Natural gas conversion: can a 1992 Q be converted?

[kdkrone]

Does anyone know what would be involved in converting a 1992 Q to natural gas? Would it be reasonable to do so if we develop a national infrastructure for distribution or does it require a new car??

ThanksKen K

[Q451990]

Hard to say... I'm sure it would be very expensive. I once researched what it would take to convert a CNG Dodge Carovan to gasoline when my dad was looking at one at a GSA (federal govt. surplus) auction. If I recall correctly, it was pretty in depth... different ECU, intake, injectors, fuel tank, etc.

I'm sure anything can be done - the question I can't answer is "at what cost?"

Refueling can be done slowly at home...http://www.myphill.com/ but forget about a road trip at this point

Heath
Modified by Q451990 at 10:14 PM 9/8/2008

[Q45tech]

CNG is easy at warmed up cruise and acceleration the hard part is designing for cranking and warm up.

A dual fuel system allows cranking and warm up on gasoline then switching to CNG.Emission testing is done with gasoline http://autoparts.rasoenterpris...d=139

My guess is that $5,000 for car and $5,000 for home compressor + installation in a garage [220 + gas piping]. The home compressor will have to be rebuilt every 3-4 years so a spare is necessary or a source of CNG.

Giving up trunk for CNG tank is the tough sell.

It would require a technical genius to CNG a Q engine and deliver the same acceleration under all conditions as the gasoline does now.

Ford couldn't do it on their dedicated CNG 4.6.http://www.baftechnologies.com...a.pdf

[qship96]

Jusbuy a Prius or Smart car as a runabout mate to the old Q guzzler....cheaper and less {no} headache of re-engineering and retrofitting. Chicks dig the Smart car, especially the convertible.

[Q45denver]

Honda sells a CNG Civic with a home fill kit. $5000 to convert is about what it would cost for a couple sets of ethanol challenged JECS fuel injectors. Plus possible government tax credit, subsidy from T. Bone Pickens, and/or 50% lower fuel costs?

[Q45tech]

CNG would be a good system to learn and become expert in conversions since you could swap the system for the next 20-30 years from car to car as long as you can reprogram ecu and repair the expensive flow controls.

Unlikely that Nat Gas will go anyway as too many homes use it for heat and US supplies are now good for 30 years [unless too many convert].

Just tell the local gas company you installed a gas clothes dryer and swimming pool heater if they ask about increased consumption in Summer.

[kdkrone]

Nice to see your good sense of humor, Q45tech...!

I will be most likely be dead in 30 years (I am 63 now). I was just wondering what would be involved. Having discovered that it would be an expensive PITA, I think I will wait to see what CNG vehicles come out as the infrastructure for the distribution of the fuel...

Ken K

[dusred]

You and Tech are close to the same age.

I think it would be cool to see a Q converted over to Nat Gas. The term "Economy at all costs" comes to mind.

[Q45tech]

If you use a relay to shut off gasoline injectors and fuel pump on highway all you need is a big CNG nozzle in plenum to cruise down highway.

Acceleration gets a bit tricky but can be solved in a similar way as done on an old carb using vacuum [pressure] changes like the fuel pressure regulator.

The cats will clean up much of the error.

CNF operates leaner than gasoline depending on the exact composition of Methane. You will need to add a wideband O2 and adjust cruise 17:1>15:1 depending.

Just like gasoline the throttle and rpm [cam/valves] control the air flow so all you can do is vary the amount of CNG in plenum.

""""BI-FUEL FOR CHEVROLET CAVALIERThe new bi-fuel Ecotec 2.2-liter (L42) operates on either gasoline or compressed natural gas (CNG). The bi-fuel 2.2-liter is an option in the Chevrolet Cavalier for Federal Clean Fuel Fleet service. It is expected to be used primarily in fleet service and replaces the CNG variant of the 2.2-liter (LN2) four-cylinder.

Compressed natural gas is the 2.2-liter (L42) engine's primary fuel. It uses CNG as long as there is sufficient pressure in the storage tank. If pressure drops below a prescribed level, the engine automatically switches to gasoline operation. The change occurs without driver intervention and is indicated only by a ``gasoline operation’’ light in the instrument panel. The driver cannot manually override CNG operation.

Hardware differences between the 2.2-liter (L61) and 2.2-liter (L42) are entirely in the cylinder head and fuel delivery system. CNG does not have the lubricating properties of liquid gasoline, and it tends to produce more surface erosion than gasoline as it flows into the combustion chambers. To ensure maximum durability with CNG operation, the engine has unique valve seats and intake valves that are more resistant to erosion. The seats are manufactured from an alloy called Brico 3010, a sintered powder metal with higher chromium, tungsten and copper content than the alloy used for the regular gas version's valve seats. The engine's intake valves are forged from a premium alloy that includes tungsten, vanadium, manganese, and silicone, and has more chromium than conventional iron-alloy valve material. These alloys virtually eliminate the possibility of valve face and seat erosion with CNG operation.

Fuel-delivery systems on the 2.2-liter (L61) and 2.2-liter-CNG (L42) are substantially different. The CNG engine actually has two fuel systems in one, with sequential port injection for CNG running parallel with the multipoint gasoline injection.

The CNG injection has its own stainless steel fuel rail and uses an adaptor plate, molded from the same nylon composite as the intake manifold, installed between the manifold and the cylinder head. The plate is 8 millimeter thick, with a boss and narrow passage molded at each intake port. The CNG injectors mount on the bosses, roughly one inch to the left of the standard Multec II gasoline injectors, and deliver CNG through the passage in the adaptor plate to the port. The natural gas injectors are fired sequentially. The engine adds a second injector driver module (IDM) to manage the injectors. This solid-state device controls the CNG injector pulses electronically.

To manage the second IDM, the engine has a unique powertrain control module (PCM). The PCM uses software developed specifically for bi-fuel operation.

Maximum fuel delivery pressure in both of the fuel systems is the same: about 65 psi, with a normal operating range of 40-45 psi. Nonetheless, the CNG is stored at tremendous pressure up to 3600 psi. The CNG tank is installed in the Cavalier’s trunk, over a high-pressure regulator that reduces gas pressure to 170 PSI and sends the fuel through a line under the car. A second intermediate pressure regulator mounted on the transmission further reduces fuel pressure to about 45 psi for delivery to the injectors. Two electrically operated shut-off valves--one on the tank, the other under the hood--can shut down the CNG fuel system if the on-board diagnostics detect the slightest malfunction. In such circumstances, the PCM switches the 2.2-liter to gasoline operation and advises the driver of the problem with a ``service engine’’ warning light in the dash.

The Cavalier’s CNG tank has a capacity of 6.2 GGE (gasoline gallon equivalent). At full capacity, the tank stores the same amount of energy, measured by BTUs, as 6.2 gallons of gasoline. The bi-fuel engine is expected to extend the Cavalier’s range 150-200 miles over the dedicated gasoline vehicle. CNG operation reduces the engine's maximum horsepower and torque approximately 10 percent """""""

[texasoil]

It should not be difficult--similar to 'propane' conversion with a central flow nozzle just aft of throttle plate, metering fuel from MAF, etc. Leave in place gasoline system?

Should be relatively simple, much easier than metering gasoline to each cylinder. Just get the fuel:air ratio right at the throttle body, trim with the O2 sensor output..