7.4 Optimum RPMs?

[Knot Waiting]

I just purchased a Sea Ray 260ov with a 7.4 Mag turning a Bravo 1. Seems like she runs a good cruising speed at 4000 rpms. Does that sound about right? My old boat (23' 5.7 Alpha 1) would cruise at around 2500-3000. I dont want to damage or over-rev the engine. Thanks

 

[HT32BSX115]

Re: 7.4 Optimum RPMs?

I just purchased a Sea Ray 260ov with a 7.4 Mag turning a Bravo 1. Seems like she runs a good cruising speed at 4000 rpms. Does that sound about right? My old boat (23' 5.7 Alpha 1) would cruise at around 2500-3000. I dont want to damage or over-rev the engine. Thanks

Howdy,

Depending on the model (carbed/EFI) and year model, they usually have a 4600 or 5000 max RPM (I think the MAG MPI engine is rev limited at 5100)

Mine is a 1997 model with the Thunderbolt V ignition. It's rev-limited at 4700. My boat is 21ft long and weighs about 4500 lbs (boat and engine/drive)

It "cruises" nicely at 3000 RPM and 30 MPH and is flowing 10 GPH at that speed. (3.0 mpg)


What RPM does it turn at WOT? If it's turning right at 5000 RPM, you're probably propped "just right".


Regards,


Rick

 

[Don S]

Re: 7.4 Optimum RPMs?

Your 91 454 Mag has a WOT rpm of 4600 to 5000 rpm according to the OEM service manual.

 

[Knot Waiting]

Re: 7.4 Optimum RPMs?

Thanks guys. With that info it sounds like I have nothing to worry about. I just have a few new boat jitters I'm working to smooth out.

 

[rschap1]

Re: 7.4 Optimum RPMs?

There should be a tag on the valve cover stating max rpm.
And there are different big blocks.
Mag motors can rev a few hundred rpms higher than base 7.4s.
I had a 1995 7.4 with Bravo III. It ran up over 5,200 rpms once.
It hit the rev limiter in the ignition. Sounds like a miss in the engine.
It was a freak thing for my boat and only once did it ever hit the limiter.
But, the decals on the motor should tell you if they are still there and legible.