Just finished reading the new info on the 5.4L engine of 2004. Variable Cam, new intake manifold, special air flapper in the manifold, three valves, etc, but didn't find specific MPG numbers. Does anyone know if these changes actually resulted in an improvement in MPG?

 

Anyone got any info?

 

We can always hope! It would be my guess, only a guess, since I have not seen any real stats, yet, the added efficiency should add maybe 2MPG. This is only a guess, perhaps supported more out of hope than anything else.

 

I think 2mpg improvement would not be possible. The only real change is the cam timing and the flappers in the manifold. I think the cam timing would have marginal benefit at normal driving conditions because the existing cam is already tailored toward the low end. the flappers in the manifold can probably help with some increased swirl action. The 3 versus 2 valves would probably have little benefit at low rpms. My guess would be that we see a 3% improvement. This would take the 'real' 12mpg city 16mpg highway, to 12.4mpg city and 16.5 highway.

 

Your probably right! So much for hope. I still want the 300HP, though.