How diesels work?

[jordan572]

I understand that diesels don't use spark to ignite fuel and that they use injectors to send fuel to the cylinder but how do they suck air into the cylinder and push exhaust out? DO they still use a cam with an intake and exhaust valve?I have always been into gas engines and want to at least understand how a diesel engine turns its crank. I cant find any articles. I hope you can help me out.

[JD3020]

Diesels are a lot like a gas motor. Except instead of a spark plug the very high compression ratio heats up the air in the cylinder, so when the fuel is injected and atomized it ignites. Otherwise they are pretty much the same engines, with diesel's generally being built stronger and better. I've seen quite a few gas engines converted to diesel, and i believe GM did it back in the 70's or 80's.

If i'm wrong please correct me.

[jordan572]

so instead of gas and air going through the intake valve like on a gas engine only air goes through the intake valve and the injectors supply the fuel?

[Eagle 33]

HowStuffWorks "How Diesel Engines Work"

[JD3020]

Originally Posted by jordan572

so instead of gas and air going through the intake valve like on a gas engine only air goes through the intake valve and the injectors supply the fuel?

Yes, for the most part. Technically diesel's don't have a throttle that controls the amount of air going into the motor. Just the amount of fuel.

Now IDI's have a pre-combustion chamber where i think the fuel and air is mixed in a pre-combustion chamber before the cylinder head. I still haven't totally figured out indirect-injection diesels cause i'm never around them.

[05_PSD_Erik]

Heres an animation too

[t613]

Gas- Air controlled (throttle), spark ignition. Engines draw a vacuum in the intake manifold. More air/fuel mixture (open throttle plate)= more power.

Diesel- Fuel controlled (no throttle blade), compression ignition. In theory, no vacuum in intake, because there is no throttle blade. More fuel= more power.

Pretty cool idea. I don't know why American car makers don't make a modern clean diesel car. VW has a great plan with the TDI.

[powerhoghp]

The prototype build 6.0s had throttle bodies with no blade.....

[firemedichensley]

Originally Posted by jordan572

I understand that diesels don't use spark to ignite fuel and that they use injectors to send fuel to the cylinder but how do they suck air into the cylinder and push exhaust out? DO they still use a cam with an intake and exhaust valve?I have always been into gas engines and want to at least understand how a diesel engine turns its crank. I cant find any articles. I hope you can help me out.

Diesels still use valves to push air into the cylinder and exhaust out. The only main difference between a gas and diesel is the way they ignite the fuel and air combo, gas being spark plugs and diesel using compression. Diesels can run at much lower RPMs and also have much air combustion ratio's due to the amount of air they can intake.