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Topic: Power Tech Gen, with vs without sound shield  (Read 1162 times) previous topic - next topic

Power Tech Gen, with vs without sound shield

I tried find previous post on my question but could not so here it goes.

I see that the Power Tech 10Kw generators went from the old style to the new style with the sound shield around the year 2000.  So my question is how much of a difference in exterior and interior noise is there between the two models. I guess the sound shield model might be a bit more difficult to inspect and work on.
Thanks
Bill 

Re: Power Tech Gen, with vs without sound shield

Reply #1 –
Bill,

You have it Toyota! You can walk by a late RV with an enclosed style diesel generator in a campground and hardly notice it's running. I have never worked on a sound box type generator but if intelligently designed, the enclosure should be easy to open for work with a pull out design. Sound shield generators are required in more and more places, even in India.

Dave is in the business. How about it Dave?

Pierce

Re: Power Tech Gen, with vs without sound shield

Reply #2 –
Quote from: nelo –
.......................my question is how much of a difference in exterior and interior noise is there between the two models. I guess the sound shield model might be a bit more difficult to inspect and work on....................................
Bill,
I had the Power Tech 8K Isuzu based 3 cylinder generator in our 1998.....without enclosure.
I now have the Power Tech 12K Kubota 4 cylinder generator in our 2002.....with quiet enclosure.
Both excellent, but they have very different characteristics:
8K:
    • Always acted as though strained during start (after glow plugs and pre-lube, turned over slowly, dependably fired, then sounded and felt like it was pumping crushed rocks for a minute or two - until it warmed up and accepted the (timed out) delayed loading.  Engine mounted radiator had to be modified to prevent (STOP) the radiator self destruction from engine thrashing, but was entirely problem free after modification.  Nice to have a D1 compartment (Driver's side, first compartment) for wet/dirty item storage.  Easy gen set access for routine and (w/slide out) extended service.
       
    • Once warmed up, comfortable quiet purr inside the coach with little to NO vibration felt in hard surfaces throughout the coach.  For example, didn't need to change TV volume for running vs. not running.
       
    • Outside coach, a rather raucous, sharp note in near vicinity to coach and a heavy, low note at large distances from coach (up to several hundred feet away).
12K:
    • No strain during start (glow plugs time out faster, rapid turn over, instant start, smooth running right from the start, no rock crushing, almost imperceptible load acceptance after time out).  D1 compartment completely lost to remote Gen Set radiator/fan/expansion tank use.  Miss that compartment!  Routine service items are very well designed and easily accessible.  Extended service items look like they will be very time consuming, even with the pull out tray, although haven't actually tried to disassemble the quiet box yet.
       
    • Whether warmed up or not, inside noise is MUCH more noticeable throughout coach,  increased interior noise level seems to be entirely independent of generator loading (from minimum to fully loaded), little perceptible difference between the cold and warmed up conditions, VERY perceptible vibrations in hard surfaces all the way back to the bathroom area, for example; definitely have to turn up the TV volume several notches to overcome increased background noise, vibrations are high pitched, frantic, strong amplitude vs. the Isuzu low pitched, low amplitude, quiet, purr or hum.
       
    • Outside, the quiet box really shines!  It is truly amazing how well it reduces the exterior sound from minimum to maximum loading.  Near or far from the coach it has a low pitched purr that, like Pierce has said, is barely perceptible.
In retrospect, it seems to make sense.  The sound energy, in a quiet box, must be dissipated somewhere, and what isn't absorbed in the box's interior insulation makes its way to the frame. The 4 cylinder has a higher prime frequency than the 3 cylinder and the higher mass lends amplitude.  The engine mounts on both are in excellent condition.
Hope that this is of some help to you,
Neal

Re: Power Tech Gen, with vs without sound shield

Reply #3 –
Neal has a good take on things. Vibration isolation is almost a black art to get totally right so you don't feel much inside. This had a lot to do with our decision to go with the panels on the roof. Just wish they could run the AC. The water heater and fan noise from the furnace bother me so you can imagine what the generator does.

Pierce

Re: Power Tech Gen, with vs without sound shield

Reply #4 –
Red Tractor had the only Power Tech that I saw with air bags for mounts.

Re: Power Tech Gen, with vs without sound shield

Reply #5 –
I had one coach without the box and two with it so I have had 8kw 10w and 12kw now. I will say that the 12 is the smoothest to run but it does have a vibration you can feel in the coach and it is the quietest.  The 8 never was a problem and worked perfectly and it was a bit louder outside but not inside.

Re: Power Tech Gen, with vs without sound shield

Reply #6 –
My 10 kw works great.  Just had new insulation put in at Bernd's while they replaced my steering box.  The old insulation either fell off or I pulled it off to prevent it from getting into the generator- a very bad idea.

The bottom of the insulation can hold moisture and cause rust on the bottom pan- want to guess how I know that?
If you have insulation on the bottom, please check it carefully before it rusts out the bottom and perhaps the mounts.
I was lucky, mostly surface rust, mounts still are good.

No insulation on the bottom for me.

Ted

Re: Power Tech Gen, with vs without sound shield

Reply #7 –
Thanks everyone for your comments.  I was also interested in the outside noise.  With the earlier Power Tech models, the ones where you can see the complete gen & engine with the front open, there is some shielding that may be helpful on the inside of the coach but for those in the surrounding areas the running generator may be a bit bothersome (I don't know this for sure). On the newer models (post circa 2000 model years) with the Power Tech sound shield enclosure it appears that the enclosure would provide considerable noise reduction. I am sure that there is a difference between the two models, but I just don't know how much. I am just being conscious of others that we might be around when we are parked and this is just another consideration when it comes to deciding which FT we end up with.
Thanks
Bill

Re: Power Tech Gen, with vs without sound shield

Reply #8 –
Not to thread jack.... Well maybe ;)  We have a 12k without sound shield.  I find the exhaust noise is very offensive compared to the gen noise itself.  Do those mufflers ever go bad?  There is no corrosion or anything.  Just a very pronounced cylinder hit high combined with a diesel low rumble.  I thought about getting a $25 auto parts store muffler and putting it on the end and seeing what the difference was (just as a test)

We find that even without a quiet box the noise our actual generator makes (not the exhaust) is pretty quiet.  You can't hear it from more than 10 feet or so away.

Re: Power Tech Gen, with vs without sound shield

Reply #10 –
We have a 10KW in our 96' with no sound shield other than the leaded foam provided by the factory.  The sound level is not offensive inside or outside the coach.  Ours is equipped with the 4 cylinder Kubota engine, is very smooth and has been trouble free.
Just a note, a great deal of generator engine noise is actually generated by the engine air intake, not the exhaust.  If you really want to quiet it down, add an "S" shaped rubber radiator hose to the air inlet--- you will be amazed!

Re: Power Tech Gen, with vs without sound shield

Reply #11 –
Bill, My 95 U280 had the roadside mounted 4 cyl Kubota and I had no problem with the sound, no one ever complained to me and it was barely noticeable inside the coach. In fact the few times we slept on the road with it running for AC the sound was rather soothing and it tended to block the sound of highway noise and trucks parked nearby.
Gary B

Re: Power Tech Gen, with vs without sound shield

Reply #12 –
@piku

I also find the exhaust sound to be more noticeable than the engine noise.  I've also thought about changing out the muffler but it is down a bit on the list of things that I'm trying to get done on my FT. 

Mufflers | Power Technology Southeast Inc

The BMA mufflers are supposed to reduce noise by 35 db. 

http://www.burgessmanning.com/files/2513/2983/9212/BMA.pdf

Probably wouldn't hurt to give PowerTech a call and see what they have to say.

Re: Power Tech Gen, with vs without sound shield

Reply #13 –
My 95 U320 has air bag mounts which I believe can be adjusted. I have never messed with them. Now I'm going to give it a second look.

Re: Power Tech Gen, with vs without sound shield

Reply #14 –
Our 1995 U320 originally had air-bag mounts, but they had some problems (I'm not sure exactly what) and so the previous owner had them replaced with conventional rubber mounts. He was much better pleased with the rubber mounts.

Re: Power Tech Gen, with vs without sound shield

Reply #15 –
In the late ' 80s, FT hired some English sound engineers to record a lot of sounds in and around all of there models, both rolling and still. I drove all the units. At that time recorded outside, at the same distance, the gas and diesel gen sets were the same sound level.
 

Re: Power Tech Gen, with vs without sound shield

Reply #16 –
Quote
If you really want to quiet it down, add an "S" shaped rubber radiator hose to the air inlet--- you will be amazed!
Would you mind posting a photo of your generator with that hose attached. Mine just has a piece of flex hose hanging down. Thanks.
jor