Dedicated LPG?

[lowact]

Currently upgrading my V12 to HE, EFI, by swapping heads and pistons and a new ecu. Hoping to set new records for cleanliness and efficiency. Question is, should follow Marek and convert to LPG?

I really like the idea of dedicated LPG (no petrol) liquid phase injection (LPi). Petrol tank and pump replaced by LPG tank and pump, petrol injectors replaced by 12 LPG liquid-phase injectors (Vialle), each controlled sequentially by new programmable ECU.

Potentially improved performance. The last cars built in Australia included dedicated LPi Fords, they are quite impressive, out-perform their petrol counterparts. Reason is the liquid injection. Upon injection the change of state (liquid to vapour) absorbs heat, lowers the temperature and increases the density of the intake charge, i.e. you can pack more in (very high volumetric efficiency). Also, liquid can be precisely metered, not possible with vapour injection, so LPi can be significantly more economical than earlier generation LPG systems.

The LPG LPi synergies with HE V12 seem good. Jaguar really pushed the limits with the design of the HE, consequences: highest quality 98 octane fuel is essential; engines can overheat; relatively dirty engines, pic shows the as-found conditions inside the rocker covers of my 70k mile e-type engine and 90k mile XJ12S3 HE engine.

With LPG LPi these limits disappear; LPG octane rating is over 100, the phase-change cooling effect prevents overheating and unlike with petrol, oil is not washed off the cylinder walls, there is less blow-by.
Other benefits: the fuel is naturally cleaner, negligible particulate matter and CO, a lot less HC, less NOx and CO2, I would not need catalytic converters to achieve socially acceptable emissions.

Then there are the disadvantages:

Slower to start, fuel system needs to be primed to > 30 bar before engaging the starter motor. Maybe much the same as now, having to wait for the fuel pump to stop ticking.

Petrol lubricates valves to a degree. LPG does not. The Ford LPi engines had different top piston rings and valve seats. Dunno how our Jaguar items compare, I would like to think that “lean-burn” HE engines would be up to the mark ...

Range would take a hit. My car (US emissions spec) could manage 450 km between refills. After the current HE/efi mods + OD I would be hoping for 650 km if petrol. If LPG, with the biggest tank that would sort of fit after removing the petrol tank and losing the spare wheel, range would be maybe a tad over 400 km.

Biggest concern is the apparent unpopularity of Autogas (LPG) meaning the number of service stations that sell the stuff is reducing, so the rumor goes? There is an app that locates all the Australian Autogas service stations. I am trying to find out if it is kept up to date, including removing any stations that stop selling it? No luck so far …

[MarekH]

I'm a bit tied up at the moment, but will reply on Monday/Tuesday, perhaps via pm.

The extraction of latent heat point still has benefits with vapour injection in that the coolant gets about 6-7'c taken out of it so I generally run at ~79'c cruising and the thermostats never quite open. At idle, it also helps and the 82'c thermostats cycle.

Jags have hardened valve seats.

Startup on lpg vapour is a cynch, as the fuel is perfectly vapourised. The starter motor quite often disengages after just half a turn of the crank, i.e. the third cylinder to be fuelled has fired the engine up so revs run away and the ECU has already switched off of the start map and onto the main map.

I don't buy the argument that it is harder to meter propane gas than it would be to meter propane liquid, as the vast majority of lpg cars are gas not liquid propane. I run Keihin orange spot vapour injectors.

Megasquirt can run both petrol and lpg.

If you are savvy, a 90 litre tank will fit AND you can keep the petrol setup.

I spent about GBP1500 on fuel injection and the same again on LPG. Bear in mind most commercial LPG products are powered by piggy-back ECUs.

Fitting 24 fuel injectors into the "V" is a challenge.

I generally don't run petrol - why would you if you can have 105ish RON(?) fuel which is half the cost of petrol?

There are thumbnail pictures on jag-lovers.com in my photo albums if you click on "old website".

kind regards
Marek

[AussieEtype]

Colin - not a V12 but a Rover Thor V8 - currently running on carbs and vapour LPG and petrol - I have a petrol injection and LPG injection system to go on sometime.

LPG availability - yes is an issue as lpg taxis have gone so have LPG outlets so careful planning is needed on a trip. However in Canberra is not yet an issue as LPG is still readily available. I use an app called PetrolSpy to see what is available and at what price.

The injection system still uses a gas converter that converts the LPG from liquid to gas. While the injection and vapour systems use different units they do the same function. The issue is that heat is lost when converting from liquid to gas so the unit freezes - hot coolant from the engine fixes this but on start the coolant is still cold - on cold Canberra winter mornings this can be an issue so I start on petrol and switch over to gas once the engine is running - that little bit of heat is enough. My engine can start on gas (I also have a gas primer) in summer no problems but will not start on gas in winter and the primer freezes as soon as you hot it. I have an additional pipe plumbed direct into the inlet manifold and on cold mornings I can squirt flammable gas in (Start ya Bastard) and it fires up on gas. So consider that if you go just gas cold starts may be an issue even with an injection system.

I have room to drill holes for the gas injectors next to the petrol injectors and I know you want to just replace the petrol system with the LPG but if there is room consider going dual as it is the perfect arrangement.

Most injection gas systems just splice in the injection ECU to each of the petrol cables to each petrol injector - now MS can run gas direct but in my view MS is not the way to go - over hyped and no support in Australia - maybe different if we lived in the UK or the USA - your Altec system should be able to run it direct if you want to go LPG only.

Injected LPG only should work OK but just be aware that starting on cold winter Canberra mornings, may or may not be an issue. I would consider dual fuel as the best option if there is room for LPG injectors as well as petrol injectors (a small purpose made petrol tank should fit up in the rear wheel arch space like Land Rovers do).

However given the amount of use you car will get for its remaining life (and I guess yours ) is it really worth doing the conversion.

Cheers

Garry

[lowact]

Garry thx for the app reference, PetrolSpy, kept up to date by users, I like it.
I think what you are describing is vapour mixing vs vapour injection, both use a converter to 1st convert the liquid to gas, when it’s very cold the converter needs some warmth to stop it freezing. So cars using these systems usually need dual fuel, petrol for reliable starting.
What I am looking at is next level, LPG liquid (not vapour) injection. There is no converter, it is effectively exactly the same as a petrol system; a pump in the LPG tank boosts the pressure to prevent any vaporization while feeding liquid directly to the liquid LPG injectors and, via pressure regulator, liquid back to the tank. The vapourization happens naturally as the liquid is injected into the intake port, it is all the cooling happening at this point that makes it so effective.
My understanding, such liquid-phase injection (LPi) is what enabled Ford to eventually develop dedicated, LPG only, cars. Holden never did, never progressed beyond vapour-phase injection, is why their LPG cars were always dual fuel.
Seems the only manufacturer of LPi systems is the Dutch company Vialle. Here is a link to a Vialle technical manual that I've found.
http://www.suzukituning.com/General/Via ... oc26108855

[AussieEtype]

Hi Colin - yes I certainly did misunderstand.

When you do all this - what is your intended use for your car - LPG liquid injection would certainly be usable on an everyday driver but for a 50 year old historic vehicle is the effort really worth it but I do agree it is an interesting challenge.

Please keep us appraised of what you decide to do

Garry

[Bob.]

It's nearly 50 years since I converted my Triumph Spitfire to run on LPG, on a shoestring budget and using a simple vapour mixing system. Technology has changed but on sensible budgets you can't get away from having to cart around approx 1kg of steel pressure vessel for every 1kg of fuel (IIRC). If you throw out your spare wheel and petrol tank it will help, but putting that extra mass behind the rear axle won't help handling. Unless you keep a petrol system with a significant range you will almost certainly suffer "range anxiety" at some point on LPG alone when away from guaranteed supplies.
Having said that I achieved about 10% worse mpg than on petrol which was no surprise given the lower energy density of LPG compared to petrol on a volume basis but at the time propane was a lot cheaper than petrol.
If you go ahead I will certainly be interested to follow the story.
A couple of ancient pictures and yes with the supercharger it makes the inlet tract of a carburetted V12 looks short.
Bob

[Barry]

Sir William Lyons, Walter Hassan et al would turn in their graves! The beautiful V12 was designed to run on petrol. So why on earth would you want to change to LPG? All that effort to achieve what?

[MarekH]

Dear Colin,

I've had a look at the Vialle system you propose to use and it does not deliver what you are asking of it. Like almost all lpg systems, it is a piggy-back system which starts by intercepting the fuel injection signals of a petrol based ECU and then reinterprets them for the second fuel type. This means you'll have to build up and instal a running petrol fuel injection system first. Furthermore, like all piggy-back systems, it does nothing to take advantage of the high resistance to knock that the higher octane fuel has, so you'd always be running the same old ignition system, several degrees more retarded than you need to, unless you go to the sophistication of adaptive knock related timing for petrol.

Quite a lot of the text in the technical document is somewhat out of date (their patent dates back to 1993), in the fact that it is not comparing the Vialle system with current state of the art lpg systems, but assuming (wrongly) that more primitive mixer systems are the benchmark, incapable of accurately metering the required gas. It also anticipates starting on petrol and switching over subsequently.

A further complication is that until very recently, no one has ever gone to the trouble of fully supporting twelve cylinder sequential injection for ANY affordable aftermarket ECU, let alone a piggy-back ECU, so the system will only ever be implemented as a batch fired 6 cylinder at best, or you buy two lots of front end components. (The Lucas 16CU which Roger Bywater fits is just a four cylinder system with three injectors batched per output.) I doubt the Vialle system supports more than 8 cylinders - there's no market for it.

Keihin also make CNG injectors, but I don't hear much about them. There is a reason why CNG has never really caught on. Aside from the intercooler effect, it has nothing to offer that regular lpg doesn't and that is a much more developed and mature market.

The only way to do this as a stand alone system is to go the Megasquirt (or other new-ish aftermarket ECU) route. If you go that route, it's be a whole lot simpler just copying something that already works.

Engine November 2011.jpg (190.84 KiB) Viewed 14814 times

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kind regards
Marek

P.S. Barry:- it doubles the range of the car, delivers more torque, more power, has full modern diagnostics and runs at up to 40mpg in cash terms. And just for you, it comes with this interesting little extra......(Mr Bond)

troublesome passenger switch.jpg (214.6 KiB) Viewed 14814 times

[Barry]

Thank you Marek. Not that I’d ever want to question you excellent engineering prowess. You have clearly shown it works! I’ll stick to my 6.0 litre, Roger Bywater Torque Plus engine. The thought of changing it is above my pay grade! Your LPG conversion is clearly beautifully engineered.

[MarekH]

It's not engineering prowess - I appear to be the only one who read the technical document and answered the question.

One thing is not 100% clear and that is whether Colin already has some form of fuel injection fitted and is in the process of merely fitting a different ECU, or whether is still on carburettors. In either case, the Vialle system wants to sit on top of a working petrol fuel injection system.

kind regards
Marek

[lowact]

Bob, I hope that Spitfire is saved for posterity?

Garry, my car is my hobby, making sympathetic improvements. I.e. I bought it to mod. Gridlocked in a taxi on the Tullamarine freeway, missing flight again, an FHC cruised past in the opposite direction, I had an epiphany. Bought a cheap OTS sight unseen on ebay from US when dollars were parity, did not matter how rough, rusted or incomplete ‘cos I was going to mod it. Shipped from North Carolina, picked it up from the docks at Port Kembla, drove it home the same day. It was in complete and original condition, how to justify modding it? Finally resolved that I didn’t need to justify. Now making up for lost time.

Barry, I would say the opposite, by all accounts Sir Bill was utterly pragmatic?

Marek, no injection, currently underway, here is progress …


Thx for your photos, showing enlightening detail not visible in the Jag-lovers thumb-nails.
My understanding: piggy-back LPG ecu’s require the car to start by petrol however piggy-back ecu’s are only needed if the oem ecu is not reconfigurable or is not permitted to be reconfigured or is still needed for dual fuel system. With dedicated liquid-phase lpg it is possible and better to use a single, fully configurable ecu (e.g. Adaptronic M6000 or the imminent Haltech Nexus R5) to directly and sequentially control (closed-loop) the low impedance liquid lpg injectors (pulse-width modulated), including ability to use all ecu functionality, the same as if the fuel was petrol. Both the above ecu’s have confirmed capability. Whether the fuel rail is 3 bar or 30 bar, makes no difference to these ecu’s.

Here is how I’m thinking that a tank with 60 L useable capacity could fit and, without the existing tank and spare wheel, provide 40% more boot capacity, with balanced weight distribution and good protection, due to location almost between the rear wheels with plenty of crumple zone in the event of a rear end shunt.


Currently I’m waiting to hear back from Speedgas (Vialle dealer in Aus.) re prices (tank, pump, lines, injectors, regulator, ancillaries).

[MarekH]

Dear Colin,

It's going to be expensive, as you are proposing to buy two 6 cylinder front ends plus their custom pump to recirculate the fuel and their custom multivalve. There is healthy competition with lpg vapour injection, so the parts for vapour injection are substantially cheaper.

At the back, if you are already proposing to go above the boot board, then a much larger tank is possible. Mine is bolted into custom brackets which are held on plates welded into the car. The original boot boards fit back on and believe it or not, there is space for a spare wheel inside the boot. (There isn't space for anything else mind you.) I wouldn't worry too much about a back end shunt - lpg tanks are very heavy and thick pressure vessels. The same impact on a petrol etype will be substantially more dangerous all round.

Check see whether Keihin injectors will fit the standard Jaguar manifold better than Vialle do. If that is the case, then the only thing Vialle bring to the party is the recirculating pump and the tank multivalve. If you can get hold of those two items at a competitive price, then this all looks quite promising.

The other thing to check out is the standard Jaguar 6 litre fuel rail from 1992 to 1996. This is different from the earlier version in that the injectors bolt into the rail itself both top and bottom, rather than being held by a short rubber hoses and barbs. The latter won't cut it at the pressures you are going to see.

You obviously need to make a front end trigger wheel for the ignition/fueling system. For sequential fueling, you also need a camshaft (or distributor) sensor. If you want pictures of how that can be done, then just ask.

kind regards
Marek

[Rustyred]

Colin!
I would seriously think about the LPG conversion,
Working in the Auto industry has made me change my mind about LPG use and the need to revert back to Full pump petrol.

Couple of reasons,
LPG in Australia has seen a decline in its use in the Automotive market as fewer vehicles are being converted the number of certified gas installers has dropped as well as the number of Authorised inspectors for Rego each year have terminated. Along with quality of the Gas itself, which is another very big issue as it causes on-going maintenance and repair on the converted vehicles.

LPG Injection, when it did come out in the early 90's, was the new kid on the block and was going to be a big hit, Claims of Power better than Normal Pump petrol, Less maintenance the look of the fitment of the new conversion, as it had less components than the early EFI systems required, all good so far.
Unfortunately, cost was the biggest killer at around $3500 to $4500 for the install and tuning to get it right. There were few and far manufacturers who were offering their kits, as well as minimal installers with the training to get these systems right. The early pressure systems had failures and the said vehicles had to be towed back to original repairers at substantial cost, they were not a success, later Italian manufactures finessed the system, what could of been never was.

Then the Government threw the LPG subsidy in at half cost, promoted more Gas conversions and Taxi Companies to receive more benefits, the bodgy workshops started to claim the rebates for systems that weren't even fitted, Government sold our gas offshore for nothing, then the price of gas tripled, then the whole exercise went to to crap.

LPG was always sposed to be half of the fuel cost per litre, in fact nearly went the opposite.
When I first installed Full LPG(2001) it was 29 cpl(cents per litre) Fuel was 65 cpl, 3 years later, price jumped to a steady 69.5 and fuel was 94 cpl. Now it maintains the only 1/3rd less cost.

So in my opinion it no longer is worth conversion as well as reduced Service Stations that have LPG. The other main reason is the lack of BTU's in today gas, the other reason for extra maintenance and breakdown today. LPG doesn't burn like it used to, Its not as clean, in Australia anyway. Have you ever wondered why your BBQ doesn't heat up like its used to or plate doesn't get hot anymore, it now burns yellow/orange, More Hydrocarbon or Butylene added for fill rather than performance and burn. Another way to get ripped off without ever seeing it.
Just my opinion.

Regards John

[MarekH]

I don't think a dedicated LPG only conversion is a good idea either - even here where LPG stations are reasonably common.

Also, liquid phase setups account for less than 1% of LPG conversions over here.

Good luck all the same if you choose to go this route.

kind regards
Marek