Packard Forum Index » V-8 (1955-56)

Chrysler hemi? Quite an engineering marvel

While I'll not dissagree that the Chrysler hemi was quite an engineering success, certainly a hemispherical combustion chamber was not novel at that time, it had been used well before that, perhaps even as far back as 1910 or so. The DOHC Duesenberg and Stutz have hemispherical attributes, and far before that the early "T" head engines did as well. Are you familiar with the "T" head? It's the flathead engine version of a a DOHC, a cam on each side of the piston, intake valves on one side of the block and exhaust on the other which of course then permitted the intake and exhaust manifolds to be on separate sides as well. Design benefit was much improved breathing. Some of the largest early engines built were T-heads, with sizes in the range of 600-700 cubic inches. I'd guess that the MacFarlan and the Pierce Arrow were two of the longest-lived T-head designs.

The Chev was also known as the porcupine head and semi hemi.

Chrysler did not invent the hemi head engine. The oldest version I know of was on a 1903 National race car. The french Peugeot firm built a rather sensational race car in 1912 that had a hemi head and that was the one that made them popular in race cars.

But Chrysler was the first company in the world to put one in a mass produced car sold at a price. Before that they were all in race cars, sports cars and expensive imports.

They used a very clever layout for the valve mechanism. The pushrods are quite short and stiff. Given the RPM range the engine was capable of, there was no incentive to use OHC. The pushrods were simpler cheaper quiter and easier to service and repair.

It was 20 years later that the toothed rubber drive belt came along and made OHC practical for mass produced cars.

Better breathing was only one benefit. The hemi also has a better combustion chamber shape and better cooling of the valves. This led to what Chrysler called "mechanical octane" meaning, the Chrysler hemi made full power and performance on regular low octane gas. It did not need high test or high compression. This is one of the long lasting myths, that Chryslers need special high octane gas, quite the opposite, they will run happily on lower octane gas than any comparable engine.

In fact, when high octane gas and engines of over 9:1 compression became available the hemi started to lose its advantage. So they dropped the hemi for a conventional engine.

The T head was also a misunderstood design. Ferguson, the designer of the Pierce Arrow T head engine, said his goal was simply to match the horsepower per cu in of the latest V8 engines from Cadillac and others. He considered making a V8 but at that time (1915) they had problems getting even breathing and smooth running, and they had a 4 cylinder type vibration period that made them unsuitable for a luxury car. These problems were not cracked until the introduction of the 90 degree crankshaft in 1923.

In the meantime, Ferguson took another look at the Pierce 6 cylinder. Close analysis revealed that the V8s had a much larger valve area and this was the secret of their performance. To get the same valve area in the Pierce he would need to use 3 inch valves. This was impractical due to problems of weight, valve wear, noise and valve burning.

So he tried using double valves, 1 1/2" diameter. These gave the better breathing and higher horsepower. Plus the valves and valve springs were so light, the valve action became practically noiseless and valve life was much improved as well.

The T head design was the best way to get a 4 valve cylinder. Overhead valves were not necessary or desirable. The gas available at the time did not permit a compression ratio over 4 or 4.5:1 anyway. So the large wide open combustion chamber was no problem.

The end result was the Pierce Arrow Dual Valve Six. An extremely powerful, long lived luxury car engine. It was smooth, silent, and it would pull a 3 or 4 ton limousine in high gear from a walking pace all the way up to 80 MPH without a tremor.

The new 48HP engine produced more power than the former 66HP and was as economical as the 38HP. So they dropped the 38 and 66 and produced the 48 for the next 10 years.

These are taxable horsepower ratings. The Pierce 48 actually developed over 100HP.

These engines were also popular in boats used by rum runners in the 20s. They prized them for their power, silence, and unfailing reliability.

Guy -

Well, you're the one who challenged me on a post I made to the attention of all, but without specifically naming you, where I felt that the SAE was not just "white paper" and I reiterated a request to not upload copyrighted materials without permission.

I didn't set out to put you on trial, but if you're trying to make me seem unreasonable by posting:

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...know that it is unreasonable to expect the webmaster of a site like this to be at anyone's beck and call every time something is about to be uploaded.

However, one point you made that I can agree with is:

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In fact, such a policy has been stated here - long before you came over from the AACA forums. Check the footer that appears on the bottom of every page - at least every one that I've ever seen here. Specifically, I would direct your attention to the following passage that advises:

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Yet, in the end, I believe the site owner still bears some responsibility for what is posted at their site. As such, let's try to make life a little easier for BigKev.

Lastly, I've known who the author of the SAE paper was for a couple of decades, but I'm not going to tell you. Frankly, since the engine paper is the intellectual property of the SAE, that point is moot, but I also have no wish to further communicate with you in any way. Leave me out of your discussions and games, henceforth, and I'll gladly return the favor in kind. Now, if you had paid attention to Randy's post you would already know who the author of that paper was.

Meanwhile, my apologies to other members and viewers for going further off course with this.

Brian,

I agree that "Knowledge is good," and sometimes new knowledge comes at the expense of pre-conceived opinion or a challenge to one's previously accepted beliefs.

Sometimes knowledge may come from those that you may believe do not have the "bonafides" to make acceptable suggestions, corrections or clarifications, even though their facts are essentially correct.

Yet, I think that kind of stance can defeat the purpose of these forums. Sincere input is appreciated. Strongly held opinions are sometimes necessary to get to the facts... and to spice things up a bit.

I did click on the link you provided and saw the author's name on The New Packard V8 Engine, and changed my post to read; "Who was W.E. Schwieder?" Perhaps if you have known who the author was for years, you may have more inside information.

I hope you won't feel "gamed" when a post is made to correct or clarify meaning, or challenge something that you have written. I wasn't fooling around. "White Paper" is a descriptive term, and I reiterated a definition for it when you posted a challenge to it. I just replied that, by definition, The New Packard V8 was such a paper, but I did NOT say it was necessarily authorless nor free of copyright restrictions. Those were assumptions that you drew from my posts.

I don't presume to speak for Kev, which is why I wanted to point out that it's essentially up to the poster of copyrighted material to get permission from the author(s) or publisher, but I think it's still customary to report the addition to Kev--where it will appear under "Newest Packard Articles."

I've never found your posts or replies offensive, I've just sensed a fairly frequent unwillingess to give my input credence.

I am guilty of replies that "tweak" what I feel are unnecessarily picayune comments about what I feel are trivial nuances.

No need to apologize for going off further course with this... it is my responsibility to try to keep it on topic.

I do hope you continue to read and answer my posts. You were the first encouraging voice I heard on the "other" Packard board, and maybe you still consider me the "newbie" from all those years ago.

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You are correct sir! But they did trademark the term "Hemi"?

Lots of fascinating info, especially the "T" head configuration. I never would've thought that a flathead could successfully employ a hemispherical combustion chamber (it didn't: see Rusty\'O'Toole's note below)GS.

The resulting "cross flow" design would be a real improvement on ordinary flathead performance.

Overhead cams were not unheard of, though. And I did not know that the ribbed belt camshaft drive was a great practical advantage.

I would guess that the reason for the "mechanical octane" mainly the lack of much "quench" are in the hemispherical vs wedge combustion chamber. Hemi's are also noted for low "swirl" requiring the centrally located spark plug.

All right, Guy, let's just call it over and done with (and stop splitting hairs).

I do believe you have credibility with regard to your own family ownership of a V8 Packard and your own private readings and online participation. I don't consider myself the end-all authority on any Packard, but have only been studying the V8 cars and collecting related literature, casually, for a few decades. Of course, no matter how much any of us think we know, there always seems to be something more out there to discover. Yet, the facts as we know them are based on our own perception, and perceptions are so often selective.

I admire your want to learn even more about Packards, but sometimes you ask, and repeatedly, for things that the site doesn't have and aren't immediately available. Personally, I feel that if the material is available for posting, without infringment, it will come home to roost - sooner or later - here at P'Info, without a lot of pushing for it.

P'Info has been up and running less than three years, but take a look in the depths of the archives (that is, the Packard Articles section) to see how much has already been donated. You will find as much, maybe more, factory information on the V8s as anywhere else online - even longer.

You will also find reprints of many technical papers for sale at the SAE site on a variety of other topics that were published by Packard engineers that this site doesn't have, but I have my doubts that SAE would agree to online posting of such material.

As regards Wm. E. Schwieder, I've never seen much else written about him, except that his name is cited in conjunction with Wm. Graves, V.P of Engineeering (who headed up the V8 project), in a footnote to a statement about keeping the the V12 revival (based on the V8 tooling) alive in Ward's The Fall of PMCC. Though nothing highly technical, there's a book that is every bit worth a read as the Kimes History... that we all hold in such high regard. (BTW, have you checked out the Packard Bookshelf feature here?) I can only assume that Schwieder was one of the staff eningeers dedicated to the development of the V8.

By all means, move forward on collecting material for donation, but with care. There's no contest here.

Brian,

Thank you for your kind words. The feeling is mutual. I somehow was not aware that Randy had gone ahead and started a thread on The New Packard V8 Engine document. I'll give it a look in comparison with the PI article.

No one can make any "assignments" here, which makes it a pleasant place to visit, and if I ask more than once about an item, I hope to be encouraging, and sometimes it works! Without, I hope, posing too much inconvenience on anyone. But I know of few here who would consider being a contributor to the archives an inconvenience.

Sources for direct quotations should always be cited, with pages noted where appropriate. Ignoring this rule of thumb may not always result in an "actionable" case, but better safe than sorry. It also makes the references much more valuable to those who wish to purchase the source material, or look up more on the topic in their own copy.

There never was any argument from here about getting permission to upload copyrighted material. I would hope all would know it is standard operating procedure to do so.

Glad to know that Wm. E. Schwieder was at least connected with engineering at Packard, but I would guess--purely a guess--that he worked in a PR capacity with the engineers as sources of information. Those reading The New Packard V8 Engine article might see what I mean. Schwieder does not appear in the Name Index of the Kimes book.

My book budget is awfully restricted, but I remember your list of recommendations posted on the other site held The Fall of PMCC in high regard. I've occasionally see books like that net used at quite reasonable prices.

The T head was not a hemi design. It had a wide flat combustion chamber. A poor design for a high compression, high RPM engine but very good for a low compression, high torque engine.

Sorry for the confusion.

All T head and flathead engines had open combustion chambers at that time. The Ricardo head was not introduced until 1921 or 22 by an English inventor, Harry Ricardo. This was the first high compression flathead. I believe Chrysler was one of the pioneers of this layout in America. It was one of the features of the first Chrysler high compression 6 in 1923.

In the meantime, from 1918 to 1928 Pierce used the T head in their big long wheelbase chassis which was meant for chauffeur driven cars. They also made a smaller lighter Model 80 which had a conventional flathead 6 cylinder. This "small" Pierce was about the size of a Cadillac.

The ribbed belt cam drive is what made overhead cams cheap enough for mass market cars. It is also quieter than a chain.

Few people remember that the Pontiac OHC 6 was the first mass produced car with a belt driven OHC in 1966.

I believe the main advantage of the hemi, in terms of octane, is the superior combustion chamber shape. Theoretically the ideal combustion chamber would be a sphere with the spark plug floating in the exact center LOL. This is impossible in practice. The hemi head with central spark plug is the closest to the ideal.

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Rusty,

I misunderstood--post revised. With valves on each side of the cylinder, it would have been a "cross flow" design, though, I believe. An interesting layout for a flathead, but the "T" head was probably quite a bit more expensive than the common "L."

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I did not know what what drove the cam, but I did look at one of those OHC Pontiacs back in the '70s. I believe it was a Le Mans. That was one tall 6 cylinder!

When Ford (Pinto) and Chevy (Vega) started with the belt-driven cams in the '70s, a lot of people were shy of them. Now they're almost standard issue.

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Owen,

Sorry I neglected to thank you for these offers. Probably because I was in too much of a snit at the time.

The good news is the "How Potent is the Packard V8?" article is posted!. A BIG THANK-YOU to Kev and whoever else was involved in getting it added to the PackardInfo "Articles."

I think I read the article on the internet once long ago. Reading it now, it's easier to notice how closely it follows the PI article/ SAE paper that's been discussed. Packard must have pitched that copy for magazine placement. Having been in the ad and PR biz, it reminds me of how I used to pitch editors (and, of course, ad space reps) to get articles published for clients. In this case, ol' "Racer Brown" had some pretty good stuff to churn out a story with--and say nice things about the Packard V8.

It's interesting reading references to the valve springs, oil/vac pump, and other weaknesses that hadn't been exposed yet.

Especially nice is the reporting on the torsion level suspension. It's poignant to read Racer's predictions about it being adopted by other manufacturers, and knowing it wouldn't come true.

The comparisons of the Hudson and Nash versions of the Packard V8 are interesting as well, with lower compression ratio and different metal in the cams. Give Racer his due, he evidently did some research on that part.

PS
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Brian, just to clarify, we had 3 of 'em!