<VV> VirtualVairs Digest, Vol 166, Issue 25

[kevin nash]

Message: 4
Date: Tue, 27 Nov 2018 07:53:00 -0800
From: John Pinard <corvairjack at yahoo.com>
To: virtualvairs at corvair.org
Subject: <VV> Nash fan
Message-ID: <E4A5C575-2ABE-45B1-A1B7-5A6C6AF33CED at yahoo.com>
Content-Type: text/plain;       charset=utf-8

Good work Kevin.
Question:
In simple terms at what point on engine is pressure and flow measured, and how is it measured.
Thanks,
Jack Pinard
?Not an engineer but appreciate good engineering?
Overlooking the blue pacific


Thanks John!! The pressure was measured using a digital manometer, the point on the engine
where this pressure tap is located is a bolt hole in the top portion of the shroud that is closest
to the firewall. The bolt that normally goes there normally holds a metal strap thing that is
normally used to support the front part of the engine seal shroud at the firewall. I did not
measure flow, as there's GM pressure and flow data that I have access to, and was able to
use that data to predict what the flow should be for a given pressure. The formula is
pressure= kXq^2, where k is a constant, and q=flow. When the pressure is known, then to
get the flow, you take the pressure, divide by the constant then take the square root of the
result. For the mag fan on a 140, for example, k turns out to be .00000411. According to
Gm data, the mag fan would flow 750 cfm at 2.3" at 2000 engine rpm. To predict the pressure
with this formula, you would square the flow (in other words, 750X750) and multiply by
.00000411 to get 2.3", which is what they got. It works! It also works the other way, using
the pressure to get the flow.
  Kevin Nash
  63 Turbo port injected daily driver
   coolest most unique fan on the Planet!!