Thanks Bruce!! Its always better to hear this from someone who does it all the time, and has a total understanding, rather than keep quoting other sources.
BTW, I believe you multiply the cfm@ 10" by 1.58 to get cfm @ 25".
Bruce, whats the industry standard (in inches of water) for testing carbs.??
Thanks Bruce
Matt
In a message dated Mon, 12 Mar 2001 7:03:49 PM Eastern Standard Time, "Bruce Bridges" <bbridges@flometrics.com> writes:
<< Hey all,
Thought Id help muddy the waters here!
Flow numbers are used for standardization and comparison between products.
I picked 25" of water due to Hughes's use of 25" of water. Thats how much
pressure is required to move a column of water 25" against gravity. Sooo,
You put the TB on a flow bench and crank up the fan! The flow rate is
measured by an inclined manometer and the pressure by a standard manometer.
As I increase the speed of the fan, the air flow through the throttle body
increases AND the negative pressure increases at the bottom of the TB
(sucking through the TB). I can take flow numbers at any negative pressure
up to the maximum of the flow bench! The higher the flow, the higher the
pressure! The more restrictive the throttle body, the higher the pressure
for any given flow rate! Higher pressure= more restriction! or, you want
the maximum flow rate at any given pressure... You can go too far.. a
manhole flows pretty good, but wont work on your truck...
If you test a product at a lower pressure (with a lower associated flow
rate, like 454 CFM @ 10"H20, you can "do the math" and figure out what it
will flow at 25" H20... The flow regime is turbulent all the way, so its
pretty straightforward!
Bruce
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:00:07 EDT