318 MAX fuel economy builds?

Dmopower said

You may be right. My thought was after reading posts from guys porting these 920 heads is that they are in the 135 cc port volume area. The j heads factory are in the 170 area. That last number may be wrong but assuming it is 170 that's 25% more volume moving the same cfm. Thats without calculating in the increase piston speed as little as it may be and I get heads capable of similar hp as factory J heads with a much more efficient 1000 to 3500 rpm and a much better quench allowing me to take advantage of as much timing as possible. No?

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For a full throttle run I'd say yes for the lower rpm but lower rpm don't matter much spend little time under 3500 rpm when getting on to it, but at part throttle the cylinders aren't even close to being filled and zero need to be, it's about needing less fuel and air to do the job. Don't know if velocity will help mpg much or at all maybe someone else can chime in my guess ported 920 vs stock j vs ported j wouldn't notice much difference.

The way I see it say you want 325hp, ported j heads would need the smallest cam to do so and get the best gas mileage cause of it and have the best powerband.