Another "which prop for me" thread... VP 4.3 sx

[scooper77515]

OK, volvo penta 4.3 with sx outdrive.

redline for my engine is 4400-4600 rpms.

I have a 21 pitch aluminum 3 blade prop that gets me 49 mph at 4800 rpms, my prop of choice, with a great hole shot.

my spare is a 23 pitch aluminum 3 blade prop good for only 43 mph at 4200 rpms.

I want a 4 blade stainless prop. Currently 14.3" diameter, should I go to 14 or 15" diameter, and 19 or 20 pitch in 4-blade ss?

I want to keep as much top end as possible, but more importantly, keep the 18-22 mph range on a plane for wakeboarding.

What prop am I looking for?

 

[steelespike]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

limited info There are 2 versions of 4.3 225 and 190 my info 225 is 1.89 ratio,190 is 1.97.
Prop calculator says boat can't go 49 with the 1.97 ratio 1.89 gives 3% possible but kind of rare.
Is it a 225? Of course the speedo could be wrong, though 4.3 usually produces speeds around 49-50.
As far as the 4 blade If your turning 4800 with the 21 and rated for 4600 a 4 blade 21" should put about there (4600)
Thats al to al if you introduce ss it becomes more unpredictable. and cost about 3 times as much.
The al Solas Amita 4 blade has done pretty well. I'd go with the 14" if there is a choice of 14 or 15.

 

[scooper77515]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

Sorry, this is the 190 hp motor, and speeds are from GPS.

So, yes, 49 on smooth water with about 25% of trim up.

 

[steelespike]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

So either your tach is wrong or your prop size is different than you think.
My guess would be your rpm is probably really 5,000 which would indicate about 3% slip.
Of course my info may be wrong?? But specs say 1.97 and and matches you stated 4600 rpm.

 

[scooper77515]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

That 49 was most likely a fluke. I was alone, perfectly calm water, etc. Usually 47-ish, but since the wife wasn't with me, I got brave and screwed around with the trim until I maxed out the speed at 49.

so the extra blade is only going to cost me 200rpm? That isn't much of a change...

 

[steelespike]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

That is approximate.Usually suggested to drop 1" pitch when going to a 4 blade to maintain rpm.
Your allready a little high.
Usually expected to lose a little top end with an improvement in hole shot,ability to stay on plane and handling both at speed and around the dock.

 

[scooper77515]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

Handling around dock is a plus, but mostly want to keep on plane in that 18-22 mph area while wakeboarding.

After a session of boarding, my wife is more tired than I am, having struggled with the throttle trying to keep it on speed.

 

[steelespike]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

The 4 blade should do it.If you wanted to really sinch it; drop the 1" pitch it just won't remove that slight overrev.

 

[scooper77515]

Re: Another "which prop for me" thread... VP 4.3 sx

Re: Another "which prop for me" thread... VP 4.3 sx

Ended up with a Stilleto Baypro III 14.25X21. We will see how it works when I get a chance to take it out.