How does the governor work?

[rickrat]

My stock 83 6.9 in a F-350. First I have heard that the governer kicks in at 3400 no load, and a bit more under load? Is this true? How does it know whether you are under load or not? What is a safe max rpm to run for extended periods?

Thanks!

 

[Agnem]

The govenor is RPM dependent. Doesn't have much to do with load. It has no idea what the engine is doing other than how fast it is spinning and how much your foot is into it, and what kind of fuel presure it sees. These are the only three inputs to the system. The govenor works by compressing a spring, which can only be compressed when the govenor weights are heavy enough to do it, which can only happen at the specified RPM when centripital force creates enough presure to overcome the spring.

 

[FordGuy100]

Under load the engine should turn less rpm's governed than if you were to rev it while in neutral.

 

[argve]

Safe rpm should be anything under gov'nd rpm. At least that is how I ran the Enterprise.... Most diesel engine manufacturers state that the engine can be run at governed speed all day long. Now I will tell you that most of my IDI engines only lasted 2 years and 70k miles... So you may not want to follow my rule...

Now the governer does not care what the load is but if you are rolling down a hill and go to a lower gear it will go above the gov because you are forcing it above the gov reduces the fuel to keep the engine at or below the rpm setting.

Now in neutral as stated it will go above it but only for a split second then will settle right back down this is because you are approaching the magical rpm so quickly that the engine will have enough stored energy that it can slide past it but take away the fuel and it will settle right down to it. But still it will settle right back to the same rpm everytime.

 

[rickrat]

Not sure how accurate my tachometer is, but it registers the high reading, and I have it showing 3450 rpm.