Prop Finish?

[jaxracer]

Okay so to throw a curve ball into this discussion, if we've established that in regards to hydrodynamics, polished/smooth is drag and something along the lines of 220 grit is optimal, could this also be applied to the internals of our engines as well? Everyone talks of polishing ports and things of that nature, would it actually be beneficial to do the opposite and leave a rougher sanded surface on our cranks and sleeves?

-Mitch

 

[Daniel's Racing]

Guys,

For the face Dremel makes a quick change radial brush wheel 1" in diameter with a 36 grit.

For the rest of the propeller, hub included, a 3M EXL 2 S Fine wheel approximately 220 grit.

The only problem with beading is you throw off the final balance ever so slightly. Sand blasting the propeller with

Walnut shells works great for a nice finish. Some propeller shops use that finish for water ski propellers.

Some of the latest surface finishes are with a CNC machined swirl pattern machined into the face.

On ABC's latest Game Changer Propellers series Jim is molding a specific finish on the face of the blade.

Plenty Of Options Out There,

Mark Sholund

Those 36 grit Dremel brushes are definitely the ticket for the final finish on the working side.

Love the 3m EXL fine wheel on the buffer also.

Stocked up,

 

[Daniel's Racing]

Okay so to throw a curve ball into this discussion, if we've established that in regards to hydrodynamics, polished/smooth is drag and something along the lines of 220 grit is optimal, could this also be applied to the internals of our engines as well? Everyone talks of polishing ports and things of that nature, would it actually be beneficial to do the opposite and leave a rougher sanded surface on our cranks and sleeves?

-Mitch

On our two strokes it doesn't make a bit of difference in the induction or transfers because the high oil content we use has the surfaces wetted with oil film so thick it is same whether the oil film is laid out on polished or a fine texture. The flow is always going to be on the wet oiled down surface and it has the same flow no matter how the finish was left under it. It does not do anything for turbulence or atomization at all. It would need to be gouged up heavily to even begin to do anything different with the flow of fuel/air mixture.

A polished surface allows you to see how nice and straight and flat your porting is done. You can take the shine off later if you feel differently and like a little less polish.

The exhaust can benefit from polished as it is a drier flow and helps keep the carbon buildup thinner without the coarseness to collect carbon and give it a surface to build up thick on..