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View Full Version : Prop pitch for 4-blade vrs 3-blade



fasttrucker
10-13-2009, 11:57 AM
My 200hp johnson outboard on my 16 donzi is running 58.2 mph gps@ 6000 rpm.Its only rated to go 5000 to 5500 rpm so I need to add pitch. It now has a 3-blade raker prop which says 20 pitch but was told it was tuned to a 23 pitch.I was told that he had a 25 pitch 4-blade on the boat but it was stolen.He claims it was great.Anyway, I found a 14 1/2 x 26 pitch raker on craigs list guy wants $295.Iam wondering if a 25-pitch 4-blade = a 26-pitch 3 blade?How does it work again up or down size 3-blade vrs 4-blade.?????:confused:

MOP
10-13-2009, 01:00 PM
Propping as you know can get VERY expensive quick! Your outboard had the large gear case the same as the late OMC drives, for the sake of your wallet put a post in wanted. Try to borrow a couple of props to give you a base line, once you establish that then you can plunk your $$ down. We have quite a few Cobra dive members a few may let you try stuff as long as you pay the shipping.

Phil

mrfixxall
10-13-2009, 01:24 PM
My 200hp johnson outboard on my 16 donzi is running 58.2 mph gps@ 6000 rpm.Its only rated to go 5000 to 5500 rpm so I need to add pitch. It now has a 3-blade raker prop which says 20 pitch but was told it was tuned to a 23 pitch.I was told that he had a 25 pitch 4-blade on the boat but it was stolen.He claims it was great.Anyway, I found a 14 1/2 x 26 pitch raker on craigs list guy wants $295.Iam wondering if a 25-pitch 4-blade = a 26-pitch 3 blade?How does it work again up or down size 3-blade vrs 4-blade.?????:confused:


if your running a 26p then yes a 25 p 4 blade will soppose to = a 26p 3 blade which put you at 5400 rpm.take the prop off and have it measured first,who knows what that prop really is? also my calculations may be off as to i dont know what the pitch of the prop your running ..

fasttrucker
10-15-2009, 11:37 AM
if your running a 26p then yes a 25 p 4 blade will soppose to = a 26p 3 blade which put you at 5400 rpm.take the prop off and have it measured first,who knows what that prop really is? also my calculations may be off as to i dont know what the pitch of the prop your running ..
Thanks,Ill take it off,take it to my local shop"MR PROPS" and measure it this weekend.

fasttrucker
10-16-2009, 12:20 PM
Iam looking at this TXP OT-4 turbo prop randy told me about.Now have to figure out correct pitch. www.turbo-props.com