2H EDIC Overfuel as extra fuel for a Turbo under boost?

[BrickRunner]

Background:
The 2H injection pump has 3 fuel positions controled by the EDIC system: shutoff, fuel, and overfuel for starting. Both shutoff and overfuel are spring return the the neutral position fuel. With the EDIC system removed and replaced with a cable to shut down the engine, the overfuel becomes unused.

Questions:
Does the overfuel position make it possible to add more fuel than what is normally available at wide open throttle?

If so, could a pneumatic actuator teed off of boost be attached to the overfuel linkage and used to add extra fuel above a certain boost threshold?
(This is assuming EDIC is removed)

 

[duncanrm]

I've seen a few DIY boost controllers for 2Hs over the years.. JH Hilux in Australia do one. They take the place of the fuel screw. There's nothing special about the overfuel position inside the pump, when the EDIC pulls the Fuel Control Lever back to Overfuel it just allows more rack travel. A macgyvered Boost Controller could certainly provide for that range of movement too.

 

[duncanrm]

JH Hilux..

 

[BrickRunner]

Let's check my understanding.

The fuel screw has a built in spring pin that the rack and fuel lever cannot move on their own. This is the normal rack upper limit. The EDIC overcomes this spring pin when commanded to overfuel, shifting the upper limit and allowing the rack to move this extra distance.

In the case of JH Hilux boost controller, the rack upper limit is set by the boost controller's linkage that pokes through where the now removed fuel screw was (the linkage and therefore limit moving with varying boost pressure).

 

[duncanrm]

Let's check my understanding.

The fuel screw has a built in spring pin that the rack and fuel lever cannot move on their own. This is the normal rack upper limit. The EDIC overcomes this spring pin when commanded to overfuel, shifting the upper limit and allowing the rack to move this extra distance.

In the case of JH Hilux boost controller, the rack upper limit is set by the boost controller's linkage that pokes through where the now removed fuel screw was (the linkage and therefore limit moving with varying boost pressure).

Yes.. the leather diaphragm cannot pull back hard enough to overcome the spring.. only the EDIC has the ability in a stock setup to overcome that spring whilst cranking. My HJ47 only has a stop cable and no EDIC, I have never struggled to start in cold weather (but we're only talking -2degC at most), I really dont think the overfuel function is needed.

Your understanding of the JH Hilux setup matches mine, I havent seen this pump in person though and cant confirm if he might have implemented a spring in there that the EDIC can pull against..

 

[BrickRunner]

Yes.. the leather diaphragm cannot pull back hard enough to overcome the spring.. only the EDIC has the ability in a stock setup to overcome that spring whilst cranking. My HJ47 only has a stop cable and no EDIC, I have never struggled to start in cold weather (but we're only talking -2degC at most), I really dont think the overfuel function is needed.

Your understanding of the JH Hilux setup matches mine, I havent seen this pump in person though and cant confirm if he might have implemented a spring in there that the EDIC can pull against..

Thanks, you are a bundle of knowledge!

The EDIC on mine was long dead and already had a stop cable when I got it. It also starts just fine without the overfuel, but I give it a few notches on the hand throttle until it warms up to smooth out the cold idle.

 

[BrickRunner]

Made my own. It allowed me to crank up the fuel at high rpm while not smoking at low rpm. Highly recommended!
If I were to do it again I would up the bracket a gauge or two and use a larger actuator for more fine tuning.

 

[bj70bc]

you guys are ingenious buggers, wonder if this logic applies to a 3b pump as well

 

[BrickRunner]

you guys are ingenious buggers, wonder if this logic applies to a 3b pump as well

I would think so. I've only seen pictures of the 3B, but the 3B pump looks like a mirrored 2H pump with 2 fewer fuel lines. The governor, fuel screw, and fuel rack lever are very similar if not the same.

 

[duncanrm]

Made my own. It allowed me to crank up the fuel at high rpm while not smoking at low rpm. Highly recommended!
If I were to do it again I would up the bracket a gauge or two and use a larger actuator for more fine tuning.

Superb.. I love your work.

I wish we had SendCutSend in Australia

 

[dirtyham]

 

[silvius]

Made my own. It allowed me to crank up the fuel at high rpm while not smoking at low rpm. Highly recommended!
If I were to do it again I would up the bracket a gauge or two and use a larger actuator for more fine tuning.
View attachment 3728271View attachment 3728272View attachment 3728273View attachment 3728274

Very good work, Can you feel the difference in performance ?

 

[BrickRunner]

Yes! I also have power numbers, though I don't have numbers without the boost compensator. However, if I hold my stop cable in the neutral position, preventing the fuel lever from moving, the loss of power is quite evident. Also, when I let go, I can watch the compensator pull the stop cable in as boost increases.

Max boost @10 psi: