Aluminum to Stainless conversion

Dan F.

Dan F.

Cadet
Joined
Feb 10, 2010
Messages
13
Current test prop is a Solas alum.15 1/4x15p. Want to install a stainless but it appears no one makes the same prop in stainless. Turning 4900rpm @WOT on a 2000 model Mercruiser 4.3l efi which is 100 rpm too much. Figured the stainless would knock that 100 off since there is less flex and gain a couple more mph at the top end. Other important info is boats an '85 Wellcraft V-20(heavy boat) and top speed right now is 48mph. Should I go with another 1/4" of diameter with the same pitch or less diameter with more pitch? Just repowered and am confused as what to do. Thanks for any advice in advance.
 
usskydvr

usskydvr

Chief Petty Officer
Joined
May 27, 2009
Messages
494
Re: Aluminum to Stainless conversion

For that Solas 15 1/4 x 15 alumium 3 blade you would actually go to a slightly smaller diameter for the stainless, say 14 7/8 or so. See Ballistic 345131 or Apollo 993042
 
D

dazk14

Ensign
Joined
Jul 22, 2008
Messages
966
Re: Aluminum to Stainless conversion

Dan,

Unless you have access to a prop shop that will do exchanges (or deep pockets), I would strongly suggest you read the stickies and fill out hwsiii's form.

48 seems darn high for a v-6 with a 15" pitch prop. Are you using a gps?

Switching from aluminum to SS is tricky. Switching manufacturers adds even more variables. Even same brand different models can yield vastly different results.

It's not an exact science and you'll need the "Top Dogs" previous trial and error experience AND databases to give you the best shot at a "One and Done" prop experience!

Hope this helps.
 
Tail_Gunner

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Re: Aluminum to Stainless conversion

What is needed is your gear ratio..somethings a miss.. your pitch are you sure thats a 15??? or you have some high gears....Or your tach is off Hmm is that GPS speed

@ WOT does the ignition cutoff kick in ...That is a almost unoticable miss in the engine..the efi models are rpm restricted to 4950 after that there is a electronic limiter..;)..at least i hope so
 
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