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oil pan 4 01-29-2014 02:33 AM

Ecomod gasoline generator
I got my $50 CL generator up and running really good. Its an old coleman 1875 watt generator on an old horizontal briggs 5hp.
I need 2 settings, a fuel saver mode and a power mode.
The power mode runs a cold air intake, and sets the generator to 63Hz and runs up to 125v. The power mode runs air compressors or welders.
The fuel saver setting I turn the generator down to about 50Hz which produces a little over 100v that can be boosted up to 120v with a varrac, that will run most gadgets that put a light load on the machine, charge power inverter batteries, stuff like that.
I think a warm air intake might help some. The generator will be out side and I will most likely need to run economy mode in winter during unexpected power outages.
EGR will be useless with out a way to advance the timing.
Then in power mode when I have to fire up the welder.

I also want to add a nice up sweeping straight pipe exhaust that I can add a muffler to. The straight up exhaust will blow poisonous CO up and away from people and the house. I need to figure out the best length to make the pipe. 2 or 3 feet will be no problem. More of a safety and power mod, not so much an economy mod.

Cobb 01-29-2014 07:58 AM


Most eco minded generators use a dc to ac converter and an electronically controlled throttle that ramps the engine rpms up and down as needed depending on the load. Since the output is done electronically the hz is the same regardles of rpms. Think of it as the gas motor is driving an alternator and that is powering an inverter.

The engine mods do the same across the board. Most small engines the exhaust is the most restrictive part because of the spark arrestor, noise damepning. The timing can be advanced by use of different keyways and some ignitions have some wiggle room to rotate the housing some as well as positioning of the magnetio to the flywheel.

You can also shave the block and or cylinder head to up the cr.

Daox 01-29-2014 01:13 PM

Interesting project. How do you plan on monitoring fuel efficiency and if your mods are doing any good?

oil pan 4 01-29-2014 01:19 PM

To monitor fe I will use a kill-a-watt meter, timer and filling the gas tank all the way up.

Daox 01-29-2014 01:20 PM

Do you have outtages that often? Gas would go bad long before I needed to use it here.

P-hack 01-29-2014 01:58 PM

I guess that is a fair point, I mean if the most you save is a couple gallons/year then how much tinkering is that worth? You might want to measure current gph at high load and again at low load for starters and see what the potential return is (with a small graduated tank presumably). You need some benchmarks. Serious gains might be rather involved (i.e. fuel injection, electronic ignition, custom ECU (arduino can handle it), egr and throttle solenoids, etc).

oil pan 4 01-29-2014 02:06 PM

The main use will be powering the welder or air compressor in remote areas.
Plan is to normally keep it set up for high power use.

To keep the gas from going bad I use ethanol free gas with a little bit of 2 stroke oil.
For most outages I hope to just use power inverters. Only going to fire up the generator to cool down deep freezer and fridge and recharge inverter battery packs.

P-hack 01-29-2014 02:14 PM

I picked up a small 3hp generator at a garage sale for $35. If this 5hp is your bread and butter, you might want to leave it be (and be able to run the fridge while you are on the job leaving the 3hp @ home), might even get the smaller one to run on natural gas.

arcosine 01-29-2014 02:46 PM

You could lean out the mixture screw for eco mode, make the spark gap bigger, and put on a hot air intake. As long as it doesn't bog. Not much you can do with timing except make the point gap wider. Maybe thinner weight synthetic oil.

oil pan 4 01-29-2014 03:50 PM

The carb has fixed jets, there is an idle mixture screw. But since it idles at 3600rpm I dont think it will have much effect.
I will widen the spark gap, good idea. I forgot about that.

I will pick up bigger a diesel generator at some point. I have a requirement for 220v power that isnt currenty being met by my little 5hp gasoline unit.
Next one will have to put out at least 6kw.

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