Packard Forum Index » V-8 (1955-56)

Ross, maybe it has to do with emphasis on horsepower and not on torque. What I find attractive about Diesel powered vehicles is the maximum, or near-maximum, torque is developed at relatively low RPMs - when compared to gasoline engines. You can stay in top gear going up hills and long grades and still maintain steady speed. Of course, turbo and supercharged gasoline engines develop good medium engine speed torque. In a modern vehicle, I have favored Diesel with a low pressure turbo. It's all about torque and range.

(o{I}o)

I had a Mercedes 240Diesel in the early 80's that with the 2.4liter non turbo engine and 4 speed automatic trans. which got about 35mpg on the highway. My 1989 VW Gold Diesel by comparison got about 60mpg with the little 1.6 liter engine and manual trans.
I have owned 4 Ford Crown Victoria since the early 1980's and the last two with the 4.6 engine and 4 speed auto consistently get between 33-35 mpg on the highway.These are 4000lb cars loaded with options and go from 0-60 in about 8 - 9 seconds. These mpg figures are with the Imperial gallon.

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.

What 55PackardGuy says about the 13 mpg(US) is basically true.
I am no longer using my 55 Pat as daily transport but, for the approximately three years that I did, I found that it would average about 13 mpg consistently in combined city and highway driving on trips back and forth from Orlando to Miami, driving in fairly heavy traffic with the A/C running most of the time. My best highway mileage would run 16-17 mpg at approximately 3650 rpm (where I found that mine 'wanted' to run). At various times I monitored this with both a vacuum gauge and an electronic tachometer. With my multi-spark ignition setup, using stock points as breakers, I was able to improve upon this slightly - but not all that much.

My recollection is that this average 13 mpg was pretty much standard for large luxury cars of this era (except of course Chrysler Imperials). Even up through the 70s all of my full-sized Caddys averaged about 13 mpg - whether tuned or not, tires properly inflated or not - whatever.

Thanks for the confirmation, Lloyd. Somewhere, my dad is smiling. Your comments are very much in line with his observations. It's not that you can't chase that ultimate mileage figure, but just be realistic about what the car can be expected to do.

Remember everybody, the point is how well these engines delivered over a range of rpm. Efficiency generally went up enough as rpm increased to compensate for rolling and wind resistance. That's the mark of a basically good engine design,in my opinion.

By the way Lloyd, at 3650 rpm, what was the speed you were traveling, and do you recall the final drive ratio of your Patrician?

The A/C adds another interesting variable, especially if it was factory.

55PackardGuy:

The car was a bit of a bastard stepchild when I acquired it. It is my understanding that it had been in a museum in Ohio until shortly before I bought it from a dealer in Maryland in 2004 and it had obviously been used as a parts source with the intention of selling it off after it had been thoroughly mined. It came with a non-serial number matching 55 352 engine, a (aluminium-cased) 56 Twin-Ultramatic without push-button control and a 56 Twin-Traction rear end assembly.

The car had factory AC at some point because the original (frozen) compressor and bracket and the drier were still present although someone had cut all the refrigerant lines with a hacksaw. I installed a system from Classic Auto Air in Tampa with a Sanden (R-134) compressor and interior box that mounted in approximately the same position under the dash as the original. The heater box on the engine room side of the bulkhead was eliminated in this application. It is my understanding that the exact model/system that I have is no longer offered but that there is a newer, similar model.

I have no idea what the gear ratio in the differential may be but would assume that it would be whatever came with a similarly equipped 56 senior. I am running radial tires of as close to the same height and width of the original equipment tires as I could find and my speedometer appears to be about as accurate as was usual on 50s American cars. I had a friend check it on the turnpike using my 2003 Mercury Grand Marquis as a chase car/comparison. The 3650 rpm coincides with 76 - 78 mph on both cars speedometers. I was using the car regularly, at that time, to drive back and forth from Orlando to Miami and back and didn't want any unwelcome surprises from the FHP.

Loyd. Physically measure the outer diamter of your rear tires and u can come up with the axle ratio based on your stats listed above. IF u can't calculate it i can. Based on the 76-78 mph @ 3650 i'm guessing the rear axle ratio is close to 4.00. Rather short ratio to expect any good gas mileage
56 Packard and clippers have a small metal tag on the rear axle indicating axle ratio.

PackardV8 - Will measure diameter of tires/look for tag on diff at first opportunity. Have a friend in rehab for hip replacement whose animals, cars and home I am babysitting just now. May be a while before I can get to it.

If it's a 56 the metal tag should be attached with one of the bolts that holds the rear cover on the centre differential carrier very close to the gas tank on the very center rear of the axle. i.e. directly between the axle and the gas tank ON the differential housing.