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for the official registration documents in germany i need to know the official top speed for my car. i must show something official from Packard. something like a technical sheet. does anybody know for what kind of publication i should look for? my car is a 1947 overdrive sedan. thank you very much in advance for your reply. BR Josef

You might need to find a 1992 issue of the Packard Club magazine Cormorant and the article in Road & Track 1950 with top speeds for all cars that says (according to someone memory) the 356 top speed was 99mph. Add overdrive, another 27% , and perhaps 125 mph.

"I reserected an old Packard Cormorant magazine issue of 1992 in which there is an article comparing the 1947 Packard Super Clipper with a 1947 Cadillac Model 62. Not surprisingly the top speed bias is in favour of Packard . The article states that in 1950 Road and Track rated all domestic (US) cars for top speed and it concluded that the Packard Custom with the 356" engine and Ultramatic was the fastest car in the US with a top speed of 99MPH, The Lincoln V-8 second at 98 and the ohv Cadillac at 97. The Packard mag article does not state how the tests were conducted however or whether the Caddy had a Hydamatic. One author Jan Norbye in his book " The 100 Greatest American Cars' claims a top speed of the 356" engined Clipper at 110MPH.
The 356 Packard was engine rated at 165HP and 292 ft. lbs. of torque at 1800r.p.m. With overdrive and 4.09:1 effective gearing is down to 2.95:1. I would suspect that a 1940's L-head Cadillac at 150HP and without overdrive would not approach this speed. A 165HP engined Buick might I suppose. I personally have had my Packard up to 85mph and it doesn't seem at all stressed but with bias ply tires and a 57 year old car I have not had the temerity to test the car beyond this speed. I once owned a 1947 75 Series Imperial limousine Cadillac with hydramatic and it was not as fast as the Packard in my opinion but it was a lot heavier car also!"

EDIT These guys might look it up for you. Then you could buy the issue. I think that's as official as one could get. I don't think Packard advertised top speed except by Speedometer (up to 120 on my 1940).
https://www.ebay.com/itm/Road-Track-1950-to-1962-Back-Issues-Please-contact-for-specific-issues/122546118104?hash=item1c88515dd8:g:~ysAAOSwRXRZPt-W


Good luck researching.

I would think a Packard equipped with a 3 speed and overdrive would be faster than one equipped with the Ultramatic.

Talking top speed achieved, not how fast you get there. The gear ratio must play a big part.

Dear all, thank you very much for your reply. I think your comments are pushing me in the right direction for my search. i will have a look on magazines from these days. best regards, have a nice Packard weekend! Josef

Increasing final drive ratios (decreasing numerically) does not increase top speed beyond the required power output. In other words, the higher ratios serve to reduce engine wear factors at cruising speeds. Thus, the normal practice in the old days was to select final drive ratios that resulted in the fastest top speed. With today's multi-speed transmissions wear factors are reduced via high final gear ratios that bring rpm down to the optimal 1900-2200 range. Some may find the Packard going faster in direct rather than overdrive.

And yes, I do think the top speed of the Ultramatic may actually be higher than the overdrive because of this.

First, my condolences on dealing with the delightful combination of French-style bureaucracy and German-style inflexibility - the fast road to stuck on stupid. I've heard of more issues with old car registration in Germany than in any other country.

Top speed is usually when max power equals drag, or when max revs are reached. And as pointed out, changing drive ratio does not proportionately increase speed because of that. It is not uncommon for a car's top speed to be in direct instead of overdrive.

Some review articles would publish a "speed in gears" graph - this would be ideal, but I don't know if any exists for the 356. I would bring in any document on any similar Packard of any straight eight - once a number is typed into your paperwork no one is going to look at it again.

Tim, I'd really like to understand this, but my pea brain (the left one) can't quite get its folds around it.

Maybe numbers would help. I have a 4.09 rear-end (differential gear?).

The fastest I've driven in the Duchess was 90 mph on a freeway (17 near San Jose) that was finished but was slated to open the next day. I moved a wooden barrier just enough. At 90 mph, I felt that if I opened the vent window even a crack, the car might spin around. I was a kid in 1960.

But on the way to my granddaughter's graduation from Santa Clara last year, I found myself doing 80 mph easily. I was on a freeway with light traffic and that's how fast most cars were going. I was just moving with the traffic, Officer. (I slowed to the speed limit.) But I was genuinely unaware of going that speed.

But I could honestly tell you I would not have the nerve to drive 80 mph in direct drive for fear of blowing up the engine, even if that couldn't happen. It would sound like that to me. Even going 45 mph without engaging the overdrive feels to me that I'm redlining. (I don't have tachometer, but maybe that would help me understand this.)

The mathematical formulas for calculating top speed are all over the road. Tire and wheel measurements, transmission gear ratios, differential ratio, rated horsepower, wind drag, tire drag, and probably more factors. I quit.

This all seems to Me, something like The Trial of Bumble the Bee, a kiddie song I learned. The bumble bee's body is too big and his wings are too small. "If you see one buzzing by, don't believe what you see with your eye; because science says, and figures don't lie, the bee, the bee, the bee can't fly."

I can go faster in overdrive than direct drive, I think. ??

In a low rpm engine like this, I would also expect that OD is faster than direct.

dear all, thank you very much for your sympathy and the many ideas that will help me. yes it can be difficult to drive an old car here in germany. if it gets really annoying, expensive expertises from today engineers can be necessary to prove that a technical solution is original and has been working well for 70 years. all not pleasant. but i don't want to spoil your sunday. thank you very much and best regards josef