GC what is your standard depression for flow testing?

[SirYun]

just wondering,

I have seen all kind of numbers, some of the americans using as much as 80' h2o (and 30 odd vacuum motors).

thank you

Joost

[Guy Croft]

Hi

I have a Superflow 120E and I use 10" test pressure.

GC

[CoupeFan]

Guy, being in the US, you would expect me to be used to Imperial measuring units, however, my work forces me to stick to SI units. I'm guessing the 10" you quoted, is 10" under from atm as read on a gauge (about 500 Torr) and not absolute (about 290 Torr)?

thank you,

Cesare

[Guy Croft]

Hi Coupefan

yes, gauge pressure/manometer.

For readers who have no idea what we're talking about see pic below. The machine draws air thru the inlet port (or blows it out of the ex port) to measure the volumetric air flow in say, cu ft/min (cfm). By doing this at a fixed level of suction we can assess the benefit of mods to the ports and seats.
Under the test plate (that the head sits on) there is a chamber, with a high power air pump at the exit. The vacuum generated by the pump in the chamber is adjusted to 10" on the vertical test pressure manometer by means of flow control valves (inlet or ex) on the front panel. Each time you make a test where there is an improvement in flow eg: lifting the valve higher, the valve has to be opened more.

The air goes from the pump to a series of orifice plates at the top of the machine, they are opened up in various combinations to suit the amount of air the head flows. These plates give you a flow reading on the diagonal manometer and that reading, when applied to a calibrated graph, will tell you the flowrate.

I bought this machine 2 years ago and it's the best spend I ever made, allowing me at last to break free of the 'he only does Fiat/Lancia Twin-Cams' shackles and apply my years of expertise to many other heads.

GC

[SirYun]

Hi Guy, is that a pitot tube in the right of the picture?

if so, do you use that for mapping port velocities ?

(a pitot tube is basicly a device for measuring airspeed..the sticky out bit on a jet nose usualy does that same).


slighly of topic, but have you seen the wet flow rig mondello makes ?

see also :http://www.rehermorrison.com/techTalk/40.htm

it looks like real time computational fluid dynamics you see screenshots of,

And I would think that actualy seeing where the air goes should help enormously.

I hope to have my own flowbench within the next year or so (food has a higher priority now :? ) but this seems doable in DIY form.

[Guy Croft]

Hi Siryun

not pitot, just a total pressure manometer, handy from time to time when tracing cause of velocity/stagnation related problems.

GC