A practical way to vaporize fuel for high MPG?

[tech99]

I am not sure we see unburnt fuel in a modern spark ignition engine, so I am doubtful abut the advantage of pre-vapourising the fuel.

 

[jack action]

I am not sure we see unburnt fuel in a modern spark ignition engine, so I am doubtful abut the advantage of pre-vapourising the fuel.

If there was no unburnt fuel at all, we wouldn't need catalytic converters.

 

[Ranger Mike]

If there was no unburnt fuel at all, we wouldn't need catalytic converters.

Absolutely brilliant reply, Jack!

 

[russ_watters]

I'm going to be lazy about this: Google AI tells me it's less than 1%.

 

[NTL2009]

I think this is a pretty good reason to believe there is next to no benefit:

Just being liquid vs vapor doesn't say much - it doesn't change the amount of energy available by more than a few percent (e.g., you could preheat a liquid fuel). In order for there to be much of a performance hit due to the fuel being liquid, it would have to be not burning or burning very late, and that just isn't happening.

Yes, but there is still a twist here. The author does state that running on vaporized fuel alone would have terrible performance. So modern engines set up with propane or LNG would be tuned differently, and not be talking (supposed) advantage of the lean ratio.

From my reading, it seems that the propane/LNG are delivered to fuel injectors as a liquid. So all the vaporization has to take place in or just before the cylinder. I'm guessing that still has time to vaporize, as it is vapor at normal atmosphere, but maybe not? But if it does have time to vaporize, and this allowed lean ratios, it would seem the computer could adjust for this, and provide lean ratio under light loads only (again, assuming there is a benefit)? So either there is no real benefit (as much of this conversations seems to point to), or there isn't a big enough market of propane/LNG vehicles to research leaner mixtures for low-load, or there are other problems with the lean mix - I think I've read you might need some unburnt fuel for the catalytic converter to handle other pollutants?

 

[NTL2009]

If there was no unburnt fuel at all, we wouldn't need catalytic converters.

According to the Wikipedia article, it might sort of be the other way around?

https://en.wikipedia.org/wiki/Catalytic_converter

These "two-way" oxidation converters combine oxygen with carbon monoxide (CO) and unburned hydrocarbons (HC) to produce carbon dioxide (CO2) and water (H2O).

So reducing carbon monoxide. And...

"Three-way" converters, which also reduce oxides of nitrogen .... three-way-converters require fuel-rich or stoichiometric combustion to successfully reduce NO<em>x</em>.

reducing NOx - but some unburnt fuel is needed for the conversion. I think you can have very complete combustion, but with high NOx levels. So that would be a problem, and the 'solution' is - more unburnt fuel! Well, engineering is always a balancing act, right?