volvo prop pitch correct?

[cubbug]

I have a Bayliner Tropy 21' w/ a Volvo 125 H.P. Inboard and 270 O/D. with a 15 x 15 prop.. I'm showing approx 4200 rpm and 22 mph on the gpr. Can I gain a bit more speed by bumping up to a 15x17 prop, or will the engine not perform? Any help is MUCH appreciated! Thank you, Dave

 

[Dhadley]

Re: volvo prop pitch correct?

It depends on what model motor you have. Is that the old AQ series?

My guess is that 4200 is at the low end of the rpm range for that motor and unit. It was probably rated at something like 4200 - 4600. Maybe 4000 - 4400. At any rate, putting on a prop with more pitch may get you slightly more speed but a 15 will cause a loss of about 400 rpm. I don't think that's what you want to do.

 

[cubbug]

Re: volvo prop pitch correct?

It depends on what model motor you have. Is that the old AQ series?

My guess is that 4200 is at the low end of the rpm range for that motor and unit. It was probably rated at something like 4200 - 4600. Maybe 4000 - 4400. At any rate, putting on a prop with more pitch may get you slightly more speed but a 15 will cause a loss of about 400 rpm. I don't think that's what you want to do.

 

[cubbug]

Re: volvo prop pitch correct?

Hi. Thanks for the reply. Does this speed sound right @ 22 mph on the gps @ 4400 rpm? You're right, it is an older Volvo 125 H.P. very low time tho. That is a great little motor. 4400 rpm sounds a bit high and it'll keep climbing. Probably 5000 is tops.. It seems to like to run around 4200, but maybe I'm a bit too conservative. Thank you again, Dave

 

[Dhadley]

Re: volvo prop pitch correct?

If it'll go to 5000 then I'd definately try a prop with more pitch. Perhaps we should verify the tach first though. That little motor is tough and will last a while at 5000 but the drive won't like it. Perhaps on the I/O forum someone could look up the correct rpm for the AQ125. I can't remember off the top of my head.