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Subaru Bi-Fuel (LPG+Gasoline)


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3 replies to this topic

#1 rverdoold

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Posted 22 November 2007 - 03:58 PM

I have seen some questions around about subaru's on Propane or LPG gas, as well as Bi-fuel or EcoMatic. Besides the '91 legacy i own my dad drives a 05 outback wagon with 2.5i egine (+4EAT) which is a Bi-fuel.
The Bi-Fuel or Ecomatic changes are:
  • Removed spare tire (special tire fix spray is included, tire as well but there is no space in the car cause LPG tank is fitted there. In germany spare tire is obligator so extra mount is made for smaller tire. On the Forester the tire can be mounted underneath the car. Tank contains roll-over valve, emergency overpressure purge valve (above 35 bar). This empties the tank when the car is on fire to prevent that the tank explodes. Actually this is much safer than a normal gasoline tank on fire as shown by german road safety organisation (although a bi-fuel has both).
  • Second ECU to controll the propane injection, is linked with 1st ECU to get gasoline injection points and timings as rest of car information. This ECU monitors: Tank presure (9 to 14 bar), high pressure injectors, temp, timing ect.
  • Tank monitor and LPG/gasoline switch (to switch between power sources)
  • A connector on the side of the car to fill the tank.
Some images:
Tank in the back of the car with Pressure Regulator Valve (PRV) and safety valves as well as a manual turn off knob/valve.
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On the left side of the car is the connector for the hose. Never dirty hands with spilling its just propane.
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Then on the dash on the left side, just under the vent on the far left is the switch with tank fill indicator.
Posted Image
In the egine bay on the passenger side (LHD) the propane regulator is, the ECU is mounted next to the transmission.
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The propane regulator from Bosch (LPI pressure injection system)
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On the intake manifold the injectors are build into this
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The system works fine, when tank is full (14 bar) there is even more response than on 98 octane (propane is 104 to 110 octane). Sometimes on Kick-down the system can not supply enough propane (lower tank pressure) and drive is switched to gasoline which is not always very shock free. In Europe propane is widely available for 1/2 to 1/3 of the gasoline price. The fuel efficency is 11 litres per 100 km while the computer still shows 8.6 litres per 100 km so there is no communication between those values on the computer.
Because the propane is injected under low temperature (-10 to -20 C) it cools the pistons and valves reducing egine wear.

Car ran now 105000 km and just had its big maintenance service. Intervals are every 15k to 20k km. Never had any problem with the car (except bad front brake discs but think all outbacks had that). Driving was not the most friendly this means: high revs (well warmed up engine though), high speeds (above 150 km/h) long periods of time (>4h) on the german autobahns to Italy, even driving periods (30 mins) at full throttle/full speed of 200km/h on the GPS. This car is just perfect and very strong.

EDIT: reworked images, might change them later

#2 hklaine

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Posted 29 November 2007 - 10:20 AM

what does this conversion/addition cost?

#3 rverdoold

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Posted 29 November 2007 - 03:42 PM

what does this conversion/addition cost?


This conversion including labour done by a specialized company was around 2000 euro's (dont convert to dollars it does not give realistic numbers:confused: ).

reason why conversion done:
Road tax for the weight of the car per 3 months
  • gasoline (1.5 euro/l, 8.8l/100km) = 150 euros
  • LPG (0.55 euro/l, 11l/100km) = 190 euros
  • Diesel (1.2 euro/l, 5.6l/100km) = 300 euros
So after driving more than 7500 km a year its cheaper to drive on LPG

Nowadays conversions are sold for 995 euros on new cars, especially because of lower emmission while fuel efficienty is not that low

#4 rverdoold

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Posted 29 November 2007 - 04:01 PM

There are a few manufacturers of LPG systems:
Koltec-necam which is used by factory LPG systems in subarus
TeleflexGFI is a manufacturer which is widely used in VW (+group) and BMW, these are also sold in USA but i have no idea how and where. maybe www.teleflexgfi.nl (partly in english) can help. I also dont know if they work in subarus.
Eurogas (www.eurogas.nl)
Vialle (www.vialle.nl)

As nipper stated there can be problems with emission checks. Althoug i can not imagine why because LPG has a cleaner burn than gasoline it also does not contain other stuff (like sulphur ect.)




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