80 Series Engine Swap Options (2 Viewers)

[SmokingRocks]

No a turbo is only more efficient if the engine is built that way to begin with.

For example the new F150s have both a 2.7L and a 3.5L turbo ecoboost engine. This gives them an advantage to report higher mileage than say their 5.0 or 6.2L because during the EPA mpg test they don't have to be under boost so you have a smaller engine out of boost you will see better mileage. But when really leaned on and under boost the power will be comparable.

If you have the exact same engine before and after turbo, there is no possible way that the post turbo motor will get better mileage.

The 1fz-fe under closed loop will try and be 14.7:1 might richen up under full throttle open loop.

But when properly tuned a 1fz might see:

14.7:1 - 22-10mmHg
13:1 - 10-0mmHg
12.5:1 - 0-4psi
12:1 - 4-8psi
11.5:1 - 9psi+

So you can see unless you stay under high vacuum you won't stay at the stoic ratio that the 1fz tries to maintain while NA. And the truck is too big and heavy to stay below 10mmHg, when cruising at highway speeds you are above that.

I've heard this before and while I understand what you are saying this is a too acute vision of the total impact of extra power from a turbo /supercharged engine. To keep it short with the turbo/supercharged engine you would be in the power a shorter duration to get up to speed. The NA engine would need to be in the power longer, harder or both to get to the same speed. You are right though it all depends on the tune.

My Honda accord F23a4 got 25mpg hwy NA and about 28-30 turbocharged and tuned. (averaged over 20,000 miles)