Re: V8 gas mileage

Posted by 55PackardGuy On 2010/12/14 21:32:40

The question is whether you're talking about the efficiency of the the vehicle, kind of like the Plymouth vs Chevy post, or the ultimate efficiency (volumetric efficiency if you want to get technical) of the actual engine itself, bench tested. As has been noted, some of the most efficient engines never got the credit they deserved because they were in big, heavy cars with marginal aerodynamics. Never heard of anything quite so phenomenal as Clipper47's Fords, but the 4.6 in my '95 T-Bird got in the mid-20's. An even bigger engine, in even heavier cars, was the last newly designed the "real" pushrod V8 design: the Buick 430/455 which routinely lugged around Electras at 20 mpg plus at highway speeds.

One mark of an engine's efficiency is how well it holds its gas mileage over a range of road speeds. If the mileage stays steady from say 55 to 75 mph, that engine continues to run MORE efficiently as it is called on to overcome increased wind and rolling resistance.

An engine that would do this is the Packard 352 V8. Initially the mileage, typically 13 mpg, isn't very impressive for highway, but it can continue to deliver that mileage at 80+ mph. At least the three of them I was familiar with would.

As for the initial question on this post, that is my answer: Expect 13 mpg in ordinary highway driving from the Packard 352 V8 as built, installed in a Packard or Clipper with Ultramatic--running clear non-oxygenated gasoline. Any better mileage than that is pretty much gravy.