3 ms·

Not sure this applies here Top Fuel engines are nearly burning a liquid rather than a gas. And yes I know you can't really compress a liquid. The typical ratio

Not sure this applies here Top Fuel engines are nearly burning a liquid rather than a gas. And yes I know you can't really compress a liquid. The typical ratio is 1.7 pounds of air to burn 1 pound of Nitromethane. It burns slower than gasoline tho. And normal gas engine runs in the vicinity of 14.5:1 air to fuel.

bumby 4y ago
>And yes I know you can't really compress a liquid. Sure you can, it's what the bulk modulus measures. You may be right. My assumption is that, by definition, a detonation is an uncontrolled pressure wave and controlling the pressure in an ICE cylinder is a big deal that a lot of engineering goes into. As you point out, the major benefit to nitromethane is that is requires less air because it brings it's own oxygen. So the size of the combustion chamber isn't as much as a limiting factor. I don't think it's intent is to change the flame regime, though. It just crams more energy into the cylinder.
- lazide 4y ago
  Keep in mind, there is a very common type of ICE that is really a IDE (internal detonation engine) - diesels. With strong enough engines, detonation isn’t ruled out.
  - bumby 4y ago
    I don't think that is correct. Autoignition doesn't automatically imply a supersonic flame front. Diesels should not detonate. The autoignition in a diesel occurs by the piston compressing the air/fuel mixture; in detonation, the autoignition occurs by the flame front compressing the air/fuel mixture. To the OP, the definition of detonation is a flame front that is supersonic; that is not the intended operation of a diesel cycle. Diesels do not have a "flame front" like a spark-ignition engine because combustion occurs at various parts of the cylinder as the air/fuel mix reaches autoignition temperature. So by definition, properly operating diesels cannot detonate. The rattle-y sound of diesels is from the high pressure rise and local ignition of air/fuel, but it's not the same as detonation.

bumby 4y ago

>And yes I know you can't really compress a liquid. Sure you can, it's what the bulk modulus measures. You may be right. My assumption is that, by definition, a detonation is an uncontrolled pressure wave and controlling the pressure in an ICE cylinder is a big deal that a lot of engineering goes into. As you point out, the major benefit to nitromethane is that is requires less air because it brings it's own oxygen. So the size of the combustion chamber isn't as much as a limiting factor. I don't think it's intent is to change the flame regime, though. It just crams more energy into the cylinder.

lazide 4y ago
Keep in mind, there is a very common type of ICE that is really a IDE (internal detonation engine) - diesels. With strong enough engines, detonation isn’t ruled out.
- bumby 4y ago
  I don't think that is correct. Autoignition doesn't automatically imply a supersonic flame front. Diesels should not detonate. The autoignition in a diesel occurs by the piston compressing the air/fuel mixture; in detonation, the autoignition occurs by the flame front compressing the air/fuel mixture. To the OP, the definition of detonation is a flame front that is supersonic; that is not the intended operation of a diesel cycle. Diesels do not have a "flame front" like a spark-ignition engine because combustion occurs at various parts of the cylinder as the air/fuel mix reaches autoignition temperature. So by definition, properly operating diesels cannot detonate. The rattle-y sound of diesels is from the high pressure rise and local ignition of air/fuel, but it's not the same as detonation.