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[Martin_1962]

Part 1 The basics

The Omega is quite a good car to convert to LPG as it is large has plenty of room and runs well on gas as well.

Firstly you will get a power drop - this is unavoidable but can be miminised, I am estimating a similar drop in power as the difference between a hot day and a cool day - about 10bhp on the V6.

LPG is Liquid/Liquified Petrolium Gas and is Propane - I use LPG as  both a generic term or for describing when Propane is a liquid, I call it gas when Propane is a gas.

There are a number of types of LPG system but I will only deal with Sequential Gas Injection, there are quite a few makes of kit but I will only deal with Romano System N which is fitted to both my car and Taxi Drivers car.

As the name suggests Sequential Gas Injection (SGI) injects gas (rather than LPG), sequentially, the LPG ECU monitors the cars signals to the petrol injectors using what is called cut injector cables, these fit between the car loom and the petrol injectors, and monitor when the injectors fire. Unless the wires are connected to the ECU this is one
stage where the car is immobile.

The Romano System N monitors the following

RPM from the green wire on the cars ECU
Injection timings from the cut injector leads
LPG pressure at the tank (for gas fuel gauge)
Gas pressure at the injection manifold
Evaporator temperature

It controls the following

Solenoids on tank and evaporator
Gas injectors
Cuts off petrol injectors

The Romano ECU slaves from the Omega ECU for when to fire injectors and for how long.

Parts - I'll start from the back

Filler - this is the Dutch standard bayonet filler - every European country seems to use a different filler design this most be mounted within the vehicle plan but outside of the body. It is connected to the tank with 8mm gas pipe.

The tank can live in various places and is available in multiple designs, one warning DO NOT USE DOUGHNUT TANK IN THE SALOON AS YOU WILL NOT BE ABLE TO CHANGE LIGHT BULBS. I have a 70l Stako tank which holds around 60l.

The tank is always fitted with a valve assembly, this has the solenoid to the 6mm pipe, one way valve on the 8mm pipe, a physical pressure gauge and connections to the LPG ECU fuel gauge and solenoid feed.

Any pipe within the body must be vented to outside of the car - 34mm "vacuum cleaner" style hose is used.

The main gas pipe runs from the bot throught to the engine compartment, it must not go near the exhaust (very difficult with the V6s) and must not be bashable.

The next item is the engine end solenoid which protects against front end leaks, it is still a liquid here.

Just after the solenoid the LPG enters the evaporator, this turns the LPG into a gas, and is fitted with a hot water feed, the insides are not simple as it adjusts flow depending on intake vacuum.

The gas then travels via hose to the injector manifold, where the pressure is monitored and the gas is passed to the injectors,  the injectors are connected to the cars inlet manifold, mine go via brass nozzles which fit into the plenum and squirt straight into the inlet manifold very near the petrol injectors.

That is the basic layout of a SGI system I will go into more details next post.

This is worth a read!

http://www.autogasworldwide.co.uk

[Martin_1962]

Location Location

Where can I put the parts?

In the saloon the best bet for the tank is a cylindrical one in the boot, (insert picture from my car) a toroidial tank would prevent bulbs from being changed in the left rear light cluster.

In the estate a toroidial tank fits on the floor quite well. (insert TDs comments and TD picture)

Filler quite often this involves drilling a hole in the rear quarter panel, there are various regulations regarding (Martin look them up!) fitting this. If you have a tow bar a very good place is on a bracket on the tow bar, this is very common with off roaders as well. The filler must be within the plan of the body and must not project beyond the body, however tow bar fitted fillers appear to be fully legal (pic of mine)

The evaporator is used to turn the LPG into gas for the injectors, this uses engine hot water to do this, there are various places to get hot water from but the best is the heater circuit from behind the engine, there is insufficient flow from the throttle body heater and other pipes are not suitable.

There are stepped size T pieces with 16mm and I think 20mm on them, one is used on the thicker pipe from block to Heater Bypass Valve and one on the pipe returning from the heater and the Bypass Valve

This sorts out the hot water.

The evaporator itself is awkwards to fit, as it is the biggest item which goes under the bonnet and needs pipework attached, I ended up fitting mine under the air box, removing the side of the airbox and putting a plate inside to repair it. I also had to move the auxiliary coolant pump about 50mm towards the rear of the engine compartment, this was the most difficult part of the installation I found.

The evaporator also has the forwards solenoid bolted to it so the connections to the evaporator are.

Water

Two pipe to heater circuit

LPG and gas

LPG pipe to solenoid, pipe from solenoid to evaporator, hose from evaporator to gas manifold

Air

Vacuum pipe to pressure sensor and plenum or inlet manifold.

Electric

Solenoid power, and sensor wiring for evaporator temperature.

The ECU also needs to be fitted and the most common and easiest place to fit it is under the scuttle P side, jasmming the pollen filter in. Mine is on a GRP panel which slides into position and bolted into place as I was unable to drill holes in the bulkhead to match the ECU.

Control switch - Depends on how you feel, but you have a choice, if you remove Traffic Master you could put it there, or
you can mount it in the pre facelift coin tray, on the facelift on the dash underside or fit a single DIN head unit and put the control switch in that new cubby hole. (piccies)


Wiring is too much for this article - see a future article where we go into more details.

Injector nozzles, two options here, Romano systems tend to use brass nozzles through the plenum squirting into the manifold, other systems have nozzles fitted direct to the inlet manifold. (piccie)

[MartinP]

Part 1 The basics

The Omega is quite a good car to convert to LPG as it is large has plenty of room and runs well on gas as well.

Firstly you will get a power drop - this is unavoidable but can be miminised, I am estimating a similar drop in power as the difference between a hot day and a cool day - about 10bhp on the V6.

Sorry about the picture size, will have to upload a bigger pic.

Just to support the 10BHP drop claim, this is my power graph from Jamsport earlier this year.

The car suffered from a 20BHP power drop from book value on petrol, but the LPG was only 9 BHP under that

[archermk]

Hi Martin, excellent write-up there. I know we've discussed this before (you-know-where), but I'm interested in where other people have located their gas ECU. My reason for asking: the unit that was replaced in mine following heavy rain some months ago drowned again last week after those thunderstorms. It's being replaced this week. Mine is presently in the scuttle panel exactly where yours is but the LPG engineer wants to move it somewhere else (possibly inside the cabin under the dash). I know that space is tight with a V6 under the bonnet but just wondering what others have done?

Regards
Jeremy

[Martin_1962]

MIne is in the scuttle an installer put one in the airbox but that chokes Omegas

Keep that drain hole clear!!

[Taxi_Driver]

Mines in the same place....being pally with the pollen filter  [smiley=shocked.gif]

[MartinP]

My ECU is in the relay box, (front near side next to the battery). The fuel relays (pink ones) had to be repositioned  further down the box.

[Martin_1962]

You have twin mixers though both Dave and I have Romano System  N SGI (him a 3-4 me a 5-6-8) and the ECU is pretty big!

[Martin_1962]

Wiring - well there is quite a bit to do but nothing difficult, the injector looms, control switch, cut injector cables all have connectors.

Soldering is expected for conversions not crimping, this is a standard which manufacturers of kit insist on, I crimped then ran solder into the connectors.

For a Romano 5-6-8 we have the following.

2 Injector leads, to go to injector looms.

2 Cut injector leads, these connect to interface cables which are fitted between injectors and the Omega loom

Control lead, 4 wire lead to the controller in the car.

Tank level lead. This is a two wire lead to the tank measuring the amount of gas, this will require more wire added and soldered on.

Pressure sensor lead, this is another 4 wire lead, to the pressure sensor unit.

Temperature sensor lead, this needs extending to reach the temperature sensor on the evaporator.

Solenoid leads, two wires which will need more soldered to it to go to all the solenoids in the system, mine has a tank solenoid and a front end solenoid.

Power, connect to battery

RPM connect to green wire from ECU.

NOTE: Mine was originally wired with shared earth betwen tank solenoid and level sensor, also they used what looked like mains lead and I was sure it was under the car.

I am assuming scuttle for ECU and under airbox for evaporator.

Wiring routes

From the ECU to right hand side of engine bay, I routed injector cables through a ground out half hole and slightly cut scuttle trim. Presure, temperature and front solenoid were through a cable hole in the scuttle trim, and they were wrapped then cable tied to the brake pipe behind the engine. All cables are routed from RHS so when plenum is removed it can be swung to the cars right.

I put the cut injector, power, and RPM through the big grommet on the front of the scuttle air filter area, and put the controller cable and enough leads to run the length of the car through the grommit into the passenger compartment. TBC

[Martin_1962]

Between the ECU and tank you really need 4 wires unless you want to share the return. best place is under the side covers under the rear seat and into the boot.

More to come!

[Jim]

How much did your LPG conversion cost?

[Martin_1962]

How much did your LPG conversion cost?

WHich one - the bodged MV6 was 1850 and the DIY was about 100 in bits.

I reckon you can DIY an Omega for a little over £800 using a Romano System N SGI

[MartinP]

My Install from back to front, had the car a year now and only just got round to taking all the pictures

This is a single point system that has largely been superceeded by the multi-point sequencial systems

All pictures can be used for reference by othere on thes site  
Filling point


85 Ltr Tank arrangement


Vent sheath on pipework


Gas supply solonoid lives under the scuttle

[MartinP]

Vapouriser


Vapouriser outfeed valve, (Martin will tell us what this does and how it is controlled) + volume control valve with splitter



Twin Inlet ports


"Leonardo" CPU lives here



Gas control switch, (TC button moved to row above, facelift button)

[Martin_1962]

Interesting, does the evaporator make maintenance there awkwards?

Also this is a mixer system isn't it?