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Part 2 - LPG Conversion Kit

<< Part 1 - Research | LPG Conversion Index | Part 3 - Installation >>

LPG Kit Contents

ScoobyLPG-WiringLoom.jpg: 480x640, 338k (August 28, 2009, at 10:11 PM)
ECU and wiring loom
ScoobyLPG-TankPic.jpg: 306x243, 10k (August 28, 2009, at 10:12 PM)
LPG Tank
ScoobyLPG-Injectors2.jpg: 640x480, 322k (August 28, 2009, at 10:16 PM)
ScoobyLPG-BracketMoun2.jpg: 640x480, 332k (March 29, 2014, at 09:41 PM)
ScoobyLPG-PressureSensor2.jpg: 640x480, 294k (August 28, 2009, at 10:14 PM)
Pressure Sensor

The LPG kit bought comprises the following parts supplied:

  • Bigas LPG ECU and wiring harness.
  • Bigas Liquid-phase shut-off valve.
  • Bigas RI-21 Double vaporizer/reducer.
  • Bigas injector rails, biagiotti fast x 2 banks.
  • AEB 1090 fuel sender unit.
  • AEB 025 pressure sensor.
  • AEB 750B changeover switch/level indicator.
  • Vapour-phase LPG filter x 2
  • Stako LPG tank Cylinder Type, 360 mm x 892 mm 80 litres gross, 64 litres (i.e. 80% of the gross capacity) LPG
  • Tank bracket and straps.
  • Europa multivalve 30 degree 360mm.
  • UK bayonet filler - 90 degree.
  • 8mm copper fuel pipe.
  • 4mm LPG pipe - used for pressure, vacuum and injector connections.
  • LPG rubber gas pipe.
  • Flashlube valve saver kit
  • Software and programming lead for ECU.
  • Latest version of the code of practice for fitting LPG systems to motor vehicles.
  • Full fitting instructions.

The above kit is very comprehensive and all other required fixings are in the kit. The only other parts I needed to buy were those that were required to relocate the washer bottles and battery on my car. I did fabricate brackets, as shown in the installation section, to mount the various parts as space is very limited on the Impreza. I also decided to use flexible 8mm lpg pipe as this made things a lot easier for routing the LPG pipe from front to rear.

The kit supplied from Tinleytech cost 930 inc vat and del.

Summary of the kits operation.

The above system is designed as a sequential multipoint LPG injection system. The double reducer (also known as a vaporiser) is able to supply a substantial amount of gas and is rated to 350hp. When coupled to the larger injectors supplied, this is feasible.

The ECU allows the car to start on petrol and when a programmable predetermined coolant temperature is reached (the reducer is connected to the coolant system) it will automatically switch over to LPG ( if the car was stopped when running on LPG the last time). If stopped when running on petrol, the driver must switch over to gas after starting the vehicle. With either method the transition isn't noticeable and normally takes 25 seconds after initial starting (subject to temperature) which is done even when driving. The switch over is smooth due to the sequential switch over method. One gas injector takes over from its petrol counterpart while all the other petrol injectors continue injecting. Each one in turn is then switched over until all 4 are running LPG.

The LPG ECU mirrors the injector signals from the petrol ECU and in doing so injects the correct amount of gas to match the AFR of what it would be on petrol.

At high loads (and boost pressures) the system can be programmed to either switch back to petrol entirely or provide a petrol contribution. RPM and injection times in ms are used to program this. As some vehicles have idle problems with LPG it can also be set to return to petrol at low rpm.

The unit has a failsafe mechanism that will always leave the car able to run petrol even if a component fails. It can also be started on LPG in an emergency situation where petrol for whatever reason is unable to power/start the vehicle.

Summary of the mounting of the parts.

The tank can be mounted either inside the boot or externally on the vehicle. If mounted internally a gas tight box is used where the gas enters and exits the tank. The LPG lines and wiring from the tanks shut off valve and sender unit are routed via vent tubes. This ensures that no gas enters the cabin in the event of a gas leak.

The filler unit is of a bayonet type is mounted just about anywhere on the rear of the vehicle. This can be on a rear quarter panel or even the bumper. A bracket can be used to mount the filler without having to cut holes in panels.

The LPG supply pipe is mounted under the vehicle away from exhaust and suspension components.

The reducer and shut off valve are to be mounted on the bulkhead or inner wings, but not on the engine as it moves too much. A coolant supply is connected to the reducer in order to vaporise the gas at the right temperature and pressure.

The ECU can be fitted either inside the cabin or under the bonnet making sure that the wiring connectors face downwards to stop water ingress.

The injector banks can be mounted on the engine due to the rubber gas pipes that supply the LPG. The injectors supply nozzles at no more than 30cm distance, with the nozzles themselves being tapped into the manifold no more than 5cm away from the petrol injectors.

The LPG map sensor is mounted nearby the ECU.

The change over switch is located in the cabin on the dash board. It indicates the current fuel state and the tank level of the LPG.

The LPG code of practice supplies the information necessary to perform a safe installation.

Information Source - ScoobyLPG website, republished with permission,

<< Part 1 - Research | LPG Conversion Index | Part 3 - Installation >>

Page last modified on June 14, 2008, at 10:03 PM
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