Best Pitch for 3.0L Mercruiser- Moving to SS prop

itcowboy

Cadet
Joined
Apr 8, 2007
Messages
17
2001 Stingray 3.0L 18 footer. The boat currently runs about perfect in WOT rpm range using the stock 3 blade 14.25x21 alum. prop. It is a bit sluggish on holeshot when pulling a tube and I want to move to a stainless steel prop. Should I stick with the 14.25x21 in a SS or go to something like a 14.25x19? I wasn't sure if just the move to SS at the same pitch would affect holeshot enough.
 

aerospot

Seaman Apprentice
Joined
Nov 18, 2007
Messages
38
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

Is the 3.0 liter the 140 hp? I have this engine in an 18' V-hull bow rider. It has a 15.25 X 15 prop and love the performance for skiing and tubing. Good hole-shot and fair cruise gets me to the fishing hole or up on skis... Just my 2 cents.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

Needs to be based on your WOT numbers. Remember aerospot, he could have a different gear ratio than your boat and be lighter or heavier . . . ;)

SS of the same pitch will have slightly worse hole shot and slightly better speed assuming they are of similar design/shape. You say "about perfect", be more specific and we can help more. Either way, if you are near the top or the bottom of the range, go down in pitch for stainless, especially if you need hole shot improvement. You just might retain your top speed AND improve hole shot.
 

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

Your going to get the speed with the 21" OR better the hole shot with the 19" ;)

i have a 17" ,19" 21" and 20" 4 blade that i switch to suit the task of the day as 140 HP only goes so far

The 3.0 tends to have trouble getting past the 3000 RPM range when the prop is on the big side as the HP is so low at this RPM
 

itcowboy

Cadet
Joined
Apr 8, 2007
Messages
17
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

WOT with average load of 2 kids and 2 adults runs about 4800, which is at the high end of recommended range I think. I have seen it hit 5000 on smooth water and light load but this is rare. It currently runs about 40-44mph with the above load. Sounds like the 14.25x19 would be the way I want to go. I don't mind losing some speed, as we do more tubing and playing than cruising. Will it have much affect on gas usage?
 

xxxflhrci

Chief Petty Officer
Joined
Jun 14, 2008
Messages
637
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

I use a 19p Mercury Silverado. It runs 40 mph at 4600 rpm. Towing two 200 pounders on tubes or kneeboards is easy. It easily gets up one guy on two skis. I can pull a 200 lb+ slalom skier up if he does his part.
 

itcowboy

Cadet
Joined
Apr 8, 2007
Messages
17
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

Looking at the different performance charts, here's what I notice. Comparing at prop of same pitch and diameter, the alum. version seems to outperform the ss in low-end. So if i stuck with the 14.25x21 but went SS most likely I would gain top-end speed but possibly suffer more at low-end power. Back to the charts, dropping down to a 19P SS prop seemed to increase the low-end over a 21P alum. prop. The 19P looks to be the way to go for me but I may just have to be careful about not overreving if I run WOT on a light load. Does that sound about right?
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

Yes ^^^^
 

Matt's 175

Cadet
Joined
Feb 14, 2008
Messages
21
Re: Best Pitch for 3.0L Mercruiser- Moving to SS prop

I tried a total of 7 props on my Bayliner 175, which has the 3.0 Liter and a 2.0 ratio alpha drive. Out of all of them, I liked the Stiletto 14.25 x 19 pitch the best. It jumps right up on plane from a dead stop and the was NO loss of top end MPH over the factory 14.25 x 21 pitch aluminum. With 4 people in the boat and a full cooler, I hit 43.4 mph (GPS verified) @ 4800 RPM. When boating with a light load, she'll hit 5000 easily, so you just have to back it down to 7/8 throttle.

Also, I tried a 14.25 x 21 Stiletto. The max RPM I could get was 4400 and 44.5 mph (GPS) and it felt very lazy out of the hole. The trade off wasn't worth the extra 1 mph, so I stuck with the 19 pitch.

Either way, make sure you buy from a place with an exchange program. That way if it doesn't work out for you, your not stuck with it.
 
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