Compression at which gasoline will ignite

[abaird]

Originally Posted by Moppie

Of course you all realise that Direct injectin Gasoline engines make all of this redundant?

wtf is a direct injection gasoline engine?

[curtis73]

Originally Posted by abaird

wtf is a direct injection gasoline engine?

Pretty much what it sounds like. Its an engine that injects the fuel directly into the chamber. Unlike diesel, it still uses a spark plug, but it moves the mass of fuel downstream. Benefits include an easier intake tune, more accurate metering (since you don't have to account for fuel sheeting on the intake walls) and for the same reason better economy.

Cody_e. You're on the right track, but just remember, heat in equals heat out. In this case the "heat in" comes as stored energy in the fuel. "Heat out" is in the form of force on the piston, sound, light, and hot exhaust. If you add more heat to the first side of the equation (by raising the temperature of the intake charge) you will increase how much comes out on the other side of the equation. In this case, like you've already identified, that heat will probably cause detonation.

To get fuel to evaporate you have to add energy. In the case of a carburetor, it uses mechanical means to force gas to evaporate and it sucks heat from its surroundings. In the case of HFI, you're using actual heat. In the case of those little vaporizers, you're using kinetic energy in the form of motion. I would think it would have the benefits of fully evaporating the gas without the drawbacks of heating it.

[curtis73]

http://www.volcanicfuelinjection.com/index.html

There it is... Evidently HFI was already taken by the hydrogen fuel injection, so he changed it to reflect his last name, Volcin. Its VFI now.

[cody_e]

Originally Posted by curtis73

Cody_e. You're on the right track, but just remember, heat in equals heat out. In this case the "heat in" comes as stored energy in the fuel. "Heat out" is in the form of force on the piston, sound, light, and hot exhaust. If you add more heat to the first side of the equation (by raising the temperature of the intake charge) you will increase how much comes out on the other side of the equation. In this case, like you've already identified, that heat will probably cause detonation.

But you also have to take into factor that you are "recycling" this heat. The heat given off in combustion will go back to vaporize the next batch of fuel. It would basically be a cycle of heat recycling.

[curtis73]

True... so the only "extra" heat to deal with will be during combustion. That could be combatted with a little extra EGR or retarding timing. The EGR would pay off big time, but the retarded timing would reduce economy measurably. Maybe not as much as the complete vaporization would recover, but an interesting thing to ponder.

How would you work this with a cold engine? Preheater?

[cody_e]

Originally Posted by curtis73

True... so the only "extra" heat to deal with will be during combustion. That could be combatted with a little extra EGR or retarding timing. The EGR would pay off big time, but the retarded timing would reduce economy measurably. Maybe not as much as the complete vaporization would recover, but an interesting thing to ponder.

Like I said I'm just a student so I don't know what EGR is. What is it?

How would you work this with a cold engine? Preheater?

That's another problem I thought of. Yes I would have to find some way to preheat it. Or maybe I'll have to experiment with it a bit and see if it's better off starting like a normal car would and running liquid through the thing and then as it heats up start vaporizing the thing. These are all little kinks I have to work out with this.

[curtis73]

Originally Posted by cody_e

Like I said I'm just a student so I don't know what EGR is. What is it?

Exhaust Gas Recirculation. It recirculates exhaust back into the intake during low load situations like part throttle. Its primary function is to reduce NOx emissions by lowering the combustion temperatures. Properly functioning EGRs don't cost much power at all, but allow full ignition advance (which is one of the keys in MPG)