- Joined
- Dec 7, 2020
- Posts
- 6,801
- Reaction score
- 17,081
- Location
- Minneapolis, MN
- Ram Year
- 2017 2500 Laramie Crew Cab
- Engine
- 6.4L HEMI
Exactly - and the differing Reid Vapor Pressure requirements by the Federal Government for summer & winter (higher in winter, lower in summer). Higher RVP formulation has less energy density and higher evaporation, hence higher fuel consumption for the same loads (and for colder winter ambient temperatures), and it's cheaper to produce being a higher fraction cut of crude from the distillation tower.I have an in depth knowledge of the combustion and octane requirements. I have been building and drag racing my own stuff for over 30 years. It never ceases to amaze me how people will argue over required octane. Also, one must keep in mind that all 87 is not the same. If the fuel has a high R number but a lower M number, it may detonate in an engine that a different 87 is fine in. Higher vols of winter fuels may detonate in a high load summer application etc.
I do know that so far my truck is happy on 87.
The reason EPA regulates summer gas to lower RVP is to reduce emissions of VOC (Volatile Organic Compounds) into the atmosphere from refueling.