CNG conversion

[tallyF350]

I am looking into the CNG conversion.

This is the blog that gave me the inspiration....
F250 Powerstroke Natural Gas Conversion Project Pt. 5 « The CNG Times



What do you guys think? Is it too new and/or dangerous for the 7.3...

[Lucky Eddy]

I bought my 2004 model F 250 7.3, 2nd hand in Dec 2006, with 104,000 kms or about 60,000 miles on it.

A few months later in early 2007 I had our equivalent of what you call "CNG conversion" done (We call it LPG, Liquefied Petroleum Gas but really it is a mix of whats known here collectively as "autogas" which is Butane and Propane mixed).

This is the dyno figures straight after fitting.



Bear in mind this is stock standard 7.3 with no performance modifications i.e. DP Tuner chip or enlarged dump pipe exhaust etc...

Now in 2012 some 6 years and another 40,000 kms (24,000 miles) later the LPG side of it has given me no trouble at all.

That said - I DID have an unrelated issue with a Injector Drive Module located up inside the left fender and all 3 specialist diesel mechanics etc who had a 8 month long stint at trying to diagnose and fix the problem, blamed the LPG conversion, about which non of them knew diddly squat!

I guess we have very few F 250s here and a lot of remote places with no Ford dealer - so being mining industry areas most of the diesel fitter / mechanics are all used to working on Cat diesels from mining equipment, and the F 250 with its Navistar T 444 E and throw in a LPG conversion and it all gets just "too hard" for them!

Had I NOT bought a Auto Enginuity brand Diagnostic tool and software from the USA and had it air freighted downunder, I reckon they would still be scratching their heads and trying to figure why one bank of 4 cylinders just stopped working!

It was my own fault - I drove thru a brown water muddy puddle up to about wheel hub height on the left passenger side - and the mud got over the electrical connectors on the IDM module up in the left front wing panel - and because the local area was apparently full of the mineral "magnetite", it stuck to the electrical pins on the IDM and created an electrical short that no one seemed to be able to clean off, to make it work again.

$1500 and a new IDM module controller from the USA, and it worked again and hasn't missed a beat since, but I am very leery now days of any water crossings.

All up that repair was 8 months off the road and over $8000 in total to repair by 3 different repairers (Which Ford Aust wouldn't cover under my useless $2000 extended warranty).

At the time I didn't have a choice about the water crossing - there was a cat 4 cyclone bearing down upon my somewhat hairy clacker, and the only way to get the boat and my family outta there post haste, was to drive thru this small stream across the road from the boat ramp, that the pre-frontal rain from the cyclone had created.

It wasn't until a few days later when that muddy water with the magnetite grains in it, dried inside the rubber electrical connectors shield on the IDM controller module that everything went to crap..

Anyway the point I guess was that every mechanic who can't diagnose whats wrong with your diesel will blame the LPG conversion - its an easy excuse for them...rather than admit they don't know shyte from shinola when it comes to diesels that have computer controlled electronically fired injectors!.

Least that's been my experience for what it is worth. The Gas is a good system and works well - but mechanics will just shrug their shoulders and say the LPG / CNG is the issue - when they can't figure whats wrong with your engine.

To most mechanics it seems the gas conversion that runs in conjunction with the diesel is some kinda "white mans magic" best avoided at all costs.

All 3 reckoned if they removed the LPG they could have fixed my engine - when it was nothing to do with the LPG, but they all wanted to rip it out!

Cheers!

[tallyF350]

That makes sence. From what I have read one can see 50-60 mpg running a CNG conversion. We are getting our first station here in Tallahassee Florida next month so I am looking at this option hard.

What PSI tank does your system have?

[Lucky Eddy]

Without looking I believe it is about 160 psi max but they pressure test the vessel to over 300 psi when new i.e. before install.

50-60mpg just isn't going to happen, not even if you ran it on cocain!

The LPG conversion might add maybe 10% to your straight diesel mileage...

You can adjust it to deliver a little more under load, however - here at least that dyno chart was done while the govt auto engineers were exhaust gas emissions testing to make sure the engine output stayed within manufacturers specifications, so the gas installer was very careful not to dial up the gas as high as it can go, because then it would fail the exhaust emissions tests and not be legal for license to use on the road.

The installer did say to me that if I was of a mind too - after the emissions testing and certification - I could take it back too him and he would wind it up a notch, but that if I somehow got caught (pretty unlikely) that he never heard of me...

I never bothered to take it back.

My experience towing between 4 & 5 tonnes of boat at 60 miles an hour over long distances has been that I usually get about 5 kilometers per liter....which I know means diddly squat to you Imperial measurements guys in the USA who like miles per gallon so I will convert it for you....

Our English imperial gallon [4.45 liters] is about 25% larger than your US Gallon [3.38 liters] so I will convert it to US miles per gallon so it has some meaning for you!

~1.6 kms per statute mile.
~ 3.38 liters / US Gallon

I make that about 10.5 miles per US gallon towing a load at speed.

Without the load on I get about 17 Miles per english gallon so about 13 miles per US gallon.

Those are just rough workings...but should give you some idea.

CNG or LPG conversion is good for a little extra performance but not a great deal - I just did it at the time for a little extra few horses and some extra distance.

I put in a 73 US gallon diesel long range tank and the 160 liters of LPG lasts me 2 tanks of diesel.

The LPG conversion cost me about $4500 for the LPG tank and fitting etc and the long range diesel tank(s there's actually 2 of them joined with a short hose to make the total of 73 US Gallons) cost another $1200

I will never make that back in fuel savings if I live to a thousand years old so I didn't do it to save dollars I did it to give me extra horses and extended fuel range for long range remote towing as part of my charter fishing bidness.

It's not uncommon to tow for 2 days straight and over 1000 miles to go for a fish here...

Hope this info helps out.