prop choice

[firetechjay]

I have a '94 dynasty 17' with a 4.3l alpha one gen II spinning a 3blade 19p aluminum. Overall I am satisfied with the performance
unfortunately I hit a stump and damaged the prop. Now I am faced with replacing the prop l am thinking 4blade if so can I go to a 21p for a little more top end without sacrificing low end. Any input would be appreciated.

 

[Bonus Check]

What was your WOT RPM with the 19P prop you had?
Was it in your WOT range as recommended by the Manufacturer? 4400 - 4800 RPMs
I think 4 blades are more for the big V8 engines. Generally when you go up to a 4 blade, you drop 1 degree of Pitch. I run a 21P SS 3 blade on my 4.3L with WOT at 4600 RPM and top speed of 47 MPH GPS. It's on a Q6 Tahoe which is 20'6" . Half a tabk of fuel with about 500 lbs of gear and people. Checked it today. I would not recommend a 4 blade but would recommend a 3 blade 21 P in a SS prop.

 

[firetechjay]

I am running approx.4700@wot and about 35-40mph with around 700 lbs people and gear

 

[littlerayray]

I've got a 3 blade 21p 14.25 in diameter, on a Tahoe q4. I will be purchasing a 4 blade 20 in 14.00 diameter prop, I'm at the top of my rpm range. I have a 3.0 4 banger in my boat 18.5ft long . A four blade prop is fine IMO, but you don't necessarily need stainless. stainless is More for power plants pushing 200+hp. they keep their shape at higher rpms. where as the smaller motors don't spin fast enough, to distort the props. aluminum props are also more forgiving when you strike something .

 

[steelespike]

Most motors will work well with a 4 blade prop.If there are 4 blades made for a motor they will work with the following results.
Typically going to a 4 blade you would reduce pitch 1" to maintain rpm. And you would lose a little top end.
But the 4 blade should resist ventilation, have a faster hole shot, stay on plane better at reduced throttle,seem smoother and may respond better around the dock.Usually a ss prop will improve overall performance but you need to consider if its worth 2 to 3 times the cost.Also a entry level ss prop may only be marginal better than a good al prop.
The Mercury Spitfire 4 blade is said the maintain top speed.

 

[firetechjay]

Well I bought a 3 blade 21p today mainly because it was a good deal and the guys at the shop talked me out of the four blade hope to tru it out this weekend will post results

 

[Bonus Check]

Well I bought a 3 blade 21p today mainly because it was a good deal and the guys at the shop talked me out of the four blade hope to tru it out this weekend will post results

I think you'll be happy with it. Remember to check speed with GPS at WOT.

 

[littlerayray]

I just picked up the merc spitfire I went down.25 in diameter but kept the same pitch as recommended by mercury I will post results I'm hoping it's worth the 250 I will post results the prop is installed and comparing it to the stock prop the blades seem more agrees I've with a straight but slight cupping on the trailing edge it looks really good hope it's all its made out to be