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I'm back on the Imperial planning thing again.

With a stock or very mild 440, what is a reasonable cruise rpm that will return the best mileage on the highway and not lug the engine down?

I'm talking about moving over 5,000 lbs of car at 65 mph. The originally came with 3.23 or 2.94 gears. They would turn 2500 rpm at 65 mph but were sluggish around town.

I plan on dropping a 3.73 gear out back and sliding my 518 OD in the car. That will be equivalent to a 2.54 gear.
Those gears will have the engine spinning 2,000 rpm at 65 mph. Will a mild 440 have the torque at those speeds to pull that heavy of a car?

Disregard my turbos. They will not make any difference at cruise.

I remember when we dropped the TKO in the 440+6 RR with a 3.54. It got better mileage at 75 mph than it did at 65 mph. The engine was lugging at the lower speeds. The carbs could have used a little attention. That car weighed about 3900 lbs.

When I had the 833 OD and 3.23 gears in the hot rod it would pull 75 mph at 1800 rpm and 90 mph at 2200. That was using stock heads, the 236*/.474" and 232*/.483" cam, and a 3800 lb car. In this case the engine didn't feel like it was doing any work until 2700 and over 110 mph.

I know the smallish ports on a RB will help keep port velocity up compared to other engines. However, they're not going to be the same as some of the late model engines turning lower speeds in lighter cars. The 9:1 or lower compression I'm going to run won't help.

I won't be able to get away with 1600 rpm at 65 mph like the LS1 cars.

I fired off an email last week to Comp Cams to get suggestions for a bump stick but haven't heard anything back yet.

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