Low RPM's on a 4.3l 190hp mercruiser

[rich757va]

I have a 19' Bayliner. I just replaced the engine and noticed that my RPM's are not as high as the manual says they should be. With my old engine I only ran about 3800-4000 RPM's in WOT. Now with this new engine I am only running about 3400-3500 rpm's in WOT. The engine now has about 10 hrs on it. The motor runs and sounds real smooth. I only run in WOT for a few minutes just to see how fast she runs and how many RPM's she is at. When I test the idle rpm's it seems to sit at about 650 while on the trailer. Sometimes it drops a little when in the water but a little trottle advance and she goes up to about 500-550 rpm's.
Again everthing seems to be running fine just not sure why rpm's in wot are so much lower then the manual (4400-4600 rpm's) says it should be. I have a 14.5 X 19 Prop and I also have a Hydro Foil attached. Not sure if the hydro foil makes a difference but wanted to provide as much info as possible.

Any ideas, suggestions, or comments would be appreciated.

Thanks,
Rich

 

[180shabah]

Re: Low RPM's on a 4.3l 190hp mercruiser

First place to hit would be the stickies at the top of the forum - there is a great write up on "low WOT" Start eliminating what you can from the list, we'll help with the rest...

 

[Vamike757]

Re: Low RPM's on a 4.3l 190hp mercruiser

You are breaking in your new engine according to the manufactures recommendations I hope.

 

[Bondo]

Re: Low RPM's on a 4.3l 190hp mercruiser

I have a 19' Bayliner. I just replaced the engine and noticed that my RPM's are not as high as the manual says they should be. With my old engine I only ran about 3800-4000 RPM's in WOT. Now with this new engine I am only running about 3400-3500 rpm's in WOT. The engine now has about 10 hrs on it. The motor runs and sounds real smooth. I only run in WOT for a few minutes just to see how fast she runs and how many RPM's she is at. When I test the idle rpm's it seems to sit at about 650 while on the trailer. Sometimes it drops a little when in the water but a little trottle advance and she goes up to about 500-550 rpm's.
Again everthing seems to be running fine just not sure why rpm's in wot are so much lower then the manual (4400-4600 rpm's) says it should be. I have a 14.5 X 19 Prop and I also have a Hydro Foil attached. Not sure if the hydro foil makes a difference but wanted to provide as much info as possible.

Any ideas, suggestions, or comments would be appreciated.

Thanks,
Rich

Ayuh,... Read This,....