What Is My Optimum RPM?

[Restless22]

I'm trying to figure out the optimum RPM for the best combination of speed and fuel economy.

My boat is a 88' Wellcraft Aruba 232 with a 350 Magnum MPI and Alpha 1 Outdrive. I'm running a 17p SS prop now, and find it comfortable at 3900 RPM and 32 MPH on the GPS. If I increase the throttle up, I'm not really gaining no matter how much I trim up or down.

Also, I guess I'm still not used to the idea of screaming RPMs on the boat. I have a Tahoe with a 350 and I find it comfortable at 2200 RPM, lol. I rarely lead foot that truck, as I tend to be light on my vehicles.

I assume that optimum RPM is supposed to be higher for boat engines?

 

[QC]

Re: What Is My Optimum RPM?

Optimum RPM for a boat is actually moire optimum speed for the hull. The engines suck fuel in boats no matter what. What is your top priority? Fuel? Then that is usually close to where she plains off nice and flat. Often around 3500 RPM. That is not because the engine likes it there, it is because the hull is efficient there. Usually they are pretty close on fuel for the same reason between 300 and 4000. Top speed is wide open and trimmed out. Your engine can run out to 5200 RPM without killing itself.

I am going to move this over to non-repair I/O. We try and keep this section free of engine questions, even though I said this is a hull issue :facepalm: