New pistons? Absolutely not old chap. LPG is Liquified Petroleum Gas. It needs no modification to the engine, just how the fuel is delivered. Depending on the complexity of the engine depends on what system you need. A 2.7 twin turbo engine needs a different system to a 1.1 Yugo from 1982.

As for the conversion itself, you basically have a tank in the boot/trunk or spare wheel well, a fuel line to the engine bay, a fuel rail, injectors and a box of electronics that controls everything in the engine bay, and a fuel guage and switch in the cabin. The whole think can be bolted on, with no mods to the engine (your engine can run on both lpg and petrol).

 

I don't know about the States, but here in the UK it's the cost of petrol that's insane. Let's takes someone who averages 1000 miles a month. I'll use UK Sterling prices here but just double them for dollars. The conversion costs approx £1500.Petrol for 1000 miles a month in a 2.7t costs approx £220 and is rising. LPG costs for the same mileage are approx £80, saving £140 per month. Therefore, after 11 months the conversionhas paid for itself and I'm £140 a month better off every month thereafter. That will (should!!) more than pay for running costs and repairs.

 

The problem in the USA is with the lack of refilling stations for LPG and CNG, and EPA and CARB certification of conversion kits. Also, the USA is very large, so larger tanks are required for longer distances between these refilling stations. Another problem is that the summers are very hot in the USA. I even had an unusedspare tire blow up once, in a Ford Taurus wagon. A short time ago,a company in town had tanks stored outside in the sun that caught on fire and turned their place into a fireworks show, with tanks flying through the air in
to nearby homes and businesses. Locating these tanks inside a hot unvented uninsulatedcar trunk (boot) is more risky than even outdoor storage.

 

LPG has been largely ignored in theUK until recently,until petrol costs started to rise at the rate they have the last 6 months. There's now one new LPG filling station a day across the country (although the UK is slightly smaller than the USA lol).Most cars will take an 80 litre tank and all tanks are fitted with pressure release valves when the temperature starts to go up - we do have a few days of hot weather here as well sometimes lol. At the end of the day you have to weigh up the benefits and drawbacks, like anything else really.

 

Apparently, a defective tank or pressure release valve on a hot summer day in the trunk (boot) could result in a leak which could ignite even if vented to the outside. A hot summer day would be 100 degrees farenheit plus, so the inside truck temperature would be 140 degrees farenheit plus. There are places in the USA that get over 115 degrees farenheit for more that a few weeks. This is one of the hazards of high pressure systems. Also, this venting of gas in the USA may be in violation of EPA and CARB emmision regulations.

 

Here in Mobile it can get pretty hot in the summer.
Having a tank of lp or cng in a trunk that is probably around 110-120 F concerns me a bit.

I wonder if the cost of lp/cng per thermwillcontinue to be lower than gasoline.

 

I think you're overly worrying about the temperature. Like I say, we also get some hot weather here in the UK believe it or not. In 2006 we had over95F for most of June and I left my A6 in the car park at work in direct sunlight. However, it didn't explode, leak, catch fire or even smell of gas. The manufacturers of LPG equipment need to take environmental issues and risks into account. After seeing the construction of LPG tanks and valves etc. I'd take my chances with LPG over a plastic petrol tank any day of the week.

In the UK, the government has always touted LPG as a green fuel. They've agreed a limit on the tax amount for so many years and Industry has agreed they won't raise the cost of LPG above 50% of petrol/gasoline.

 

When I was travelling in India, years ago, they had CNG in their old rusty taxis. It was part of a drive to lower polution. The same is true in other parts of Asia, where it gets pretty hot.

If they can sort out CNG without tanks exploding, I would hope they could fix that problem in the US.

 

Well done LiquidTuna for running on LPG.

Running on an alternative fuel has several complications but in Europe one very large cost advantage.
Payback of £1550 can be expect every year if you currently spend £70 per week. But we know that the price of petrol is going up and up - lpg will increase too, but will rise at the 50% differential. Cheap conversions cost less and better lpg installations a little more than £1550.

Safety is paramount, then fuel tanks and lines are over-engineered (bearing inmind the fuel is the same as in plastic cigerette lighters) and the system instantly shuts the fuel valves down when the engines stops. Making the system inherently safer than diesel vehicles.

Modern systems can be retro-fitted by competent mechnics, the inlet manifold is drilled with injection nozzles, the water system t-pieced to circulate around a vapourier, wiring interpts on the petrol injector signals, mounting of associated injector rails and ECU and bolting a tank on somewhere. It takes us some 25-35 hours a vehicle - others recon they turn them around in a day!

Sampling of the petrol injection signals allows the gas calibration programme to calculate a gas injection correction, that is applied to the petrol injection duty cycle to produce the opening duration of the gas injector on that channel. Once the correction value is optimised the existing engine management system does all the work of varying the petrol injection opening time under different load coditions, oblivious that its indirectly running lpg injectors, leaving the petrol ones closed and the fuel being recycled back to the tank as in normal operation.

Examples of what vehicles we have lpg converted can be seen at www.gascarco.com.gallery
Have a look amongst the car autogas conversion albums there are 1.8T engines, 2.0 litre, V6 engines in the Audi TT, lpg conversions to V6 Turbo engines fitted to the A6, the V8 engine in the stateley A8 and the Passat W8 - which is a beauty.

Enjoy driving past forecourt price signs again, this time have a little chuckle to yourself. Saving 60 pence a litre (June 08) over petrol at £1.18

Big-in' the whole show up, one might say, "Get on gas, have yourself more cash"

Details of FSI engines and our lpg conversions can be found at http://www.arunautogas.co.uk/lpg_and...on_engines.htm