Sharpened Venturi Runners

[1FastTrespiper]

Looking for speed as always sharpened the venturi runners to see what would happen. I’m really not sure if I gained any speed, it would need to be tested back to back with an unmodified one. Ok ….. I think it gained ½ mph but don’t hold me to it.

The solas 15/20 would spin real bad out of the hole. Now that these runners are sharpened it doesn’t spin at all…I was very surprised by doing this it made the pump more efficient.

[Yuji]

Well...if it worx then I say good on ya! Nice find
I love it when people try the un-tried...Keep us posted

[CrazyA]

The solas 15/20 would spin real bad out of the hole. Now that these runners are sharpened it doesn’t spin at all…I was very surprised by doing this it made the pump more efficient.

Which is odd, because it seems to defy conventional wisdom on pump dynamics.

Just goes to show ya...

Excerpt:

Impeller and pump specialists point out that leading edges of things like the anti-swirl vanes behind the impeller are rounded for a good reason. The angle at which the water approaches them changes with impeller and boat speed, and round edges are easier for the waterflow to curve around. Knife-edging seems like it ought to be an improvement, but when the water approaches such an edge at an angle, the flow will cavitate behind it on the low-pressure side, reducing efficiency.

From:

http://www.parkeryamaha.com/index.as...n=Custom&ID=31

[1FastTrespiper]

I'm not saying for anyone to try this. This is just what I found. It took 2 hours to sharpen for little gain.

Need to find something that will stay in the pump cone bolt hole voids that can be removed easy.

[CrazyA]

Oh... I understand completely!!!

And I'm not saying it doesn't work by any means, just pointing out that sometimes we must try things regardless of what we think we know about them!!!

I'm actually all for experimentation.

[1FastTrespiper]

A few weeks ago it ran the best of 75.3 mph @ 8100 rpms, this morning with the same outside temp. and fuel, the water is now 10 degrees warmer it ran 75.4 @ 8050

Not much of a gain but it all adds up.

[CrazyA]

Not much of a gain but it all adds up.

Agreed... 100%!!!

[Kinchyle]

I wonder if being at the 8050 which is more horsepower helped any.
I know higher rpm is supposed to be more mph but....

[Hydrotoys]

Do you guys ever take RAD readings on these test days?