Jun 6, 2014

Conversion Of Diesel Engine To Natural Gas Engine

As the name says diesel engine is one which use diesel as a fuel to produce power and CNG compressed natural gas engine is one which use natural gas to produce power. All diesel engines can be converted to natural gas. The power level of the engine after conversion depends on numerous issues, such as
  • natural gas quality
  • power level of the original diesel engine
  • emission levels required

If Engine Conversion is done properly then Natural Gas engine can produce as much power as diesel engine does. Diesel engines converted to natural gas generally require added components as well as some mechanical changes to the engine. Following are the steps which are involve in conversion of diesel engine Natural Gas engine

Conversion Steps

1- Disassemble the engine.

First step in the conversion of diesel engine to Natural Gas id to disassemble it because there a many parts that have to be replace and many parts to upgrade in order to make the new engine work properly For disassembling an engine you need a skill worker because it is really a difficult job to disassemble an engine is proper and safe way.

Following are the steps involve in disassembling the engine in proper way
  • Remove center bolt & flywheel
  • Drain engine fluids
  •  Remove front peripherals
  • Remove side & top peripherals
  • Disassemble valve train
  • Remove cylinder heads
  • Remove oil pan & timing set
  • Disassemble block underside
  • Disassemble pistons
  • Remove crankshaft
  • Remove plugs
  • Remove valve assembly

2- Checking and replace necessary components.

Diesel engine relay on high compression ratio to produce the ignition that’s why they have high compression piston, long connecting rod and special camshaft. Natural Gas engine on the other hand use spark plug to produce the ignition. So there is a need of changing the piston, connecting rod and camshaft to produce the low compression ratio.
Diesel engine do not have spark plug and CNG engine need spark plug so there should be some redesigning of head suction to make a place for spark plug.
There are many other changes like changing gears in the gearbox to get the right gear ratios to suit a gas engine, the exhaust system to get the right catalytic converter, use the right vents and filler cap for gas instead of diesel and changing the fuel injectors and fuel pump and maybe the tank too.

3- Modify For lower compression ratio.

Diesel engine did not use spark plug to ignite the fuel rather they high compression to produce the ignition but CNG engine work totally in opposite direction they have very small compression ratio and use spark plug to produce the ignition in fuel. So there is need of making some changes to produce low compression ratio in diesel engine to make it fit for CNG

Following are some of the ways you can make low compression ratio

Low compression pistons

Low compression piston is smaller and light in weight in than conventional piston. Because of their small size and lighter weight they cannot produce the high compression ratio and there plus point is that they can move faster than conventional piston.

Shorter Connecting Rod

Making the connecting rod shorter will have a dramatic effect on compression ratio because it reduce the stroke the length and results in low compression ratio and fast working

5- Modify cylinder head for spark plugs.

As already mention natural gas engine need spark plug to ignite the gas but spark plug is absent in diesel engine so it is necessary to install a spark plug in the head suction of diesel engine. This required the redesigning of the engine head suction. Proper skill are required to do this job perfectly

6- Install camshaft sensor and timing wheel.

The Camshaft Position sensor is typically located in the cylinder head of the engine and has a cylindrical portion that inserts into the head. The Crankshaft Position sensor is normally located in the timing cover or on the side of the block with a cylindrical portion that inserts into the block.
The timing gear is connected by chain, gears, or a belt to the crankshaft at one end and the camshaft on the other. It is marked with tiny increments all around its perimeter, which correspond to degrees of timing from the straight-up timing position of the camshaft and crankshaft. These marks assist the individual who is tuning up the engine to set the timing to the determined optimal timing degrees of the camshaft and engine designers.

7- Reassemble engine.

Up till now all the changes which had to be made inside the engine has been completed now it is time to reassemble the engine. It is done step by step like the disassemble of the engine. A highly skill worker is needed for this job

8- Install throttle body, ignition system, gas mixer or fuel injectors.

Throttle body is a device use to control the intake of fuel in engine. They are installed just before the engine and controlled mechanically and electrically. In natural gas engine the controlled the amount of gas passes to engine

Most ignition systems on natural gas engines are weak and cannot assure ignition under all operating conditions. This hurts fuel consumption, power and emissions. Furthermore, frequent replacement of low-quality ignition wires and the associated downtime is a big expense. Capacitor Based Ignition Wires assure combustion initiation and low cycle-to-cycle variation in lean burn natural gas engines beyond Lambda 1.6.

Gas mixture or fuel injection system is one which prepares the air and gas mixture according to the requirement that is according to power being produce by the engine.

9- Tuning of the engine (fuel and ignition).

Engine tuning is the adjustment, modification or design of internal combustion engines to yield optimal performance, to increase an engine's power output, economy, or durability. Tuning can describe a wide variety of adjustments and modifications, from the routine adjustment of the carburetor and ignition system to significant engine overhauls. At the other end of the scale, performance tuning of an engine can involve revisiting some of the design decisions taken at quite an early stage in the development of the engine.

Last Words

So that’s was all about the conversion of Diesel engine to natural gas engine. We hope that you have understood each and every point about the conversion of engine. If we have miss any information or you think that you have more interesting information on this topic please feel free to comment in below comment box 


Post a Comment