Misconceptions and confusion, I need some clarity!

[Adrielp]

Okay so I am coming to the conclusion that I didn't know as much as I thought and I need some clarity on some questions I have.

First, if one is testing the intake or exhaust port, do you need to create 28" of depression at every lift(this is something I am unclear on)?

Second, how does one go about running a test on the exhaust ports(Pictures may help here)? From the videos I've seen, the cylinder head stays in the same configuration as when the intake is being tested, but how is the depression achieved? Would one reverse the polarity of the vacuum motors such that they are blowing air thus creating a 28" depression in relation to the air in combustion chamber area?

I hope my questions were clear, I am in the process of assembling a flow bench and we will more than likely be re-assembling it with more powerful vacuum motors or a centrifugal blower. I will try to post pictures of the current set up at some point as the individuals maybe able to offer some critiques of things to do to make it better.

[jfholm]

The standard method of flow testing has you set the test depression the same at each lift - as you open the valve to test a different lift your test depression will drop so you would turn your vacuum motors up to get the same test pressure as example 28" H2O.

In Bruce's bench design for the PTS bench it has an ingenius method that changes the flow direction by a plate you remove and flip over and then the bench blows out the head to test exhaust.

[Tony]

You don't actually "need" to test at 28 inches (1 psi), although that has become the standard accepted test pressure.

How much airflow and blower power your bench has, along with the flow of the part being tested will determine what test pressure you can reach at full flow.
Some people test at even higher pressures than 28 inches, and a modest bench may force you to test parts below 28 inches.

Ports need to be tested in the normal direction of airflow.
Inlet ports are tested by creating a low pressure below the head.
Exhaust ports are tested with a positive air pressure below the head.
That will allow full access to the open port while testing, experimenting, or probing for air velocity.

You "could" blow air into an inlet port, or suck air out of an exhaust port.
But that would be much less convenient than doing it the more usual way.

[SSR]

You could always use floating depression.......

[Tony]

You could always use floating depression.......

You are hereby sentenced to "the ducking stool".
Floating depression indeed.....
The very idea !

You will be lowered by fixed increments, and flow tested in very cold water.
It is the only way.

[jfholm]

You could always use floating depression.......

You are hereby sentenced to "the ducking stool".
Floating depression indeed.....
The very idea !

You will be lowered by fixed increments, and flow tested in very cold water.
It is the only way.

LMAO!

[ivanhoew]

You could always use floating depression.......

You are hereby sentenced to "the ducking stool".
Floating depression indeed.....
The very idea !

You will be lowered by fixed increments, and flow tested in very cold water.
It is the only way.

gosh tony ...your even older than i thought !!!

[SSR]

Hahaha, I knew I was skating on thin ice there, tongue firmly in cheek.

[Tony]

gosh tony ...your even older than i thought !!!

Yup.

Youth and inexperience are always trumped by old age and treachery.

[BigBro74]

You could always use floating depression.......

You are hereby sentenced to "the ducking stool".
Floating depression indeed.....
The very idea !

You will be lowered by fixed increments, and flow tested in very cold water.
It is the only way.

LMAO!

I also LMAO!
although this punishment hasn't cured me