port mapping

[engineczar]

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 or something much less because it's above the valve, and does it matter what diameter the tube is. My bench is an orifice type and this will behave like a pitot setup.

[ozrace]

The reading you get will depend on the velocity of the head. i.e. With your example - a small efficient port that flows 200 cfm @ 28" will read much higher than a large poorly designed port that flows the same.
I have never used a simple vacuum probe, but a proper Pitot can read higher than the Depression the bench is pulling on a high speed port.
i.e. If you are flowing the head at 28", the pitot can read 28" or higher, but normally less than the depression.
The tube diameter doesn't matter except from a flow obstruction point of view.
I don't understand the statement " My bench is an orifice type and this will behave like a pitot setup."

[engineczar]

What I meant is that my bench is similar to a Superflow or the MSD bench with fixed orifices.
Putting a tube into a port to measure the deadspots is kind of like using a pitot tube is it not?
BTW thanks for giving me a range to shoot for. I do all my tests at 28" and I'll probably get a manometer that goes to 48"+

[MikeyFIN]

[color=#000000]Well what you ask yes and no...
You have a manometer with a probe and you want to measure at same depth from the intake but in different places within the port using the middle as a reference or starting point , right?
Actually that

[Christian]

Hhmmm im thinking of port mapping myself, first of ther is a physics equation for such probes that takes into consideration the different desnity of water, i can supply that equation if wanted, also about port mapping i had some ideas, wasnt there some sort of theory by smokey yunick to test ports during 70-80perc. valve lift since there the valve has the most "mean" flowamount?? With pistonvelocityebuationsw one could calculate the piston velocity leading to intakevalocity of course not considering the sonicphenomenia happening. Most of the somwhat good engine software also does pressure indicatordiagrams with crankangle on the x axis. also i think i read once an article by reher where he said probing is done at about 12" but im not quite sure about that. But hey you made me curious about the book! Is there a title and were can on order?? Do you want the equation???