RPM question

[stugots]

I have a 94 stingray with a 4.3LX merc and it came with (what it looks like) a crappy 19P prop, now the boat does NOT have much pickup but up top it seems to stop at exactly 4900 Rpm (dont know the speed since my speedo is broken) I have read here ( http://www.stingrayboats.com/products/reviews/lb5-95.html )

that with a 23" lazer prop it did 56 mph at 4900 so my question is with a 19 shouldn't I have MORE RPM? or should I go with a smaller prop to achive that?
bare in mind the new prop im buying is SS and my current one is NOT.

Thanks in advance

 

[Bondo]

Re: RPM question

Ayuh,....

If you're now running 4900rpms with a 19" aluminum prop,...
And,..
You install a 23" SSteel prop,...

You will No longer see 4900rpms as the WOT rpms.....

Matter of fact,... You'd be Lucky to see 4000rpms,... Which is Lugging that motor....

4400/ 4800rpms is what you Want to see at WOT rpms...

 

[achris]

Re: RPM question

Buy Stainless steel, but stay with the 19"... Go to the 23" and, as Bondo said, the engine will be lucky to make 4000... The boat will be a dog and the engine will die a premature death....

Chris.......

 

[stugots]

Re: RPM question

ahhhh I got cha ok. Cool thanks alot guys.

So its either the 19" penta or the 19" high five

 

[stugots]

Re: RPM question

you guys don't have any opinions on those 2 props by any chance do you?

 

[achris]

Re: RPM question

Yes.... I like stainless... I know all the 'stories' about stainless props killing gearboxes... but they are rubbish (the stories, not the props). I have seen boxes chewed up beyond recognition with an ali prop on, and I've seen stainless props so badly folded up I expected the box to be totally destroyed inside, with no damage at all... It just 'luck of the draw' as to how much damage will be done on impact.....

Stainless props are thinner and so offer less drag. They are stronger, so flex less under load. They wear less and will last a lot longer. They are easier to fix if you wrap them up. And they look heaps better

Chris..........

 

[stugots]

Re: RPM question

the Penta 3 blade im looking at is stainless and so is the merc high five blade.

Which do you think is a better prop?

 

[Tail_Gunner]

Re: RPM question

the Penta 3 blade im looking at is stainless and so is the merc high five blade.

Which do you think is a better prop?

Just a personal opinion, but those are high priced props...If your going to spend that much.....A stilletto product would be a better choice.... In a 4 blade the baypro 11 series have tremendous amout's of midrange power and stern lift...The 3 blades do not have as much lift but just as hard out of the hole and cornering......

You may want to check the Solas prop's I just tried a one with great results..almost the same as Stilletto just not as much stern lift (lower planing speed) but 1 mph faster in the 4 blade titan

 

[stugots]

Re: RPM question

what do you think the top speed would be with that prop?

with the Penta its 53 Mph and with the High five its 49 Mph (of course the High five has much better 0 - 49 times)