Hey all! I've tried to send this a couple of times but bad results. Hope
this one makes it 'intact'.
Terry
I have my Chev.302" disassembled for an upgrade. Cylinder head development
and the induction system are the areas that I'm trying to understand more.
I'd like to put out some information about four heads with different intake
port volume:
a.. 1st: Tha AFR 180 (A good street head, 23 degree, 180cc intake port
volume, good velocity for mid range)
b.. Lift --- Int. --- Ex.
Cu/ft per cc of runner
c.. AFR180 .200---152----113
d.. .300---193----164
e.. .400---230----193
f.. .500---250----203
g.. .600---255----214 83%
1.416
h..
i.. 2nd: The Brodix Tract 1, and entry level racing head. (23 degrees,
215cc intake volume and very good numbers)
j.. Brodix Tract 1 .200---130---103
k.. STD 215 cc .300---178---142
l.. .400---223---165
m.. .500---252---275
n.. .600---259---183 70%
1.209
o..
p.. 3rd: The Brodix-12 SP/P (It's a 15 degree, 230 cc intake volume with
big numbers)
q.. Brodix-12 SP-P .200-152---113
r.. 230cc .300---224---158
s.. .400---278---202
t.. .500---316---226
u.. .600---331---234 71%
1.439
v..
w.. 4th: Chevrolet 15 degree (CNC ported, Big numbers with a pretty big
runner, maybe too big.)
x.. Chev 15 degree .200---153---120
y.. 252 cc .300---225---175
z.. .400---284---213
aa.. .500---335---245
ab.. .600---353---276 76%
1.406
ac..
Velocity is an important consideration, but so is flow. Getting these factors
balanced for a particular size engine so it will make the maximum HP possible
is the trick. Also, for our type of all out racing with say a 302 incher,
high RPM levels have to be anticipated. Is the cu/ft per cc of runner figure
an indication of the efficiency of the port? Is this in some way related to
velocity? What about plenum volume.?
Looking forward to your opinions on this subject............. In need of
education.
Terry Hunt, Guam Bomb 743
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