Porting School #4 - Budget Bench Electronics

[rsicard]

David: I want to thank you and your team for putting together this series of articles. In the future I will purchase the Flow Quick hardware and software. Thanks again.

[Unknown]

I've been studiously reading this forum for a few weeks now and its great

I have had a flow quick for 5 years now and its been a really reliable, repeatable peice of kit.

I also thought it was reading correctly until Flow Specialist brought his calibration plates down. My numbers were 7-11% off partly due to the pressure tapping being in the wrong place.

There are a couple of things I've found:

1. It doesn't work when blowing through exhaust ports. To get reliable results you have to suck through the exhaust port with the bore adaptor in place (thats 5 years of flow tests down the drain!) Now I can tell Dave the valve and port sizes and he gives the the flow figures within a couple of CFM so its not far off the mark.

2. The flow figures are not linear. When using 2 of Flow Specialist's plates there is a difference between them and if I ever get around to making the rest of the plates then I'll have a complete map of errors.
I have mailed Audi Tech a while ago and they seemed to be quite keen in the idea to add a correction factor to the software so you can enter the flow errors at different points and then the software would try to correct these out.
I'm not sure if this is an acceptable bodge but it would seem logical (I'm sure dave will have the maths to prove it either way)

My bench has 11kw of hoover motors powering it. At low pressure drops (ie with only a couple of motors running) the flow figures vary and you have to use the averaging feature to get reliable results but when all the motors are going then I just wait a couple of seconds and then the numbers settle to approx +- 0.5cfm which is good enough for me.

Overall I feel its a great asset and the best part is its very quick to use which makes testing much less tedious which is always a benefit for me.

And I'd just like to say to Dave Vizard: Its all your fault! If your books and articles weren't as good I'd have never got into this! (Just kidding )

[marti]

Hello, this is my first message to the forum.
I am doing some research on ORIFICE PLATES for a flow bench.
Tried an orifice on a SF 110 to make correlation with formulas presented by Dave
in this forum section.
The results didn´t agree with the calculations suggested by Dave.
I may missing some thing or doing wrong calculations or using wrong units.
So, I am asking help.
Will describe what I have doned.
Made a wood box measuring 10 x 10 x 10 inches with all faces closed except
a 5 in. holes at bottom and at top.
Fixed the box bottom at the SF110 working table with the SF CALIBRATED ORIFICE at the top.
At the middle of the box, internally, had installed:
AN ORIFICE WITH D= 1.604 in. , that equals an area of : 2.022 sq. in.
To measure de DIFFERENTIAL PRESSURE -"DP" at this orifice plate had installed
- 1 pressure p/ups at 1 in. downstream and another 1 in. upstream of the plate and
- 1 pressure point close to the top SF orifice plate
With 10 in.H2O inlet pressure get:
SF CFM = 158
Top manometer : 10 in.H2O
D. P . = 8.6 in.H2O B]
Tried the PTS Forum Excell formulas and found only : 102.3 CFM

For DAVE`S formula found:
M1 = 10 in.H2O = 254 mm H2O
M2 = 8.6 = 218.4 mm H2O
To have the orifice target flow: 2.022 x 0.60 x 87.2 = 105,9 CFM
(87.2 is related to the venturi flow of 138 per sq in at 25 " transformed for 10")
So, square root of M2/M1= 0.927
Thus : 0.927 x 105.9 = 98.1 CFM !!??
SF 110 Flow : 158 CFM

Appreciate your comments and corrections on this experience .
Jorge

[larryc]

Originally Posted by marti

Hello, this is my first message to the forum.
I am doing some research on ORIFICE PLATES for a flow bench.
Tried an orifice on a SF 110 to make correlation with formulas presented by Dave
in this forum section.
The results didn´t agree with the calculations suggested by Dave.
I may missing some thing or doing wrong calculations or using wrong units.
So, I am asking help.
Will describe what I have doned.
Made a wood box measuring 10 x 10 x 10 inches with all faces closed except
a 5 in. holes at bottom and at top.
Fixed the box bottom at the SF110 working table with the SF CALIBRATED ORIFICE at the top.
At the middle of the box, internally, had installed:
AN ORIFICE WITH D= 1.604 in. , that equals an area of : 2.022 sq. in.
To measure de DIFFERENTIAL PRESSURE -"DP" at this orifice plate had installed
- 1 pressure p/ups at 1 in. downstream and another 1 in. upstream of the plate and
- 1 pressure point close to the top SF orifice plate
With 10 in.H2O inlet pressure get:
SF CFM = 158
Top manometer : 10 in.H2O
D. P . = 8.6 in.H2O B]
Tried the PTS Forum Excell formulas and found only : 102.3 CFM

For DAVE`S formula found:
M1 = 10 in.H2O = 254 mm H2O
M2 = 8.6 = 218.4 mm H2O
To have the orifice target flow: 2.022 x 0.60 x 87.2 = 105,9 CFM
(87.2 is related to the venturi flow of 138 per sq in at 25 " transformed for 10")
So, square root of M2/M1= 0.927
Thus : 0.927 x 105.9 = 98.1 CFM !!??
SF 110 Flow : 158 CFM

Appreciate your comments and corrections on this experience .
Jorge

What did you use for a coefficient of discharge when you plugged in the numbers in the Excel Workbook?

[DavidVizard-GFN]

OK guys,
for all those patient people who waited for details of where to obtain a Helgesen flow bench calibration plate here is the source. I seems that Bryce Mulvey and Roger ‘Dr Air’ Helgesen have teamed up and Dr J’s Performance will be selling all of the Helgesen developed porting tools. Fort more info Check out their site as per below. If you have any enquiries email them at: sales@dr-js.com

Dr J's Performance, 436 Montgomery Street, Orange CA 92868 Tel: 714-943-3404 Fax 714 -527-2769 Dr J's Performance - Dr. J's Performance - Home email

[marti]

Used 0.60
JM