Well, we re-calibrated our flow bench because we have been noticing that it has been reading lower than other SF 600 benchs for quite sometime. We finally knew something was wrong when i flowed some SS heads for a guy in Sweden that we have been helping out. The last time he was here, I flowed it and it would only do 307-308 CFM no matter what we did. When he left and took the heads back to Sweden, he flowed them on his bench, and they flowed 323. He worked on them and gt them flowing 337! He was very happy, as this is by far the most he has ever had them flowing. So he comes back to the states[his buddy lives in Phoenix, and they have a racecar there], and brings the heads back as he wants confirm the improvement he made on them. Well they still only flowed 307 on our bench.
So that brings us to today. We have been going round and around trying to find if there was something wrong with our bench. We could find nothing wrong with it. Today a friend of ours from Wisconsin was in town, and he specializes in airflow dynamics, and flowbenchs. He couldn't find anything wrong either, except that when he flowed some calibrated flow plates, our bench came up short. He re-calibrated it using those square edge orifice plates, and made us a new flow range spec sheet. Turns out our bench was a fair amount low, because the flow range sheet I have been calculating all the flow with was done at 25" of water, and not 28" plus it was calibrated with a plate that was not a square edge orifice.
With our old flow range spec sheet I was calculating all the flow off of 297 CFM being 100% of flow range 4. In reality, at 25" water, it flowed 311.1 CFM. So using these new specs, my head actually flows a lot better than I thought. Here are some new numbers based off of this new calibration.
.250" = 193.8 cfm
.300" = 230.2
.350" = 258.8
.400" = 278.1
.450" = 286.8
I need to bring my last flow sheet home so I can recalculate all the lift points to .800". Because I had 280 something at .800" before, which should put me well into the mid to upper 290's. I'm getting excited to start grinding on them again.
Originally Posted by gtofreek
Worked on the head some more today. I ground the guide leader out, and now it is at 176 CC's. I also re-did the valve job with a different cutter that accents this flat floor chamber a little better. Here is the new flow numbers.
.500"____282.5 with use of a flowball, carefully placed in top divider radius, just above the short turn. It still turns over around .475" lift.