Diesel Fuel Injection in a Two-Stroke Petrol

[diogof]

Hi everyone, I am working on a university project where we are trying to convert a small two stroke single cylinder petrol engine to work on diesel, but we are the keeping the spark plug and the compression ratio the same, and trying to work out the best way to deliver diesel so that it doesn't just smoke up.I am going to be keeping the carburetor but just use the throttle, and am planning to fit an injector in after the carburetor to inject the diesel. So I'll be building the fuel injector system from scratch as well as the mounting for the injector :yikes: My plan so far is to have an injection system consisting of a fuel pump, filter, injector and fuel pressure regulator which I am planning to regulate using just mechanically rather than driving it on intake manifold pressure. My questions:Can you use diesel on a PFI petrol injector? I do not need the high pressure that a diesel system usually runs on so was planning to use diesel on a petrol-like system.Do you have any advice relating to setting up such a fuel injection system?

[Terminal_Crazy]

Hi everyone, I am working on a university project where we are trying to convert a small two stroke single cylinder petrol engine to work on diesel, but we are the keeping the spark plug and the compression ratio the same, and trying to work out the best way to deliver diesel so that it doesn't just smoke up.I am going to be keeping the carburetor but just use the throttle, and am planning to fit an injector in after the carburetor to inject the diesel. So I'll be building the fuel injector system from scratch as well as the mounting for the injector :yikes: My plan so far is to have an injection system consisting of a fuel pump, filter, injector and fuel pressure regulator which I am planning to regulate using just mechanically rather than driving it on intake manifold pressure. My questions:Can you use diesel on a PFI petrol injector? I do not need the high pressure that a diesel system usually runs on so was planning to use diesel on a petrol-like system.Do you have any advice relating to setting up such a fuel injection system?

Hi
Is this your idea or a couse project?

I'm not an expert so could be talking out my ass...

I don't think the fuel injection side would differ too much. Work out how much you fuel you need & spray it in,
What I suspect you'll find and/or have problems with is the difference in fuel and getting it to ignite.
Diesels use high compression which helps their efficiency.
This also heats the fuel allowing it to start burning easier.
The diesel will probably burn slower without the compression so you may need to alter spark timing.
Flat top pistons, milled deck & skimmed head are in your future.

Changing cam/valve timing will help with static/dynamic compression and heat in the cylinder as well as with spark timing.
Installing some glowplugs in the head will definately help the fuel ignition until it warms up.

Again i'm no expert but anything you can do to improve the fuel atomization would help ie smaller injector & higher pressure.
Spraying as near into the cylinder / open intake valve would affect the atomization less by low speed airflow.

If you intend to keep the spark plug you will probably need a decent HD coil.
Capacitor discharge would help the spark duration.
Hotter spark plugs again to retain heat


I presume you have no control over the fuel used (ie regular diesel).
Some older tractors (50's/60's Massey Ferguson etc would run on parafin or petrol).
Research some of the newer Hi performance diesels as they probably ignite easier with different additives but then you may as well run it on petrol.....

HTH
Keep us posted on your findings and we want pics & viedos of anything interesting.

Let me know what I got right.


Good Luck
Mitch

[diogof]

Yes this is a course project, hopefully by end of March we should have a running engine.Was thinking of installing a glow plug in the cylinder head as well but will probably save making changes to the cylinder head for if we have problems starting it - after we get the injection system running we may also try to pre-heat the engine before running, but I have no idea what to expect apart from probably a lot of soot!Thank you for the advice, I will share any interesting developments on here!

[Terminal_Crazy]

Yes this is a course project, hopefully by end of March we should have a running engine.Was thinking of installing a glow plug in the cylinder head as well but will probably save making changes to the cylinder head for if we have problems starting it - after we get the injection system running we may also try to pre-heat the engine before running, but I have no idea what to expect apart from probably a lot of soot!Thank you for the advice, I will share any interesting developments on here!

Does it run now ?
How about staring it on petrol. when hot, see if you can spray diesel into it & keep it running. Run it at a healthy rpm then shut the fuel off and spray when it dies.
it might give an indication of how much fuel you'll need.