PTS Flowbench Forum

65mustang393 wrote:SF number are low. They probably calibrate it wrong and after issuing over ten thousand benches, they won't admit a mistake.

Problem is that unless every SF owner is willing to bump their numbers by 3-4% you're gonna have people who cry foul because 350 PTS cfm is only 336-339 SF cfm.

So if you have a home made bench, just save yourself a lot of grief and keep some "SF numbers" to go along with the real ones.

Funny thing is that I bet alot of DIY bench guy's heads still do better in performance and flow than the others even after throwing a % factor in to try to lower them to match SF#'s.

blaktopr wrote:

65mustang393 wrote:SF number are low. They probably calibrate it wrong and after issuing over ten thousand benches, they won't admit a mistake.

Problem is that unless every SF owner is willing to bump their numbers by 3-4% you're gonna have people who cry foul because 350 PTS cfm is only 336-339 SF cfm.

So if you have a home made bench, just save yourself a lot of grief and keep some "SF numbers" to go along with the real ones.

Funny thing is that I bet alot of DIY bench guy's heads still do better in performance and flow than the others even after throwing a % factor in to try to lower them to match SF#'s.

No doubt you're right, but are we talking ability or relative equipment readings here?

I'll tell you what I tell people, fix your bench!

I'm not trying to change the SF World, just trying to do what math and physics are telling us. It's really not that hard, and neither lie. However, a company that sells a ton of benches, doesn't provide some sort of true calibration, and then later develops a set of calibration plates to "fix" the bench, makes this subject ridiculous as best. In fact it kind of insults my intelligence. So I'm going to accept the fact that just because the bench is marked X, it's acceptable and correct? Not this guy..

Chad Speier wrote:I'll tell you what I tell people, fix your bench!

I'm not trying to change the SF World, just trying to do what math and physics are telling us. It's really not that hard, and neither lie. However, a company that sells a ton of benches, doesn't provide some sort of true calibration, and then later develops a set of calibration plates to "fix" the bench, makes this subject ridiculous as best. In fact it kind of insults my intelligence. So I'm going to accept the fact that just because the bench is marked X, it's acceptable and correct? Not this guy..

It's all relative Chad, and your numbers are "relatively high". Why even spend the money on a SF bench if you weren't worried about getting called out by your professional peers?

Maybe you need to have an asterisk next to all your numbers. Something that says *3-4% high when compared to the faulty industry standard.

65mustang393 wrote:

Chad Speier wrote:I'll tell you what I tell people, fix your bench!

I'm not trying to change the SF World, just trying to do what math and physics are telling us. It's really not that hard, and neither lie. However, a company that sells a ton of benches, doesn't provide some sort of true calibration, and then later develops a set of calibration plates to "fix" the bench, makes this subject ridiculous as best. In fact it kind of insults my intelligence. So I'm going to accept the fact that just because the bench is marked X, it's acceptable and correct? Not this guy..

It's all relative Chad, and your numbers are "relatively high". Why even spend the money on a SF bench if you weren't worried about getting called out by your professional peers?

Maybe you need to have an asterisk next to all your numbers. Something that says *3-4% high when compared to the faulty industry standard.

Can you read? It's NOT about what my numbers are, it's about proving what I already know.

If you accept the bench reads those plates that low, you need to leave this discussion. THAT is part of the problem and your not offering any help. Your just saying that is just the way it is and you'll need to change 1000's of benches. Well bullshit!

Check this out, straight from the SF600 manual...

The values for all ranges are shown on the Calibration Data Card mounted on your SF-300/600
flowbench for 25” (60cm) of test pressure.

Important Note: The SF-300/600 flow ranges are based on a test pressure of 25”(63.5cm) of
water. If other test pressures are used, the flow scale calibration ranges should be corrected by
the following amounts.

There is a problem with the SF benches reading low vs PTS cal plates. They all read low, there are thousands out there and they will be used for comparison. If we change the SF to match the PTS plates, then our bench becomes "generous", "loose" or any other number of deragatory terms.

I have the owners manuals for the SF300 and 600 here. If you flow at 28" instead of 25", then you multiply the intake results by .997 and the exhaust by 1.003 . I would manually calc that on the SF300, not sure if the Flowcom does it auto on the 600.

Either way .003 for 300 cfm comes out to 0.9 cfm.

I have a small Superflow(110) bench and I've found that when comparing numbers between a couple of friends who have the big SF600 benches is that I agree with one of them on the intake side and the other on the exhaust side each within 1%! Yet I've compared numbers with another friend who has a home made bench(Audie components) and we agree almost exactly and certainly within 1% in both directions. I don't think that their SF600's are within 3 or 4 percent on the intake side when compared to one another!

For whatever reason one of the SF600 benches has a range number 4 that reads very low but only in the exhaust direction. It's low when compared to my bench and another SF600 by about 6%.

I would put a lot more faith in the PTS flowbench generated numbers than the ones from the SF600.

What I'm getting at is that I don't think that the Superflow benches were really carefully calibrated at all. For instance, when I installed a Flow Com on my SF 110 about 10 years ago I had to enter different numbers for the ranges than what were shown on my little bench. They were different on intake vs exhaust directions too. Then later when I started using the Performance Trends software I had to do a correction of about 5.7% higher to get the numbers to correlate with benches belonging to friends. I don't think that the SF benches were ever intended to be anything more than a flow comparitor. If you make the flow X better or worse percentage wise then the difference will be about that much percentage wise on any bench irregardless of what the number say. From what I've seen the SF600 benches while seen as some sort of industry standard tend to vary a LOT when compared to other flowbench solutions.

I know that Performance Trends assumes that the plate that comes with the SF bench is a calibration plate and they have you use it as such but it's really not. I think mine reads 153.5cfm at 10 inches of water.

I would very much like to have a plate that was tested by some real airflow expert like many of the folks here that I could just drop onto my bench to see if the numbers I generate are reasonably close to a real standard.

I put up data and pics with no agenda. It is what it is and now people who cal to PTS plates will have an idea of what their work may show on an SF bench.

This is a great forum, Bruce sells great products, period. All my data shows is why your DIY bench may be reading a little high (if it is) compared to the guy in the next town with a SF bench.