Generator sound box

[skihor]

I just got a 16K propane generator. Honda 690 CC twin powered. 3600 RPM. Specs said 74 DB. WOW this thing is LOUD. Advantage: $3100 shipped, (brand new).
It's going to power our Food Concession trailer, and yes I need every bit of the 16K. Anyway, in my research I've read that you need to put air IN for cooling with holes to let air out. And to put that air in at the top with the outlets at the bottom. This seems completely backwards to me.I would think you would put aux. air in the bottom with "exhaust/escape" holes at the top. I intend to "baffle" all inlet/outlet holes. Of course this project is on a tight budget. I'm thinking of a single box as opposed to a double or triple box setup. I've identified a soundproofing product 2" with a burn point of 1200*F. http://www.ebay.com/itm/Auralex-2-Mineral-Fiber-Insulation-Soundproofing-NEW-/270324958012?pt=LH_DefaultDomain_0&hash=item3ef09f833c
Any help is appreciated.

Don & Sheila

[chev49]

if i had something like that, i would install a blower to run at same time a gen set... did that 25 yrs ago when all i had was a contractor generator...it was noisy even in the box....

[TomC]

Yes your genset has a Honda engine (which is good)-but who made the generator head?  It sounds like you're going to put major hours on the genset.  After you run the genset and wear it out, I'm quite sure you'll want to invest in a Diesel genset.  Advantages-very reliable, much lower fuel burn, and being liquid cooled, can be made to be just about silent running. A contractor type genset like you have will become tiring listening to its' busy (3600rpm) drone all day long.

While I'm sure you'll get a few thousand hours out of your genset (in the neighborhood of 4-5000hrs) before it is worn out, I have a friend that had a 8kw Kubota (1800rpm) Diesel genset on his big rig truck that had over 24,000hrs (that's like running for nearly 3yrs continuously) on it when he sold the truck, and was still running without burning oil.  Good Luck, TomC

[gus]

I have a 6KW Honda gas liquid cooled genset which is both quiet and vibration free and is installed in a plywood box with dry fireproof lining from EHP. It is mounted on a 3/16" steel base bolted to a slide so that the complete box and genset pulls out inside two channel iron guides. The bus genset compartment is completely open at the bottom

My Honda is designed to blow hot air out the bottom which helps cool the exhaust.

It is also designed to be inside a box with a surprisingly  small front cooling air opening of a specific minimum size. The bottom heat exits are pretty small holes but hot air is forced out by the radiator cooling fan setup.

It also must have specific clearances on each side of the box to provide adequate cooling.

If you install it in the box according to instructions you will have no cooling problems.

[skihor]

May be I'm not being clear enough. It's air cooled, NOT designed to be in a box. I have to designa box or eat the $3100, sell it, something. I will not embarass myself with this unit at events.
What I need is real world experience on building a box that worked.

Thanks, Don & Sheila

[TomC]

I think the point most are trying to make, is you can have an air cooled genset that's not designed to be in a sound box, but not be all that quiet because of the massive amount of hot air you'll have to remove.  The vent size for a 16kw (which sounds like you have the V-2 Honda engine) will make putting it in a sound box almost a moot point. 
You can create an totally enclosed box, but would have to use a squirrel cage blower of 1 horsepower size that pushes cool air into the box and then have equally sized exits for the hot air-and have the exit air ducted to cut down noise.  This will take ALOT of space.
My suggestion is to return the genset and get a genset that is proper for your application.  It's too bad you didn't confer with us on the board before you bought that 16kw air cooled genset.  There are many water cooled gasoline/propane powered gensets that you can use.  They will cost more-but then you can take that cost off your taxes too!  Good Luck, TomC

[wal1809]

When they are talking about using the blower to keep it kewl they are not off of track.  I have a liquid cooled unit.  I use a 1 hp squirrel cage fan to force air through the radiator.   IMPORTANT!!!  These buses create a force of air that is not easily overcome.  So let's say you build your box, you are already starting off behind the 8 ball because you don't know what that force of air will do.  So in my opinion you will need the squirrel cage drawing air from the bay and forcing it out the floor under the bus.  I am not sure if it will be enough.  The reason I say this is I mounted my radiator in a box.  I used a small fan first and it did not work.  I used a big squirrel fan and it worked but not that good.  At the suggestion of others I sealed space between the sides of the radiator and the box.  I didn't think it would make that big of a difference.  Well it did, by about 20 degrees on the guage.  So blowing air into and out of a box may not be the most efficient way to cool the genset.  I am just not sure.  What I am sure of is you need a massive amount of air flow to overcome the forces of air the bus creates going down the road.  Good luck on your project.

[dougyes]

I did this once. These units are made to be noisy so you can't get them very quiet. We built a fire proof insulated box with air inlets and outlets. Harbor Freight has a yellow axial fan that we used to move the air. We welded an exhaust pipe to get the exhaust out of the box and fitted a car muffler on the end. It was better but you couldn't exactly call it quiet.

[Zeroclearance]

I recently heard that alot of the BIG time converters like Liberty will mount the genset radiator on top of the roof now.   Has anyone see one?

[buswarrior]

I fooled around trying to box a 9k air cooled generator with a V twin Honda engine, long ago and far away...

Boy, am I glad I had one of those newfangled infrared temperature guns...

Anyway, after watching the temps climb and climb, and the noise pretty much undiminished from out in the open, I disassembled the box, put the stock exhaust back on it and it does back-up duty at my parent's house. Lives in the garage with a wheel kit, roll it into the doorway, plug it in, and away she roars.

It is already difficult to communicate in/out of a food concession trailer with all of the equipment running and whatever other event noise is going on, if this generator is going to be mounted on/in the trailer, the staff are going to be even more frustrating to the intending customers that they can't hear the orders?

Will excessive noise risk driving customers to the competition?

If there is a space to build a sound box for a water cooled 1800 rpm diesel genset, remote the radiator, and add one of those good hospital zone mufflers to it, vertical enclosed exhaust stack, (no burned fingers touching things they shouldn't) you will be pained in the purchase, and then there will be no more pain?

happy coaching!
buswarrior