Port Mapping

engineczar · Post by **engineczar** » Fri Jan 07, 2005 10:24 am

I'm looking to do some port mapping. I've seen in the Reher Morrison book where they say to just hook a tube up to a manometer and probe the different areas of the port looking for dead spots. However what sort of numbers are you looking to pull on the manometer. On a port that flows say 200cfm@28" how many inches would you see? I'm asking because what range would be needed for the manometer? Are we talking 28" like what's set in the plenum below the head or something much less because it's above the valve, and does it matter what diameter the tube is.

bill jones · Post by **bill jones** » Fri Jan 07, 2005 2:38 pm

-I found an air toggle switch that allows me to use my vertical manometer on a velocity probe at the flick of the switch.
-I get the flow adjusted where I want it, flip the switch and now the vertical manometer measures from my probe.

dougk · Post by **dougk** » Fri Jan 07, 2005 10:30 pm

Doesn't your probe have two tubes from it? I'm curious because I'm about to make a probe. I thought you needed a pitot tube probe but maybe you could get something meaningful out of a straight probe. Anybody?

bill jones · Post by **bill jones** » Fri Jan 07, 2005 10:57 pm

-I actually use a single probe connected to an old WW2 zero to 300mph airspeed gauge that has a high pressure port and a low pressure port.
-I use one port of that gauge for pressure of the exhaust ports and the other port for the vacuum of the intake port and I use a single probe.
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-I did the air switch on the vertical manometer during some booster, air bleed and airfilter testing.
-it's handy when you are needing a temporary second manometer.
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-Port mapping with a bonifide pitot tube is not high on my priority list because I tried the pitot tubes for a while and never found anything that I couldn't find with the air speed gauge.
-I don't have any of the latest greatest digital computerized equipment nor the mentality to understand it so I work on what I know makes a difference and I do very few projects where I care to have 20% of the port full of epoxy.
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-One thing that really turned me off about port mapping is 180 degree manifolds and even cast aluminum single 4barrel manifolds on V8 engines and the long curved EFI manifolds
-You just can't get in there and measure what happens with those manifolds installed.