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Installing your multipoint sequential system
It may seem like a bit of a nightmare when you first get it all out of the box! But do not fear, its really not that bad! Have a read through this page before you get started.
The first thing to decide is where you are going to put everything, it is worth spending a bit of time mapping out the position of the major components.
All installations will have a filter/shut-off valve and a reducer/vaporiser. Unless the shut-off valve is fitted directly to the reducer, the pipe between these two should have an anti-vibration loop in it. So, allow the necessary space for this.
Do not mount the shut-off valve or reducer on the engine – it moves too much.
The reducer should be close to the filter/shut-off valve. I tend to use a double ended fitting known as a nipple, which allows you to fit the shut off valve directly onto the vaporiser. If the vehicle is used off-road, try to fit the reducer so that it will remain clear of any water when wading. The reducer requires heat in order to vaporise the LPG. This usually comes from the heater circuit. Decide how to route the two water hoses from the engine (heater circuit or throttle body circuit) to the vaporiser. If the flow rate through the chosen circuit is low, try to fit the reducer lower down to avoid air-locks.
The gas is introduced into the engine through a gas injector rail. The rail will have the correct amount of injectors for your vehicle. In the case of a V6 or V8 engine you will nornally have two pairs of injector rails. threes or fours.
These rails should be within 30 cm (pipe length) of the injector nozzles. This is the ideal and certainly with the first few kits that I fitted, I was very carfull to observe this. But I have since expermented and found that keeping the pipes all the same lenght or more than 30cm makes little differance. My advice would be, do a neat and tidy job and if this means a couple of pipes are longer than others so be it! When I questioned Bigas on this point they agreed and gave the following reason.
Imagine the gas in the injector pipes as a row of busses all parked nose to tail, when the injector opens and releases more 'busses' they push the busses at the bottom of the pipe into the manifold. The pipe stays full of gas so if one pipe is a bit longer than another, so what!
In my opinion, the following paragrah is far more important. I have witnessed lots of well fitted systems that run like a bag of nails and for only one reason. The injector spuds are to far away from the petrol injectors!!
The nozzles themselves should be fitted as closely as possible to the original petrol injectors. Positioning of the injector nozzles is very important.
They should be placed near to the petrol injectors (max. 50mm away, it is extremely important to fit the nozzles close to the petrol injectors). Try to fit them in the middle of the manifold branch to allow even distribution of gas (especially on multi-valve engines where the nozzle should be centred between the inlet valves).The injector spuds should be mounted radially and slightly inclined towards the valves if possible
However in practice this may not always be possible. The golden rule is to keep the nozzle the same distance from the valves as the petrol injectors are. If this means fitting the nozzle to one side of the manifold pipe then I would take this option rather than placeing them 50mm away.
Drill injector holes to 5mm and tap with M6 x 1.0 thread. Remove the manifold if necessary to prevent swarf from entering engine. Most installers will admit to drilling manifolds in situe. If it is drilled carefully with plenty of grease on the drill bit and a hover to hand, it should not be a problem. Plastic manifolds can often be ‘drilled’ using a heated 5mm pointed rod to reduce swarf.
Another good tip, which I do often is to connect a air compressor the the manifold, by starting with a low air pressure and slightly increasing it as you drill more holes, you can blow any swarf back out of the hole you are drilling. In my opion this is the best way to reduce the swarf.