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View Full Version : X-18 and top end props



Blewbyu
08-18-2001, 03:38 AM
:cool: Hey 'Poodle and other X-18 drivers with a garage full of props-Whaddya find is the best all-around prop for the X-18 for top end behind a Volvo? I'm running a 290 lower case/270 upper, and haven't any idea what the final DR really is.With a 14 1/2X22 Spinelli thinned/labbed-been holding engine to 5200 tho it will turn 56-5800,and I have a helluva holeshot.Engine is very strong now-just rebuilt/balanced,.30 over,and CR brought down from 9.8 to 9.5.Dyno'd at 357 HP with bad dist (rebuilt/recurved today).Expect to see 380+ HP.Knowing that-can you scientists tell me if I can turn a 25" prop at least 47-4800? Would a Mirage 23" whip my Spinelli? Scott-if I grabbed your 27",would my holeshot tank so bad as to not be able to pull a 200lb skiier out of the water? How did the 27" work on your X-18? :D :D :D Cant wait to breakin new motor tomorrow.....it ROCKS!

Philip47
08-18-2001, 06:52 AM
healthy engine! what are the specs on the motor?

GEOO
08-18-2001, 07:12 AM
BlewByU,

I found the Volvo Ultra Prop 26" with added cup to work the best. When I ran the 290 drive, with a 360-400hp 383ci she ran 66-68mph, 1:61 gear 5400-5500. The only problem with the Ultra prop is the hub is rubber and they don't last long!!!
The boat needs bow lift, so a prop with alot of rake works better. At higher speeds the Volvo runs with a lot of slip, cupping the prop helps hook the blades up better and allows you to trim higher. GEOO ;)

Blewbyu
08-19-2001, 01:00 AM
Thanks GEOO. The Spinelli has a steep rake, and a "super" cup on both the tips and trailing edge.Just ran the new motor today,and gave a short burst of WOT after about 3 hrs running.I'm turning easily 5800, and it gets there fast.Boat airs out nicely-no chine walk.Think I may wanna drop a few RPM just to preserve the valvetrain life.May try that Volvo,if I can ever find one.
Regards-Jeff :eek: :eek: :eek:

Blewbyu
08-19-2001, 01:05 AM
P47-I have the motor specs in my registry remarks.Only diff-it's now a 355 (.30 over)and has 9.5 CR vs orig 9.8 (when new).New engine is balanced and blueprinted.Sweet runner-Smooooth and quick.HONKIN holeshot!!
Lotsa grunt for a mouse motor, and a very unusual exhaust tone. :D