:that HAVEN'T been flow tested on cylinder heads? The chart
below gives a pretty good idea how the different manifolds
vary, but a good point in a couple of posts that I found in
search was that the information was gathered by different
sources and that the cylinder heads could have altered the
numbers due to possible modifications to the heads. Not sure where you read that. Three sets of heads were
used for all the data shown.
- Stock Heads #1,
. . . Stock Exhaust Manifold Hand Ported.
. . . Stock Exhaust Manifold Extrude Honed.
. . . Greg Dupree Tubular Manifold.
. . . Greddy Tubular.
. . . Pentroof Tubular.
. . . Turbo Boss Tubular.
. . . Mike Smith V1 - Stock Heads #2,
. . . Mike Smith V1 + Enlarged Valves. - Stock Heads #3,
. . . John Abler V1
Now, to clarify, ALL heads were flow benched open, with out
a manifold. This data was taken into account to normalize
all three heads and ensure as accurate information as
reasonable prudent. *
Harry at Ztuner notified me that I did have an error with
the normalization of the John Abler manifolds and has been
since been corrected. The Ztuner heads flowed less then the
other manifolds, so the data was reworked to show this
difference (data * 1.077) The chart below shows this change in data. Is there,
or will there be a flow chart for these manifolds without
being tested on heads?
No other data has been presented, but I dont visit day
to day anymore, so I may have missed a post or three. If
something is new, or needs to be added, let me know. 
(* There has been plenty of discussion on the difference
between the front exhaust port, middle, and rear exhaust
port flow numbers. All numbers in this example are taken
from the drivers side head, Middle port. Since our engines
are 6 cylinder engines, there will be variances between all
6 ports. Take it with a grain of salt.)
Petz #3
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