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View Full Version : Right Prop for L18 X45?


johkur
03-22-2008, 10:45 AM
What prop is 'right' for an L18 X45? Dry weight is 5000 lbs, main goal is wakeboarding, but ranging from waterskiing with attitude plate down to wakeboarding with full 1000lb ballast and about another 1000 lbs of sacs plus people. Dealer at one point specified the 'high altitude prop', so I want to make sure I even got the right normal-altitude prop.

Which prop would MC ship for a normal altitude X45 L18,
Which would we really want, and are we talking 4-blade or 3-blade?
I'm about 900 ft above sea level, so not thinking about high-altitude really.
If the new-style rubber flaps with baffles versus straight-thru Exhaust tips with SilentMaster makes a difference, how would that change the 'right' prop?

I'm not looking for perfection, but want to make sure I start out with at least a prop that's in the range of reasonable, and have read some posts where it seemed that there's been some dispute about what prop should normally be shipped versus used with the L18 for performance, minimal oil consumption, etc.

Thanks.

EJ OJPROP
03-23-2008, 07:56 AM
The new standard propeller for the 8.1 is 14.75 X 17.5 LC 4B. Another option would be 14.75 X 15.5 LC 4B.

johkur
03-23-2008, 11:05 AM
I heard that the 06 X-45 w/the L18 (and silent master of course) came w/a 14.5 x 22. It works great for boarding, but the speed at WOT is about 46 mph which someone said was disappointing. For you to be recommending 14.75x15.5 or x17.5 for the 2008 seems like you're expecting alot less power than in 2006, given only 1/4" increased diameter, but much lower pitch. So is the distinction that you recommend one prop for the 2006 class L18 X45 (with silentmaster and no baffles) versus 2008 class L18 X45 (no silent master and baffled tips with rubber flaps?). Or what would you recommend for the 2008 with or without silent master (and baffles only on the non-silentmaster models)? Is the '08 L18 setup really so much less power? The European package always includes silent master, so what would you tell them for an '08 L18 X45? Is that the issue?
Thanks.

EJ OJPROP
03-24-2008, 08:35 AM
We have not supplied the 14.5 X 22 in several years. I would think the 22 would not be very good at all for boarding. The 22 would be very sluggish on the low end, it seems the 22 is now too much propeller for the 8.1. Interesting because I built the 14.5 X 22 and 14.5 X 23's just for that motor a few years ago, now the motor cannot pull either prop. The most recent propellers that have been standard were the 13.7 X 19.5 and 14.25 X 14.75 4-blades. I have not tested propellers/boats/mufflers as you are asking. I have tested the new 14.75 X 17.5 and it performed very well in all areas. I suggested the 14.75 X 15.5 for a heavily weighted application.

johkur
03-24-2008, 09:18 AM
So it seems like you're saying that the 14.5x22 and 14.5x23s were built for the 8.1 a few years ago, but then they didn't work out for those boats, or only didn't work out for the newer 8.1s? Same exact model boat/weight, or just that newer boats are bigger and heavier with the 8.1? I'm wondering if the 8.1's power changed (including exhaust and other things that would effect it), or just that newer boats were heavier or more demanding at the low end due to different sport. Did the 14.5x22 used to be a good match for the L18 X45, just not recent year models? Seems that people with older L18s are happier with that prop.

I assume for potentially heavier loads, the 14.75x17.5 would be better than the 13.7 diam prop (would slip?), and better than the stock 14.25x14.75, and seems like it would do better at the top end as well?

EJ OJPROP
03-24-2008, 10:12 AM
The newer boats seem to not be able to run the 14.5 X 22's. Not sure why but the new motor will not pull that much pitch. They did pull that much pitch in the past as I built them specifically for the 8.1. The new 14.75 X 17.5 works well on both ends with the new 8.1.

johkur
03-26-2008, 02:38 PM
My 8.1 X45 just shipped with the 13.7x19.5 4blade. So am I right to interpret that to mean, compared to the 14.75x17.5, that MC is expecting better out of the hole performance from the engine than you are (19.5 pitch instead of 17.5), but you're covering slippage better for a heavily loaded boat? Why would they use 13.7 instead of 14.5?

MYMC had mentioned in another thread that the 8.1L uses too much oil with the stock prop that MC ships, so should I be happy with this prop, not sure which one would be 'wrong' for the L18 X45.

EJ OJPROP
03-26-2008, 03:01 PM
As far as I know the 14.75 X 17.5 LC XMP EDGE replaced the 13.7 X 19.5. The 14.75 X 17.5 will have much better low end than the 19.5 and in testing at the factory, the top end did not suffer with the 14.75 X 17.5. Try the 19.5 and 14.75 X 17.5 and then decide which size fits your needs. I wil be happy to send you a 14.75 X 17.5 to try when your new boat arrives if you are interested.

MYMC
03-26-2008, 03:44 PM
MYMC had mentioned in another thread that the 8.1L uses too much oil with the stock prop that MC ships, so should I be happy with this prop, not sure which one would be 'wrong' for the L18 X45.
That was with the 2007 prop not the current one, and was also regarding the X-Star not the X-45...I have no data on X45 performance.