[iowagold]

Let's assume for the moment that we have a main LP regulator that puts out exactly 11 in. WC with an unlimited flow rate potential (ideal).... just to put pipe diameter and other constraints out of the equation.

On the other end of the line is an LP appliance, a generator, that has a demand regulator and with the load block set to sustain the genny up to 100% full load.

Given that the demand regulator responds to engine vacuum (or lack of), does it also work to regulate the flow rate that's fed into the combustion chamber depending on the engine load?

Another way to put it, so if the load block was tuned to sustain the engine at 100% load, there's a certain flow rate associated with it. What happens to the flow rate when the engine ramps down to say, 75% load or 50% load.... does the flow rate:

a) Go down, or
b) Remain constant (as per load block setting)?

The thing I'm getting at is LP fuel consumption. Will a generator consume less LP when it is partially loaded VS fully loaded?

exact parts and part numbers always figure in to the equation.

yes on every thing matters.
every pipe and hose angle and length, hose, pipe and fitting diameter, gas pressure and flow volume , etc.
the demand regulator has orifice inside.
and there are different styles of demand regulators to select from. they all do the basic same thing.
but they have subtle ways of getting to the proper flow. as well as how the flow and flow volume is triggered.
and yes on the demand regulator setup doing the flow regulation to rpm and load.

now here is the kicker.
the fuel system needs to be engineered.
as every thing matters or makes a flow difference.
the whole picture needs to be viewed....
rpm and horsepower and cc's of the engine are all the big things that work in to a mechanical fuel system.

this is why i like the idea of electronic fuel injection.
an engineer sets up the system for narrow and wide band the computer program selects the proper fuel
it is all lambda.... air fuel spark.... and time is a big thing. that is where the computer map does the heavy lifting.
it takes the data from the sensors and calls for the exact mixture required for a perfect run.

for the fuel engineer
a flow bench helps with doing the AFR (air fuel ratio) engineering.
as well as a good grasp with the math ...
it is as close as you are going to get to a live system in the lab.

and yes real world is not the same as the lab.
you have all of the other things as variables like temperature, air pressure including altitude, and then the fuel delivery variables including quality.
that is where EFI (electronic fuel injection) stands above a basic fuel system.

 

[iowagold]

and soooo important that (the signal) or vac on the plate or injection on the carb setup is perfect and responsive.
it needs a good point that is responsive and fast reacting so the demand regulator can do it's thing.

best point is after the venturi on a carb....
just before the throttle plate...
but that is hard to do on some setups...
they have a dandy carb for the gx200 and another for the gx 390...

pm if you need links for those low cost universal setups.

 

[iowagold]

yea....but you get a better signal on the down stream side of the venturi.