[ 3 / biz / cgl / ck / diy / fa / ic / jp / lit / sci / vr / vt ] [ index / top / reports ] [ become a patron ] [ status ]
2023-11: Warosu is now out of extended maintenance.

/diy/ - Do It Yourself

View post   
File: 1000 KB, 1024x768, 456714-mwc_wp1_1024.jpg [View same] [iqdb] [saucenao] [google]
851120 No.851120 [Reply] [Original]

Hey /DIY/ I need some info or a link to some info. I want to convert a small sub 20 HP engine to Natural gas and use it to drive a alternator. I will likely use pulleys to increase the speed of it so it can operate at a lower RPM. I'd like to run the engine at less than 800 rpm or so and run it 2400 rpm. The slower it goes the longer it will last. The engine will likely be used weekly for 10-20 hours a week. Maybe more in the summer. I will use it to charge a battery bank on my solar system. I want to run a small AC unit. With losses I would need the alternator to put out around 1000 watts. Just an idea for now, I am looking at property with free NG. I want to leverage it for all its worth.

>> No.851144

>>851120
Running it slower and gearing up won't work... You'll lug the engine and make it wrear out faster.

Get the literature on the engine and determine the rpm of either peak torque or peak efficiency. Would guess around 2500-3000 rpm.

Nat gas carbs are simple but I don't know anything about them.

>> No.851148

>>851144
Thats why i plan on over sizing the engine. It won't be doing anything else. The plan is to have the idle speed low in a large engine with enough torque to drive the alternator easily. NG is free so gas efficiency is irrelevant. Is 80 amps going to be a strain on a 15-20 HP engine?

>> No.851207

>>851148
Well, assuming that's @ 120V, 80A is around 9600 W. Or, 13 HP. So yes, it will.

You don't seem to have a firm grasp on how IC engines work. They're not meant to develop power, or turn anything, at near-idle speeds. If you've ever driven a car with a clutch, this would be intuitive. A fixed engine like that works best operated at design speed that maximizes torque, or power with respect to fuel consumption. Even if you hooked a V8 up to it you wouldn't run it at 800 RPM, you'd run it around 1200-1500, for the simple reason that they're not designed to run at near idle speeds for long periods of time.... hard on oiling system, cooling system.

>> No.851208

>>851120
>The slower it goes the longer it will last.
This statement is incorrect. It's correct in that an engine run at 3000 RPM will last longer than one at 4000 RPM (assuming it's designed for those speeds), but in your case, you're running it too close to idle speeds at 800 RPM.

>> No.851215

Presuming your in a 60 hz country 1800 rpm.

Like the other anon says a vehicle engine is designed very differently to a well head engine.

Not the flywheel size and cylinder length in vid related.

https://www.youtube.com/watch?v=mTaP-C1-fZk

>> No.851216

>>851215
>1800 rpm
And that is for a 4 pole alternator.

>> No.851310

>>851215
Now that is an engine designed to run at low rpm. Max speed is probably 800 rpm and idle 60.

>> No.851433

>>851207
12 volts, just the alternator.
>>851215
Looks like a lister, thought about it but I can't afford the cost. I just want to build a dc generator. I want it to last as long as possible on NG. I dont really need AC since my inverter does that already and DC requires a lot less regulation and cost.