Well I can speak with experience of the alloy Pierce 5 port head - it makes
no more power than my previous less than full race iron head, possibly
less. My dyno go expected my engine spec to make more.
I haven't seen flow figures for the Pierce 5 port head but I've heard even
with the larger valves they are very average.
SO, WHY I AM EVEN RUNNING A PIERCE HEAD?
Simple really, it is significantly lighter than the iron head and that's
more important to me than more peak horsepower. I don't need more peak
horsepower to make my Spirte go quicker I need improved aerodynamics on it.
As for the MGB cross flow head well it's not a Pierce design is it? He
simply copied the HRG Derrington crossflow head (no patent issues) and
marketed it as his.
So, I'm still not excited about a Pierce 7 port A-series head, especially
since it's not likely to be lighter solution than the Pierce 5 port head I
already head.
Weslake-Monza 1330
In a message dated 29/08/2009 21:52:37 GMT Daylight Time,
twobees@sprynet.com writes:
"There is no guarantee the Pierce 7 port head will make more power than a
really good iron 5 port. When there is I'll be interested in seeing it.
Also the weight of the 2nd Weber, manifolding, and air filter is a weight
increase that doesn't help."
While I can't speak directly of the Spridget head, allow me to relate my
experience with one of their early X-flow MGB heads.
When I bought my '66 MGB, it had a rebuilt engine with mild cam. I had
Sasco Motorsports modify a head for me - ported, polished, shaved & o'size
valves. Running 1-1/2" SUs it made a good difference from about 3,000rpms
on up. No idea of h.p. increase. But, it WAS apparent. And, I used that
set up when I first started racing the B.
Bought the early Pierce x-flow (un-modified) & installed it with 1-3/4"
SUs.
>From 3,000 rpms up it felt at least as good as the Sasco head. BUT, from
idle to 3,000 the h.p. increase was dramatic. I would estimate the h.p.
changes to be from stock actual of c. 90, to 95 with the mild cam, to 105
to
110 with Sasco head, to 120 with X-flow. Ultimately, I installed a
purpose-built near race engine by Fab-Tek rated at 145 h.p. I would have
to
dig out my Race Logs to see the e.t. difference. But, my times did come
down substantially with each change
No need for twin Webers, I ran a single 45DCOE. I always wanted to
re-install the x-flow on the Fab-Tek lower end (Carillos, JEs) and install
the twin 45s I had. Never got to do that before selling it. One of the
guys at Pierce told me they had a relatively stock MGB with their head,
pair
of 45s & a good cam putting out 195 h.p. From the looks of the head, it
is
possible.
As for cost of a "really good iron 5 port" Longman high performance heads
run c. $1400 to $2400.
So, for $750, the Spridget x-flow sounds like a good value.
Norm
948 powered Turner
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