Interesting, Dave....thank you.
The Pierce alum head is NOT a racing item or, in other words, a "mass flow"
head. The
porting and valve sizes, as this head comes
out of the box, have "port velocity" rather
than "mass flow" in mind, considering the
application (as this head comes right out
of the box) is designed with street torque
in mind.
Of course, one can modify the stock alum
head (MiniMania's 1.4 version, fr'instance)
more toward "mass flow" but in consideration of the "exhaust data", it seems
work on the exhaust side of the
equation would be in order on this or any other version of the alum head wherein
an increase in inbound flow is to be
undertaken.
However, I do not think there should be any
question in anyone's mind that the stock
alum head certainly outflows the stock cast
iron item, considering it's performance when matched to the Minisport, which is
a modified (to one extent or another) stock cast iron head and generally backs
up Don
Racine's flow bench check's wherein he
found the stock "out of the box" alum
head flowed as well as the cast iron item
modified to Longman GT3 spec.
But this is only part of the story, in any
event.
The OTHER advantages of the alum head lie in it's lighter weight and superior
heat
handling characteristics which allows for comparitively higher compression
ratios
(or lower octane requirement....take your
pick) all else being equal.
Further....
another thing with the alum head is it's
"off the shelf" 24cc (as opposed to the cast
iron's 21cc) combustion chambers. This allows for more flexibility in piston and
different bore combos for the greatest
range in choice of compression ratios.
Cap'n Bob
Basic Frog
|