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-   -   Generator Propane Conversion (https://ecomodder.com/forum/showthread.php/generator-propane-conversion-35628.html)

Stubby79 09-14-2017 02:11 PM

Generator Propane Conversion
 
3 Attachment(s)
Thought I'd show my recent experince with one of these guys:

http://ecomodder.com/forum/attachmen...1&d=1505411023

Available on ebay for a whopping $25.

I wasn't expecting much. Oh, I was hopeful, but still...I hate gasoline and carburetors! So for $25, I had to know.

It was a direct fit for my cheap chinese generator. Swaps directly in place of the old carb, and is identical to the old carb, except for the additional propane delivery stuff and the aluminum float bowl:

http://ecomodder.com/forum/attachmen...1&d=1505411040

It runs on low pressure - after some research, it turns out to be the same pressure range that BBQ regulators put out. (about half a psi) So I salvaged a regulator from a trashed BBQ:

http://ecomodder.com/forum/attachmen...1&d=1505411049

https://www.youtube.com/watch?v=O2hNb6PLXOw

It works! :eek: Even with a decent load on it -- not a hiccough! Not bad for $25! I'm thrilled! :D

(Ok, so starting it takes some finesse, but once you work that out, it's pretty easy to do again)

Disclamer: For demonstration purposes only.
I am in no way suggesting anyone else does this, nor am I in any way responsible if you blow yourself up, burn down your house, or suffocate yourself. Nor do I care if your engine runs lean and burns a hole through the piston. If you chose to do this, you are responsible for your own decisions. Heck, man up and start being responsible for all your other decisions while you're at it!!!! :mad:

Hersbird 09-14-2017 06:29 PM

I wonder if I could put that on my Honda 55 and run those little disposable propane bottles. They are only about 1/4 gallon though, and I would refill them myself. I suppose I could just put a 20# cylinder on the back rack but that's too much.

I didn't realize they have gotten that inexpensive. Thanks!

oil pan 4 09-14-2017 07:09 PM

A 1lb propane bottle holds about 10,000btu, or about as much energy as 10 ounces of gasoline.
A 20lb propane tank only holds about as much energy as 3 gallons of gasoline, but costs 3 times aa much.

Hersbird 09-14-2017 11:09 PM

Quote:

Originally Posted by oil pan 4 (Post 549933)
A 1lb propane bottle holds about 10,000btu, or about as much energy as 10 ounces of gasoline.
A 20lb propane tank only holds about as much energy as 3 gallons of gasoline, but costs 3 times aa much.

Factory tank is 1.6 gallons, it would just be cool, maybe I could run it around the house that way as well LOL!

Actually I think these are dual fuel so I could have extra range as well as refill from the big tanks on my camper.

Stubby79 09-15-2017 01:48 AM

Quote:

Originally Posted by oil pan 4 (Post 549933)
A 20lb propane tank only holds about as much energy as 3 gallons of gasoline, but costs 3 times aa much.

Ahh, well...not here, not when you fill it at Costco. It costs literally half as much per liter as it costs for gasoline. So I'm still "in the black", even with only 3/4 the energy content. (This was a major reason for wanting to do this...I'd stick to gasoline if it was equal or more)

Stubby79 09-15-2017 01:52 AM

Quote:

Originally Posted by Hersbird (Post 549952)
Factory tank is 1.6 gallons, it would just be cool, maybe I could run it around the house that way as well LOL!

Actually I think these are dual fuel so I could have extra range as well as refill from the big tanks on my camper.

Even though propane burns cleaner, it's still not safe to run in an enclosed space. Even if it does run cleaner, you'll still have carbon monoxide to deal with.

And, yes, they're dual fuel. It can still run on gasoline.

oil pan 4 09-15-2017 02:08 AM

My small generator has a 7 gallon tank then I added another 4 gallon tank on top of it, the the big generator has a 16 gallon tank.
The big one uses 1.6 gallons per hour at half load.

The 3x gasoline prices is if you use swapped out 20lb tanks. Bulk propane would be cheaper.

Stubby79 09-15-2017 03:19 AM

Quote:

Originally Posted by oil pan 4 (Post 549956)
My small generator has a 7 gallon tank then I added another 4 gallon tank on top of it, the the big generator has a 16 gallon tank.
The big one uses 1.6 gallons per hour at half load.

The 3x gasoline prices is if you use swapped out 20lb tanks. Bulk propane would be cheaper.

You're absolutely right about swap-tanks costing too much. And having to get my tank refilled means going out of the way; I probably wouldn't want to keep messing around if I had to do it very often.

On the other hand, since I don't use my power equipment much, it's nice not having to put up with gas going off and/or it wrecking the carb when I forget/can't be bothered to drain it every time between uses. I'm stoked with the idea of not having to mess around for an hour to get my power equipment started each time I go to use it.

oil pan 4 09-15-2017 05:21 AM

Why do they take an hour to start?

Stubby79 09-15-2017 10:10 AM

Quote:

Originally Posted by oil pan 4 (Post 549967)
Why do they take an hour to start?

Because even fuel stabilizer has it's limits and doesn't necessarily stop a carburetor from getting gunked up.

Someone suggested it might be the ethanol in gas these days.

Then again, I let my Miata sit (sheltered, mind you) with fuel stabilizer, and it started right up. Again showing me that me and carburetors don't get along.

oil pan 4 09-15-2017 06:09 PM

Must be the ethanol in the gas, my stuff starts right up.

Stubby79 09-15-2017 09:54 PM

Quote:

Originally Posted by oil pan 4 (Post 550012)
Must be the ethanol in the gas, my stuff starts right up.

After how long sitting unused?

roosterk0031 09-15-2017 11:02 PM

Explain hard to start, I haven't started my generator in 5 years+, if I try I have to run it dry with stabil like I did last time, so haven't even tried. I should tomorrow, the day I bought it, it wouldn't even start without cleaning the carb. I like the idea of switching it to propane just for that reason, and propane doesn't get old.

Stubby79 10-09-2017 04:48 PM

Conversion #2
 
https://www.youtube.com/watch?v=bFX0gpjqNrc

Did another one. :thumbup:

Somehow very satisfying. Now I want to strap an engine to just about anything I can get my hands on. :D

I probably mentioned it already, but don't use the choke when starting up on propane. Just push the "power button" to give it a blast of propane and leave the choke turned completely off. If you don't, it will fire once and choke immediately. That would suck to figure out without an electric start. (you'd think I'd have remembered that from last time)

oil pan 4 10-09-2017 06:10 PM

I don't have any problem starting stuff that has been sitting up to a year. A few things will start right up after 2 or 3 years like my echo saw.

Stubby79 11-27-2017 03:04 PM

10 Attachment(s)
Converted my pressure washer over. Will take more shots of the finished product, once it's all together. Just have to finish the propane bottle mount.

I couldn't easily use the "Mitsubishi" engine that was on the pressure washer - it isn't a direct knock-off of a Honda GX, so the propane carb wouldn't just bolt on. I chose to swap out the engine with a used chinese clone I had sitting on the shelf, collecting dust. Had to fix the keyway on the crank shaft first(welded it and made it round again). It mounted the same, but was a tight fit with the propane carb. Wound up modifying how the propane mixer(?) mounted, so it would fit and be accessible:

http://ecomodder.com/forum/attachmen...1&d=1511864638


I got really curious about how these things work, so I pulled the one off my bigger engine and mucked around with it.

There are two hoses going to the mixer. I figured one was for delivery, and one was for vacuum. I was wrong! We'll get to that in a minute...

Looking through the carb, there's an extra port:
http://ecomodder.com/forum/attachment.php?attachmentid=23043&stc=1&d=15118646 47[/IMG]
Strangely, it's just before the venturi. The far end of the port is right before or right at the start of the venturi, unlike the port for the gasoline, which is right in the middle of it.

Initially this made sense, if the mixer metered propane based on the vacuum it would pick up from the other hose on the bottom of the float bowl; it would just be there to deliver the fuel, which is under (minor) pressure...so it wouldn't need vacuum to suck it through.

Delivery port, on the outside. Not much to say here at the moment:
http://ecomodder.com/forum/attachmen...1&d=1511864656

Looking at it from the back:
http://ecomodder.com/forum/attachmen...1&d=1511864676

Yellow: The gasoline shut-off solenoid; does not affect propane use.
Lower Yellow(my bad, didn't change color): Low-pressure Propane/natural gas intake port.
Blue: Propane delivery pipe.
Red: The second hose.

Following the second hose to where it connects to the mixer, there's a big screw on the other side:
http://ecomodder.com/forum/attachmen...1&d=1511864686

Figuring the second hose needed vacuum on it to make the mixer deliver propane, I put a bit of vacuum on it...and nothing happened. It held the vacuum, nice and tight...put it back up, took off the screw...yup, it goes to the float bowl alright. But there's no openings in the inside where the hose connects to the mixer...

It's just a drain screw!! Make sense, since the other drain screw on the float bowl is hard to get at with the mixer in the way. Convenient. I'm surprised they bothered.

That threw my theory out the window.

Turns out, it's all up to there being vacuum on that port by the venturi. Put just pressure on the mixer's intake port...nothing flows. (that's good - safe) Put just the tiniest bit of vacuum on the delivery hose, and propane flows. That's it.

Metering must be dependent on how much vacuum there is on that brass port, which presumably needs to be a specific size to get the mix right.

There's also the propane/natural gas selection switch(red), which has two different size orifices through it(green):
http://ecomodder.com/forum/attachmen...1&d=1511864698

Compared to this:
http://ecomodder.com/forum/attachmen...1&d=1511864706

Why? Density of the two different gasses might have something to do with it, but mostly because they are delivered at different pressures. ~0.5 PSI for propane, and ~0.25 PSI for natural gas.

So, to summarize how it presumably works...vacuum is created as the air flows past the port/venturi, which in turn activates the mixer, allowing propane to flow. The stronger the vacuum, the more propane is let flow. No vacuum, no flow.

Hence why you have to shut off the choke completely to run it on propane...it will "flood" instantly. With the combustion chamber filled with propane, completely starved of air, it isn't going to fire!

And also hence why starting it with an electric start is effortless(gets steady vacuum going, so propane will flow), and pull-start is best done by forcing it to deliver a bit of propane first(by pushing the button in the middle of the mixer for a moment).

...All this was because I wanted to figure out if I could adapt it to work on other carbs and such. I think I could, with some careful planning.


Alright. Now, from some reading, it seems that you want to advance your timing when running propane, because it burns slower than gasoline, supposedly. If you don't, you risk burning your exhaust valve. Makes sense...I'd better see about advancing the timing on these small engines.

More reading said the opposite...yes, more advance than gasoline at low RPM, but less at higher RPM.

Sooooo....Which is it?

Well, what few charts for timing I could find for propane show to stop it around 25 degrees, while gasoline can continue to be advanced further(and further yet if you run high octane), as RPMs rise.

Well, my RPMs aren't going to rise, so that's a moot point. And 25 degrees is, apparently, the more common ignition timing for these GX clones(Honda runs 20 and 25 on the GX200 and GX160, respectively, but the clones tend towards the higher of the two in spite of displacement). I should be where I need it to be already.

So...screw it. Maybe it'll run rich, or the timing is too retarded(it certainly is!) and I'll burn the exhaust valve. Maybe it run lean and melt my piston. Maybe it won't do either. The heck with it. I only paid $35 for the engine anyway; it can be my guinea pig. I'll find out on it before I find out (The hard way) on my generator.

So, I figure the spark plug should tell me a bit about how things are inside. I'd only run the pressure washer for a minute or so, but it ran like a champ and worked hard while it was on.

Propane pressure washer spark plug, Honda clone:
http://ecomodder.com/forum/attachmen...1&d=1511810515

Nice and clean! But not crazy/too hot clean(white). Running on propane cleaned it up. I don't have a before shot, but I have a couple of shots from similar engines that were running on gasoline:

An actual Honda:
http://ecomodder.com/forum/attachmen...1&d=1511810530

And the Mitsubishi:
http://ecomodder.com/forum/attachmen...1&d=1511810538

Now, to be fair, the Honda was probably run with no real load on it last time it ran, and probably didn't get up to operating temperature, which might have a lot to do with it looking rich. The mitsibushi on the other hand was used in the exact same circumstances as the propane, and was fully warmed up, so it has a similar disposition. But while the electrode is about as clean, there's notably chunkier carbon around the rest of it.

There's barely enough carbon around the base of the propane's spark plug to leave a mark on your finger. And the story is the same inside the exhaust port on the engine, and on the exhaust valve...no "chunky" carbon. This engine was "well used", but looking at the carbon on/in it, after running propane, it looks almost new. (I also ran it in my shop with just the window open, and it didn't noticeably haze up the air with it's exhaust). Presumably it isn't running remotely rich, or there would be more soot/carbon.

Now I just need to come up with an excuse to use it. What should I turn in to my first victim? :p

freebeard 11-27-2017 04:39 PM

Internet says: Clean all the things!

Stubby79 11-28-2017 02:42 AM

Where did my pics go? :confused:

Re-uploaded them. Dunno wtf is going on.

Stubby79 11-30-2017 01:19 PM

1 Attachment(s)
http://ecomodder.com/forum/attachmen...1&d=1512065930


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