Sequential LPG/CNG kit - Knowledge base

Have shared my knowledge on sequential kit. Hope this helps to understand before making decission.

When we press the pedal. the air pass to the  engine through the air cleaner/filter and proceeds to the throttle plate.   It is then distributed through a series of passages called the intake manifold, to each cylinder.  At some point, fuel is added to the air-stream by either a fuel injection system or, in older vehicles, by the carburetor.

In morden machines, the ECU sees the throttle valve open and increases the fuel rate in anticipation of more air entering the engine. The fuel is supplied to the engine by injector. Once the fuel is vaporized into the air stream, the mixture is drawn into each cylinder as that cylinder begins its intake stroke.  When the piston reaches the bottom of  the cylinder, the intake valve closes and the piston begins moving up in the cylinder compressing the charge.  When  the piston reaches the top, the spark plug ignites the fuel-air mixture causing a powerful expansion of the gas, which pushes the piston back down with great force against the crankshaft.

Sequential Kit, Parts and Functioning

1.Tank
2.Solenoid valve
3.LPG/Petrol change overswitch   with indicator
4.Gas filter
5.Reducer/vaproisor
6.Gas injectors
7.controller
8.pressure sensor

Tank
Tank is where the gas/propane is stored. The two most common LPG tank options are either a cylinder shaped tank, fitted in the rear boot space, or a toroidal/donut shaped tank, fitted in the spare wheel space.

Solenoid valve and Change overswitch
A solenoid is an electromechanical device which allows for an electrical device to control the flow of a gas or liquid. solenoids are fitted to the outputs of Gas tank and is controlled by change over switch connected to it. The switch is used to change between fuels.

Filter
Filters are used to filter dust.

Reducer/vaproisor
A vaproisor is designed to convert the LPG/CNG from liquid to gaseous stage. It reduces the input pressure of 20 bar to a output pressure equal to atmospheric pressure and the reduced pressure of LPG/CNG is supplied to engine.  Because of the refrigerant characteristic of the fuel, heat must be put into the fuel by the reducer. This is usually achieved by having engine coolant circulated through a heat exchanger that transfers heat from that coolant to the LPG.

The vaporized LPG/CNG is then fed to injector rail with nozzles which are screwed into holes drilled into the runners of intake manifold.

Injector
A fuel injector is nothing but an electronically controlled valve. It is capable of opening and closing many times per second. When the injector is energized, an electromagnet moves a plunger that opens the valve, allowing the pressurized fuel to squirt out through a tiny nozzle. The nozzle is designed to atomize the fuel -- to make as fine a mist as possible so that it can burn easily. There is usually one injector for each cylinder. The amount of fuel supplied to the engine is determined by the amount of time the fuel injector stays open. This is called the pulse width, and it is controlled by the ECU with helo of sensors.

conti...

Controller
One of the most important function of the controller/ECU is it controls the fuel mixture used by the engine. The controller/ECU determines when is the right time to deliver the air and fuel ratio to the engine. Based on the data gathered by the sensors, the controller/ECU works by pulsing or controlling the fuel injectors in the engine. If the injector is turned on, the fuel is sprayed at the back of the intake valve.

Sensors
Oxygen sensor(s) - Monitors the amount of oxygen in the exhaust so the ECU can determine how rich or lean the fuel mixture is and make adjustments accordingly.
Pressure sensor - Monitors the pressure of the air in the intake manifold

Each injector can open just before the intake valve for its cylinder opens and this is called sequential fuel injection. The advantage of sequential fuel injection is that if the driver makes
a sudden change, the system can respond more quickly because from the time the change is made, it only has to wait only until the next intake valve opens, instead of for the next complete revolution of the engine.

Advantages of sequential kit

1. Performance will be identical to petrol. Driver will not notice the machine running in LPG otherwise stated. With CNG, a power loss of 10% will be noticable.
2. FE almost equal to petrol.
3. No maintenace other then regular maintenance required. The gas filter must be replaced every 25,000 km. The reducer should be inspected every 40,000 km to make sure that no oil or various residues are present due to the different composition of the LPG.
4. No tinkering other then few holes drilled in manifold and in boot for tank . These days manifold comes in plastic.
5. The machine always starts with pertol and changes to gas on move. Various parameters set as RPM, temperature etc
6. No chanegover required if fuel goes dry. Automatically changes to petrol if LPG/CNG goes dry.

Guys, Please share if I  have missed any.

- Redline