08-09-2009, 08:27 PM #1
Clipped Blade stock Impeller 3-4 mph gain!
Most of you saw my thread before about my jacked up impeller. The erosion was enough to sufficiently freak me out enough to pull the pump for my first time. So I started cleaning up the impeller the best I could without removing it from the shaft. Once done with that I started thinking about the mods I used to do with my race props on my F120 boat.
The clipping of the blades made huge gains in midrange power and top end. I saw an average of 3mph right off the bat and stretched it to 4.5 mph once the fuel level dropped to 2 bars. Torque from 40 mph is phenominal and yes it still cavitates out the hole but when it hooks, she goes like a rocket!
If anyone wants to try this "Tango Mod"... just send me a stock impeller and I will knock it out and ship it back.
08-10-2009, 07:23 AM #2
Is this for real? You just cut the front edge of the stock inpeller off and you gain 4.5mph!? What kind of gps #'s are you getting? You sure it's not just back to stock speeds after you repaired the damage? Not trying to sound too skeptical.
08-10-2009, 07:35 AM #3
I couldn't be happier with the performance gains. In comparison to the GPS the display is only 1-2 mph off on the average. In the past I had seen only 72-73 mph tops... now in a light ripple water condition at 2-bars fuel, one click high trim and my 230# ass, I see a steady 78 mph which the gps shows a top of 76.4 mph.
Also note that I have mods that are a bit different due to making the pump and hull as efficient as possible. I have completely sealed every seam, gap and bolt recess under the ski and in the pump housing with Pro Seal. I am sure that helps with efficiency too. Another huge gain was installing the skegs which allows 100% of thrust to go forward needing no steering effort at speed to offset thrust torque. Another fact is that I have sanded my lower section of the bottom hull from the inside chines to the rear... typically where it would ride in the water at speed.
So, looking at the mod database I am on par with my speed based on mods, saltwater giving lower drag and adding the same 2 mph that the skegs gave when I first installed them. I am sure as the speeds go up with the power, their part in delivering faster speeds will play a larger part in the end results.
If someone sends me their stock impeller I will do the mod for free so we can all see if the gains are consistent.
08-10-2009, 10:43 AM #4
- Join Date
- Sep 2007
- Gainesville, VA
Wow, great results! I guess I need to order Jim's R&D plate to get some more speed. Mine still feels like a turd.
08-10-2009, 11:05 AM #5
08-10-2009, 11:30 AM #6
- Join Date
- Jul 2009
Can these Skegs be fitted to any ski? With the same benifit?
I'm thinking about some for my FX140.
How are they fixed on and could you post some more pics?
08-10-2009, 11:47 AM #7
The are mounted using reduced head aircraft screws with coated "jap nuts" with a passivated washer. This way they won't have corrosion issues with dissimilar metals but high strength.
I assume you could make them work with any kind of rideplate. The SHO cruiser rideplate was easy because it already has channel with a mini-skeg built in. What I like is there is no washout when going over a boat wake. Meaning there is no rear movement to the side like the ski is sliding up or down a wake at an angle. It simply slices over it straight.
08-11-2009, 03:53 PM #8
- Join Date
- May 2009
- hangin out at the body shop at night!
How thick is this aluminum angle plate you used and what length ?
Also how far down does it hang in the deepest section ...
08-11-2009, 05:23 PM #9
OK, so even if you picked up 4.5 miles per hour over stock, that would put you at a little over 70 mph. Not 76.
Who cares what the speedo shows or how close it is to actual mph as confirmed by GPS. My digital speedo actually shows different speeds on different days. One day is shows me going 78, the next it will never read over 60, and I can guarantee I am doing over 60.
I'm sorry, I'm just not buying all this. You have no other mods besides skegs and this impeller?
08-11-2009, 06:03 PM #10
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