Surprising result from HPL use

[doublebase]

I may not say this exactly, one hundred percent correct, but here goes…
The warmer the air, the less dense the concentration of oxygen.
So, the PCM puts less fuel in the combustion chamber in order to maintain the optimal 14.7:1 ratio.

That’s usually been my thought process as well.

 

[TiGeo]

Logged (timing etc.) my Sportwagen yesterday on a Costco 93 fillup...yep...summer blends confirmed based on knock-retard I saw (less).

 

[hrv]

I went from using QS Euro 5-40 to HPL Euro 5-40. After 3k miles, I’ve noticed an increase in gas mileage. It has increased a little over 1 mpg. The way I drive this ML is consistent. I keep my eye on the fuel mileage readout(can’t tell you why I just do). Not scientific but I’ve noticed an increase. Could it be the high moly??

Placebo Effect....

 

[Triple_Se7en]

The warmer the air, the less dense the concentration of oxygen.

I've spent years brisk walking in both the high temp heat and low temp cold. My oxygen fight not only occurs in very warm weather, but also very cold weather.

 

[supton]

I may not say this exactly, one hundred percent correct, but here goes…
The warmer the air, the less dense the concentration of oxygen.
So, the PCM puts less fuel in the combustion chamber in order to maintain the optimal 14.7:1 ratio.

But then you get less power. So in response you put your right foot down harder, so as to burn the same amount of gas (so as to get the same amount of power).

What you say would be correct for WOT. If the engine lived at WOT, then power output drops as temperature goes up, and less fuel would be consumed (but in turn accomplishing less work).

 

[Kira]

Placebo Effect....

Is that what the "P" in HPL stands for?

 

[RDY4WAR]

I may not say this exactly, one hundred percent correct, but here goes…
The warmer the air, the less dense the concentration of oxygen.
So, the PCM puts less fuel in the combustion chamber in order to maintain the optimal 14.7:1 ratio.

It's not about oxygen, at least not in that context. Maintaining a set speed requires a given amount of power to overcome vehicle weight, wind resistance, rolling resistance, etc... This requires slightly higher throttle opening to ensure enough oxygen to burn enough fuel to make said power. Therefore, fuel delivery does not change. What does change is pumping loss. Since the throttle is slightly more open, there's slightly less intake vacuum and thus less power lost when the pistons have to draw against that vacuum on the intake stroke. Aside from that, warmer air is less dense which means there's less wind resistance against the vehicle. It's the same reason a car gets better fuel economy at higher altitude than at sea level.

 

[AJB0009]

I think you guys are correct regarding WOT.
I was thinking about "back in the day" (30-35 years ago) racing snowmobiles in northern WI and MN. If it got really cold out (-20 / -30 F) we would have to step up to the next size of main jet, or the engine would run so lean it would burn a hole in the top of the piston. Saw it several times. In that case, was certainly always running at WOT for extended periods of time.
So, how does that actually work? Let's say we are at sea level. If the temperature changes from +90 F to -30 F, isn't there still 20.9% oxygen content in the air?
Another question I am pondering in my mind. My cousin has a '95 F-250, 7.3L PS. Turbo, but no intercooler. When he is in NC or WI and the temperature is, say 35 F, he says when he pushes in the clutch to shift, the boost gauge will stay up a bit, then he shifts and accelerates, it builds much faster. In south FL during the summer, 95 F and humid, he says when he pushes in the clutch, the boost gauge instantaneously drops to zero. Then he shifts and accelerates, it takes longer to build boost back up. Is that somehow related to all this as well?