Whichever way you look at it, the BA – BF Falcon XR6 Turbo is one of the best all-round big used family cars you can buy in Australia. Now available from around only $18,000, with the turbo Falcon you get plenty of space, performance, comfort, towing ability – and good ride and handling. Trouble is, the 4 litre turbocharged engine also drinks a lot...
But there’s an answer – convert it to electronic gaseous LPG injection.
The consumption of fuel won’t decrease – it actually rises a bit – but with the much cheaper cost of LPG, you can (at the time of writing) literally halve your weekly fuel bill. And that’s no idle claim – we talked to XR6 Turbo Falcon owner Michael Beltrame about his car. Michael has owned the car since new and the 6-speed manual now has about 50,000 kilometres on it. It’s recently been converted to gas injection by Parnell LP Gas Systems and not only could we ask Michael about his experience, we were also able to sample the car for ourselves.
But first, the gas system.
The system uses components primarily developed by Prins Autogassystemen BV of The Netherlands. Prins supplies the dedicated LPG ECU, the wiring loom, regulator/converter and filter/sensor assemblies.
However, the most important parts of the system – the injectors – are manufactured by Keihin, a Japanese company with close links to Honda. On the Falcon the injectors are mounted in two blocks of three. The same size gas injectors are used in both naturally aspirated and turbo Falcons.
The injectors are connected to the inlet manifold runners by short hoses.
The gas tank is conventional and contains a level transducer and external electronic solenoid lock-off valve. It is mounted behind the seat.
The gas then flows to the converter / pressure regulator that changes the LPG from liquid to gas and regulates its pressure. In a turbo application the gas pressure is boost-referenced. From the converter/regulator, the gas flows to the filter assembly that uses a combined sensor for gas temperature and pressure.
On turbo cars like the Falcon, a specific MAP sensor is installed.
The LPG ECU mounts under the bonnet.
The system is calibrated for the car by a laptop software package. This also allows fault diagnosis and graphing of sensor outputs. As seen here, the software has a specific ‘turbo’ mode.
An OBD scanner is used to check the LPG tune – if the tune is correct, the short and long-term fuel trims should not show major and ongoing change values.
In operation, the car always starts on petrol. This is primarily because there is minimum coolant temp below which the converter cannot function in converting the liquid LPG to a gas. A short time after the coolant has reached the minimum operating temperature (both the time and the temperature are programmable), the LPG control system automatically switches off the petrol injectors and turns on the gas injectors.
The driver is provided with a small dash-mounted interface unit. This combines the function of LPG fuel level gauge, gas/petrol changeover switch, warning beeper and fault code indicator.
The internal beeper sounds if gas pressure falls too low and the system switches back to petrol (eg because the gas is running out). It also warns the driver if a major fault condition has developed that again causes the car to switch back to petrol.
The LPG system can log about 50 faults, including stalling on the switch to LPG, gas temp too high or too low, gas converter slow to warm up and ‘missing’ at high revs. A particularly interesting fault that is logged is when the gas system pressure falls to less than 1.25 bar within 4 hours of the engine being switched off – indicative of a gas leak.
As shown here, the system cost $4,400, that price including fitting and GST. However, the government will give you back $2,000 so the total out-of-pocket expense is only $2,400.
So how does that stack up in terms of payback period? On the basis of current LPG and premium unleaded prices, Michael’s fuel bill has dropped from $100 a week to $50. Do the maths and you’ll find that the pay-back period is only 48 weeks! Yes, in less than a year the conversion cost will be paid for – and after that, it’s like fuel is at half price. (Of course, those figures are based on current petrol and LPG prices.)
But if the car drives like a pig, or performance is way down, the trade-off for the conversion will be measured in a lot more than just dollars and cents.
First we talked to Michael about the car’s driveability on gas. He told us that he couldn’t detect any difference in power or aspects like idle quality. In fact, the only difference he could feel on gas was that when the over-rev cut and traction control action occurred, the effect was softer. That is, the actions of the rev-cut and traction control system weren’t as harsh.
But surely power would be down? Well, it might be a fraction – but you’d need a dyno to find it. On the road the car drove just like any other standard XR6 Turbo – that is to say, linear in power delivery, refined and comfortable. Throttle response on petrol and LPG felt the same, and full throttle performance was undiminished on gas. There wasn’t a hint of stutters, missing or flat spots.
In fact, cover the in-cabin switch and we wouldn’t have been able to tell if the car was running on LPG or petrol...
We couldn’t find any downsides in the driving but the installation does have one negative. With the gas tank installed behind the back seat, two things occur. Firstly, available boot space decreases. Michael, a family man, told us he could still fit a large pram in the boot, but there’s no escaping the loss of useable volume. Secondly, while the rear seat still folds, the opening is blocked by the tank - long objects can’t be loaded to take advantage of the joined cabin and boot space.
An alternative tank position is available – it uses a donut-shaped tank that replaces the spare wheel. This costs about $800 more than the behind-seat tank but the main reason that Michael didn’t opt for it is that he was concerned that with the more rearwards tank location, the weight balance of the car might have been changed. He likes the car’s standard handling balance, and the current location of the LPG tank hasn’t altered that.
This conversion looks like a win/win to us. The end result is a car that retains all of its factory pluses and yet costs the petrol equivalent of getting about 5.5 – 6 litres/100km fuel economy! If you do high kilometres, the conversion is paid off very quickly – and even if travelling more modest distances, it will still be paid for in only a few years.
Michael Beltrame – a qualified engineer and budding Formula Ford racer – has absolutely no complaints...