Jack,

Not posted anywhere on Packardinfo.com. Here they are:

<h2>Packard V-8 head air flow</h2>
<p>
Testing performed Sept 4, 2000 in Orange, CA by Pete McCarthy. Test performed
on a Superflow 600 Bench at 25in of water.
</p>

<table border=1>
<tr><td><b>Intake port</b></td><td></td><td></td></tr>
<tr><td><b>Lift</b></td><td><b>55 Pat</b></td><td><b>56 Est</b></td></tr>
<tr><td>0.100</td><td>65</td><td>67</td></tr>
<tr><td>0.200</td><td>105</td><td>108</td></tr>
<tr><td>0.300</td><td>138</td><td>142</td></tr>
<tr><td>0.400</td><td>167</td><td>172</td></tr>
<tr><td>0.500</td><td>180</td><td>186</td></tr>
<tr><td>0.600</td><td>184</td><td>190</td></tr>
<tr><td>0.700</td><td>190</td><td>196</td></tr>
</table>
<table border=1>
<tr><td><b>Exhaust port</b></td><td></td><td></td></tr>
<tr><td><b>Lift</b></td><td><b>55 Pat</b></td><td><b>55 good seat</b></td></tr>
<tr><td>0.100</td><td>25</td><td>50</td></tr>
<tr><td>0.200</td><td>77</td><td>80</td></tr>
<tr><td>0.300</td><td>110</td><td>110</td></tr>
<tr><td>0.400</td><td>129</td><td>129</td></tr>
<tr><td>0.500</td><td>138</td><td>138</td></tr>
<tr><td>0.600</td><td>144</td><td>144</td></tr>
<tr><td>0.700</td><td>146</td><td>146</td></tr>
</table>

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

<h2>Volumetric Efficiency, percentage</h2>
<p>
This is data from DynoSim 2000. I tried to make these engines are similar as possible to get a "fair comparison".
On all 3, compression ratio is 9.5:1, carb is 4bbl 600CFM,
intake is stock dual plane, exhaust system is stock, cams are
similar, but not exactly the same.
</p>
<table border=1>
<tr><td><b>RPM</b><td><b>Packard 374</b</td><td><b>Chevy Gen-1 348</b></td><td><b>Chevy Gen-2 396</b></td></tr>
<tr><td>2000</td><td>69.8</td><td>68.9</td><td>70.2</td></tr>
<tr><td>2500</td><td>71.5</td><td>70.7</td><td>72.3</td></tr>
<tr><td>3000</td><td>74.9</td><td>74.8</td><td>76.2</td></tr>
<tr><td>3500</td><td>76.8</td><td>78.0</td><td>78.5</td></tr>
<tr><td>4000</td><td>76.5</td><td>79.7</td><td>79.2</td></tr>
<tr><td>4500</td><td>73.8</td><td>80.0</td><td>78.4</td></tr>
<tr><td>5000</td><td>69.4</td><td>79.0</td><td>76.3</td></tr>
<tr><td>5500</td><td>64.3</td><td>76.2</td><td>72.3</td></tr>
</table>
<p>
I think the reason the Gen-1 348 has a better VE curve is that it has a relatively good flowing head (somewhat canted valves slightly bigger than Packard) on a somewhat smaller engine (348 vs 374). The reason the Gen-2 BBC is not better is because the cam is too mild for even better flowing heads (canted valves). The Packard head is an inline wedge, of course.

Craig

Quote:

Good question, but maybe it would only appeal to the engineers on the board.

One major problem with the 348/409 was the angled deck. Most machine shops could not bore it.

One major problem with the early BBC was weight. It weighed as much, if not more than the Packard. Later, with the aftermarket involved, the "Rat" motor became a killer with alum heads, blocks and all kinds of cool stuff. Maybe the Packard would have evolved the same way, but I doubt it.

On the subject of gas mileage, there's no particular reason that the 55-56 Packard V-8 should get better or worse mileage than any comparable design of the era. Although the big Packard will run on the freeway and NV roads all day at 85+MPH and still get decent mileage.

In one long PI tour that I drove in through NV and AZ based out of Laughlin, my Pat got 16.1MPG. The best Packard got about 18MPG, IIRC. The rules were to fill up at the same gas station before the tour (a couple of hundred miles of both freeway and stop-go intown driving) and after the tour. The official mileage was then provided by somebody "official" and the the mileage calculated. I thought 16MPG was pretty good.

I have somewhere some engine VE curves and also aerodynamic drag and tire friction curves (power required at speed) if anyone is interested in some info that is more hardcore than anecdotal.

Craig

At least the grille is cool, kind of like the "Predictor."

Interesting thread.

Thanks Jack for all the detail.

There are several design flaws with the Packard V-8 which probably made it a "dead player" in the above cited study, despite being big and cheap.

Putting aside weight and strength issues for drag and NASCAR engines (not really a problem on the street), IMO, the intake and exhaust port placement, i.e., valve-order-in-head is the biggest drawback to performance. This has been discussed elsewhere, but at least Pontiac (among those GM experts cited above), had a way to "solve" the siamesed center exhaust port problem. See Pontiac's 1968-70 Ram Air IV, 1971-72 455HO and 1973-74 455SD "round port" (exhaust) heads. No such modification could have been applied to the original Packard design. Packard V-8 heads would have required a complete redesign, ala the Pontiac Ram Air V (303, 366 and 400).

Also interesting is John Delorean's migration from Packard to Pontiac, although apparently there was no real transfer of engine tech, the two engine designs being developed more or less in parallel.

Craig

Packardtaximan said: <i><b>Pontiac front sub frame with a super duty 455 engine</i></b>

What kind of front sub frame? Gen-2 Firebird?

A REAL 455 Super Duty???

BTW, I have an original 55 Pat with Packard V-8, but I am thinking seriously about transplanting a 455 Pontiac (non-SD) into a 56 400 I have that needs restoring.

Craig

Or, since 1951 is basically the same as 1955-56 you could go electric. Contact julianos.com I have a conversion on my 55 Pat and it works great.

Craig

Hi, Kev,

Is it desirable to move the crankshaft info to a different thread? Seems if we might make future searches easier if we left this one thread for head numbers, started another for crankshafts and I plan to begin another for connecting rods.

thnx, jack vines

Good idea Jack. It would certainly be easier to search for the individual discussions later.

Maybe there could be one, overarching, summary thread at the end.

Craig