what % of h.p lost between crank, and prop.
 

what is the horse power lost % between crank h.p to prop h.p
my liberator has 375 h.p at the prop, just wondering what my 502 omc has for h.p. I have a omc king cobra book that shows a 454 with 370 h.p@ the crank, and 310 h.p @ the prop with 60 h.p lost, and a 460 omc king cobra with 340 h.p @ the crank, and 295 h.p @ the prop with 45 h.p lost... it seems that the more h.p the more h.p lost you have. thanks for any help u can give me.

As a rule 10%, some drives may have a little more or less loss.

What kind of GPS speed do you get with your boat? What prop and rpms are you turning at WOT?

i have engine mods done on my boat, my best is 64 mph@5100 rpm the prop I have is 14 1/2 x 20 raker , but I average 63mph...

Is your speed via GPS? If so you have great prop slip numbers!

yes that is gps #s I have my prop out to bblades for some mods, they claim I should be consistant 65 mph. bret recomended the mirage 21 pitch prop I would like to try one to see the diference.

I'm in Onekama and would let you try my Mirage 21 but I'm pretty sure you would need a differnet hub. I'm sending my prop in to Bret as soon as the lake thaws and I can get some base numbers.

Thanks! what kinda gps mph are you getting? I talked to Bret yesterday, I hear he is the man when it comes to props, I've heard nothing but good things about him.

Last summer my best was 64 @ 5900 rpms with a standard Mirage in poor condition. I'm hoping to gain a few MPH going to the Mirage Plus and a few more by having Brett do his stuff.

What gear ratio you running? 1.36?

I have a 1.42 gear ratio on my 221 liberator.

6% according to the numbers he posted. That is impressive.
Not many V bottoms are that low.

Never seen one that low, I am at 9.8% and that is pretty good. Double check your gear ratio, here is a site that may help you out http://www.rbbi.com/folders/prop/propcalc.htm

I know, I was really shocked with that number as well. My Formula is around 16% slip. The liberator has a shallower V though, it's 21 vs a 24 degree bottom. I'm sure this helps a lot. When I run the numbers that Four Winns lists which is 58 mph @ 5000 rpms with a 20 pitch raker I come up with 12% which is still good.

I have the original brochure on my boat and it shows 1.42 gear ratio on the omc king cobra 502, and the 454 that year. I was thinking about a nose cone for my out drive last year, and they told me it wouldnt help me because my slip numbers were so low.