Hey guys! Got this new 8000watt generator and its kind of loud. Got an idea of building a sound proof box or something.

This is my idea for the box: exterior and interior wall is gonna be some kind of sound proof board, in the middle ill put insulation, and on the inside ill double or triple layer with car deadening material. Obviously ill have exhaust going outside, and an air intake fan. aaaand diamond plate on the outside to make it look nice.

Got any ideas on sound proofing?

 

I would consult the manufacturer. There maybe a heat issue. If it's a gasoline generator, another thought would be to exchange it for propane or natural gas.

 

Move it away from the house.

 

For the heat I would have fans blowing hot air out and cold air in the box. Is propane or natural gas generators quiter?

 

Thats not an option in my situation

 

I think that propane or gas would be quieter. Besides that, when there is a storm, obtaining gasoline can be a problem. Also, with an 8,000 watt generator, why would you waste using some of that power on fans, to cool it?

 

Two fans will use max 90watts and I got a barrel of gas for that thing.

 

Engines and even the generator head produce a tremendous amount of heat. You will need a considerable amount of ventilation to provide enough cool air and I don't think two 90 watt fans will be enough. Small engines are only about 20% efficient so 80% of the fuel you burn is producing heat, not electricity. Much goes out the exhaust but a lot must cool the engine case & cylinder. Don't under estimate the amount of air flow you will need.

Also consider that all that air you must get into and out of the enclosure needs an open path to flow... which is also a path for sound to get out. Some of the sound is from the exhaust like you'd expect and can be helped with a bigger or better muffler system. There is also a lot of noise that exits the carburetor and is transmitted through the engine case (the cylinder firing, valves slamming shut...). Basically it's very difficult to quiet an air cooled engine much.

Your sound deadening will help if you provide enough cooling air flow but just don't expect miracles. I would not expend a great amount of effort or money. If you want a quiet generator I would pay for it up front and buy a quieter generator.

 

Thats exactly my point. Expensive generator like Honda or Yamaha all have closed boxes, how come they dont over heat? They dont have a cooling fluid cooling the engine like in cars, therefore they are also air cooled. Generator that im looking at right now has honda engine gx390, and should be quieter than most OHV engines, but its not enclosed.

I agree with you on the muffler part, ill definitely get a car muffler or something to kill that noise.
About the fan part, as long as hot air coming out and cold air coming in its all good. Its a small box to ventilate not a warehouse

I just wanna know what kind of materials would be best for sound deadening/absorption/killing etc ?

 

How far away are your neighbors? Distance is the cheapest and easiest ways to make it quieter.

Long ago I had the noisiest generator ever made. You had to wear ear plugs to approach within 20 feet of it. I removed the tiny tuna can muffler and attached a small car muffler. That greatly reduced the exhaust noise but there still was an extreme amount of valve noise coming through the engine case and intake. When needed I moved the generator out into the yard as far as I could and dry stacked cement blocks around it creating walls. I ran them up to about two blocks above the generator and left the top open. This shot most of the sound straight up so it was noticeably quieter off to the sides.

Another option that I saw a hunting lodge was a simple plywood box with four sides; three sides and a top. The box was big enough to allow a good deal of room around the generator for cooling and one side was left completely open and aimed away from the lodge. For something so simple it did a very good job of reducing the higher frequency sounds and when you walked around to the open side it was easy to tell it was doing it's job. The box could be tipped over to have easy access to the top of the generator for refueling.

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Even Honda, Yamaha and other premium work site type generators can be pretty loud. I think they are better than most less expensive units but still in the loud category. If you can afford an inverter style it will most likely be the quietest and most fuel efficient.

I have a Honda EU3000i and a couple EU2000i inverter style generators that come packaged in their own enclosures and they are very quiet. Boy do you pay for it but they are really quiet and have a magical ability to run forever on a tank of gas. When you open them up you can see that they put a lot of work into making them quiet. Big expansion, multi-chamber mufflers (I think). Special fan on they flywheel and ducting for cooling. They don't blow the air around willy-nilly. It's sent exactly where it's needed I assume under pretty good pressure. Serpentine air paths in and out. Everything inside attached with rubber shock absorbing mounts. Electronically controlled throttle so the engine runs at the lowest possible speed to produce the required power. Heavy plastic or steel outer housing lined with dense open cell foam. Case openings and access panels are sealed with foam gaskets and a layer of hundred dollar bills glued over every surface to help justify the cost.

 

Thank you very much for your suggestions! It really helped.
I would love to get a honda inverter generator but dont wanna pay so much money ( unless i win the lottery haha).

So far im thinking of building a 1m by 1m by 1m box with Roxul sound and safe insulation in the walls and some kind of sound absorbing board on outside and inside. For ventilation im thinking of putting two very good inline fans (100CFM - cubic feet per minute) that will take care of taking hot air out and cold air in for sure. Also a thermostat inside so i can see the temperature.

Im thinking it will work because we are talking about a pretty small engine (only 389cc) and it doesnt produce much heat compared to car engines and the inline fans at 100CFM will be more than enough to help with temperature control. Gonna start building this weekend, ill put pictures when done.

By the way, where are the cooling elements in your honda pointed to? maybe i could direct air to that location in my box set up.

 

I know that you are going to do what you are going to do regardless of the advice offered here but I can guarantee that two 100CFM fans won't keep the interior of that box cool. You would be better off by building a maze, lined with the Roxul S&S or AFF insulation on both the inlet and the outlet of the airflow and then using a 20 inch box fan to blow the air into the box. No need to add anything to the face of the Roxul as it would decrease the efficacy of the Roxul in attenuating the noise.