From: hotrod@dixie.com (The Hotrod List)
Subject: Re: cng conversions (fwd)
Date: Tue, 12 Jan 93 01:45:13 GMT
Organization: Dixie Communications Public Access.  The Mouth of the South.
To: hotrod@dixie.com
Reply-To: hotrod@dixie.com
Posted-Date: Monday, Jan 11 20:45:10
X-Sequence: 3364
X-Gifs-To: met@sunset.cse.nau.edu
X-Gifs-From: ftp.nau.edu

>  
>  Hey,
>  	Bill Clinton's choice for Secretary of Energy drives a car which
>  runs on either gasoline or compressed natural gas.  I expect that there
>  will be a dramatic increase in the federal tax on gasoline within the
>  next few years.  The EPA has approved natural gas as an automotive fuel
>  with NO emmission standards.  Here at the University of Georgia, all of
>  the physical plant vehicles are being converted to run on compressed
>  natural gas.  
> 
>  [The emissions situation is changing even as we speak.  EPA hasn't got
>  anything else to do so now they're formulating emission standards for
>  NG vehicles.  JGD]

>From my understanding, factory produced NGV's either have to or will soon
have to meet the almost the same emissions standards as gasoline vehicle,
with the only difference being the standard for HC emissions, which is
broken up into methane and non-methane HC amounts.  Factory produced
NGVs even have to meet gasoline NOx standards.  Because of this, GM
is using 8.5:1 (I think, may have been 8.0:1) on their CNG fueled
pickups.  Actually its kinda disgusting that GM took the low compression
approach, since NOx can be reduced sufficiently with intake charge
dilution, and GM's earlier NGV prototypes succefully used this approach.
I guess GM decided a lower sticker price was worth a 25% loss in power and
economy.

> 
>  	Can anyone point me toward some literature that will contain
>  information about converting carbureted, gasoline engines to run on
>  compressed natural gas as a second fuel?  My thoughts are that a second
>  carburetor mounted above the stock carburetor will fit the bill.  The
>  engine starts on gasoline and when it reaches operating temperature, the
>  gasoline is switched off while the cng is switched on.  

This is exactly how most conversions are done, although most conversions
I've seen have been on latemodel cars & trucks that use EFI instead of
a carb for gasoline use.  However, there is no reason to start on gasoline.
You can start on either fuel and switch at any time.  For colder climates,
some method of starting enrichments will make starting on CNG a little
quicker (and from my experience, and MSD-6A will make starting a LOT
quicker).
The only reason any starting problem exists is that all CNG carbs are
rather crudes.  Fortuanely there are a few companies that are making
gaseous fuel injection kits.The one I'm familiar with is the Stewart
Stevensen GFI system, which I haven't had a chance to run yet but it
looks very impressive from the installation manual.
I'm not sure of any literature offhand, since whenever I've needed
CNG specific parts I've gone thru the local gas company (they're
picking up the tab for CNG specific parts).
 Another thing you should also check on is your local and state regulations
concerning natural gas vehicles.  Here in Texas a shop (or person?) can
be fined $10,000 per vehicle per visit for servicing components of the
CNG system without proper state certification.

>  	There are millions of open system cars in the south and west
>  which will be junked or converted to cng if gasoline approaches $3.00
>  per gallon.   Many of the cars we talk about on this list can easily be
>  converted.   I'd rather convert than drive a Civic.  But if I had my
>  druthers, I run a car with an 11:1 compression ratio on aviation gas.
>  Tom Root

Or how about running dedicated natural gas with 14.4:1 compression?
or 11:1 compression with 7psi boost?  And only pay 70 cents for
the energy equivalent of a gallon of gasoline?

The biggest problem with natural gas is storage...  it takes approximately
(this is from memory) 2500scf of natural gas to equaly 22 gallons of gasoline.
To carry this much CNG at 3000psi, my truck has two 13x72 inch tanks
and one 13x36 tank.  And tanks aren't cheap, either.

The biggest selling point of natural gas is that the US has more of
it than anyone else.

> 
> ----------
> Posted by: emory!marie.stat.uga.edu!tom (Tom Root)
>  
> 
> 
> 


-- 
Jon Lusky
lusky@gnu.ai.mit.edu

 79 Rx-7 12A/Holley 4bbl
 67 Camaro/350/4spd (under construction)
 89 Jeep Wrangler/258 (currently self destructing)

----------
Posted by: emory!gnu.ai.mit.edu!lusky
Newsgroups: alt.hotrod,wiz.hotrod