Well thanks for some replies. It looks like I can expect 16 mpg so I will have to opt for lower compression to favor 87/89 octane fuel. One other idea/question is about Rhoads lifters. What is the collective experience on variable lifters? Can I use say a Comp Cam XE270 for high rpm HP and then have a 258 degree cam at low speed? Japanese high tech engines now use variable lifters even though U.S. street rodders have had Rhoads and Crane variable lifters for years. Are variable lifters noisy? Does use of a high volume oil pump spoil the effect so that one should use a stock oil pump with variable lifters? Why don't more rodders use variable lifters? The bottom line is: can variable lifters help mileage AND keep high rpm HP?

Don Shillady