Packard Forum Index » V-8 (1955-56)

Quote:

Some quick calculations reveal that at 100 MPH the engine would be revving 3838 RPM and at 110 MPH the engine would be revving 4221 RPM. This is assuming stock size 8.00 15 tires, 31" diameter and stock 3.54 rear axle ratio.

Peak HP is given as 260@4600 RPM. 4600 RPM would be within an eye blink of 120 MPH. Fastest lap in the test is given as 114 average for the 2 1/2 mile track which would be 4375 RPM.

It seems quite possible the car ran at a sustained 4000 to 4500 RPM for 25000 miles. It would actually be less strain on the engine to run at or near its power peak. The fact that the run took place in the rain is significant. The air resistance of the big Patrician body must have been tremendous. The same run at the high altitude Bonneville salt flats, in thin dry air, would have cut the power required by half.It must have taken full throttle and full horsepower to push the big Patrician through the cold dense wet air at 100+ MPH.

As to how the oil pump stood the gaff, I believe that most Packard V8s never had any trouble with their oil pumps although a small but significant number did.

The story states that the first effort had to be aborted at 10,000 miles due to lifter failure and a whole new engine installed. This could have been caused by a bad oil pump and the company quite naturally tried to minimize the bad publicity by calling it lifter failure.

Very good analysis Rusty.

One piece of criteria used i do not understand:
"This is assuming stock size 8.00 15 tires, 31" diameter and stock 3.54 rear axle ratio."

My 55/56 factory parts cataloug lists "std" rear axle ratios up thru 5560 only. There is no "std" ratio listed for 5580. ONLY "opt" ratios for 5580. The cataloug has 3hree such pages with revison dates from Nov 55 thru april 56.

So i'm not sure how u arrived at 3.54 as a "stock" rear axle ratio.

Even if there is authoritative documentation of the test and/or my parts cataloug is in error i find it nearly impossible to believe that such a short axle ratio would have been used (stock Standard or otherwise) for such a test with the speeds in excess of 100mph and track specifications/environment conditions as stated in the test articles.

Keith -

Specifications in the shop manual are also ambiguous.

However, the 1955 dealer album (p.48) shows only a 3.54:1 axle ratio for Packard with Ultramatic. which suggest that as standard.

With 3.54 listed in the parts book as the first ratio for 5580 (Gr. 12.001), and other listings are not in numeric order, by ration, the OPT designation could be a typo.

What ratio was actually used in the test car depends on what the criteria were for this test.

Meanwhile, I don't know what axle ratio was in my dad's old Exec, but he told me that he once ran it up to 110MPH on US 19, which was a two-lane blacktop highway (before they built I-79). He said the speed still was climbing, but can't say for sure what it topped out at. By that point, he wasn't about to take his eyes off the road again.

My 5672 has the 3.09 or 3.07 which ever it is. I'm confident it is factory installation.

Just as your dad experienced i had mine up to 105 mph for about a 2+ mile stretch some 8 or 10 years ago. It was just as effortless and smooth and pleasent as at 70 mph as it was at 105.

For normal driving conditions, other than extreme mountain ranges the 3.54 axle ratio is nothing less ridiculous than trying to kill a fly with a 6 pound sledge hammer.

Guy -

I don't mean to speak for PackardV8, but I don't think he intentionally quotedyou out of context. It wasn't a mere snippet, but a full sentence - the question you asked of him.

As for the use of the word "stunt", I don't think Keith meant that anything was falsified, but that the endurance run was conducted as much (or more) for the purpose of promoting the new product as it was for product evaluation. I mean, what owner would ever be able to a car at a "sustained" 104.7MPH for 25,000 miles? Yet, the Car Life's "Far and Fast" article suggests that the average owner should be able to drive twice as far at half the speed without serious mchanical problems. That sounds like a reasonable conclusion - that is, back when the cars were new and driven regularly.

Yet, I don't believe that the endurance run - though interrupted by stops for refueling, driver change, etc. - would be as telling as stop-n-go city drving or even town-and-country driving. No doubt, you're aware that vehicle manufacturer's provide an alternate maintenace schedule for "severe use", which includes such short-trip driving. The oil gets a lot blacker a lot quicker with short trips than it does with interstate driving.

So, it's possible that an oiling issue could have escaped that 25K run. For the first year, most of the factory bulletins and articles on oil-related issued with the V8 during all of 1955 seem to be pointed at complaints of oil consumption and lifters that were simply noisy at a cold start. The first indication of an issue specific to the oil pump only came in the Spring of 1956, when dealers were instructed to inspect the pressure relief valve for sticking. Two months later, there was a redesigned pump for production with a sump tube kit for field service, but vehicle asembly ended the following month, and Packard ceased publication come Autumn. Time had simply run out.

Nothing more happened until 1975, when PI announced a modifaction service, which did away with the piggy-backed vacuum pump in favor of thicker bottom plate, but I never had any faith in that. The point is that nearly 20 years had passed before anyone else publicly addressed any oiling issue with the Packard V8.

It's more clear, in recent years, that the culprit is one of wear between the driving shaft and its bore in the pump body. Lots of short trips and cold starts would accelerate that wear - worse yet with "colletible vehicles" that are only driven occasionally.

Yes BH. Also note that the PI website ca. 1998-2002 indicated that the V8 oil pump would cause problems at as low as 25K miles.

Am i the only person that remebers that from the PI website or am i just having somekind of halucinations????

"So i'm not sure how u arrived at 3.54 as a "stock" rear axle ratio."

I was quoting Chuck's post.

In any case, I would bet Packard used the 3.54 gears or even lower (higher numerical). To those not used to high speed competition this may seem scary. But in practice, for a run like that, you want the engine running at the speed that gives max HP or close to it. As long as the engine is capable of maintaining 4600 RPM without overheating or blowing up, this is easier on the engine than straining at a lower RPM. Plus, I severely doubt they could have made that speed with a higher gear. Remember they did the run on a banked oval track, this means more friction or resistance than a flat straight track. Plus they had to push a full size Patrician body through dense, cold, wet air in the rain.

One experience that comes to mind is this. About the same time as this run took place, within a year or 2, Chrysler took some cars to Daytona Beach expecting to break all speed records. They didn't make it. Tom McCahill warned them that they needed a lower rear axle ratio to make the speed they needed. Ideally, the engine should be revving OVER its max HP speed when they went through the traps. Chrysler's engineers replied that their blockbuster Hemi engine could pull the higher ratio through 4 feet of fresh snow. They were wrong. The dense sea level air and the drag of the wet sand defeated them.

A week later they took McCahill's advice and tried again this time with the stemwinder gears he recommended. They finished the run with engines screaming and added 5 or 10 MPH to their speed, ample to have set new records. But it was too late, Speed Week was over.

The same car or cars, could have been geared higher and would have gone faster at Bonneville because of the thin dry air at high altitude. The thin air would have reduced HP by 10% or so but by the same token, would have cut air resistance.

The 3.54 ratio would give a speed of 120 @ 4600RPM which is where their engine made max horsepower. This ratio, or close to it, would have been the best choice for a sustained high speed run. With a lower numerical ratio I doubt they could have even reached the required speeds let alone maintain them for 25000 miles.

Quote:

The original 1955 Popular Mechanics report says the first attempt was aborted at 10,000 miles because of "lifter failure".

Could it be that the engine did suffer "lifter failure"? And the failure was caused by a defective oil pump? But Packard tried to minimize the bad publicity by calling it "lifter failure"?

They then installed a whole new engine and made the 25000 mile run successfully.

This ties in with the experience of Packard V8 owners on this board. Some have suffered lifter noise and low oil pressure, others have driven the same model for years with no problem. So not every oil pump fails but a significant percentage do fail. This tends to be borne out by the factory's repeated efforts to change or fix the oil pump.

Keith -

I don't think I have the 1975 copy of the PI magazine, which is the earliest reference I have, stored here at home to authenticate that.

Yet, if 25K is true, that's awfully low mileage at even at that point in time. Not to discount any issue with lubrication or metallurgy, I think the frequency of cold starts with vehicles that saw only occasional use, by that time, is a significant factor in accelerating the wear of the pump body and driving shaft.

While my dad's Exec never exhbited any oiling issues, he doesn't recall any problems with the V8 oil pump during his tour of duty as a mechanic in a Packard dealership.

"Even if there is authoritative documentation of the test and/or my parts cataloug is in error i find it nearly impossible to believe that such a short axle ratio would have been used (stock Standard or otherwise) for such a test with the speeds in excess of 100mph and track specifications/environment conditions as stated in the test articles."

Factory specs for that engine are 260HP @ 4600 RPM. Do you find it hard to believe a Packard engine would actually rev that high? Or that it could run at full throttle for 250 hours without blowing up?

Keep in mind we are talking about a car that weighs between 4500 and 5000 pounds with the driver and a full load of fuel. With a body the size of a small bus, and the streamlining of a brick. Driving on a banked oval track through cold wet dense fall air, and even rain.

I don't see how they could have gotten the required speed with any lower gear ratio.