Originally Posted by Dirty Biker
I think it would get better gas mileage at 4300 rpm at 75-80 mph going down the expressway on flat land than a a 383 or 400 or 454, and would hold up better at that sustained rpm. I travel alot, I drive to Florida, North Carolina, Tennesee, New Mexico, Montana. I need a motor built for 4000+ rpm all day long in this current truck anyway.
It really depends on how hard the engine has to work to overcome drag . Back in 1968 my dad had a Galaxie 500 4 door with a 390 2 bbl auto trans that got 18 mpg and a friend of ours had the same car with a 300 cid 6cyl with a standard transmission and got 8 mpg. So it really does depend on how much fuel you have to feed the engine to overcome the drag factors , wind not being the least , especially with your van , at 75-80 mph. And any engine will hold up better if it's not forced to work hard constantly . Why do you think they put 800 plus cubic inch diesels in big rigs that only make 350 hp at 2150 rpm . It is because they can make that hp all day long day after day and run for 750,000 mi easily . By your reasoning they should run a 350 chevy and gear the truck to turn 4000 rpm so they can get the 350 hp . Faulty reasoning . But , feel free to try it .