Topic: Are There Any Mechanical Engineers In Here?

[steelspinner]

I have been considering tinkering with a motorcycle engine and am trying to figure out how one would go about converting a small gas engine to run on diesel. If a new head design is nessecary, that's not really a problem, as I am a machinist by trade with access to practically any type of machine, and almost unlimited raw materials, such as billet aluminum. What I can't resolve in my mind, is the conversion from spark plugs to glow plugs, and if the smaller cylinders in a gas engine would work as far as creating enough heat/pressure to allow detonation of the fuel, and what to do about injecting the fuel, I immagine some sort of direct injection system would be best.
The Marine Corps is currently using a diesel Kawasaki 650 that will run 100 mph and get 95 mpg.
The manufacturer is going to sell a limited run to the general public, but the cost is going to be $18,900 U.S. more than eating up any fuel savings one would gain.
Now, a diesel engine will also run on alternative fuels, such as peanut oil. I also want to make a filtering machine to filter used cooking oil to be used in the converted engine. Immagine 95 mpg and a basically free fuel source. I mean in my small town of 22,000 people, I can think of 14 resturaunts / fast food joints / donut shops that deep fry.
I know there's a lot of information on the alternative fuels and bio fuels, but I think if a guy could make a conversion kit for a gas engine, that would be so cool.

Discussions please.

[Javora]

I don't suppose you can find a schematic to one of those diesel Kawasaki engines could you??  If you can, that might be all you need.  I realize that it's a long shot but it might be worth looking around on the web, who knows you might get lucky.

[steelspinner]

I don't suppose you can find a schematic to one of those diesel Kawasaki engines could you??  If you can, that might be all you need.  I realize that it's a long shot but it might be worth looking around on the web, who knows you might get lucky.

No luck on the schematic yet.
I really want to do this, but I am afraid that compression is going to be a huge problem.

[Dracho]

I've never heard of anyone converting a gas engine to a diesel.  I've heard of converting diesel to bio fuel, but that would be a bit like trying to put rotary engine parts in a GM 350..well, you can do it, but you're right about the compression problems.

http://autorepair.about.com/cs/faqs/l/bl015h.htm
http://www.washingtonfreepress.org/73/gasEngineUseDiesel.htm
http://forums.biodieselnow.com/topic.asp?TOPIC_ID=6567

[Javora]

Somewhere I have the schematic on how to convert gasoline car into propane.  I'll have to dig that out sometime, but it was way back before fuel injection carbs. so I don't know if it will still work or not for those types of cars.

[KBF MalaK]

Good luck.

Gasoling engines usually run anywhere from 7:1- 12:1 compression and the air/fuel is igited by the spark plug.
Diesel engines run about 25:1 compression with fuel injected inthe cylinder at about 700PSI to produce your power.

Soo, it would be cheaper to buy a factory built diesel than to try to convert a gasoline engine into a diesel.

Sorry for the bad news, I was a mechanic for 20 years.

[Commander Maxillius]

I've heard of it done with the old Oldsmobile diesel, but they ran badly to start with so....  wait, you want to go the other way...


ummm, yeah, what Malak said.  You need at least 12:1 compression for diesel to do anything at all, and you're looking for improved fuel economy so you should go get a little diesel block. 

To help you out there, start looking at construction equipment websites.  They have diesel-powered generators that I'm sure they have spare engines from for repairs.  Those would fit on a bike I'm sure.

[Soliton]

One thing to consider with such a project if your goal is to save money; you are going to spend money upfront to accomplish such a conversion, money that could just be left in the bank to pay for gas. With hybrid cars, it takes years of ownership to justify the higher initial cost with the savings in fuel.

You also are turning a resellable item into something that will probably not be resellable or will have to be sold for much less than an equivalent unaltered item.