QuestionI have a 51 Packard 288. it is rated at 135 HP.
In 1953 the 288 was rated at 150 HP.
What was changed?
The only difference I can find is that the Compression was raised,
but that cant account for added 15 hp.
AnswerHello Will,
I researched this question with the Packard club @ packardinfo.com. Several members had the same question as you. However, after a lot of research, I did not come away with a definitive answer, just possibilities:
1) In addition to combustion ratio, camshaft duration and intake/exhaust port design affect horsepower. From what I can tell, there were combustion chamber differences between '51 -53 but I could find no definitive information on the prior 2.
2) As you know, 1951 CR was 6.28 for manual transmission cars and 6.99 for automatics. Although these engines were rated similarly, at that time, it was common for AT cars to have a higher horsepower rating due to transmission slippage. For example, a 1953 Chevy Powerglide was rated 10 horsepower higher than a manual car based upon compression ratio alone. Thus, it would be reasonable to assume there was a horsepower difference between manual and automatic Packards in 1951 although the specs. don't show it.
3) The last answer may be the most frustrating: 1953-54 was the beginning of the 50's horsepower race. Given that Packard historically was conservative in their ratings, the answer could simply be that some long ago advertising guy just increased the rated HP for market reasons!
Hope this helps. Contact the preceding Packard forum if you want to delve into it further.
Best of luck with this fine car!!
Bob
