1956 Packard Panther Project

Project Topics

Computer simulations

Since almost no one is hot rodding Packard V-8s these days (if they ever did) and information from the factory is unobtainable, I decided to use modern computer engine dyno simulation software to get closer to an "optimum" equipment choice for my Panther engine.

The major components that I can realistically vary (and parameters I can simulate) are these:

Displacement	starting at 352CID and given the stock crankshaft, how much displacement can I safely achieve? Probably 374CID (+0.125") is the reasonable limit.
Compression ratio	This will vary between 8.5:1 and 10.0:1 depending following the displacement increase and piston configuration. Today's highest octane pump gas will limit me to 10.0:1 maximum.
Carburetion	This will vary from about 450CFM for the rebuilt Carter 4bbl on my Executive parts car to 1,000CFM if use a Caribbean 2x4bbl intake manifold with a pair of 500CFM Edelbrock Performer carbs. Reasonable in-between values available from Edelbrock as single 4bbl are 600CFM and 750CFM.
Camshaft	Since I can regrind the stock cam, I can get any flat-tapped hydraulic profile that can be ground on that core. This can be anywhere from very mild (stock) to pretty wild (race-only).
Exhaust system	I can install a totally stock dual exhaust system (not bad) or have custom headers and exhaust system fabricated (great, but expensive). Somewhere inbetween probably fits my budget.

To start with a simulation baseline, I'll assume the advertised HP & TQ of my 1956 Executive 352 4bbl with dual exhaust. We all know these numbers were "gross" values and maybe were "tweaked" for advertising purposes, but I'm only interested in RELATIVE performance. Anyway, Packard claimed these numbers:

275HP@4600 & 350TQ@2800

Plugging the the stock parameters into the "Dyno 2000 Advanced Engine Simulation version 3.08" yields:

257HP@4500 & 358TQ@3000 BASELINE

This is -18HP, +8TQ from advertised, but very close to the advertised numbers for the 352 4bbl in my 1955 Patrician 352 (-3HP, +3TQ). Anyway, this is close enough for my purposes. This is my BASELINE. All subsequent changes are additive. The following is a summary of what the dyno simulation claimed.

CHANGING DISPLACEMENT from 352 CID to 374CID (I'll simulate that I'm using dished pistons to keep the C.R. at 9.5:1 while increasing the displaced volume) yields:

256HP@4500 & 377TQ@3000

This is -1HP & +19TQ from BASELINE.

CHANGING COMPRESSION RATIO from 9.5:1 to 10.0:1 (going back to flat top pistons) yields:

264HP@4500 & 385TQ@3000

This is +8HP & +8TQ increase and +7HP & +27TQ from BASELINE. This just confirms the old hot rodding adage "bigger is better."

CHANGING EXHAUST SYSTEM to high performance ("Flowmaster") yields:

278HP@4500 & 398TQ@3000

This is +14HP & +13TQ increase and +21HP & + 40TQ from BASELINE. This will also make the later carb and camshaft changes more effective.

CHANGE CAMSHAFT from stock to Lazer regrind yields:

322HP@5000 & 411TQ@3000

This is +44HP & +13TQ increase and +65HP & +53TQ from BASELINE.

CHANGE CARB from stock (450CFM) to Edelbrock (750CFM) yields:

338HP@5000 & 417TQ@3000

This is +16HP & +6TQ increase and +81HP & +59TQ from BASELINE.

Finally, CHANGE STOCK EXHAUST MANIFOLDS to small tube headers (custom fabrication, probably "block hugger" style) yields:

366HP@5000 & 440TQ@3500

This is +28HP & +23TQ increase and +109HP & +82TQ from BASELINE.