Re: The Second Packard "Twin Six"

Posted by PackardV12fan On 2008/9/22 22:00:52
As you point out, getting a good "swirl" in the combustion chamber is vital. Obviously, Packard understood this, but knew this WAY before Packard engineers laid out its automotive V-12 introduced in the fall of 1931.

Packard correctly believed that given the fuel/compression ratios of the day, and given the primary uses of its products, there was no advantage to its customers, to the additional cost & complexity of over-head valves or cams for its automotive products.

As noted earlier, Packard was a pioneer in the mass-production of high-performance concepts such as over-head valves, cams, superchargers, and cross-flow heads (see the "Liberty" engine Packard designed during World War one). Its commercial and aviation division products saw these concepts; again, it saw no advantage to its customers to put them to use in its automotive line.

As I suggested earlier, my belief is had Packard felt there was a market for a car in the Duesenburg price range, I suspect you would have seen the above "exotic" engine design features, in a reliable engine that would reflect traditional Packard philosophy - translation - would have blown the doors off the Dusie !

In answer to your question about combustion chambers - as for making the angle between the bores and the top of the block different from 90 degrees, GM tried that in some of its high performance engines many many years later. Sure it works to improve power/effiency, but adds to cost from both a manufacture, production, and maintaince standpoint. I am not aware of any mass-produced automotive engine utilzing that these days.

I note some confusion over "who designed the Packard V-12". Some of the confusion stems from the obvious fact that the so called 'Van Ranst' Packard had front wheel drive, and a much smaller displacement version of the Packard V-12. But that was a drive-line issue; not a power-plant issue. With this qualifcation. Somewhere I read that Packard did NOT design the valve lifter set-up; read somewhere they had to pay royalties to use the system in the Packard V-12.

Simply put, the Packard V-12 does NOT have hydraulic valve lifters, at least not in the conventional sense. They are SOLID lifters with an "off-center cam lash take-up". Big difference.

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