Hi guys - am considering building a generator using my Kohler Magnum 18 as the power source and then buying a generator head and combining them on a skid. The 18hp is 13.4kw, so I'm guessing 10 to 12 kw is what I can run with it?? IS there anything else I need to know?
Another generator thread
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The general rule of thumb is it will output half the HP rating in KW. Although, as you state above, it's fine to have a gen head that is a bit larger in capacity than needed. Are you planning on a belt drive or direct drive?
One thing that's kind of neat with a well configured belt drive is the ability to run the engine at some RPM lower than 3600. Of course there will be diminished output, but it's often a smoother and quieter setup.
One thing that's kind of neat with a well configured belt drive is the ability to run the engine at some RPM lower than 3600. Of course there will be diminished output, but it's often a smoother and quieter setup.
https://utterpower.com/Yananfaq.htm
Question: How much horse power do I need to produce the full rated output of my generator?
Answer: Use the following continuous ratings. make sure you deduct 3 percent per 1000 feet of elevation for any normally aspirated engine. Example: my Cowiche cabin is at 4500 foot elevation, I should expect to get 8.65 horsepower out of my 10 horsepower engine. another consideration, if you are under running the rpm of an engine, estimate how much horse power it will be making at that RPM. If you direct drive at 1800, and the engines HP rating is at a higher RPM, you must factor what the engine will be making at it's working rpm, and keep your expectations realistic. Remember that elevation thing, and always size up. In the case of the 1115, it is making 20-22 hp at 2200 RPM, if we lower the rpm to 18, we should expect 18.
Size-Horsepower (approximate)
3kw= 6.5
5kw= 12
7.5kw= 15
10kw = 18
12kw = 20
15kw = 23
20kw = 31
30kw = 46
40kw = 60
50kw = 75
Question: How much horse power do I need to produce the full rated output of my generator?
Answer: Use the following continuous ratings. make sure you deduct 3 percent per 1000 feet of elevation for any normally aspirated engine. Example: my Cowiche cabin is at 4500 foot elevation, I should expect to get 8.65 horsepower out of my 10 horsepower engine. another consideration, if you are under running the rpm of an engine, estimate how much horse power it will be making at that RPM. If you direct drive at 1800, and the engines HP rating is at a higher RPM, you must factor what the engine will be making at it's working rpm, and keep your expectations realistic. Remember that elevation thing, and always size up. In the case of the 1115, it is making 20-22 hp at 2200 RPM, if we lower the rpm to 18, we should expect 18.
Size-Horsepower (approximate)
3kw= 6.5
5kw= 12
7.5kw= 15
10kw = 18
12kw = 20
15kw = 23
20kw = 31
30kw = 46
40kw = 60
50kw = 75
How will you get the power out? The most you can generally push through a 14-50 outlet is 50 amps.
The 18hp will burn 1 gallon an hour +.
The 18hp will burn 1 gallon an hour +.
Typically 18hp motor would be good for 9-10k max which at 240v is <50amp
Just making sure you are considering that vs 110v outlets or the 30 amp twist lock. Sounds like you are already planned out.
14-50?
I plan an connecting to the main at the pole (with main disconnect, so I don't back feed the grid) I'll probably use a appropriately sized wire and plug system to allow easy connection to the generator.
Am also wondering what it would take to run this thing off of LP?
An Lp carburetor and a lock off valve, hoses .etc mostly parts and install it is not really hard. There is a slight [W. A. G.] 10% ish Horse power drop when using LP as the fuel.
Gotcha, that's what I meant by how are you getting the power out.
A belt drive intrigues me somewhat - you mention diminished output... Would that be because the engine would be spinning below it's rated RPM or because of parasitic losses from the belt drive, or both? Any way to estimate a new max power output?
Also, can someone help me understand the differences between some of these heads, and why I can buy a whole 10 to 12kw gas powered unit for very similar money? The whole units are all single cylinders that I'm aware of - are they even capable of putting out the power that they're rated for? Are the heads that I've linked just built that much heavier/better?
Generator heads
Ebay generator head
And aside from the obvious differences - belt driven and equipped with plugs, is this one much different?
Northstar generator head
Generator heads
Ebay generator head
And aside from the obvious differences - belt driven and equipped with plugs, is this one much different?
Northstar generator head
I play with this stuff quite a bit. I wish I had better news for you, but generator heads are one of those subjects where there are all sorts of crazy problems.
For example the Chinese ST heads used to be a pretty good value, with copper wire, metal fans and fair bearings. Today, the wires may be aluminum, the fans plastic, and they may not even make rated voltage. You could easily pay $700 for an ST that horribly underperforms an $800 professional generator head.
The Northern Tool head you listed is expensive compared to Chinese units. Chinese copies are available at Harbor Freight. The problem is, you could (IF you are not careful) easily pay "name brand" prices and get a Chinese copy of a Mecc Alte, which brings up another point.
One company that makes good gen heads is Mecc Alte. They make products from small to large, and all are good quality. If you look around enough, you may find the right Mecc Alte for you, for a good price.
Here is one possibility. https://www.absolutegenerators.com/...30-10-2-kw-120-240-volt-single-phase-3600-rpm
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