Ok, just finishing up with porting the plenum, runners, and intake. I know I can leave the plenum rough, but should I smooth out the intake and runners or is a little turbulance ok?

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87 Z28 305 TPI, Auto, 2.73, Gutted air boxes, K & N fillters, SLP Airfoil, Dyno Max 3" cat back, Accel 8.8 mm spirals, Accel cap and rotor, Accel coil, rapid fires, and 170* Stat.
Best 15.414 @ 87.47.

 

With fuel injection make it as smooth as possible.

 

A little turbulence help promotes good fuel mixture. Leave it the way it is.

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91 Formula
305 TPI 5speed
1LE/G92/WS6
K&N, SLP airfoil, ported/polished plenum, March pulleys, TB coolant bypass,Crane AFPR(47psi),Crane Gold 1.6rrs,MSD coil,MSD6AL, Holley 9mm wires,Bosch O2sensor, SLP headers & catback,3:73s w/Auburn posi,160* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.
Street legal with stock throttle body, runners,intake manifold,cam, and heads.

 

Rough should be at the intake port in the
cylinder head. Runners intake manifold etc
should be as smooth as possible, thats why
you extrude hone intake manifolds nowadays.
BenIroc
89 Iroc, TFS heads,f*rd 9`` rear end, etc etc

 

On a MPFI system (which TPI is) you want it as smooth as possible. On a TBI or Carb rough is ok.

It goes to what is in the fluid being transported by the intake. (Air is considered a fluid, and as such, it obeys fluid dynamics). If it is just air, smooth is best since air doest have a habit of separating or anything. Smooth allows a faster airspeed.

If fuel/air mixture, rough is better. It promotes turbulence, and a slight lower speed. The reason you want turbulence is it keeps the fuel/air mixture together. lf its too smooth, the fuel might separate and drop out of the mixture, thus providing less fuel and thus less power. The slower speed is not desireable, but it is an unfortunate side effect.

Although l didnt cover everything, l think you get the idea.

Clayton