Changing Gear Ratio in 2004 VP DP

[MAGISTER31]

I have a 2004 Ebbtide with a 5.7 GXI that I bought last summer. The boat was sent from the factory with a 1.78 gear ratio. From all that I understand and have read, this is not the correct gear ratio for this engine. I am turning F4s right now, but the engine has a hard time developing the max WOT even with a light load. I really like the boat and think I would be much happier with it if I got the right gearing.

I have heard that it is possible to swap lowers on the DP unit to change the gear ratio. Is this correct? I wonder if it might be better to swap out just the gears inside the lower casing. Is there any reputable rebuilder that anyone would know here on this board that either would have some rebuilt lowers in stock or that could swap my gearing when I get ready to put it up for the winter?

Thanks for the help.

 

[Don S]

Re: Changing Gear Ratio in 2004 VP DP

Depending on the boat, the 1.78 is what normally comes with that engine, assuming the boat was designed for 45+ mph speeds. For heavier boats designed for speeds up to 45, the 1.95 would be a better choice.

Yes, you can replace just the lower unit to change gear ratio's

Might check these guys. http://www.marinepartsexpress.com/vp_outdrives.htm

 

[MAGISTER31]

Re: Changing Gear Ratio in 2004 VP DP

Thanks Don, I have heard for a heavier boat like mine, the 1.95 would be the way to go. Here is some information I found out tonight on set up (this is from PPTs) web site:

"You always want to go with the highest gear ratio sterndrive & largest propeller. Most boaters think they will get more speed by going with a lower ratio setup because it is closer to 1:1 and therefore will turn the propeller faster. The reality is that the slower turning, larger propeller is more efficient because it yields less slip and therefore more efficiency."