generator exhuast silencer?

[john_bud]

I once was on a movie set and they had a HUGE generator running that was almost silent! I have a long way to go!

Not so far, just to the bank's loan window for a hugh loan!

jb

 

[dfkrug]

Have to agee with Tom, with the engines used on these genset, much of the noise is mech noise and a muffler won't do anything for a good portion of the noise being produced.

I disagree with Chris on engine speed. Direct drive models have to either run at 3600 or 1800 rpm to produce 60Hz power. You're going to have to spend >$2k before you get into units with 4-pole genhead that operate at 1800 rpm.

Yes, Mickey, you are correct about the noise and RPM.

I tried to quiet a 10hp Tecumseh, taken from a dead generator and used to
run my hyd pump on my CADDigger. I tried different mufflers and it was
always super-loud. The problem is these flat head cheapo motors are
inherently very loud. The better motors have overhead valves, like the
B&S Vanguard or many Hondas/Yams/Kawis. MUCH quieter for same hp.

I also have a much newer Generac 5500W generator and it is hella loud, too.
Both of these motors are governed to 3600 RPM. You have to pay a ton
more, as you say, for the 1800RPM gens. RVs often have the latter.

 

[firefighter9208]

I guess I got my RPM's wrong when I posted. 3600rpm on the cheap motors and 1800rpm on the expensive (quiet) ones. One thing that I thought was interesting though is that Honda's superquiet line of Generators run at higher engine speeds. The EU1000i runs at 5500rpm EU3000 runs at 3600rpm and the EU6500i runs at 2400-3600RPM.

Chris

 

[Mickey_Fx]

Chris, the honda line of genset you are refering to and also made by others are inverter based designs. They produce high-freq, high voltage A.C. that is rectified to D.C. and this power is run through an inverter to provide proper "shore" power. 110-120V 60Hz here in the states. On this design the engine speed varies to where it only runs as fast as necessary to produce the amount of power needed by the connected loads.

 

[Donman]

The problem with box store contractor generators is the RPM they run at. Most run at 5000-6000 rpm. 1/2 the noise you are getting is from the engine noise and not exhaust.

More expensive and quieter generators run at 3600RPM.

That's a new one on me! I never heard of any genny running that fast. I thought that in order to get 60 cycle power the rpm's had to be divisable by 60. That would work at 3600 rpm and like I had with my old Onan 1800 rpm with double windings (heavy bugger). It would also work at 6000 rpm but I'm afraid those Briggs and Scrapiron engines with splash lube would not last long at that speed. I have used road kill car mufflers that I found to quiet stationary units before and that works pretty well.
On edit - I noticed after I posted this that you corrected your post concerning rpm's

 

[RavensRoost]

Txslowpoke, I could not tell if you had already bought the "big box generator" and was trying to quiet it down, or, if you are planning on buying one knowing they are noisy and wanting to have a plan before you buy. If you have not bought, the Honda inverter series are incredibly quiet: I have a 3000is which is about 2800w, a very high-quallity machine. Like others mentioned above, with no or little load, the inverter genny's just idle while still putting out 60Hz power, RPM's come up in response to load.

The bad? Cost around $1800 and it is 120v only, no 230v capability.

PS: I did successfully make an 8KW Lister-Petter diesel fairly quiet, but it wasn't easy, and as they say, that's a 'nuther story ;-)

RavensRoost

 

[Mike of the North]

A friend of mine replaced the muffler on his generator with one from a Honda and it really quieted his down.
Mike

 

[3RRL]

Here's what I did to my Cummins 20kW generator.
I ran the exhaust pipe through the roof and insulated the crap out of it where it breaks through.
I also put one of those flappers on it. It's quieter now than you would think, both inside and outside.

 

[EdC]

Rob

Nice setup. Is there any problem with back pressure because of the diameter of the exhaust being reduced?

 

[RobJ]

Rob

Nice setup. Is there any problem with back pressure because of the diameter of the exhaust being reduced?

I think that's just an insulator pipe. I think...looks like the way it's foiled together.

Rob