Poor flow, Bob???
I think you MAY be mistaken. I've not seen
anything other than opposite (at least, not
Empirical tests conducted by MiniMania
show the stock alum head (with stock valve
sizes) out of the box flows as well as a
"prepared" Longman GT3.
The cost of both fully assembled is about the same. MiniMania's proprietary "big
valve" version (1.4 intake valve) costs more
than either of the above.
One might chose the alum head to save
weight and run about a full point more in
compression ratio, all else being equal
if you "know what you want" and you are
talking directly with Dave Anton, how is
it you are unable to decide whether what
"you know you want" fits within David's
definition of "radical porting", regarding
the Turbo Head???
Maybe you need to put the machinist
directly in touch with David (remove your-self as the "middleman") so that David
can advise the machinist directly as to exactly how far he can go, according to
David's definition of "radical porting".
Let one expert talk directly with the other
expert and you'll get the best the turbo head has to offer in this respect. Your
machinist can then talk you (once he knows
how far he can go) and advise you accordingly as to which head should be
used in accordance with "what you want"
and your expectations in terms of the
performance capability of the finished product.
After all, are you planning on looking for
the "last horsepower" the engine is capable
of as in racing or is this simply a "performance" street application, Bob?
At first glance, it would appear the "best"
12G940 casting to start with for "performance" motors would be those
shown in Group E (Fig. 9.1), page 161, Vizard's bible on A Series motors.