Tractorsport Flowbench Forum Archive

Posted: **Thu Apr 09, 2009 6:32 pm**

Hi guys,

I'm looking for your opinion on something. I've been reading through a few papers and also Prof. Blairs book on four stroke tuning and there seems to be a difference of opinion on where to make the test pressure tap. Some say it should be directly under the head in the top of the bore adaptor to get the most accurate flow numbers. The Ford and AMC papers seem to have the test pressure tap at the settling tank.
Does it make a difference to accuracy and does it make a difference to calculation of discharge coefficients for the cylinder head?
Would you see the effects of chamber modifications better with a test pressure tap in the bore adaptor?
Maybe I should have a test pressure tap in both the bore adaptor and in the orifice chamber? I want to calculate the discharge coefficients for the port as accurate as possible...

Posted: **Thu Apr 09, 2009 9:09 pm**

Stef,
It seems like on this forum someplace there was a thread where someone had the pressure tap right under the cylinder adaptor. In the back of my mind he was having all sorts of trouble getting it calibrated and repeatable. My test pressure tap is in the upper outside corner like in Bruce's plans and is rock solid and repeatable.

In the far depths of this old mind I think it may have been Larry Cavanaugh helping out on that other guys problem. Larry if you check in can you remember anything on this?

Here is one thread I found that addresses this

John

Posted: **Fri Apr 10, 2009 7:52 pm**

Stef

Although i'm not a expert on flowbenches and i have only built one so far i also had trouble with deciding where to put
the pressure taps. So on that i just decided to put the taps in the corners where i thought there would be minimal airflow and they would sense just pressure which to my understanding is what you want in a orifice style bench.

Jake

Posted: **Sat Apr 11, 2009 6:42 am**

I've a few searches on here trying to find larrys post. I need to try a few different search criteria I think. thomasvaught-1 gave me some advice also.

Posted: **Sat Apr 11, 2009 12:44 pm**

Stef,
here is another thread that seems to address the same issue

John

Tractorsport Flowbench Forum Archive

Test pressure tapping location