Racing Research flow bench

[tbone]

Looking for info on this flow bench. I don’t know what each one if the orifices flow to calculate CFM. Any help would be appreciated.

[1960FL]

Your information is limited, so why don't you take some better pictures post them so i don't have to turn my head sideways and give us some more information on how it works. that said welcome to the forum.

Now it looks like there is a stack of orifices on the back side of the cylinder adapter, if this is so and these are the orifices yo are speaking of then you need to start by doing two things, 1. search the internet and get a copy of a Superflow SF110 or 120 manual read it and study it and all the formulas. 2. use digital or dial calipers and measure each hole as close and possible to +/- .002.

Also do you have all the rubber toppers for the orifice holes on the bench?

Rick

[tbone]

The bench is made by Racing Research distributed by CV Racing Products, no longer in production. It is a similar design to the SF110. The left digital display is the test pressure and the right digital display reads % of flow. Yes I have the plugs for the orifices. There are 4 orifices that measure .760, 1.050, 1.270, and 1.520. Sorry for the crude description I was on a phone trying to do the post. I have the SF110 manual and have read it. The only missing piece to the puzzle is I do not know what the 4 orifices flow to do my calculations. The only thing I am confused about is if you have two orifices unplugged would you add together the flow of each orifice? Example, you are using holes 1 and 2 that flow 25 and 40 cfm at 10 inches. Your test piece shows 80% at 10 inches. Would you multiply 80% by 65 to calculate your test piece cfm at 10 inches?

Thank you for the help.

[1960FL]

well without documentation you will have to do some testing and math, you do not know the scale of the % as in DP so you need to find it, you can do this by plugging all the holes and SLOWLEY raising the test pressure until your scale shows 100% then record the test Pressure in Inches of water. Do this like 5 times and take the average this will be very close to what your digital incline would be reading in inches of water at max flow on any setting.

Once you have the DP you can calculate the max flow of each hole.

You will have to start with one hole, do the math on it (Use Ed's Spreadsheet, oh and he has one that does % scale http://www.flowbenchtech.com/forum/viewforum.php?f=14) and then back into the calibration for the one hole. You will have issues with CD as it looks like this bench has a 5mm or 1/4 inch thick top and the original SF110/120 were like 1/16th but you can start with like .62 to .68

Remember this bench is not ratiometric and will require air/weather data for compensation in the math.

As an example the 1.52 orifice will flow +/- 100 cfm at 10" DP at standard air. so i suggest you get some calibration orifice plates and start test on hole at a time and you will be able to figure it out.

in example using 10" DP if your scale read 50% on the larges orifice you would be flowing +/- 50cfm. I am making an assumption that since this bench is digital the scale is linear! unlike inclined oil fluid manometer which is not.

Good luck

Rick

[1960FL]

The only thing I am confused about is if you have two orifices unplugged would you add together the flow of each orifice? Example, you are using holes 1 and 2 that flow 25 and 40 cfm at 10 inches. Your test piece shows 80% at 10 inches. Would you multiply 80% by 65 to calculate your test piece cfm at 10 inches?

The answer is in general Yes, so once you have the DP of the system to know what the % scale is measuring then I (if me) would do some calibration testing on each hole separately until you have arrived at a solid average CD value to use in ALL your calculation for the specific mode (Intake Exhaust) again i am ASSuming that the electronics are not self compensating for Standard Air.

After you have calibrated and know the flow of each hole i would then do a progressive testing of say #1 & #2 (2-3 & 3-4) pic a point in between and check calibration +/- do this up the scale then try #1 & #4 etc. Goal here is to see if the holes flowing next to each other are affecting the CD, if you do this a few times you could actually build a spreadsheet that has your calculations in it for any hole or combination of with correction factors for all aspects of the testing.

Remember when i say not ratiometric, the air temp and density are changing inside the bench from when it enters to when it exits the orifice so to be accurate and repeatable you will need the temperature of the air going in and coming out this is discussed int he sf110 manual.

Rick

[tbone]

Very helpful information. Thank you. I have a few questions.

1. What does DP stand for and what exactly does it mean?

2. What size calibration plates would you recommend to fully test the range of the bench at 10”?
I had originally thought 20, 40, 60, and 80 cfm at 10” but I am thinking I need a higher range possibly. I don’t mind buying 5 or 6 plates because I’m in this bench pretty cheap.

Thank you again!

[tbone]

Question 3

How will I figure the CD for each orifice and orifice combo?

[1960FL]

1. What does DP stand for and what exactly does it mean?

2. What size calibration plates would you recommend to fully test the range of the bench at 10”?
I had originally thought 20, 40, 60, and 80 cfm at 10” but I am thinking I need a higher range possibly. I don’t mind buying 5 or 6 plates because I’m in this bench pretty cheap.

Thank you again!

1.) DP or Delta P is the differential in pressure across the orifice plate. so when you purchase plates from Bruce you will often get to calibrations for two different Delta P numbers. The PTS bench uses a 16" delta P this means that the internal plate (the one that determines flow) lets say is 300cfm; It means that the plate with 16" of water column differential pressure across it will be flowing 300cfm of air.

2.) Lets not go here yet as we do not know the capacity of your bench and the range of the orifice that you have. once we have this we can recommend plates but as an interim you can drill some holes in tin or plate and we can test our theory before you invest in plates. (Which you need)

3.) please understand I know nothing about your bench i just know how benches work and how we measure air flow, this may take some time to reverse engineer.

4.) I HIGHLY recommend you get Ed's (thank you Ed) spreadsheet and play with it changing orifice size and DP and watching what happens with flow. you will see that at 10" of water (DP) your larges orifice flows 100cfm in theory and this is why we need to know the preasure at 100% on the flow meter.

Think about this the DP is what we are looking to find on your electronics, if you plug all the holes and slowly increase motors or flow when the flow gauge read 100% you read the depression in inches of water and that should be your DP at full flow. we have other tricks we can try but this is the easy for a first step.

Rick

[1960FL]

How will I figure the CD for each orifice and orifice combo?

First off over the years this has been an issue in understanding, once the bench is calibrated you will have a CD for intake and a CD for exhaust you don't change them as this is fudging the numbers. Later as you learn your bench you will see it is NOT linear and you will now based on orifice combinations what is more accurate then not I/E 1 & 4 may be more stable and linear than 2&3 though they both cover the range of flow you are looking to test.

I have a question which is important to the discussion, what are you flowing? and what is the best head you know flowing? this will help us understand the range the bench and you are working in and help us help you calibrate that bench.

Rick

[tbone]

For figuring the DP, I plugged the 4 orifice holes and got a really low reading on the test pressure digital readout when the percent of flow was adjusted to 100%. It was 0.2 inches of water. When I plugged the 4 orifice holes and covered the test piece inlet also I got 2.9 inches of water for a test pressure.

I will be flowing carburetors and heads for go kart engines. 100 CFM will be plenty of capacity for my needs at the moment.