Efficiency gains with Orbital LPG system words - Jeremy Bass Time is running out for petrol diehards as LPG closes the gap with petrol It's already a given that LPG is cheaper and cleaner than petrol. Now it's freeing itself from the traditional driveability and reliability catches as well.
If you want a pointer to the value of liquefied petroleum gas (aka LPG or propane) as automotive fuel, look no further than the nation's taxi fleet. No car owners or drivers are more dedicated to extracting maximum kilometres for minimum dollars, first in day-to-day fill prices, then in long-term running costs and durability. There's hardly a cab in this country that doesn't bear the red LPG diamond on its plates, and there has to be a reason for that. There is: LPG, branded Autogas at service stations, is a proven cost-cutter.
Traditionally, LPG has been seen as an inferior alternative to petrol. This is a view that's changing fast, particularly with the advent of liquid injection systems, which iron out many of the driveability and performance problems hitherto taken as synonymous with the technology.
"LPG early on had a reputation for being a bit cranky -- a bit rough, a bit hesitant when you didn't want it to be," says Phil Westlake, a mechanic by trade, but now business development manager with engineering firm Orbital Auto Gas Systems, one of Australia's larger LPG systems suppliers.
"The newer systems -- even the aftermarket bolt-ons -- are on a par with petrol systems in performance and smoothness," Westlake says.
Indeed, Orbital's own dynamometer testing has shown an aftermarket kit to produce minor power and torque improvements over ULP on a VE Commodore (see graph).
There are three basic ways you can make the move to LPG. You can fit virtually any model car with an aftermarket kit that works in parallel with the existing petrol system. This takes place entirely independently of the auto maker, with all warranties coming from the installer and/or the component manufacturer.
Or you can buy some models with factory-approved systems. Figuratively speaking, these comprise approved components fitted to the finished car by approved aftermarket installers out the back of the car factory.
Both these systems are bolted on to the finished car, making it dual-fuel and switchable between the two. The primary advantage here is that it near doubles the car's range. The primary disadvantages: it comes at the cost of boot space taken up by the LPG tank, and it means the engine can't be optimised to take full advantage of LPG's different combustion envelope.
Third comes the more complex and sophisticated option: factory fitted, dedicated LPG packages in which the LPG tank takes the place of the petrol tank and the EMS is recalibrated to take advantage of LPG's specific combustion characteristics and higher -- 103 to 107 -- octane count.
By virtue of its acquisition of Boral Alternative Fuel Systems in 2008, Orbital has inherited the contract to supply Ford with components for its factory-fitted, dedicated E-Gas pack. With the existing system now more than a decade old and therefore thoroughly outmoded, Ford will be giving the Falcon E-Gas a massive overhaul later this year, with the move to liquid injection system using components from Perth-based Orbital and Melbourne-based Alternative Fuel Innovations.
It's better for your engine and the environment Because it enters the combustion chamber as a gas rather than as a spray of tiny droplets, LPG burns cleaner than petrol. That means less carbon buildup on engine components, with less wear and tear on spark plugs, engine oils and all the parts they lubricate, so it can actually extend service intervals and, ultimately, the life of your engine.
These benefits took a dramatic hike in the early 2000s, when vapour injection systems came to market to replace the old fumigator systems. "The old systems amounted to little more than carburetion, where the fuel would be sucked into the manifold on the intake stroke," says Westlake. "Vapour injection ironed out a lot of those reliability problems by making the whole process more precise, efficient."
Liquid injection boosts that efficiency by a similar factor again. The key lies in the way it keeps the LPG under sufficient pressure to remain in liquid form through the injector and into the intake manifold. Propane boils at -42C degrees, so the moment it enters the manifold space it expands some 270 times into gaseous form. This has a near-freezing effect on the air with which it mixes, keeping the mechanicals cooler to boost power and fuel efficiency and reduce emissions.
And because LPG burns as a gas, as opposed to a petroleum's spray of tiny droplets, it burns cleaner, meaning it emits 10 to 15 percent less greenhouse gas and around 80 percent less in the way of particulates and other toxins (and 90 percent fewer than diesels). And that's right from the moment of ignition, so even when the engine's cold it's running cleaner.
The LPG value proposition -- how it pays for itself Calculating the comparative costs of running your car on LPG against petrol boils down to two basic facts.
First, the bad news: a substantial disadvantage in energy density means it takes 50 percent more LPG to travel the same distance as petrol under identical driving conditions. An example: Ford puts its current E-Gas Falcon's fuel consumption at 14.9L/100km combined. The ULP equivalent uses just 9.9L/100km.
Second, the good news: LPG is normally 50 percent cheaper per litre, often more, than the cheapest ULP or diesel. It's plentiful, and it attracts none of the excise governments attach to petrol and diesel. And it's available at 3200 service stations across Australia -- that's about half the total number.
At $1.20 a litre for ULP, that Falcon using 9.9L/100km of petrol will cost $11.88 to drive 100 kilometres. At $0.60 for LPG, the same drive will cost only $8.94, even with that massive disparity in fuel efficiency.
LPG Australia estimates the potential savings over a year thus: if ULP averages $1.40 a litre over that year and LPG averages $0.65, a Commodore driver putting in a busyish 28,000 km a year on LPG would save about $38 a week -- more than $2000 a year.
For a Toyota HiAce owner, 40,000 km year on LPG would save about $55 a week -- more than $2,800 a year.
And governments pay you to convert Almost any ULP engine (including PULP) can be converted to LPG, albeit dual-fuel, not dedicated. Expect to pay between $2,500 to $4,500 installed, depending on the car, the fuel system and how you option it up.
But payback is hastened dramatically with the federal, state and territory governments paying you to do it. Through the LPG Vehicle Scheme, the federal government will pay you a $1750 rebate to retrofit a unit if you do it before July 1 this year. After that it drops to $1500; after July 1 2011 it drops to $1250; then to $1000 from July 1 2012 until June 30, 2014.
The grant goes up to $2000 if you buy a new car with a factory fitted or factory approved LPG fuel system. The threshold here is first time registration -- if it's already fitted before the car is registered, the full $2000 applies.
On top of that, Western Australians are eligible for a further $1000 rebate from the state government on both retrofit kits and cars with factory-fitted LPG systems. In the ACT, LPG earns you a 20 per cent concession on your registration.
If you want to work out how fast you'll recoup your conversion costs, LPG Australia's website (http://www.lpgautogas.com.au/) includes a little payback calculator.
If you're running commercial trucks or buses over 3.5 tonnes, chances are you're eligible for subsidies of up to 50 per cent on new vehicle purchases, retrofits and LPG system upgrades from the Australian Greenhouse Office, under the Alternate Fuels Conversion Program.
Note, though, that for post-2003 vehicles this is contingent on their being fitted with a system that meets current emissions test standards.
Dedicated or dual-fuel? Dedicated LPG systems deliver the greatest benefits to fleet operators. It's administratively easier, with all warranty issues dealt with by the manufacturer. Plus it gives fleet buyers a way of tightening their rein on fuel costs.
"Because of that old perception that LPG is somehow inferior to petrol, it's pretty common for fleet drivers to use their fuel cards to sneak petrol into the car rather than gas," says Westlake. "Obviously they can't do that when the car only takes LPG."
In calibrating an EMS, there's a three-way trade-off to consider, between power, fuel consumption and emissions. In calibrating the fuel system, aftermarket suppliers worked on the principle of finding a sweet spot between those three. Car makers have the extra advantage of being able to calibrate the EMS to favour any of those, but it will always be at the expense of the other two. This is a pointer to how the consumer benefits from a factory-fitted system like Ford's.
"Aftermarket installers can only calibrate the fuel system components -- they can't fiddle with the ECU to optimise it for LPG, whereas the car maker can," says Westlake.
Liquid injection represents another quantum leap in the technology's progress towards mainstream acceptance.
"It's killed all the old objections to LPG. Even with the dual-fuel aftermarket systems, it takes considerable expertise to tell the difference, or to identify the moment of cutover."
What about LPG and diesel? While LPG is more often touted as a complete alternative to diesel, the two aren't mutually exclusive. There are kits available for 4x4s and heavy vehicles that infuse injected diesel fuel with a little LPG. Advocates say this can push combustion efficiency from a normal 75-80 percent to over 95 percent, boosting power and torque while dramatically reducing sooty particulate emissions.
"It's a pretty simple idea," says Orbital's Westlake. "You save money by displacing about 20 percent of the $1.60-a-litre diesel fuel with $0.60-a-litre LPG. That can add up to a fair amount of money a year for a semi putting in 100,000 kilometres a year. But it's restricted to puttering along freeways under light loads. Once they load up, or when the driver puts a foot down, it reverts to pure diesel."
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To comment on this article click here Published : Friday, 26 March 2010
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