Well, I had mentioned this to a friend and he suggested I make a build post for any progress.

As the title mentions, I am building a CNG (compressed natural gas) powered Disco 2.

The engine will not be getting any notable upgrades outside of hardened valves and seats. The engine will be fully refreshed prior to starting this project, currently in the middle of that with several sets of heads being dropped off to the machine shop for them to decide which is best.

The donor: A 2003 Vienna Green D2 with around 100,000 miles. This has been a good truck to me, however bores me immensely. It has not broken once, the previous owner took way too good of care of it, and kept it rust free.
The (other) donor: I may use a 2004 Zambezi D2 that I bought with 220k miles for $3000. It is a well maintained running and driving car, however the further I look, the more rust I find. I bought it in the dark. This may become a secondary parts car for the Vienna D2.

The kit: The CNG kit I am using is an Impco self-tuning kit that is a rebrand of the Italian brand GRC. The regulator, injectors, ECU, and a few other pieces are all GRC branded and made in Italy. In the bi-fuel world, this is a very good thing..

The tank: The tank I am using is a factory Honda 8 gallon (GGE) from a 2012 Honda Civic. It is a fiber glass tank rated for 3600 psi and only weighs around 220lb with the heavy duty steel mounting bracket. This will be good for hopefully 80-100 miles of dedicated CNG driving.

The Home Compressor: We have several other natural gas vehicles in our fleet, some factory and some self-converted. To fuel them at our home, we have 2 main compressors and a small fast-fill station. Both are Coltri made in Italy compressors, one MCH10, one MCH14. The fast-fill station consists of 2 sets of factory Dodge CNG tanks totaling to about 35 GGE of fuel. This can fill the 8 gallon tank in about 10 minutes.




WHY AM I DOING THIS?! I'm already $3500 in, and I haven't even touched the truck.

Well, I am currently paying 79 cents per GGE of natural gas. And yes, that is road taxed through a separate meter.

79 cents, per gallon of gasoline equivalent fuel. No discernable difference in performance, or fuel economy has been noted on our previous conversions. At least not for road driving, and light towing.

The kit does have a connection to the knock sensors, MAF, and o2 sensors to vary fuel input. If you decide to do some police chasing or towing, it will automatically return to gasoline and provide as much performance the truck can.

Cheers! This is going to be a post with LONG wait times. I am incredibly busy with work, so this will be in my spare time.

 

Boy, there's a name l've not thought about in decades...Impco. Did propane conversions on a fleet of vehicles back in the late 80's (yeah, l'm that old...lol). After a few years, we converted them back to gas, drivers complained about power/mileage issues. I believe, as mentioned...this was years ago, so memory be damned...but...l believe natural gas had 1/3 BTU content of gas, or less. And propane had 2/3's of gas. Mileage went from 8/9 to 3/4 mpg (these were mid-range duty vehicles). Plus, carrying compacity was less, we used 40 gallon tanks for propane, whereas gas had 60 gallon capacity, so we lost range there too. Drivers ABSOLUTELY HATED the system, filling vehicle twice a day and the process was noisy and smelly and somewhat dangerous (at that time). Now, l know technology has improved over the years...so hopefully it's worth the effort now.

Side note about CNG vehicles. They were also in the game back then, conversions, and my neighbor worked for the company doing them. Well, one day he's filling his car, which had two small CNG tanks in trunk. He hears a little cracking noise while filling one day. That was about all he remembers after getting out of the hospital with 3rd degree burns over 90% of his body. CNG tank split on the bottom and blew the gas tank below it apart, they found parts of his car two blocks away. He was very fortunate to live, as he heard the cracking noise he had present of mind to turn away from car..his face was the only thing that survived unburned. Not going to lie...he was a gruesome sight with his shirt off.

Did some quick math on your .79 cent CNG...and if it still provides 1/3 the BTU (which l would assume, since it's still the same gas it was back in the 80's) so, I'd say you're going to get about 4/5 mpg, ...unless technology has improved substantially...which should put you in the $2.40 range for the equivalence of gas.

Good luck, with conversion...and it will be interesting to see how it turns out.

 

I was going to say... how have you not noticed any change in performance in your fleet after conversion? I grew up in New Zealand, where CNG and LPG conversions were commonplace throughout the 80s and into the 90s. I personally had a van, a station wagon, and two sedans on CNG. Sure, you could keep a vehicle moving in a straight line on it, but getting up to speed was interminable -- although a caveat here: they were all carbs and not injected. I can't imagine how weak the Disco is going to be on gas. Still, I'm interested to follow this as an exercise.

 

To answer the question of mileage, the current systems have been absolutely fantastic. We have done GM 5.3/6.0s, Ford 4.6/5.4s, Ford N/A 2.0, and have had both Honda Civic GX NGV and Bi-fuel Chevrolet Impalas.

No noticeable drop in fuel economy with the Technocarb or Impco kits, no real performance loss either.

In the Chevrolet Impalas, we have a 2016 and two 2015s, if you are on CNG and floor it, then switch to gasoline and floor it I'd bet money you wouldn't be able to tell the difference. They're factory cars too!


We started out in the early 90s doing propane conversions. My father switched to CNG in the early 2000s with Ford F-150 factory conversions. Even at that point, technology was a lot better but fast forward to today it's seamless.

They're still doing LPG conversions over in the UK. Very common to see Rover Classics, Disco 1s, and even Disco 2s on LPG. Ask anyone that has it, they'll tell you there's no performance loss. Although older less efficient kits did pose a slight hit to fuel economy, the current kits seam to fix that.


Mollusc, the current kits add 8 more injectors to the engine. Each one is either cupped to the original injector, or a separate hole is drilled in each individual intake runner. Each cylinder gets its own fuel supply. I reckon this helps with economy and performance quite a bit, outside of having a separate ECU that connects to all of the engine sensors.


And yeah, I've heard tanks exploding and this and that. The current tanks, as long as they're certified, are entirely safe. You still don't want to drop them onto the valve or anything, but there's there's heavy steel surrounding the valve to make sure nothing happens in an accident. I haven't seen one (modern) fiber glass tank fail yet. If it is good enough to be in a load of Honda Civics, it's good enough for my old D2.

There was an explosion at a CNG station in Madison I believe. That station was improperly serviced either that day or the previous, can't quite remember now.

 

Interesting. Technology has allowed for improvements...for sure. We were in the early stages of conversions, so a lot was learned...the hard way.

Funny story...

We had a unit die right downtown, cranked over but no spark. So, naturally...the driver is cranking it over the whole time we are in route to retrieve it. Well, the propane just keeps getting thrown through the engine cylinders...ending up in the muffler, which is quite large, 18"" diameter by three feet...anyhow, we get there, detremine the coil is bad and change it...not knowing he's been cranking it for a half hour.

Jumped up inside and hit the key...OMG...LOL...it was like the vehicle blew up, sound wise. The other mechanic was standing on the front bumper, peering into the engine compartment when the muffler blew...his hair was standing straight on end and his face was all black around his safety glasses. Boy, those were the days.

 

That is funny. Reminds me of when I had a failed coil on my RRC. My buddy sprayed some ether into the intake and it spit it out in a fireball. Beard, eye brows, and arm hair all slightly charred! No injuries though. Scared the living crap out of my buddy.

But yeah, I see your concern. All of the kits, LPG or CNG, start on gasoline. Any dedicated alternative fuel vehicles will stop supplying fuel after a certain amount of cranking. Although that is kind of detrimental in the winter where temperatures are too cold for CNG/LPG to start up easily. That is why I prefer the bi-fuel.

 

OP - there is a gentleman on a Facebook group that has a narrative going on FB group "Land Rover Trading Wall MERICAN Version" on a purchase of a 2003 D2 off Ebay -- which is relevant to this forum as you also listed it on this site here in classifieds.

I would recommend you reply to him either privately or here / Facebook in a public forum to clear things up.