Downhill Jake MPG

Out of gear, no jake, no accelerator. Hang on and enjoy the fuel savings and the ride !!


Do NOT try this . It was simply a bad attempt at a little humor today !!

 

Anytime the Jake is on, you're in a zero fueling situation. Going downhill no Jake, you may or may not be in a zero fueling situation depending on the grade. Light accelerator, you are giving it fuel.

 

For myself, always in gear, engine brakes only when needed and absolutely zero accel. That is what works best for me even though my service manual says light throttle one to three mph can help to improve fuel milage.

 

The black stuff out the pipes is fuel being partially burned.

 

Study up on how a Jake works, and you'll understand. The noise comes from the compressed air being rapidly released from the cylinder. When coasting whether the Jake is on or not you are in a zero fueling state.

 

Pretty certain that the electronic readout in my cab will show '0.0 gal per hour' fuel consumed when engine braking.

Guess I haven't noticed what it reads when rolling with no throttle/no e-brake, but I will assume that would be '0' also since the driveline is still turning the engine, just no extra braking effect. Don't look at that sensor value very often.

Noise produced when e-braking is the engine being turned by the wheels throught the drivetrain as well and the e-braking (compression release).

Rolling but in neutral would cause the engine to have to idle which is burning fuel at a rate of up to 1.0 gal per hour.

Highside is correct by me.

 

Some engines put out a small amount of fuel while coasting, I know my old Volvo didn't. Jaking or coasting = no fuel = infinity MPG.