Bought new HRX opened box and has GCV160?

[bertsmobile1]

Incredible historic perspective (particularly on the Victa "Vortex") !

If we had the same "limited to 75-dba" mandate, I would not be bringing up the issue. It's the 90-95 db.+ levels at very ear-sensitive and damaging levels that is very concerning --particularly with prolonged exposure. The engine and exhaust noise is by far the most concerning.

The sound from blades spinning (at any speed) would be at a frequency (spectra) benign to our hearing. It would be/is far too low in frequency to be of concern. I must say, the "Vortex" example you provided is most bizarre; are battery operated mowers also dangerous/hazardous as a result of their 60-70-db. noise (humming) levels ? I've yet to see a strobe light version, but of course this isn't 1986.

The (combustion) engine/exhaust frequency spectra at 90-100 db. levels (at operator distances) is very concerning.

There is no reason why a simple "hat" cannot be fitted to reduce noise levels by 10-20 db., while simultaneously designed for the required air flow. This user-installed/removable "hat" (engine cover) could be both economical, practical and safe.

In any event, for anyone using powered equipment for extended periods of time, ear-plugs are highly advisable.

If not practical or in itself too dangerous, other methods must be employed to ensure those 75-dba. noise levels (that are indeed quite commendable) are maintained.

peter jasz

It does not matter if you can hear it or not.
Sound is a pressure wave and a dangerous pressure is a dangerous pressure.
Infra sound can destroy your hearing just as well as ultra sound can.
It is the amplitude of the wave that causes most damage not the period of it.

Start the engine and stand 30 foot away, then engage the blades ( or get some one else to )
It will seem a lot louder with the blades spinning because the lower frequency high volume energy waves of the blades spinning carries the higher frequency lower energy exhaust noise with it.
To make the 75 dBa Victa put a snorkel on the intake to reduce induction noise and the exhaust outlet is under the deck.
I think some Lawnboys did the same exhaust trick.
The amount of sound is exactly the same but it now eminates from a large annulus around the deck and not a small muffler outlet.

As an aside when California mandated lower exhaust noise Rolls Royce had to increase the engine size from 6.25 L to 6.7 L to compensate for the power loss cause by the quieter muffler.
They also increased the lenght of the exhaust pipe by running the exhaust manifold foreward to the radiator then under the engine and all the way to the back.
I ride a B40 BSA in military spec.
Standing behind the bike you can feel the pressure pulses and the engine sounds very loud but you can not hear the engine 200 yards away in open ground.
I also had an SR 500 Yamaha, a bike Yamaha built to counter Harley's claim that the California noise levels were impossible to achieve with an air cooled motorcycle engine.
When riding it is so quiet you can hear the chain running on the sprockets yet you can hear it 200 yards away.
We did a side by side once because we had consummed a few too many beers and there was some money riding on it.
The HD could still be heard 1000 yards away , the SR & the B40 could not but a 250 Suzuki was in fact the loudest bike we could still hear it even after we got far enough away for the Harley's exhaust sound to vanish.

 

[bertsmobile1]

Incredible historic perspective (particularly on the Victa "Vortex") !

If we had the same "limited to 75-dba" mandate, I would not be bringing up the issue. It's the 90-95 db.+ levels at very ear-sensitive and damaging levels that is very concerning --particularly with prolonged exposure. The engine and exhaust noise is by far the most concerning.

The sound from blades spinning (at any speed) would be at a frequency (spectra) benign to our hearing. It would be/is far too low in frequency to be of concern. I must say, the "Vortex" example you provided is most bizarre; are battery operated mowers also dangerous/hazardous as a result of their 60-70-db. noise (humming) levels ? I've yet to see a strobe light version, but of course this isn't 1986.

The (combustion) engine/exhaust frequency spectra at 90-100 db. levels (at operator distances) is very concerning.

There is no reason why a simple "hat" cannot be fitted to reduce noise levels by 10-20 db., while simultaneously designed for the required air flow. This user-installed/removable "hat" (engine cover) could be both economical, practical and safe.

In any event, for anyone using powered equipment for extended periods of time, ear-plugs are highly advisable.

If not practical or in itself too dangerous, other methods must be employed to ensure those 75-dba. noise levels (that are indeed quite commendable) are maintained.

peter jasz

You mean like this from 1976


Or this from 1984

 

[allhifi]

"recently bought" = warranty issue


Interesting discussion re: sound levels and sound quality.

I always thought if "they" would only put a little bigger muffler on ... guess it's not so simple. That said, it's a wonder that any 1-cyl engine doesn't just rattle itself to death.

Re: bigger engine, quieter engine
Yep, and my father-in-law's zero turn is noticeably quieter than any push mower I've heard.

" ....That said, it's a wonder that any 1-cyl engine doesn't just rattle itself to death.." I love that ! So true.

pj