flowbench design - floaing depression

[bruce]

A flowbench has always been a tool that was little understood by the average person, this forum has done a lot to change that by showing people how easy it really is to build a simple, repeatable and accurate flowbench.

I'm always open for new thoughts and ideas but look at the past posts here and you will see some of this has been discussed in great detail and the pro's and con's have been openly talked about.

A cheap and simple bench can be built for half the cost of the Flowquick which is being discussed on another forum which is fueling this discussion in my opinion.

How many forum members are using that product?

Show of hands please? ???



Edited By bruce on 1215082663

[bruce]

As a followup . . . I think you will find there are so many products and ideas out now on building a flowbench that you will have to find the one that suits you best for your application.

Use the info found here as a tool to help you do that . . .

[106-1194218389]

I "was" using it. That should be enough of an answer. When it worked it was great but I never had full confidence in it. Audie Thomas was always very good to work with and the product was fine. I had an early one and seemed to always be doing something to calibrate it or fuss with it. Do not take this wrong I am not bad mouthing the Flowquik, but after using both it and my PTS flowbench there is no comparison. The PTS FB is easier for me to use and to build. One big thing is the knowledge I received from building it. I can correct my flow bench if needed now. So far I have not needed to.

[Sir Yun]

you could use the maximum depression your bench can pull for a certain part of the lift.

not floating depression ( although i think that if you do the math (all of it and correctly) it will give results). more like ''stepped depression''

mostly because while you can't move enough air to pull 60'' depression at full valve lift but you might be able to pull 40'' for quite a bit of it... and 25'' for all of it.
and for the first few thousands valve opening you can pull 90'' stuff might show up this way that you otherwise never see just because it takes 2468 vacuum motors to pull 90'' of vacuum at 1.990 lift..

and the better the port ..the more vacuum motors needed..(one could argue that one could express bulk air flow capabilities of a head in No. of vacuum motors

but i'm shure someone has thought about this before.

now for the exhaust....

gunpowder anyone :p

[Tony]

Yes, but the maximum depression your bench can pull may vary from day to day. How do you know if a small measured pressure decrease at low valve lift is due to some experimental valve seat work you did, or your blower revving just a bit lower for some reason ?

Running out of airflow and pressure at high valve lifts is just a matter of having a large enough air blower and the power to run it.

And what about a really efficient air blower that has a very flat pressure/flow curve? Something where the pressure hardly changes at all over a very wide flow range. It would make this method completely unworkable, because the measured pressure would hardly change from zero valve lift to full valve lift. It would be completely insensitive to any port, bowl, or valve seat modification.

It would only work well with really crappy restrictive air blowers where the delivered pressure falls of VERY rapidly as flow increases.

[Sir Yun]

[color=#000000]Hi Tony.

i'm not talking about a flow quick

where i live the main voltage is pretty much 220v +/- 1 v maximum. weather is really stable and i'm at sea level (slightly under it actually). But space is very limited (think japanese limited..about 6ftX10 ft and that has to hold EVERYTHING workshoppy at this point)

but even then.
I'm not suggesting giving free reign and let the blowers decide the depression you are testing at today (unmeasured).

just using the available flow capacity to be used to test at maximum depression. i will never be testing a BBC, and probably the the biggest flowing pieces i will work on are honda 4 bangers and bike heads which i reckon would benefit from testing at higher depression (but not different than anyone is doing here)

but

[bruce]

Just how much floor space can your bench occupy?

[Sir Yun]

14 inches by 2.5 feet-isch.

[larrycavan]

[color=#000000][quote="Sir Yun"]Hi Tony.

i'm not talking about a flow quick

where i live the main voltage is pretty much 220v +/- 1 v maximum. weather is really stable and i'm at sea level (slightly under it actually). But space is very limited (think japanese limited..about 6ftX10 ft and that has to hold EVERYTHING workshoppy at this point)

but even then.
I'm not suggesting giving free reign and let the blowers decide the depression you are testing at today (unmeasured).

just using the available flow capacity to be used to test at maximum depression. i will never be testing a BBC, and probably the the biggest flowing pieces i will work on are honda 4 bangers and bike heads which i reckon would benefit from testing at higher depression (but not different than anyone is doing here)

but

[Otto]

14 wide?? 24 deep? hmmmm some thoughts

[JMR]

[larrycavan]

I read that GFN thread on floating depression.

They're not breaking any new ground that I can see. More of a case of trying to prop up theories in an effort to support an under powered flowbench as a viable tool for cylinderhead development.

I'm not shooting down the entire concept or saying there's absolutely no value in what they're theory is. But the complications involved in their calibration process, combined with the way they're obtaining flow data, surely leaves a lot to be desired IMO.

Besides, if you wanted to do a variable depression test, you could do that on any standard bench.

If you're getting 1% accuracy and repeatability variations with your setup, you have a tool that will provide you with good data, no matter how you choose to conduct the test or analyze the results.

We have to keep in mind that a lot of guys are still developing good heads with little SF110 benches. However, it does leave me thinking that their development may be even greater if they had some power to work with...

JMO

Larry C




Edited By larrycavan on 1216468577

[bruce]

JMR, Excellent reply!! Real world testing using the Flow Quik, it might be the fit for some people's flowbench testing.

I'm still waiting for the GFN crowd that made a mad dash over here to join this forum to add in to this discussion?

I realize there are some members on that forum that have been doing heads (and writing books) for a very long time and have a lot of experience, but we have been discussing flowbench design exclusively here on this forum for almost 10+ years now. Most of us are just average people but I "think" we all have a pretty good idea of what is a good starting point for a flowbench build. Heck, I'm a convert to the orifice design myself now after building one

I've had a hard time following along with their bench build and test procedure. Seems a rather complicated process in the long run, something we have strived for here to make the whole flowbench "black art" easy and somewhat uncomplicated for the average user who wants to test his/her own parts. I think just reading the Pass-Around-Plate thread would open people's eyes to how repeatable and accurate a homebuilt bench can be.

For all the lurkers out there reading this; Spend some time reading and researching here on this forum, educate yourself before making a decision on which way to go with your bench build. With 10,000+ posts on the subject I think we have a pretty good handle on flowbench building :;):

I have more than a few customers now who 6 months ago had no idea how a flowbench operated; bought my plans and now have a kickass flowbench in their shop!*



*shameless PTS Plans infomercial but the truth non-the-less



Edited By bruce on 1216493680

[106-1194218389]

Yes, I must admit that I am now "Borg" and I am part of "collective" and I have been "assimilated"

John "Borg 6"

[Bob's57]