Polishing Intakes

[blue1]

Forced induction doesn't really worry that much how polished the runner is when you have 20lb of boost trying to get thru its the inlet valve and cam timing that will give you your flow. n/t is a different matter but you never mirror polish the inlet in those either smooth is good but leave some sort of finish from an emery flap wheel or similar for best results, flowbenches dont lie! Interesting about golf balls though i didnt know half that shit.

 

[MNGSX]

Wet vs dry intake manifolds make a difference.

Carbs need turbulant air.

Sheet metal intakes are pretty smooth.

On a turbo car a brushed metal surface or even a mirrored one would'nt hurt.

Either are better than that sand cast.

 

[kpt4321]

As long as the golf ball has topspin, then the dimples could very easily create lift. However, in order for them to create lift by this method, they must also create turbulence. Lift increases are inherently almost always offset by drag increases. Drag is bad in a car.

jltcat: That "ball-bearing surface" you are talking about is the boundry layer. When air flows over a surface, the friction between that surface and the air molecules touching it, will cause these molecules to slow down. Thus, right on the surface, the molecules actually can "stick" and then the velocity will gradually increase as you get towards the outside of the boundry layer, until you get into the free flowing air, where the velocity will all be the same.

With a non-smooth surface, more air is going to get caught up in the boundry layer, and more air is going to get trapped in the small grooves and holes and peaks. How you think this is a good thing, I do not know.

I am actually a bit skeptical of the old theory that you need turbulence when there is a fuel and air mix. Even with a rought finished cast manifold, there is only going to be turbulence at the outer edges in boundry layer, and the middle will still be laminar flow....

....Kyle T.
93 TSi AWD "TURBO4"

 

[MNGSX]

there is only going to be turbulence at the outer edges in boundry layer, and the middle will still be laminar flow

I think on a carb engine that is the idea. If the outer edges were smooth it could pool or puddle. If its rough any fuel vapor that approaches the edges will get mixed up as opposed to condensing or pooling on the intake. It's probably more to keep the fuel in the air as opposed to get it in there.

 

[Defiant]

Originally posted by kpt4321
Defiant, would you like to explain this further?

""Use the Search" is not an acceptable response by itself.
Link to the answer and explain how the info can be found, or just move on and say nothing."

Yeh, sorry. I meant to say, "Do a GOOGLE search for 'laminar flow' and 'boundary layer' and get back to us."

My apologies.

 

[kpt4321]

Actually, I don't think that we need to do a search, because there are several of us who are already familiar with those concepts.

Maybe you should read what we have written and then chime in, if you have something to say.

As of right now, the agreement is that polishing is good.


....Kyle T.