SF Sizes

[Chad Speier]

It's skewed. I used #4 for the test on the SF. The old #3 was 149.5 and the new is 150.0

I used #4 for the test.

[larrycavan]

It's skewed. I used #4 for the test on the SF. The old #3 was 149.5 and the new is 150.0

I used #4 for the test.

That would only put the manometer out of it's sweet spot at .200 lift From there up it's a great comparison. manometer was above 60%.

Now, that said, if you retest and use a more appropriate range for .200" lift & if it yields numbers more in line with the PTSDM, you may have solved the issue with getting numbers to match up either high or low but not both.

[Chad Speier]

The only lift I could use #3 range is .200.

.300 and .400 are still off regardless, and I have to use #4.

I can make the low number match, but the high flow is 8-10 low.

If you look at the curve, it's linear where it's low.

PTS...SFMAN2

.200 134.2/142.4= -8.2
.300 200.6/208.6= -8.0
.400 245.2/253.9= -8.7

[larrycavan]

Convergence is .505" for that valve. Coincidentally, that's right about where things start falling in line real well..

LIFT PTS/MAN1/MAN2/PF

.200 134.2/141.0/142.2/145
.300 200.6/206.4/208.6/209
.400 245.2/251.3/253.9/254
.500 273.2/276.1/278.2/273
.600 274.2/272.5/274.4/274
.700 278.6/273.7/276.2/276
.800 278.5/274.8/277.1/276

I'd be curious to see a test sometime with another head & as small an intake valve as you tend to deal with......

[larrycavan]

The only lift I could use #3 range is .200.

.300 and .400 are still off regardless, and I have to use #4.

I can make the low number match, but the high flow is 8-10 low.

If you look at the curve, it's linear where it's low.

PTS...SFMAN2

.200 134.2/142.4= -8.2
.300 200.6/208.6= -8.0
.400 245.2/253.9= -8.7

Using #3 range for 200 lift will probably pull the numbers in closer to the PTS numbers. The manometer would be in a better zone.

[larrycavan]

In consideration of how manometers work, if you try to compare head flow results from two benches, it may be wise to look at the total sum of the flow. Afterall, it's claimed that orifices have "sweet spots". We know analogue manometers have sweet spots....

The end result can be that it gives you a bonus here and robs you there. So I compared the results that way. Taking into account that the .200 lift flow was out of the manometer's sweet spot, it skews the sum considerably. When that lift is removed, it closes the gap a fair bit.

I personally have flowed heads on both my bench and then on a SF110 located about 20 miles away and slightly higher elevation. I have never seen the variances that this test revealed. Some, yes, but not that large. Also, one would have to take into consideration that the larger the scale, the greater the difference when percent is converted to cfm.

Anyway...I'm a bit bored at the moment so I did this analysis today.

[Chad Speier]

I personally think this is why the Audie Pro Flow is the choice for SF600 users. They have fixed the issues with the software.

Maybe I'll buy one and confirm that!

[Brucepts]

I personally think this is why the Audie Pro Flow is the choice for SF600 users. They have fixed the issues with the software.

Maybe I'll buy one and confirm that!

So once Rick figures out the coding and we do the testing I can then sell a PTS DM "Pro model" for more $$$'s to meet the need of the Professional?

[larrycavan]

Have you checked port velocity with a water manometer at the lifts where you have significant differences in readings? They shouldn't change. If they do, then something is in fact affecting the airflow differently on the bench.

And I didn't see a digital read out on the SF bench. Only digital was the PTSDM. T in the FP1 with the SF manometer or hook it up the same way the PTSDM was hooked up like Larry M. had his setup.

Have you tried that with either digital box?

[Chad Speier]

I've had both digital boxes on the SF. The results are in this thread someplace. Neither matched the calibrated manometer numbers.

The pitot readings were the same. However the PTS pitot was way hot with the manometer. The Performance Trends pitot was dead nuts with the manometer, but I broke it.

Like I said the issue with the SF is the way it was calibrated. My plates match perfect at 10", but not 25 or 28". I can get either processor to match low or high number, but not both to the PTS. Exactly what the phone calls were telling me, I was 8-10 high with my PTS numbers, compared to a SF with Flowcom or manometers. Exactly what I found.

My PTS with the FP matched Darins SF w/Audie within 1-2. However, even with the Audie he still rotates the orifice disc. AND he is anal and calibrates his bench properly.

My thinking is the square hole in the SF is at a major disadvantage over a single sharp edge plate. Therefore, doing like I describe above nets the best results.

This all started because I think the SF is wrong and I'm right. I made it my mission to find the discrepancy.