the picture below.

Before doing this I am just after some advise. Do you think that the runner openings are too large if I was to do this, how would it effect performance? Do you think it would benefit a vehicle that only revs to 6500rpm. Would the intake velocity decrease considerably and effect the performance? Would it be better to simply remove the butterflies and port match teh intake with out cutting out the material between the butterflies and other openings?

As I say I will be doing the diff ratio and stall converter so a loss in low down power and torque is not a big concern.

Edited 29/05/08 11:35 AM by toddyp

[SILK RSPEC]

I Imagine those guides which were there was to help channel the air into the motor much the same as when they use a double wing in formula one to hold the car down with down force, removing it may reduce the aerodynamics the only way would be to stick it on a flow bench to see the difference at different pressures.

Rule of thumb for intake plenum's is the large the plenum the more top end big horsepower (dragracing), but lower end throttle response is lost. I would go 6 throttle body type setup if you are wanting to get really serious because you will get great throttle response, depends if it is a street or race track car or a drag racer.

Someone else might be able to go into it in a bit more depth.

[ETM]

I reckon those dividers are only there because ford was too lazy to build a new inlet manifold for the turbo which does not the butterflies like the na one does.

It is just the same manifold less the butterflies,there is no good reason for having 2 entries to the port.

[phildub]

I reckon those dividers are only there because ford was too lazy to build a new inlet manifold for the turbo which does not the butterflies like the na one does.

It is just the same manifold less the butterflies,there is no good reason for having 2 entries to the port.

I was there many years ago when Simon tested this on the engine dyno back to back it made 1 engine hp in the mid range with the divider removed so you would have to say Zero result. This was in n/a form

[toddyp]

Really I would have thought there would be at least a 5rwkw gain N/A.