So I got in on the us carb deal and outfitted my EUs 2k.

They run just fine but I got to searching the web about propane conversions and found tons of conversions with a simple tube routed into the air intake. Hell one guy duct tapped the hose on


So I had to try it myself on my old lawnmower. Used a propane torch, 3' of tube and a brass hose barbed tapped into the side of the air intake. The torch had the end cut off and threaded 1/8" MIP (previously used for transferring gasoline). I used a hose barb fitting to connect it to the tube.

I already had a gas shutoff and the bowl was dry.

The thing ran great, it actually was better than the US carb snorkle. It cost about 15 dollars all said and done.

It also can go back to gas with a turn of a valve.

just reading/looking on the net it looks like the on demand reg just a safety device that will shut off flow if the engine stops and using it requires the snorkel to get a vacuum. If you are actively using something, then there would be no need for it IMO.

If a genny was running outside at such a low pressure, it would hardly be a hazard especially when you consider you would know when the gen stopped and could turn off the gas.


Any thoughts?

ETA know that I think about it, there are millions of grills around the country that run all the time with a open flame and are fine.

some pics

Gonna do the poor man's propane conversion to my rider mower soon.

Yep, we prime our Honda 2000's when it's real cold by sticking an unlit torch into the intake, and posted abt it here...  


The purpose of the demand regulator is to modulate the flow of propane based on the DEMAND of the vacuum effect derived from the venturi of the intake/carburetor, with variation of load.

[The negative pressure sensed by the snorkel of one popular conversion, and the location of the propane injection point, in others]


[Not unlike the function of the carburetor venturi's and jets in an ordinary carburetor]


Notice how large the diameter of the diaphragm of the demand regulator ---is.


This large diaphragm surface area mechanically amplifies slight variations of engine intake vacuum ---depending on the LOAD requirement of the genny's engine...

And regulates propane flow, to keep the engine running relatively smoothly at a constant speed, and roughly correct mixture [although doubtfully as correct over the entire load range as a gasoline carb] ...

...w/ different loads, in conjunction with any governor that it may be equipped with.




There is no particular safety purpose of the demand regulator, other than being required for correct operation of the conversion.


Good question!  

that's what I figured

my take away is a propane conversion is very simple especially  if rednecks with beer and duct tape can do it

that was my motivation for the propane air chuck/gas transfer/ mod.

you can see in the pics i took a torch, rethreaded it, an now can add whatever I want.

which reminds me, we had a gas tube for all the LP tanks on the farm and we ran impact wrenches with it

Put in a solenoid operated valve on the gas line. Start the gen by manually opening the gas valve. Once started the solenoid is powered by the gen, gen stops valve closes.

I took this thread as a 'field expedient' way of converting to NG/LPG. I have an after market trifuel setup purchased for my gen.

OK,  I'll play.

A grill burns a constant ammount of fuel from lite to when you shut it off.  Its only fuel rate consumption change is manual by an operator using the grill.  A generator  consumes varying ammouts of fuel depending of its startup and warm up conditions and as the load changes.  A fixed flow rate fuel system will not handle these fuel demand changes as well. Additionally speaking to the safety aspects a grill is a simple burn device it is less likely to fail with remaining fuel in the tank.  A generator is more complex and could stall or get overloaded or sustain any number of other faults leaving the generator in a condition where it has remaining fuel and is in an inactive state (now with an open vented fuel supply).

Personally I like the demand regulators for the above reasons however I would definitely keep a modification such as yours in my "bag of tricks"  should the need ever arise in a shtf situation.  Know how to do it but avoid if possible.

+1

Keep in mind that in perfect conditions a 20lb cylinder contains enough fuel to blow city block.

 


Also keep in mind that when you run an engine lean, you increase chances of engine damage. Running lean increases head temps. You want the fuel/air mix as consistent as possible under varying load conditions.




You ever play with a cutting torch? Get a nice flame going then start playing with the oxygen while leaving the fuel alone. As you turn up the oxygen, the flame gets hotter (engine lean). As you turn the oxygen down, the flame gets bigger and colder, and has un-burnt fuel (engine rich). Only at that happy medium do you have a nice flame (proper engine fuel/air mix) that is a combination of medium warm flame, plenty of BTUs with no un-burnt fuel. Your system has the fuel at a fixed point, so the oxygen varies (engine throttle) while the fuel is static.


 

the vented supply would be outside and would be very minimal. We are talking 1/2PSI maybe 5 minutes at most.

I mentioned this in the OP, if your plan is to let it ride then probable a bad mod.

I already addressed the fuel venting issue and a 20lb cylinder has to be perfectly mixed in a non dissipating environment to achieve the result you are dramatically overstating.

I will concede on the fuel air mix, but at a constant use/RPM such as a genny under load, this is negligible. Maybe if you are changing loads all the time and the generator has a touchy throttle it might be a consideration.


BTW all the bubba conversions that Ive looked at have reported the engine running cooler. There are a couple where they have been run for years and show no problems with the setup.

If you havent looked at all the info out there its a eye opener

Propane is heavier than air, not free flowing a 20# tank here.

Engine rpm has little to do with air consumption compared to load. Unless you are using the Genny for steady resistive loads, the cfm of air consumed will vary wildly. As far as the engine running cooler, how are they measuring internal cylinder temps? Or they are running rich. Propane eats up valve seats when converted properly bad enough without running the engine lean.

And I have replaced more than one engine because someonewanted to lean out tthe mix to save fuel.

I don't believe this to be true of gaseous fuels. if fact, they get hotter when running rich due to
the fact that the fuel is still on fire when the valve opens.

If the engine is running rich  -excess fuel, [with INITIALLY liquid OR gaseous fuels...]

And the O2 is depleted BEFORE the exhaust valve opens...

How could the mixture be "still on fire"???

No, the unburnt fuel will tend to carry heat away from the components.


Incidentally, it's a practice with some aircraft engines, to run the engines lean of peak EGT, for cooler operation, better engine life and fuel economy.

Including, the Continental TSIO-520-BE.

sorry duplicate

read here for a simplified reason, page 36
I stand by my original post as I have seen first hand rich vs lean temperatures.

http://www.propane.com/uploadedFiles/Propane/Agriculture/Safety/MaintainingRepairing%20PropaneStationaryEngines.pdf

This? Page 28...

"In general terms, gaseous-fueled engines may run hotter when running rich rather than
when running lean because no liquid fuel is evaporating and producing a cooling effect
inside the combustion chamber. An engine running at stoichiometric to approximately
10% rich will produce more power. Conversely, an engine running leaner than
stoichiometric will improve economy but produce less power."


I agree w/ you in this case.