MY SECOND CONVERSION (done with 'Alternatech Fuel Systems Ltd' - http://www.alternatech.co.uk)

After being burnt the first time with Mr Steven P Sparrow of Go LPG, I decided to do as much research as I could into the types and makes of systems available.

I concluded very early on that there was no sense in going for anything other than a fully sequential system as my car was manufactured in 2001 making it electronically complex with a BOSCH DME (ECU) and seperate EGS (gearbox ECU). In addition, it is OBD-II compliant meaning that the LPG system needs to be able to integrate seamlessly with the car's electronics (otherwise I will have CEL - Check Engine Light errors flashed up all the time like with Go LPG's Romano N system).

The main systems to choose from were:

BRC Sequent, E-Gas, Prins VSI, and a whole host of other system based on AEB technology (Romano N, OMVL etc). I chose the Prins VSI system for reasons discussed on the Prins VSI system page.

Please refer to pictures of the conversion below:

Prins VSI system

ENGINE BAY PRE-CONVERSION (Removing the Romano N system)

Disconnecting the nasty wiring and Romano N ECU.

 

 

 

 

Disconnecting the horribly installed gas injector pipes/rail.

Taking off Romano N
SPAGHETTI JUNCTION 1

Taking off Romano N
SPAGHETTI JUNCTION 2

REMOVE THE EXISTING INLET MANIFOLD (the one butchered by Go LPG!)

Here the inlet manifold has been removed after removing the Romano N system. The pictures show:

  • Existing vehicle wiring left in a mess by Go LPG.

  • Eight ports (four either side) and plastic valley pan cover checked for coolant leaks and cleaned up.

  • Coolant pipes running from water-pump at the front of the engine to the water-manifold at the back of the engine.

Internal view
GO LPG BUTCHERED INLET MANIFOLD REMOVED

PREPARE NEW INLET MANIFOLD

A new inlet manifold was required as the previous one was drilled way too high up (not removed to save time and hence, more money for Go LPG). The pictures show:

  • New (original BMW) inlet manifold drilled/tapped with brass nozzles as close to the petrol injectors as is possible (only possible on a bench - not in situ).

  • New (original BMW) crank case ventilation valve, suction pump, pipe and vacuum pipe at the back of the new inlet manifold.

  • New (original BMW) inlet manifold gaskets installed.
   
MODIFY INLET MANIFOLD AND COOLANT HOSES

Once the nozzles for LPG had been drilled/tapped into the appropriate positions in the new inlet manifold:

  • LPG injector-to-nozzle supply hoses (as short as possible and of equal length) were connected to the nozzles in the inlet manifold.

  • New (original BMW) gaskets used, inlet manifold placed into position and new (original BMW) bolts torqued.

  • New (original BMW) coolant hoses used, 'teed' on the bench (not in situ) and secured to heater core and secondary heater pump (on the opposite end) using stainless steel 'Jubilee' (worm-drive) clips.
FUEL SYSTEM

Now it's time to remove the old LPG fuel system installed by Go LPG and fit a new system suitable for the car;

  • Single hole tank removed and replaced with 4 hole tank with flexible filler pipe for petrol-like filling speed.

  • Existing tank straps used - these were bolted to the chassis behind the rear seats (the car has no 'through-load').
  • 8mm LPG supply pipe routed safely and clipped using appropriate clips at appropriate distances.

  • Nice, neat position made in the engine bay to secure custom bracket to which the single Prins VSI vapouriser will be secured.
VAPOURISER INSTALLATION

The Prins VSI vapouriser (when compared to the Romano N) oozes quality in terms of construction and robustness. In addition, only ONE vapouriser is needed to feed the circa 300 BHP V8!

Preparing a bracket to mount the vapouriser on (the bracket was sprayed black to fit in with the colour of the vehicle).
Preparing a nice neat place for the bracket and vapouriser to be secured to the vehicle.
Positioning the vapouriser.
LPG INJECTOR INSTALLATION
Two injector rails are used with four injectors per rail (one per bank). Yellow Keihin injectors were chosen:
INSTALLING WIRING & PRINS VSI ECU

The Prins VSI ECU also oozes quality in terms of it's construction when comared to a Roman N ECU.

Integrating the Prins VSI ECU and wiring into the cars original climate-controlled ECU box is no easy task but it is a job worth doing properly to give an OEM look and feel:

ALL DONE

Three to four days of work pay off and the system is complete:

  • New (original BMW) electrical wiring covers are back on (remember, these were removed and chucked by Go LPG).

  • The LPG ECU has been placed in the original BMW climate-controlled ECU box.

  • Trunking has been used to cover hoses, wiring has been insulated and is hardly visible and the engine bay looks neat & tidy!

  • The system has been configured using Prins' own software and the car goes like **** off a shovel!

  • The new four hole tank with flexible filler pipe fills MUCH faster than the previous single hole tank which had an 8mm copper fill pipe.

  • I have used a new (original BMW) alternative rear diffuser also for a sport model but with tow-bar option. This has allowed me to completely hide the LPG fuel filler for a completely stealth install!