lol, you’re a riot man.
So by that comment am I to assume you think a larger displacement 6.2 will make more power at 20% throttle than the smaller displacement 5.3 will at 80% throttle assuming that both engines running at the same afr?
Is that what you’re saying now? Because that sounds like what you’re going for, and would be consistent with that earlier statement you accidentally deleted.
..
Nope. Not what I'm saying.
1)
You are injecting a throttle position range into the discussion where it doesn't need to be.
80% throttle in a 5.3 will not be the same afr as a 6.2 at 20% throttle.
I'm not talking about extremes of driving here as was clearly present in many of my posts. I'm talking about tip-in conditions for moderate passing, small inclines, and substantial headwinds.
These aren't scenarios where 80% throttle is even close to applicable.
Again the 6.2 equipped suv can navigate these situations with a small efficiency surplus vs the 5.3. Taking this over a tank of gas, it will show up as a small increase in fuel efficiency.
I'm not talking about some huge mpg difference. It isn't like the 6.2 can get 30 mpg in the above driving scenarios...I'm talking like 0.5-2.5 mpg
difference.
The reason the 6.2 can do this is because it can make the requisite power to do so at higher afrs, meaning it can do so with less fuel.
This is because a 6.2 filled to a 14.7 afr (for example) will make more power than a 5.3 L engine filled up at 14.7 afr.
I'm not saying the 5.3 jumps into a full power afr at the conditions specified above.
If I floor my suburban (5.3) my instant fuel mileage reads 2. When on flat level ground with no headwind the instant fuel mileage reading is 18.5 at 75 mph.
The scenarios above I've seen instant fuel mileage in a range of 8-13.
If "2" represents open loop afr then it should be about 12.8-13.1.
If 18.5 represents the lowest power demand (just barely enough to overcome wind) then this should be in range of 14.7-15 afr.
(direct injection can actually go up to 17 because of the combustion chamber design...perhaps another discussion)
So you can see that in the specified conditions for driving above, the afr in the 5.3 is not going to be 14.7.
From this very thread there are many instances of the 6.2 getting better than expected fuel mileage.
Based on displacement alone, this is justifiable and reasonable outcome.
2)
The other variable that is related to engine power is what the transmission is doing.
In the above scenarios, the transmission can downshift (1-2 gears). Especially if more than one situation is present (incline and passing, headwind and incline, etc).
If engine is downshifting more often, it will be spending more time at an incrementally higher rpm which also uses more fuel over a given stretch of distance. This is because there is more fuel injection events happening over a given time range regardless of afr.
Because the 5.3 is at a power and torque deficit to the 6.2,
because it is a smaller engine displacement, the downshifting in these scenarios is more prevalent.
Add both the downshifting and the displacement difference and a 5.3 equipped suv could have a small but noticeable deficit in fuel mileage vs 6.2.