Thread: Overstuffing pump???
05-29-2007, 07:34 PM #1
Stock intake grate with the 1,3,5 mod at top speed ONLY on glass water. My ride plate is modded, but 'ski would still act up when plate was shimmed back to OE location.
My R-12X with buck and then yaw, sometimes pretty violently. It was made even worse if you released the throttle rapidly.
Has anyone experienced this before?
05-29-2007, 07:54 PM #2
yeah i get that overstuffing the pump feeling..i'm wondering if the skat prop would keep it loaded more..i feel like the pump is emptying and then prop is getting slammed by the next wave crest. Maybe we need an 800 grate ;-]
05-29-2007, 09:36 PM #3
Dave, you got a F12x J-me got a R12x. they are a little different.
I've found as i add HP i go through a period of pump stuff and then it goes away.
On my F13x (stock intake) with a 16/24 (almost stock pump) was there at 66 mph, and it may have been there at 65, i can't remeber because that was 3 years ago. But after 69 it was gone again so I figured it was best to measure the water pressure at the pump inlet. so i ordered 2 more sensors from RacePak last year to add to my dash. I don't have a lot of data to share yet because i pulled the motor out today on my F13x for a little more work on it. lol
I'll take the R12x out and see what it does till then it's back to the dyno, i got some things im doing with the crankshaft..
Back to the Dyno today..
05-30-2007, 08:43 AM #4
I love readin' about ur adventures, Nitro. You were turnin' maybe 7000rpm's at 66mph?
Jami, I can't comment on your R.. no experience modding it, sorry.
05-30-2007, 10:09 PM #5
I experienced the same feeling at 66-68 then at 70 it went away. I think it could be more related to the ride plate than the pump. I two am monitoring pressures before and after the pump. Hope to be getting some usable data shortly.
05-31-2007, 08:20 PM #6
not sure dave that was about 3 years ago..id have to go back and look over some old recordings. Today i like to keep ever thing in the 7700 RPM range. But this week I found some more power and big! (I'm working in the crankcase) and i think this mod will work for a lot of people. Like everything there is a slight trade off, but I'm not sure of that. It could be a outright gain..... with no downside.
I'm putting a new/deferent motor together right now and it will go back in soon. but first i want to try the crank mod with the F13x.
05-31-2007, 08:45 PM #7
05-31-2007, 09:50 PM #8
- Join Date
- Oct 2005
same here, I like reading about shawns work I just may be a convert soon!...PR...
06-01-2007, 07:52 AM #9
- Join Date
- Jul 2005
- Lake Dunlap, Texas
06-01-2007, 11:37 AM #10
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