Newbie here, some questions.

[RacinNdrummin]

First of all, I have to say I stumbled across these forums and am impressed with all of the information here. I have learned more in the last couple of days on these forums than I did in the last few months of looking around on the internet.

I have to say, I have never used a flowbench, but I want to learn how to and build one myself in a true DIY fashion. I work at a sheet metal fabrication shop, and have access to a milling machine and lathe, as well as CNC plasma table and can build one very easily.

I have a few questions that I bet you guys could help me out with:

1. Is there any easily accessable reading material that would be a great introduction to the science of using a flowbench, either online or in book form?

2. What is set on the vertical manometer? Would this be the test pressure (ex. 28", 10" etc.) through the orifice?

3. I understand that the Angled Manometer is the percentage of flow that the part being tested flows compared to the orifice plate. Why does changing the angle of the manometer have an effect on the reading?

4. Is there a guide to making your own Manometers, what materials to use Etc?

5. Where is the placement of the pressure tubes within the flowbench?

6. How far off are flow numbers measured at 10" and converted to 28" as opposed to actually measuring then at 28".

Thanks in Advance- Justin

[77-1201624802]

Hi Justin,


I assume you will get more answers soon. I'm a newbee too and I'm reading this forum (plus some books) since 3/4 year. Try to catch some spare time and read as much as possible in this forum, that will solve many questions.

In general I can recommend the book: Practical Gas Flow: Techniques for Low-Budget Performance Tuning ( )
)

However most theoretical stuff I learned from some german books, which would not help you

Cheers and welcome to the forum.

Daniel

[86rocco1]

First off welcome to the forums, if you want to learn about flowbenches, you've come to the right place.

1-There's tons of real good info right here. Bruce, the owner of this forum, sells a set of plan based on extensive consultations and own personal experiences.

2-The vertical manometer is used to set the pressure difference across whatever it is you're testing.

3-The inclined manometer measures the pressure difference across the orifice. It's angled to make it easier to read because it stretches the scale out over a greater distance. And it changes with the angle because the vertical distance from the bottom of the scale to thetop changes with the angle.

4-Any clear tube with a consistant inside diameter will do, check the spreadsheet section of these forums for details on setting up the scale.

5-Pressure pickups are placed so that they are not in the direct stream of air movement.

6-Don't know for sure. But generally I think it's pretty good.

[Tony]

Welcome to the forum RacinNdrummin.

3- As 86roccol says, the sloping manometer just spreads out the scale.
If your measurement orifice creates say six inches of water pressure difference at 100% rated flow, the water in the manometer is only going to rise six inches in the manometer tube.

Now if the measurement manometer was vertical, you could only have a measurement scale six inches long to read, and that would be rather difficult to see.

So what you do is get a manometer tube sat two feet long, or maybe three feet long. The length does not matter. You make one end six inches higher than the other. The water still only rises six inches, but it will now travel a much greater distance along the tube to rise by six inches.

That would allow a measurement scale two feet long, or three feet long (or whatever) and the graduations along the scale will be much further apart and easier to read.

It is not the angle of the slope that matters, but the difference in height between the two ends.

You just build your sloping manometer any convenient length, and mark it off in percentage flow. When you calibrate the bench, you just move the high end up or down until it reads correctly. There is never any reason to even know what the actual slope angle is.

[MMack]

Something I learned on here is to make the water manometer one sided with reseviors on top and bottom. The bottom one makes it easy to zero. The top one is for screw ups. And when you find how hard zeroing a two sided manometer is, the top one is worth it's weight in gold.

Mike

[thomasvaught-1]

Welcome to the forum, RacinNdrummin (Justin) and MrHijet (Daniel).

I work at the Ford Motor Company. We typically check parts at 10" (an old SF Test Pressure), 20.4" (Old Carburetor Test Pressure), 25" the SF-300 and SF600 Test Pressure, 28" which was the test Pressure Smokey Yunick recommended in his book to flow test parts, and 67" which was a Ford test point for the LeMans project, among others.

By using all of the test pressures we get a good corrolation between the different flow test pressures and can relate those data points to many historical data points published over the years. I have never seen any major differences in the flow conversion factors but have seen differences in being able to determine things happening in the ports. One of our members Larry Meaux is a famous head porter and posts on occasion about this type of stuff.
www.maxracesoftware.com/

Tom Vaught

[tweaks]

Hi Tom,

just a quick one ..why did Ford settle on the test pressure of 67" and when you say Lemans ..is this from the early years of our youth with the 1963 / 64 Prototype GT40..

Cheers

Lynds

[rvj]

Another newbie here with my 2 cents...
3- Found some very nice Dwyer inclined manometers on Ebay with different scales, 1 inch, 2 and 3's. My bench, being underpowered at the moment, uses only the 1 inch one...and yes, the smallest mistake I make while taking measurements, and out comes the oil to the upper trap, and have to reset the zero scale. So, a longer inclined with traps is a definite way to go (unless you go digital from the start)
Ricardo

[larrycavan]

[thomasvaught-1]

Quote:

" just a quick one ..why did Ford settle on the test pressure of 67" and when you say Lemans ..is this from the early years of our youth with the 1963 / 64 Prototype GT40.."

We had very powerful Vane type compressors that used "water seal" technology to seal the edges of the rotors to the round steel housing. No real wear over many years using this method.

The compressors were located in a flow lab that had Barometric Pressure control which means that we could simulate a lot of different climate conditions.

We used 67" of water for a few reasons:
1) The compressors could pull that much test pressure without issues.
2) We found small improvements (here and there) in the intake manifolds that were not apparent at lower test pressures.
3) We had the electrical power and facilities to test at those pressures.

Smokey was the guy who advocated the 28" deal. I had a chance to talk to him a few times over the years about his history with the OEMs.
He was a "Systems guy" (He could do the whole engine) vs most engineers who are "Components Experts" where they really know one part well. I am a "Boosted Engine Systems Senior Engineer" (whatever that will buy you at the coffee pot!)

He was able to afford a Vacuum Compressor that would allow consistant results at 28" of water between his flow bench and his dyno so that is where he did his testing: Economics and Data.

Tom V.

I wasn't very young in the 60s, lol. I have been around Ford for over 30 years (Research and racing stuff) and worked for Holley carb before that. They had a 3500 cfm Aircraft Carb flow bench!