Originally Posted by
Kitdy
I have read these articles - they are somewhat informing but lack specific details and the interaction that UCP offers, although they are more authoritative.
Be careful to take any information on howstuffworks with a grain of salt
Originally Posted by
Kitdy
Just because two-strokes don't work at all like four-strokes, doesn't mean that they could be modified at the cost of higher expense and greater weight to have OHC - or even direct injection - for increased efficiency. Am I right about this?
You have to consider the pros and cons of 4 and 2 stroke engines. The Pros for 2 stroke engines are: simplicity, cheap to manufacture, normally more tough and reliable. You do not want to get rid of those pros. BTW seversl modern 2 stroke engines (for scooters) have direct petrol injection to help with emissions and power. You still won't seem them in cars
Originally Posted by
Kitdy
Now, about this whole energy density business. Diesel has a higher energy density per volume, but lower energy density per mass.
Yes mostly because it is more dense then petrol and is made up of longer carbon chains.
Originally Posted by
Kitdy
In an engine, which of these is the limiting factors - mass or volume?
depends on what you mean. Volume is obviously the limiting factor as to how much you can take with you in the car. However air/fuel ratios are based on mass so mass is important.
Originally Posted by
Kitdy
If I had to guess, based on some rocky logic, it would be mass because the volume of the gas is insignificant as it is mixed with the air - it is the mass of the gasoline in the cylinder that determines how "shit goes down", for lack of a better phrase.
Yes and no... Mass is important for determining how much fuel to inject into the engine (engines meter fuel by mass) However the volume of the fuel is never insignificant especially as it is injected as a liquid (high density low volume) but will evaporate to a gas (low density high volume). The thermodynamics of just that process is not insignificant at all.
Originally Posted by
Kitdy
EDIT: After playing around with some numbers for a while, I figured out that gasoline produces more energy than diesel in a cylinder in a typical explosion. It took a while as I had to find out the volume of air/fuel that went into a cylinder, but I believed I figured it out (the volume of fuel in a cylinder is near negligible). This was only a theoretical situation as well, I must add.
Then you got something wrong, either that or you didn't take some important variables into account. I can run through the math comparing two 500cm^3 cylinders (one running in a petrol engine and one running in a diesel).
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.