Re: Throttle Body & Intake Manifold Polishing

["Ken Keith" <auditude@neta.com>]

DeWitt Harrison <de@aztek-eng.com> wrote:
> 
> On Mon, 30 Aug 1999 16:32:16 EDT, Scott Calabrese wrote:
> >[ ... ]
> >1) What should I use to polish the throttle body and the intake manifold ?
> >
> >2) Is there a point where the throttle body and intake manifold can be too 
> >smooth ?
> >I can have the whole thing electropolished, but will it be too smooth ?
> >A friend voiced a concern that with carborated motors, you could get things 
> >too smooth and the fuel would not mix correctly.
> >[ ... ]
> 
> Just one remark concerning the "too smooth" concern: the IM is
> dry. That is to say the fuel is injected at the intake port and does
> not traverse the manifold so the fuel mixing issue as stated is moot.
> 
> Matching the IM to intake ports is at least as important as smooth
> flow through the TB and IM. This is a manual operation that simple
> polishing or honing cannot accomplish.

Good point.  The only place where wall texture would be a concern 
would be the head passages behind the valves, to the injectors.

The concern about wall texture comes from the fact that a smooth 
surface will attract atomized fuel particles to them, and they will 
stick to the wall instead of staying suspended in the fuel mixture.

Also, because of the laminar flow nature of the air and fuel moving 
through the passages, I think that making sure the walls are not 
too rough is a minor concern.  There is more flow in the center of a 
moving air mass, or a river, than there is by the walls, or by the 
banks.

Shape is more important, and as Jeff G mentioned a while back, 
the "outside corner" is more important than the inside.

If you're looking to polish the outside of those items, and maybe 
the inside could also use the same tools, you might check with the 
Eastwood Company (http://www.eastwoodco.com/) for their kit for 
doing just that.

Ken