Other 2 mph racing "secret" ??????

[steve1981]

hey guys just wondering if anybody had done this before, info came from a guy that raced back in the 90's. he talked big game but i dont know if its real or BS.

would sandblasting you impeller help it to grab the water and push it out the nozzle harder causing you to gain 1-2 mph top speed? or is this something they used to do that is not used anymore? or is it just total bullchit?

 

[OCD Solutions]

FWIW, all the skat trak impellers come with a rough finish.

 

[Layne]

Makes sense ... found an interesting article from Greenhulk.

 

[DAG]

Water does not compact, would find it hard to believe a ruff surface would "push" water harder.

You want the water to go from one end of the pump to the other as quick as possible, adding friction by sand blasting does not accomplish this.

 

[Dirtboy488]

Although you want it to go from one end to the other as fast as possible I think having some texture on the impeller keeps the system from having backpressure as disrupts the flow enought to help pull in new water faster. I had a friend that tried to re-design his pump so it would not foam the water at all. He ended up with a ski that would shoot almost clear water out the nozzle but would cavitate like mad because as you said water does not compress.

 

[X2Pilot]

I have heard that roughing up the hull by sanding the shine off of it makes it faster.....

 

[227]

I have heard that roughing up the hull by sanding the shine off of it makes it faster.....

I have heard this also. The theory being the rough texture will trap tiny air bubbles in the uneven surface areas and create a barrier between the ski hull and the water which causes less friction. Apparently it is true as I was watching a show on submarines on the Discovery Channel which said the US Navy coats there subs with a rough texture and learned the trick from sharks, whose skin looks smooth but is actually rough to the touch. The texture of a sharks skin actually helps them swim faster and more easily. The show didn't say how rough the texture was though

 

[jetsport484]

I know they say not to wax the bottom of your boat. Due to the fact it creates surface tension. I would say its something along those lines there. I'm no engineer, but it makes sense to me.

 

[X2Pilot]

Well, that being said shouldnt that apply to the blades of an impeller? Rough finish can process more water due to less friction. I wonder by how much, and as 227 points out, how rough of a texture?

 

[scotts2t]

does the same effect happen in your motors intake ports aswell? better to have a rough surface than a polished smooth one?

 

[BombThreat]

Air vs water... they have different properties.

 

[#ZERO]

Most professional engine builders/tuners prefer a textured finish on the impeller blades with the pump being as smooth as possible.

 

[the only couch rider]

use honda wax on your hull will net the same speed gains....

 

[750SX]

I have heard this also. The theory being the rough texture will trap tiny air bubbles in the uneven surface areas and create a barrier between the ski hull and the water which causes less friction. Apparently it is true as I was watching a show on submarines on the Discovery Channel which said the US Navy coats there subs with a rough texture and learned the trick from sharks, whose skin looks smooth but is actually rough to the touch. The texture of a sharks skin actually helps them swim faster and more easily. The show didn't say how rough the texture was though

x2

The same thing is done on the waxed surface on snowboards and skis to increase speed. The tiny grooves are put in the waxed surface by a wire brush.

I think some Olympic swimmers use a "shark textured" suit.

 

[jeepinxj]

I know of a guy that used to drag his race ski down the road to scrape up the bottom so it will handle better. Same concept.

 

[scotts2t]

Air vs water... they have different properties.

true true....so the we all know that dimpling the surface of an object can cause less friction with air becasuse it traps air around it allowing the oncoming air to pass around it more easily...do you think that if we casted dimples into the intake ports of race motors they would flow air faster therefore making more horsepower?

 

[Schmidty721]

true true....so the we all know that dimpling the surface of an object can cause less friction with air becasuse it traps air around it allowing the oncoming air to pass around it more easily...do you think that if we casted dimples into the intake ports of race motors they would flow air faster therefore making more horsepower?

That's a good question. I know that almost all of the top MX guys are running dimpled valves on the high performance 4-strokes. I haven't had a chance to flow the deferences between a smooth and dimpled valve but plan to sooner or later.

 

[scotts2t]

Ya, It makes sence, the golf ball effect, but I was just thinkin, we already grind out as much material as possible on stock parts but maybe somthing to look into for the guys making aftermarket intakes and cylinders

 

[Layne]

Ya, It makes sence, the golf ball effect, but I was just thinkin, we already grind out as much material as possible on stock parts but maybe somthing to look into for the guys making aftermarket intakes and cylinders

For valves it makes sense because the dimples create less drag behind the object, doubt it would help with many other things on the ski.

 

[OLD_KING_COLE]

I would think its just like trying to get a tire to hook up on a car. If you texture it it will grab the water better.