MANual_puller
Shade tree grease monkey
- Joined
- Apr 13, 2015
- Posts
- 1,752
- Reaction score
- 1,103
- Location
- Vinton, Iowa
- Ram Year
- 2011 Moose
- Engine
- 5.7L hemi
I think you missed something. And got righteous about something irrelevant to my last post.
Lowering/raising the evap point of the gas is for combustion efficiency. Fuel needs to vaporize during the process of combustion. Octane isn't the key point with that. Octane is a definition for how much pressure the vaporized fuel can sustain before spontaneously combustion.
Different fuel blends for summer and winter are for this reason:
When the air charge is cold (like in the winter months), the gas (regardless of octane) needs to have a lower evap point, so it can atomize, and then vaporize, yielding efficient combustion, otherwise engines would drivability problems like hard starting, lean mixtures, ect. When the air charge is hotter (summer) the evap point needs to be higher, so it doesn't cause the opposite drivability problems, like vapor lock, general rich conditions, poor emissions ect..
Gasoline volatility is regulated by the EPA, so you can read all about it on their website.
Nope, not getting righteous or saying you were wrong or trying to dispute any points. I was just adding to what you said. The "you" in my post was generic for the world and not directed at anyone in particular.
Thank you
My entire point is that winter blend fuel does not affect fuel mileage. It's the denser cooler air that is the culprit Port injection atomizes well enough that once the engine is running fuel mileage is unaffected. It helps with easier starts in the winter when the fuel is cold and that's about it.