Reply to "Edelbrock 351C Head Flow Numbers"

> Dan - Would you be willing to run the Dynomation simulation software using
> the specs from my engine? As I recall that software is about $400 to $500
> and I can't justify spending the money for the little that I would run the
> simulation. I would be willing to pay you for the simulation run.

I'd be willing to run the program for you. Are you looking to optimize a
combination or get a prediction of what your current engine produces (or
should produce)? Good simulation programs are best for assessing the effect
of a particular change or series of changes. They may not be so good at
predicting the actual power output since there are things the program isn't
aware of. For instance, David Vizard did a series of tests on reducing
crankshaft drag. He started with a stroker crank in a stock oil pan.
Then in, successive steps, he aero profiled the crank, Teflon coated it,
and installed a race pan with wingage tray and scrapers. The HP difference
from start to finish was very large (40+ HP). A simulation program won't be
able to predict that. However, Vizard said the program is very accurate in
predicting the effect of incremental changes. He said whenever the program
said a 3" increase in collector length would be worth 10 ft-lbs, they found
10 ft-lbs on the dyno.

To do this properly, we will need accurate inputs:

bore
stroke
rod length
compression ratio
carb or injection information
cylinder head flow
intake tract length and cross-sectional area
air to fuel ratio
header dimensions
cam type and timing (in SAE specs or Cam Doctor type lift vs. duration curve)
rocker ratio
wrist pin offset
boost & compressor map (for foced induction)
nitrous info (if so equipped)

The old computer programmers GIGO credo applies here: garbage in = garbage out.
The program needs accurate data. Actual measurements from your particular
engine, particularly head flow and intake/exhaust dimensions are best but I've
spent a fair bit of time measuring intakes and heads and can likely come up
with reasonable estimates if you can't come up with the required data.

Dan Jones