Frequency of single cylinder engine?

[Brett]

Hello - I'm trying to build an enclosure for an engine driven air
compressor. It is run by a single cylinder Kohler engine. I would
like to know how to calculate the frequencies of the engine to figure
out how much quieter it will be if I enclose it in certain materials.
Supposedly the amount of noise that a material will block depends on
the frequency of the sound. Higher pitched noises are easier to block
than lower bass-like noises? Is this correct? What would a typical
engine frequency be - would it be equal to the RPMs? As far as the
enclosure from what I've read, I want to have it airtight as possible
(I will need intake and exhaust tubes/hoses and access areas), isolated
from anything structural (I am thinking of rolling it onto rubber mat
(polynorbonene? - that rubber like substance that audiophiles use to
mount turntables and other equipment on)) and having as much mass to
the walls of the enclosure as possible (two to four layers of drywall)
Am I going about this properly? Thanks,
Brett

[Murray Peterson]

"Brett" > wrote in news:1128968356.732089.284030
@g47g2000cwa.googlegroups.com:

> Hello - I'm trying to build an enclosure for an engine driven air
> compressor. It is run by a single cylinder Kohler engine.
> [snip]
> As far as the
> enclosure from what I've read, I want to have it airtight as possible
< [snip]
> Am I going about this properly?

I assume that your Kohler engine is air cooled, which means you can't just
put it into a sealed enclosure -- it nees some serious airflow for cooling
purposes. In addition, long pipe runs for intakes and exhaust will affect
the engine's efficiency, and potentially make it unusable.

[Arny Krueger]

"Brett" > wrote in message
oups.com

> Hello - I'm trying to build an enclosure for an engine
> driven air compressor. It is run by a single cylinder
> Kohler engine.

> I would like to know how to calculate the
> frequencies of the engine to figure out how much quieter
> it will be if I enclose it in certain materials.
> Supposedly the amount of noise that a material will block
> depends on the frequency of the sound. Higher pitched
> noises are easier to block than lower bass-like noises?

As a rule, yes.

> What would a typical engine frequency
> be - would it be equal to the RPMs?

The primary exhaust frequency of a 1 cylinder, 4 stroke
engine is the rpm divided by 2, because its a 4-stroke
engine, and then divided by 60, because you want Hz instead
of strokes per minute.

For example, the 4-stroke, 1-cylinder engine may run at 3600
rpm. That gives a primary exhaust frequency of 1800 pulses
per minute or 30 Hz.

Note that the primary source of noise in an engine is the
exhaust, so an improved muffler can work wonders. Then there
is intake noise. Finally, there's noise that is transmitted
through the engine block.

I'd like to echo other poster's concerns about cooling and
safety.