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can anyone decipher this pipemax page? i'm not quite understanding the collector length. are they giving the length from the header tubes or are they talking about the length of the bolt on collector?

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They are saying 3.63 for diameter and 17.2 total collector
length from the end of the primaries to the end of
the collector
EDIT
and I would say the VE on the head is too high at
100... more like 94 to 96

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the primary tubes i understand,but where are they measuring the collector length from?

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ok, reading from the page. header collector specs(conventional straight tube) tuned lenght=17.5, so 17.5 is measured from the end of the 4 primaries to the collector flange?

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mr p. i guess i really dont know how to use this program. what do you me i need to put up a second page with more compression?

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What I said was... the difference of the 2 pages
was the compression.... one is 13:1 the other is 10.6:1
giving you the difference in the collector length.
You'll have to learn(and read the book) to get a
idea on the VE... most people will guess high on it
by at least a few points... thats why I ask the flow
and make of head to help figure VE

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thanks mike. the problem is that i dont have a book. i bought the program from the wallace racing site. so,looking at the charts are my 1 7/8 TTI's with 3" col. gonna work better with a 3.5" collector?

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You should be able to click on VE and get help...
the 3.5 collector will be better.... most any shelf
header the primaries are too long and the collector
is too small and too short... they do this for packaging
and for cost... they arent made for max power but
it also allows it to be connected to a exhaust easier
EDIT
Also you can call the company and get the book

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all I have ever seen in Pipe Max deals in specifics like VE which when given a guess that produces another guess. Collector length IMO can only be on the money when testing on the track.For my 604 it old me to use a 2.4 first tue primary for steps

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I dont know the spec you entered in Fred but usually
you will find that the more efficient it is the smaller
the primary is... and of all the stuff I've ever worked
with it never called for a 2.4 1st primary so I would
doubt the input data.... JMO... but with all the
stuff I have run with the program then built the
headers and ran them on the dyno I would say the
program is good