Do not try to do this! You will damage the petrol engine which will not be designed to use the high compression ratios that the diesel engine generates (20:1 against 9:1). Plus you need the fuel injection system which is totally different between the two engines. Test biodiesel in a diesel engine not a petrol engine; it won't work in a petrol engine anyway as it isn't volatile enough.

The use of them is different. For gasoline; we talk about Octane number for the quality of behavior of gasoline in the engine. For diesel is the Cetane number. Petrol engine is mainly composed by iso-paraffins and aromtics for a good octane number.

Conversion would be virtually impossible. A petrol engine has a compression ratio of about 8.5 to 1, whereas a diesel engine has a compression ratio of about 22 to 1. To accomplish this the diesel engine has a crankshaft with much larger offsets so that the pistons slide farther in the cylinders. Also the diesel engine has thicker walls to contain the higher pressure. So if you managed to install a diesel crankshaft and diesel piston rods in a petrol engine, it would probably explode when you started it up.

Arvindh, 13 years ago a young friend of mine made biodiesel in his garage from used restaurant cooking oil and put it in his 1980 Volkswagen diesel Rabbit. It ran very well and smelled like french fries instead of a city bus.

Thank you all..... :). I finally runned it in diesel engine..

1. Fuel injection system, high pressure pipe, pump etc etc.

2. Compression ratio petrol has low, diesel has high need to either change the compression ratio via variable compression ratio Engine or change the head of the piston.

3. Spark plug, chock it

4. Need to check the injection time at certain crank angle.

5.And to hold that high compression ..it will be difficult for a petrol engine to sustain.

Ok first of all ignore the comments that say its impossible so far.

Now, it’s possible to convert most petrol engines to diesel. If fact this has been done before by VW with their air cooled boxer beetle engine.

1. engine construction. The old version beetle had a cast iron block which made it fairly strong, while “most” modern diesel engines are forged metals as opposed to cast metals used in petrol based cars, with forged parts being used predominantly in petrol race cars rather than street cars. To this end, it’s likely to find some durability issues with cast engines as is found with some cheaper Diesel engines on the market that also used cast blocks, heads, crankshafts and pistons. So while a limiting factor it’s not enough to deem it impossible. It further also implies that a cheap race engine could be built be converting a Diesel engine to run on petrol or more preferably methanol.

2. compression. This is relatively the simple part of the job. How I would approach this issue is to find a Diesel engine that is similar to the engine you have, as far as rotating in the same direction, ignitio chamber size, cubic capacity, bore and stroke this will save you from having to re engineer and create custom fuel maps. Compression can be supplied by a turbocharger to increase the overall cylinder pressure to be the same as your donor engine, to This extent your literally copy and pasting what another engineer has calculated Already. Its unlikely that you be able to utilise the entire intake and exhaust manifolds but it may be possible to use parts of both the original and the donor engine to create one.

3. engine control and fuel injection. This is where the project will become hard. Ideally what you will want to do is use the entire setup from the donor engine, this includes ecm/ecm’s(often called a car ecu or computer), Sensors, wiring harness, injection system, fuel pump, common rail pump, etc. the sensors are unlikely to fit and will need to be customised, the if you’re unbelievably lucky the common rail injectors will screw into the spark plug holes otherwise they will need to be tapped. The previous injector holes will need to be blocked, engine timing will need to match the donor engin, etc. you will need to research more on each engine

3. an alternative custom system. While it’s going to be hard to work with a common rail system it may be easier to use a carby diesel setup. The problem with this is while there are almost no sensors to worry about you will still need to run a turbocharger or supercharger For the compression ignition system. Which while it’s possible to run both carbys and turbochargers and it has been done on a number of production cars. it is rather difficult. The main area of focus will be if the carby runs before or after the turbocharger. It’s likely that running a turbo after the carby will result is the diesel igniting before it reaches the engine due to the exhaust turbine heat and the increased pressure, but running a carby after a turbocharger will require a special carby that can both handle the pressure but is also able to injec fuel. A supercharger will run a lot cooler but some elements of compression ignition are also still an area of concern. It’s also possible to increase the compression like in pre turbo Diesel engines by increasing the stroke but the calculations on this become very complicated and finding a crankshaft that’s will supply the extra stroke length, while also fitting your original engine and also finding pistons that won’t collide with the head is even harder.

conclusion: its entirely possible and has been done before by VW but they have the ability to not only have complete blueprints of an engine but also the ability to custom engineer parts. it’s not going to be easy or cheap which realistically means it may be easier to just use a different engine but that’s for your own assessment. This is a general guide and not ment for exact instructions but a more larger overview of the concept.

Aiden's answer first states that it's possible to convert a petrol engine to a diesel - but he then gives a large list of things that have to be done for this to happen. In my view, unless you're an experienced engine designer like Aidanj seems to be, don't ry it! A long time ago in the UK Rolls Royce were tasked to make a tank engine that ran on pretty well anything - and they succeeded, with the exception of coal dust. So it's not impossible, just quite difficult and not a task for the inexperienced.

The nature of combustion is totally different. In Motor cycle the combustion is controlled by sparking while in diesel engine the combustion is controlled by compression.Regards

It is not possible to convert petrol engine into diesel engine. Because for same power output size of CI is more than SI engine and also because of heterogeneous combustion in CI engine. Also due to less CR it will not start also.