Quote:
Keep it simple. Don't reinvent the wheel. Factory standard. Get to work. Packard knew what they were doing.
That's generally true, but back in the late 40's automotive gasoline was about 72 octane (AKI). In the 50's it was around 80. It continued to increase until it peaked at 90 in 1974. It's currently running around 87. Consider what Packard had to accommodate in the design. Compression ratios increased industry-wide as octane increased. From the '48 Packard at 6.85, a '54 Packard had 8.70 compression. A '56 Packard V8 had 10.0 compression (which required premium / "ethyl").
BTW, there's a movement to eliminate multigrade gasoline and settle on a single grade of 95-97 so manufacturers can all take advantage of even higher compression ratios, which are now averaging about 10.5 but they want to go even higher for greater efficiency.
Today's regular at 87 is a long way from the 76 of 1948, so a 1948 engine can benefit from a CR bump and run more efficiently.
Edit: Trivia note -- Union 76 gas stations got their name from the octane rating of their premium "ethyl" gasoline back when they originated in 1935, 76, which had a patriotic sound to it alluding to the year 1776, hence Union 76.
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=266445