On Mon, 14 Nov 2011 17:10:16 -0500, wrote:

On Mon, 14 Nov 2011 11:31:23 -0800 (PST), Too_Many_Tools
wrote:

On Nov 14, 8:49*am, "
wrote:
On Nov 14, 8:53*am, George wrote:

On 11/14/2011 8:31 AM, Jules Richardson wrote:

On Mon, 14 Nov 2011 03:52:03 -0800, bob haller wrote:
generators running on natural gas produce about 20% less power than on
gasoline.

AFAIK, that's a worst-case for after-market conversions with poor
airflow. Best-case is about a 4% loss, and real-world typically ends up
being somewhere between the two (but I think CNG usually reduces
efficiency more than LPG does).

I have seen a note about 20% natural gas derating on the manufacturers
specifications of generators.

Same here. *I think the issue is that gasoline packs considerable more
energy than nat gas. *So, not
surprised that there could be a 20% loss.

Yes you see a reduction.

I do recall reading that a NG only generator has a longer lifespan.

TMT
Propane and CNG, being "dry gasses" are much easier on the engine -

How much? (since gasoline is vaporized through the injectors into a
hot cylinder head, and the oil rings coat the cylinders with oil)
I've read this before but have never seen stats. Cite, please?


and if the engine is DESIGNED for, say, PROPANE, and propane only -
with compression ratios etc adjusted to take advantage of the higher
octane (115AKI) a propane engine can make just as much power as a
gasoline engine. Takes more fuel to do the same job though.

OK.

--
The problem with borrowing money from China is
that thirty minutes later, you feel broke again.
--Steve Bridges as Obama

"Larry Jaques" wrote in message
...

On Mon, 14 Nov 2011 17:10:16 -0500, wrote:

On Mon, 14 Nov 2011 11:31:23 -0800 (PST), Too_Many_Tools
wrote:

On Nov 14, 8:49 am, "
wrote:
On Nov 14, 8:53 am, George wrote:

On 11/14/2011 8:31 AM, Jules Richardson wrote:

On Mon, 14 Nov 2011 03:52:03 -0800, bob haller wrote:
generators running on natural gas produce about 20% less power than
on
gasoline.

AFAIK, that's a worst-case for after-market conversions with poor
airflow. Best-case is about a 4% loss, and real-world typically ends
up
being somewhere between the two (but I think CNG usually reduces
efficiency more than LPG does).

I have seen a note about 20% natural gas derating on the manufacturers
specifications of generators.

Same here. I think the issue is that gasoline packs considerable more
energy than nat gas. So, not
surprised that there could be a 20% loss.

Yes you see a reduction.

I do recall reading that a NG only generator has a longer lifespan.

TMT
Propane and CNG, being "dry gasses" are much easier on the engine -

How much? (since gasoline is vaporized through the injectors into a
hot cylinder head, and the oil rings coat the cylinders with oil)
I've read this before but have never seen stats. Cite, please?

A lot easier. Gasoline is NOT completely vaporized. The ideal, approached
with direct-cylinder injection but not even remotely approached with
carburetion, is microscopic droplets, not vapor, although there has been
research on pre-vaporizing gasoline in years past:

http://papers.sae.org/760288 (a study from Ford dated 1976)

This describes current research measuring percentage of vapor in
direct-injection engines:

http://papers.sae.org/2011-01-2052

You can find lots of discussions about different aspects of the phenomena on
the SAE website:

http://papers.sae.org/2000-01-0537

Essentially, liquid fuel is prevented from vaporizing at, and near, the
cylinder walls, because they are too cool to flash the liquid fuel after
it's been deposited there. That washes the cylinder walls, diminishing the
lubrication.

Here are some other papers on gas-fueled engines, from a tech session at
this year's SAE World Congress:

http://www.sae.org/servlets/techSess...GROUP_CD=TSESS

Use their search engine and you can entertain yourself for hours -- although
all you'll get is the abstracts in most cases. My access has expired so
don't ask me for the papers.

--
Ed Huntress





and if the engine is DESIGNED for, say, PROPANE, and propane only -
with compression ratios etc adjusted to take advantage of the higher
octane (115AKI) a propane engine can make just as much power as a
gasoline engine. Takes more fuel to do the same job though.

OK.

--
The problem with borrowing money from China is
that thirty minutes later, you feel broke again.
--Steve Bridges as Obama