Suzuki DF140 Twins - Highest safe operating RPM?

[ShawnQ]

Hey guys,

Boat in question: World Cat 230SF
Power: Twin Suzuki DF140's

I read through the manual and it basically says the highest operating RPM on these engines should be between 5600-6200RPM, depending on your prop. It did not say what the safe 'cruising' range is.

I wouldn't think it would be safe to hold your engines at 6200RPM for extended periods. Or am I wrong....?

In other words, if I am blessed with smooth seas and can 'open her up', what would be the highest/safest crusing RPM? Anything below 6200?

This may be an hour or more of cruising...depending on how far offshore we run.

Thanks in advance,
Shawn

 

[WillH]

Re: Suzuki DF140 Twins - Highest safe operating RPM?

I have a 2003 DF140 on a 20 ft bay boat. I run it at 4500 rpms. I'm not a pro on this topic but it seems your constant rpm range is kind of high. If I were you, I think I would talk to a Suzuki rep so you can get a straight answer. Good luck

 

[JB]

Re: Suzuki DF140 Twins - Highest safe operating RPM?

The "operating range" is to guide you in prop selection. You need a prop that will allow up to 6200rpm but not more at full throttle. That has the effect of selecting the ideal "gear ratio" for the engine as you would in a car.

I doubt that the fuel consumption at 6200rpm is very friendly compared to, say, 4500rpm, but it is safe to run it there for brief periods, at least. I have seen badly underpropped DF140s turn 6500 or whatever the governed top rpm is.

I cruised my DF70 at 3,500-4,500rpm and once in a while ran it up to the "operating range" max of 5,800rpm.

 

[Silvertip]

Re: Suzuki DF140 Twins - Highest safe operating RPM?

The sweet spot for the 40 Suzy on my pontoon is 4500 - 4800. It is proped perfectly to run 5800 at WOT. I only run WOT to get away from approachng weather. The difference in fuel consumption is significant but the difference in speed is not. Besides, I'm retired and I don't have to be in a hurry.