Please explain this difference between diesel and gasoline engines

[CalG]

Yes, like that dastardly complex modern gasoline engine on my chainsaw.

Chainsaw engines are more correctly termed "Piston Port", spark ignition.

I have yet to see the added complexity of a rotary valve inlet two cycle for chain saws., (Yamaha 80s and 125s motorbikes from the 60's). Also reed valve induction used to be quite popular

 

[Grumpycat]

Chainsaw engines are more correctly termed "Piston Port", spark ignition.

I have yet to see the added complexity of a rotary valve inlet two cycle for chain saws., (Yamaha 80s and 125s motorbikes from the 60's). Also reed valve induction used to be quite popular

Kawasaki was well known for rotary valve 2-stroke motorcycle engines, and road raced many.

Reed valves are SOP on today's 2-stroke motorcycle engines. Even so, still a very simple engine with few moving parts, but a lot of high tech.

 

[CalG]

Kawasaki was well known for rotary valve 2-stroke motorcycle engines, and road raced many.

Reed valves are SOP on today's 2-stroke motorcycle engines. Even so, still a very simple engine with few moving parts, but a lot of high tech.

Modern two strokes , and four cycle as well, are all about HARMONICS.
That is how today's engines can achieve over unity volumetric filling.

I can not think of a single instance of a "modern" sleeve valve engine.
A once in a lifetime era I suppose.
Gone the way of the dinosaurs.

eta

Does anyone know of an example of a sleeve valve compression ignition engine?

 

[CalG]

Kawasaki was well known for rotary valve 2-stroke motorcycle engines, and road raced many.

Reed valves are SOP on today's 2-stroke motorcycle engines. Even so, still a very simple engine with few moving parts, but a lot of high tech.

I could mention a raft of rotary valve two strokes. Bridgestone used rotary valves. The Kawasaki Big Horn 350 was notable. Can-Am as well. Heck Yamaha had a square four GP bike with rotary induction.
Myself, I used to race a Kawi 238 Green Streak in short track , A real winner! I must brag that it was I who built the engine from bare cases . Lots of "port and polish" going on in that one. I was young then....

IIRC Rotax is still offering an engine configured this way.

 

[aircommuter]

I admit I have not read all the posts. Here is my quarter. Danged inflation, used to be two cents!
Haveing worked on gas and diesel engines, no not the modern computer controlled but the older stuff.
The gas engine has many ways to get the fuel in the cylinder, carburetor, the old "sloppy mixer" it is a poor way to maintain even distribution to multicylinder engines and at all speeds. TBI or port injection injects fuel into the air stream before it enters the cylinder, Now they are using direct injection where the gasoline is injected in the cylinder just like a diesel. All most all types of fuel injection needs a computer to control the system, that is except the mechanical injection used in the 50's on Chevrolets.
The older diesels used a rotary or inline injection pump with one injection per combustion cycle. There are at least two types of fuel injection used. 1. Direct injection where the fuel is injected in a combustion bowl designed in the piston head. Easier cold starting but noisy (diesel knock)
2. Indirect injection the fuel is injected into a "power cell" (sorry forgot the name for it) they injectied the fuel into a cell that then the expanding, burning fuel traveled into the cylinder. They usually used a flat top piston. Harder to start in cold weather but quieter. Usually equiped with a starting aid or glow plugs.
Newer diesels are called common rail, were the "common rail" is presurized to a very high pressure and the injection is computer controlled and can have many, and varried length of injections per cycle.
Since they are computer controlled they are easier to start cold, and are quieter. Also are better pollution controlled.
Not familiar with but in the Army the trucks were equiped with multifuel engines.
Also check out the statified charge engine.
In the years I worked at a farmachinery dealer we sold and serviced Nuffield tractors. The first diesel I saw that used a throttle plate in the manifold. They used a BMC diesel.
The only other diesel was a detroit with an emergency shut off on the blower. It was driver activated by the driver in case of engine run away.
With a diesel be aware if excess oil enter in intake air you will have no throttle control and the engine will run away. The only way to shut it off is restrict the air entering the engine.
Guess thats my quarters worth.

I think pre-chamber is the word you are looking for.

 

[5030]

174 posts, scary. Simple answer is a diesel engine is compression ignition, whereas a gasoline motor is spark ignition. Easy peasy.

 

[CalG]

174 posts, scary. Simple answer is a diesel engine is compression ignition, whereas a gasoline motor is spark ignition. Easy peasy.

If this were a sufficient statement, the two engine types would be "dual-fuel" compatible.

But they are not, so there is that.

Perhaps a better phrased QUESTION would be.

What are the important differences in the combustion fuel delivery systems between Diesel cycle and Otto cycle engines?

Heck, I'm still wondering what sort of carburetor is going to work best on my wood producer gas fueled engines, for when the world goes crazy. ;-)

 

[CalG]

I have found this thread most interesting, but I would like to stress one point about infernal corn bustion engines.

NO FUEL BURNS UNTIL IT IS FULLY VAPORIZED!

Droplet, sprays, emulsions ...be damned

Until the molecule of hydrocarbon comes in contact with the correct number oxygen molecules, no rapid oxygenation takes place.

Any energy given to a "droplet" only serves to break it up into it's basic unit.

The "heat of vaporization" is a real thing, even if it is a "cooling effect".

Gasoline vaporizes too easily, Fuel oils ...not so much.

The big difference between gasoline fueled engines and diesel fueled engines is apparent when trying to restart after the tank runs dry!
;-)

 

[pmsmechanic]

The big difference between gasoline fueled engines and diesel fueled engines is apparent when trying to restart after the tank runs dry!
;-)

Tell me about it. The neighbor phones and says "Can you help my wife get the tractor started?" It was -30 and had sat in the wind for a few hours. Everything had to be bled and the battery's weren't the greatest. Two diesel trucks boosting and a tarp to keep the wind off of the engine. Her and I got it going after about 2 hours. All because he didn't have the money to buy diesel. I told him, "Next time call me and I'll fill your tractor for you until you can pay me back." And yes there were cattle waiting to be fed.

On the other hand this is how you build loyalty and life long friendships with your neighbors. Both of them have never forgotten that I helped them out when they needed it.

OK back to the differences between gas and diesel.

 

[Grumpycat]

174 posts, scary. Simple answer is a diesel engine is compression ignition, whereas a gasoline motor is spark ignition. Easy peasy.

Next thing you know someone will claim the Earth is flat!