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Old 04-04-2019, 05:20 PM   #1
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Comparing Harbor Freight generators

I had the opportunity to test a couple Predator generators this week to see which one is best for my usage. I tested some things nobody managed to cover in other reviews online. if you're thinking about adding a generator to your build I hope my comparison/review helps you!

https://wanderlounge.net/comparing-h...ht-generators/
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Old 04-04-2019, 06:55 PM   #2
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The 3500 has some nice features. but at more than double the price is it worth it?
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Old 04-04-2019, 08:16 PM   #3
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It's a bit less than double the cost, but not far off. For use around other people it's a pretty clear choice, the nose difference is astounding. I'm pretty frugal and will be paying the extra for the unit that won't get me kicked out of a park.
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Old 04-04-2019, 08:35 PM   #4
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It's a bit less than double the cost, but not far off. For use around other people it's a pretty clear choice, the nose difference is astounding. I'm pretty frugal and will be paying the extra for the unit that won't get me kicked out of a park.
I thought I heard you say in the video the bigger one was around $330. Right now Harbor Freight is showing the Predator 3500 at $769.99. Any idea how loud an Onan Genset 4000 is?
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Old 04-04-2019, 09:14 PM   #5
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769 is the list price but it's 699 with the current coupon. Coupon price for the 4375 is 349. So I suppose current coupon price is a dollar more that double actually. Last week's coupon when we bought it was 10 dollars less, lowest coupon I have seen is 659.

No ideas on that Onan.
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Old 04-04-2019, 09:29 PM   #6
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I thought I heard you say in the video the bigger one was around $330. Right now Harbor Freight is showing the Predator 3500 at $769.99. Any idea how loud an Onan Genset 4000 is?
Onans are loud.
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Old 04-04-2019, 10:02 PM   #7
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Onans are loud.
I was searching YT on ways to quiet the generator, interesting solultions. This one made me laugh right away Charlie. His sample generator has a Honda engine that replaced a Subaru engine, why? "well because all Subaru's blow up, don't they?"

Since the Onan will take up most of an under bay, I'm thinking I can cut the floor out and replace it with expanded metal screen and add panels to direct the sound downward.




https://www.google.com/search?rlz=1C...zgy4#kpvalbx=1
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Old 04-05-2019, 09:15 AM   #8
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I looked at a bunch of ways to try to quiet this one. I tested and measured the common one which is leaning a board against it to deflect sound waves. More boards would do a better job of course. I've seen plans for "quiet boxes", and even commercial offerings.

Here is one commercial offering I saw videos on, talk about sticker shock! https://www.zombie-box.com/shop

It's a price difference of about $350. The more expensive unit has an electric start, it comes with wheels, and it's likely quieter than you'll be able to get the cheaper one to with reasonable effort surrounding it in wood and foam.

The difference between the idle noise levels I measured (81db vs 60db, taken at 15ft) is substantial. Every 3db rise doubles the sound power.

The only practical negative I had for the 3500 other than the price difference was the smaller fuel tank.
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Old 04-05-2019, 12:02 PM   #9
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Awhile back I saw a video where someone quieted an older one down by using muffler dual exhaust off of a little Honda or whatever and it deadened the sound enough to help but then the popping from the air intake was loud enough to keep the sound decibels up there.
Was entertains the idea to reconfigure my old one that I just rebuilt but the space the exhaust system would take up is lost storage?
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Old 04-05-2019, 12:13 PM   #10
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An enlightening video. Thanks. The important thing to know about dB and “noise level” is that dB increase is logarithmic in nature rather than linear. That means “noise level” increases in a “J” sloped line rather than a straight line so what we read as a couple of dB’s increase is actually a big difference in “noise”.
Normal conversation is about 60 dB, a lawn mower is about 90 dB, and a loud rock concert is about 120 dB. In general, sounds above 85 are harmful, depending on how long and how often you are exposed to them and whether you wear hearing protection, such as earplugs or earmuffs.3 dB = twice the power (Power respectively intensity - mostly calculated)
6 dB = twice the amplitude (Voltage respectively sound pressure -
mostly measured)

10 dB = twice the perceived volume (Loudness nearly sensed psychoacoustics).

I would say that when referring to perception of something being twice as loud to the human ear that 10dB is about right. Try it out for yourself with a vocal since our ears are most sensitive to the human voice.

Like others here I’ve looked at many Utube attempts at quieting generators—some are somewhat instructive but most will just make you laugh your ass off. Here are a couple of tips about sound attenuation: High frequency sound is best attenuated with materials like foam rubber and is fairly easy to accomplish because high frequency sound has less energy than low frequency sound. Probably the best material to reduce low frequency sound is lead but since we neither want to handle lead nor want to weight down our buses, high density rubber matting (think horse stall mats) comes in a close second. Hard surface materials like plywood or steel sheeting don’t work very well and can actually increase sound levels like the tympanum on a kettle drum. Loose weave materials (like fiberglass insulation) are practically useless in sound suppression.

One other thought. Sound is very slippery—sort of like water in that it can leak out around corners and slide through tiny cracks. The neat thing about sound waves is that they seem to reform to their original amplitude once they have slithered through a small opening and just go on being noisy. That being said, even using the right suppression materials you still have to entirely enclose the generator to get the job done. Then the generator over heats so you have to add a cooling fan—which opens a hole for sound to escape through etc., etc.

Now that I’ve run off at the mouth I’ll close by saying you can quiet a generator ( I knocked 10 dB off my Yamaha 3000iseb’s already quiet 63 dB using rubber mating, bitumen sheeting and closed cell foam rubber and both a pusher fan and a puller fan for air circulation. I do have to watch for signs of overheating but with high temp cut out switches I’ve avoided toasting my genny--so far.
Jack

Edit: I neglected to state that my dB measurements were made at three feet from the generator--not the standard 21 feet. At 21 feet you can't tell my running genny from normal outdoor background noise though I haven't measured it.
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