Old Cummins Pyrometer and Jake Brake Questions

The higher the rpms the more effective your Jakes works.
Also the fan uses 30 to 40 hp and that can be used as another stage of the Jakes.
The most effective range for most engines seems to be 1750 to 2150 rpm.

 

Depends where the pyrometer probe is, before or after the turbo. Before 1200, after 900. The Jake’s I use to run them around 1800, 2000 is fine but I would still stick around 1800

 

By golly, I don't remember. Seems like 1,000,-1200 is what most call for, but with a Cummins, I'd downshift before that. Not good to run a Cummins hot. Didn't seem to hurt the Mack I drove, however. Volvo/Mack shows a pyrometer with an 1100 "red line". Not sure what you mean with "continuous operation" of a Jake. I think what you may mean, is turn the Jake on or off when you need it, or leave it on all the time. I think a Jake will work all the way down to idle. The Jake should be okay right up to the governor. Just don't kill the motor with the Jake on, I heard.

 

I go down a lot of steep hills around CO an NM and i usally start at second stage and around whatever is five under for speed . ( speed limit is 60 , stage 2 holds at around 17-18 for a light load -10th gear , on full loads 50-55 , max on jakes and 10 or maybe 9 , depending on traffic and such . Been awhile since i had a pyro , but like was written by you and other 975 -1000 was about max

 

That's a good question, so in other words, can you over rev the motor with the Jake on, I actually don't know . I always selected a gear that I knew the engine brake would hold, I guess if the truck begins to "run away", you have no choice but to melt the brakes. It may take you down to 15 mph for the Jake to hold steady at say 1900 rpms. I never over revved a diesel on a downgrade.

 

I personally don’t like the rpm to creep higher than 2-2100. Once you start getting over 2500 you start getting into valve float territory.

 

With a big cam 3 the range is 1750 to 2100, same as your power band for pulling. And the higher the better.