Fabricating velocity probes

[cspeier]

If your theory is right or wrong, you one smart dude

Something else to think about. If all the theories were true. A cylinder head flowed in say Houston should flow different than say in Denver. I'm willing to bet that the head would flow the same reguardless. Hey Bruce, another experiment???

[bruce]

I'm still not following along with what you are saying?

If you are correcting your numbers for temp and baro (weather as you called it) then thats all you need to do to get back to standard airdensity based on 70* @ 29.9". If temp or baro go up or down you are using the corrected airdensity to get your velocity readings back to the standard. No other corrects need to be done after that?

airdensity = 1.325*baro/absolute temp (*F + 460)

I use shop temp and baro for my corrections, I do the same thing everytime. This does not take into consideration the temp/baro in the port? The impact and static port of your handheld pitot "sees" the same airdensity conditions so that should not be a problem?

[86rocco]

[cspeier]

I have a question. If you take a cylinder head and flow it in Houston and ship the bench and head to Denver, would the head flow the same, and velocity be the same? I'm willing to bet yes, no difference. Do you think the flow should be corrected to a standard, I'm willing to bet no.

How do I know this? I worked at Mapcap in Denver. We got heads from all over and checked them regurarly. Never did such a thing, always within the allowed percent, which I would label 1 percent

[bruce]

On a pitot bench it's going to flow different I can tell you that for a fact.

[cspeier]

Yes Bruce, that is a style bench is a whole different animal.

[86rocco]

On an orifice type bench all reading are automatically referenced to what ever conditions the orifice was calibrated to so provided two different orifice benches are calibrated to the same standard both benches should read the same regardless of location, altitude or weather conditions.

[larrycavan]

[bruce]

Even after all the orifice plates I have machined I'll still stick with my pitot bench

(not wanting to turn this thread into a pitot vs orifice bench discussion, that's already been discussed in various threads already. They both do the job they are intended to do)



Edited By bruce on 1145106336

[riga team]

[86rocco]

[bruce]

Good one!! My chuckle for the day!!

[SuperRunner]

I took my pitot tube out for a test run. I definatly need to make a longer one so I can run test with the manifold on. It seemed to work pretty good. i did run into a problem measuring the SSR and anywhere near the valve as I need to make the bend a little closer to the tip.

I haven't got any useful information from my data, but that is because I don't know what the heck it means. Anybody know where I can get some good info about port velocity over certain areas of the port?

[Mouse]

Myth: Pitot tubes are affected by air density where orifices are not.

Truth: In a ratiometric application (flow bench) they are both affected the same. There is no difference.

Pitot tubes are used as velocity probes, and velocity probes find themselfs on air planes and race cars to measure air speed. This is not a ratiometric application. For best accuracy in non-ratiometric applications you should apply an air density correction factor.

[Jesse Lackman]