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View Full Version : top speed at WOT for 2004 X-9


shamco
10-03-2009, 07:22 PM
Went to the lake today for one final run. Bought the boat last year and have never run it WOT. Boat has the 310hp engine. At WOT, we were running 4500 rpm and the speed was right at 40mph. Is this typical for this set-up?

ProTour X9
10-03-2009, 07:29 PM
Sounds average or slightly below, my X9 has a 350hp and it goes around 45. What size prop is on your boat?

bigmac
10-03-2009, 07:33 PM
WOT range for the Predator is 4400-4800, so you're propped in the range. Propping up a bit closer to 4800 RPM may get you more speed at the expense of some low end grunt and holeshot.

I don't know about the X-9 hull. My 2004 230VRS turns up 5200 RPM and does 50 under perfect conditions.

shamco
10-03-2009, 08:54 PM
I am not sure what prop is on it. It is the original.

justinglow
10-03-2009, 08:57 PM
What lake in DFW shamco?

cbryan70
10-03-2009, 09:43 PM
WOT range for the Predator is 4400-4800, so you're propped in the range. Propping up a bit closer to 4800 RPM may get you more speed at the expense of some low end grunt and holeshot.

I don't know about the X-9 hull. My 2004 230VRS turns up 5200 RPM and does 50 under perfect conditions.

so your saying going from 4500 to 4800 he will LOSE low end? Interesting, wouldnt he have to drop in pitch?

shamco
10-03-2009, 09:58 PM
justinglow. We were at Joe Pool Lake today. We usually go to Lake Granbury when we have more time.

justinglow
10-03-2009, 10:18 PM
Me and a couple others on here go to Lake Lavon.

TX.X-30 fan
10-04-2009, 04:49 PM
WOT range for the Predator is 4400-4800, so you're propped in the range. Propping up a bit closer to 4800 RPM may get you more speed at the expense of some low end grunt and holeshot.

I don't know about the X-9 hull. My 2004 230VRS turns up 5200 RPM and does 50 under perfect conditions.


My 04 tops at about 48, I will assume the M1 is creating less heat and less friction and not breaking down as much as my dino oil, so this explains the higher top end. :D

cbryan70
10-04-2009, 05:27 PM
he must have a lower pitch prop which allows worse hole shot and better top end....bigmac you should probably google prop pitch to make sure you have that one correct....

TX.X-30 fan
10-04-2009, 05:31 PM
he must have a lower pitch prop which allows worse hole shot and better top end....bigmac you should probably google prop pitch to make sure you have that one correct....




:D:D......................

cbryan70
10-04-2009, 05:31 PM
:D:D......................


ohhh im just an ******* 4 year old that doesnt know anything :D

TX.X-30 fan
10-04-2009, 05:35 PM
ohhh im just an ******* 4 year old that doesnt know anything :D




Could have something to do with the black-market non-ethanolized gas he uses in the boat.

cbryan70
10-04-2009, 05:38 PM
Could have something to do with the black-market non-ethanolized gas he uses in the boat.

ethanol does not effect that gas and has NOTHING to do with any problems associated with boating. The whole boating community has nothing to worried about when they go to E15 or E20.

Stabil is a hoax, yami motors have no fuel related problems (his son or nephew i forget says so)

cbryan70
10-04-2009, 05:39 PM
ohhh and shamco if your running at 4500 and would like to try to get a bit more top end you could drop 1 pitch and that should bump your rpms 2 to 300. It will also give you a bit more holeshot. I dont see you gaining top end from this move tho

TX.X-30 fan
10-04-2009, 05:44 PM
ethanol does not effect that gas and has NOTHING to do with any problems associated with boating. The whole boating community has nothing to worried about when they go to E15 or E20.

Stabil is a hoax, yami motors have no fuel related problems (his son or nephew i forget says so)




I still think the grassy knoll is a good assumption.

cbryan70
10-04-2009, 05:45 PM
I still think the grassy knoll is a good assumption.
http://magred.net/forum/images/smilies/rotf.gif

TRBenj
10-07-2009, 10:44 AM
WOT range for the Predator is 4400-4800, so you're propped in the range. Propping up a bit closer to 4800 RPM may get you more speed at the expense of some low end grunt and holeshot.
he must have a lower pitch prop which allows worse hole shot and better top end....bigmac you should probably google prop pitch to make sure you have that one correct....
ohhh and shamco if your running at 4500 and would like to try to get a bit more top end you could drop 1 pitch and that should bump your rpms 2 to 300. It will also give you a bit more holeshot. I dont see you gaining top end from this move tho
Holy misinformation on all accounts!

More pitch = worse holeshot
Less pitch = better holeshot

There is no set formula for how pitch will affect top end speed. That is more of a science that matches hull and engine powerband to the prop. Sometimes adding pitch will improve top end, sometimes it will hurt it- and vice versa. Basically, the concept is to match the WOT RPM's to the engine powerband. The closer you can get the WOT RPM's to the engine's peak power, the higher the top end should be. Prop design (3-blade vs. 4, diameter, cup, rake, etc) all come into play as well.

I'm not overly familiar with the powerplant in question, but most modern ski boat 350's will benefit from maxing out closer to 5000 RPM's than 4500. I suspect that propping down a bit (at least an inch) will get the RPM's up all over the band and improve both holeshot AND top end.

That being said, Ive heard from multiple people that the 209/X9 is one of the slower MC hulls- so dont expect to pick up more than a few MPH with a swap. Anyone claiming to run 45+ on that hull likely has 350+ hp or hasnt GPS'd their boat... or both. Most stock speedometers are pretty inaccurate on the top end, and in my experience perfect pass is even worse. The old school Airguides were the most accurate Ive seen!

bigmac
10-07-2009, 11:29 AM
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My 04 tops at about 48, I will assume the M1 is creating less heat and less friction and not breaking down as much as my dino oil, so this explains the higher top end. :D
My boat did 46 from the factory with the 14x18 OJ. I put an Acme 847 13.5 x 17.5 on it a couple of years ago which improved hole shot and top end. That smaller propeller with less pitch did increase my RPMs to slightly above max, so I had my prop guy put a little more cup on it last year. That dropped my RPMs a little but kept the speed the same.

It may help that I take the propeller off and leave it soaking in synthetic oil all winter. That's as far as I'm willing to go in admitting the superiority of Mobil 1. ;)

TMCNo1
10-07-2009, 12:43 PM
.It may help that I take the propeller off and leave it soaking in synthetic oil all winter. That's as far as I'm willing to go in admitting the superiority of Mobil 1. ;)


Don't spend the big $$ on the Mobil1 for your prop and strut, just use a good water based personal lubricant for that extra umph and satisfaction!

EarlyriserX9
10-07-2009, 01:58 PM
My X-9 runs at WOT @ 4500 rpms and tops out at about 44mph. However, I have not changed the factory setting which could be off. My prop is stock and I would be willing to bet your boat will go the same speed.

What is the best way to calibrate my speedos?

JerryW
10-07-2009, 08:09 PM
We have a 2002 X-9 with an LQ-9, and the factory 4 blade stainless OJ prop. This past weekend, on smooth water, at WOT it was running 5300 RPM and 47.6 MPH, clocked on a handheld GPS.