Re: Did Chevy consider Packard V8 BB Design?

Posted by Craig Hendrickson On 2008/10/10 11:44:32

Jack,

Good questions all. Here is my rationale on the points you brought up.

0) My general assumption was that this comparison would be something that Chevrolet engineering might have done back in the day when they were asked to evaluate the Packard V-8 (bean counter favorite) to what their design (Gen-1 W 348) would do. Therefore the common values cited above for all 3 engines. Of course the Gen-2 BBC really was only a glimmer in the eye of the engineers at that point in time, but I included it for hindsight comparison.

1) All 3 engines are pretty much OEM. I wanted a passenger car comparision, which would probably be one of the studies done by the Engineers. I have cam profiles for the Packard, but not the Chevies. So I chose profiles that were close to the Packard, i.e. approximately same VE at lowest RPM (2000). Obviously, changing cams for any of them would make a big difference in VE, particularly the Gen-2 BBC.

2) Head airflow data for Packard V-8. When I replaced the heads on my 55 Pat because of exhaust valve recession, I bought a set of used 56 Sr heads. With my prior Pontiac high performance connections, one of my old buddies volunteered to test the Packard head on his flow bench. That's where I got the flow data. Not unsurprisingly, it was fairly close to 1964 GTO head. I then extrapolated the numbers for the 56 head without sunken exhaust seats.

3) 600 CFM carb. Even playing field assumption. Obviously Chevy could have put the same square bore carb on all 3 engines.

4) 9.5:1 CR. Even playing field assumption that was common to all 3 engines at one time or another.

5) Why not 352 vs 348 and 374 vs 396? Time available for this analysis. That would be something worth doing, if there's no big objection about the simulation and we think we could learn something.

Craig