WOT speed and RPM specs, 3.0L GS

[Glastron175]

I finally have my Glastron 175SF with 3.0L Volvo Penta engine running smoothly. I now wonder if it performs as it should. At WOT it is running 4600 RPM and 36MPH. I also have a new 19 pitch 3 blade prop on it. Does anyone know if this sounds about right?

 

[Don S]

Re: WOT speed and RPM specs, 3.0L GS

Here is a list of 3.0GS models put out by Volvo, which one do you have.

 

[Glastron175]

Re: WOT speed and RPM specs, 3.0L GS

Don, I have the 3.0GSMEFS.

 

[honeys money]

Re: WOT speed and RPM specs, 3.0L GS

Gee, should run about 40 to 45 Mph, at 4,500 to 5,000 RPM.

 

[Glastron175]

Re: WOT speed and RPM specs, 3.0L GS

Yeah, I was thinking it was a little low. By the way, I have a 14.5 inch 19 pitch prop. Is this what you have?

 

[Maclin]

Re: WOT speed and RPM specs, 3.0L GS

The drive ratio makes a big difference in what speed you get from any given prop. With 15% slip factored in your drive ratio calcs to about 2.0

With a 21 pitch prop you would get 38mph if the same rpm can be reached. The higher the pitch the more HP you need to hit the same rpm.

To be accurate in any prop calculations though, you need to know the drive ratio, accurate speed and accurate rpm achieved at WOT.

Here is a link to a basic prop calculator....:
http://www.rbbi.com/folders/prop/propcalc.htm

 

[Glastron175]

Re: WOT speed and RPM specs, 3.0L GS

Thanks Maclin. I guess my real question is whether my RPM should be higher with this engine.

 

[Don S]

Re: WOT speed and RPM specs, 3.0L GS

4200 to 4600 is the specs for your engine according to the service manual.