Floating Depression?

[kennedyrd]

Any of you guys test using a floating depression as advocated by David Vizard? I wondered what your views were on it. Using a Flow Quik or similar it is easy to perform it fixed or floating so wondered what your views were if any?

[Flash]

Here is a link to a thread on the subject

http://www.flowbenchtech.com/forum/view ... p?f=9&t=70

[kennedyrd]

Thanks for that. It is the same articles I read. The bench I am using with the Flow Quik unit allows it to be tested either way. The biggest difficulty seems to be making sure there are no leaks at such high depressions at the low lifts. I tend to agree with the concept if the depressions are higher than 28 inches, but I can't see how it helps at the higher lifts to have lower depressions if flow seperations from the short side are to be detected.

[302ford]

I have discussed this type of bench with David recently and one other person in the industry. I will over then next 2 or 3 months be building one and will report on this site my findings.
I think they can be made to produce repeatable results and the type of bench isn't an issue as long as u can get repeatable results.
I know a lot of people on this website might not agree with me.
I have known David personaly for over 15 yrs and i belive he the best tech writter in the bussiness.
I am sure im going to get a lot of opions why this bench doesnt work and im open to allopions
Randy

[1960FL]

I am looking forward to your builds and hope that both of you keep the posts coming and update us regularly on the builds, designs pictures etc.

Will you be flowing the pass around plate set once your bench is done? Would love to know how this design stacks up to the other DIY benches here on the forum.

Welcome aboard.

Rick

[1960FL]

Randy,

Any word on your build I am very interested in this project and would like to see our plan and implementation.

This bench has been the point of much controversy and the forum would be a great place for it to be vetted.

Rick

[BigBro74]

Hi guys,
I'm not the OP, but last winter i built a floating Dep. bench like the one DV advocates in his recent writings. Just built it out of stuff i had around or cheap as a trial learning experiance.
The bench basically looks like the one they show in his first articles on gofastnews that Audie sends as the demo unit for the flow quick which is a plenum or settling chamber with a bore adapter ion the top. It sits on a benchtop and mine was powered by 2 big shop vacs.
I made a clibration plate like the one described as per Dr. Air, watched the line voltage to make sure all tests were done +- 1 volt and did my darndest to make sure no leaks! if all these things were in line results would repeat from day to day. the test depression was about 50" stalled and around 10.25" at 315cfm converted to 28" by the plate (or by math whichever you like to say).
I tested a couple sets of sbc heads and pocket ported one set. will post results later but intake side seemed in line with other results for the same castings on stan wiess site. the exhaust or pressure has proved a little more tricky to validate but think i have solved that problem now, more deets later.
Am now in the process of making a more permanent install so i will try to keep posted. Jason

[Flash]

I can't see how it helps at the higher lifts to have lower depressions if flow seperations from the short side are to be detected.

My first attempt to build a flow bench was with this floating depression idea.
My line voltage swing a good 10 V so the +-1v was never a option.

Mine wouldn't give the same results from hour to hour, let alone day to day.

Not trying to discourage you, just an opinion.

[BigBro74]

On the voltage where i live the highest i ever measured was 114, and the lowest 110, when i ran the plate test for cfm it was at 111. it seemed pretty easy to get repeat results with heads after things were sealed well. at first not as easy. after some learning curve and finding the things that made the system leak (mostly clamping the head to the home-made adapter), or change (like, valve not EXACTLY the same lift). after some use it was not to hard to tell when the thing was lyin'. and if it was i would always find a variable (mostly moving the head to another cyl/chamber and needed to fix leaks). the mano did take a good 10-20 seconds to settle down sometimes but then would be solid if everything was static. I think if my pressure tapping was more in a corner of the plenum it might have settled a little faster. the more i worked with it the easier and more repeatable it got. as I went the repeatability i saw was about +-1/8" water which at the higher end of the spectrum on this thing is about 2-3 cfm which was okay with me. J

[BigBro74]

Here are some results i got. Let me know how way off they look
they are the intake only as on the exhaust i could measure gain or loss but my cfm was not solid ( i think i can fix this now but was in a hurry after a while on the 461's as the engine needed to go)

Sbc 461 casting, 1.94 stock, 40 year old valve job.
.100 - 55 cfm @ 28" h20
.200 - 113
.300 - 177
.400 - 195
.500 - 202
.600 - 202

same head and vj after pocket port, throat 87% of the seat, 1.88insq measure at the pinch. I should mention i did a "garage" back cut on the valve i used for testing in the ported intakes. the valves got a back cut and a new 30 45 60 seat vj after porting but i did not have the time to test again.
.100 - 63
.200 - 135
.300 - 195
.400 - 225
.500 - 233
.600 - 233

sbc 882 stock casting, 1.94 valve factory vj, i have not ported these, and probably will not, just learning how to use the bench.
.100 - 60
.200 - 110
.300 - 168
.400 - 187
.500 - 195