SF Sizes

[larrycavan]

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.

Please elaborate a bit on the PTS pitot being hot with the manometer. That's got my attention

[Chad Speier]

Sorry Larry, meant to say the PTS probe was hot with the DM, means I need to fudge the sittings. I had to in the FP as well.

Port set at .700 lift, flows 231 w/no pipe.
Hand measure exhaust exit= 2.16 CSA

I have a straight PTS prode, and a 45º Performance Trends (PT).

PTS w/PTSDM = 325.9 @ .700
PT w/PTSDM = 309.5 @ .700

With manometer.

PTS Probe
Red: 21.5"/306.9 fps

PT Probe
Red: 21.5"/306.9 fps

The only thing I noticed is the PTS is much slower to react to either way. However, the readings we more stable.

Here is the exhaust port shape:

[larrycavan]

Thanks Chad

When I spoke to Bruce about the lag in response with my PTS J bend pitot, he said the USB version of the DM is much quicker to respond. I was going to upgrade for that but based on your results I'm not sure it will be different.

I need those small probes that Bruce makes. I had a Dwyer J bend that I gave to Bruce about 5 or 6 years ago to have for checking his as he built them. It wouldn't work in the heads I do....too large to get a centerline reading..

Pitots are a double edge sword. Make it large enought to react instantly and deal with it affecting the flow in the port...make it more ideal for the port size and deal with slow reaction time.... Frustating

I still have my FP1. I'm going to do a heads up on my bench. I'll get back to you with findings. What I know at this point is I've seen numbers from PTSDM that have corresponded will to what I previously got with FP and SF110...

I think one thing that affects what I see vs what you see is your orifice size. I use a 2.035" orifice in my bench. As such, the sensors are likely to track better than on the size of orifices you require for car heads... The nature of orifice measurement again

If you're running XP for OS, I'll send you something...

[Chad Speier]

Thanks Chad

When I spoke to Bruce about the lag in response with my PTS J bend pitot, he said the USB version of the DM is much quicker to respond. I was going to upgrade for that but based on your results I'm not sure it will be different.

I need those small probes that Bruce makes. I had a Dwyer J bend that I gave to Bruce about 5 or 6 years ago to have for checking his as he built them. It wouldn't work in the heads I do....too large to get a centerline reading..

Pitots are a double edge sword. Make it large enought to react instantly and deal with it affecting the flow in the port...make it more ideal for the port size and deal with slow reaction time.... Frustating

I still have my FP1. I'm going to do a heads up on my bench. I'll get back to you with findings. What I know at this point is I've seen numbers from PTSDM that have corresponded will to what I previously got with FP and SF110...

I think one thing that affects what I see vs what you see is your orifice size. I use a 2.035" orifice in my bench. As such, the sensors are likely to track better than on the size of orifices you require for car heads... The nature of orifice measurement again

If you're running XP for OS, I'll send you something...

I did notice a difference in the flow curve from the FP to the PTSDM on the PTS bench. Like I told Bruce, it must be in the orifice plate. I used a 2.504 in the bench for EVERYTHING up to 440cfm with the FP. I was out of air at 320cfm with the PTSDM. I have a 3.200 in the PTS currently with the PTSDM.

Again, big ole can of worms and I'm just stupid anal!

[Brucepts]

Keep in mind the hole on my probe is .0225" so I can use small enough tubing to make the .5" bend inside the outer tube. So the smaller the diameter of your tubing on your water gauge the faster it will react.

Now moving on to the Digital Manometer, computer speed, how you set your sample rate, baud rate, channel averaging will have an effect on the displayed number, again keep in mind you are only seeing an average number not an instantaneous number anyways? You are never really seeing the actual number at that one moment in time in the port no matter how "you slice it".

Anal?? Seriously?? Give me a break

Drop the averaging to 1, crank up the sample rate (240) and test away . . . those numbers will change so fast you won't know what you are reading!!!!!

[larrycavan]

Keep in mind the hole on my probe is .0225" so I can use small enough tubing to make the .5" bend inside the outer tube. So the smaller the diameter of your tubing on your water gauge the faster it will react.

Now moving on to the Digital Manometer, computer speed, how you set your sample rate, baud rate, channel averaging will have an effect on the displayed number, again keep in mind you are only seeing an average number not an instantaneous number anyways? You are never really seeing the actual number at that one moment in time in the port no matter how "you slice it".

Anal?? Seriously?? Give me a break

Drop the averaging to 1, crank up the sample rate (240) and test away . . . those numbers will change so fast you won't know what you are reading!!!!!

Ahhh...that's not what I had in mind Bruce

Seriously, with the USB version, will the pitot react quicker?

[larrycavan]

Thanks Chad

When I spoke to Bruce about the lag in response with my PTS J bend pitot, he said the USB version of the DM is much quicker to respond. I was going to upgrade for that but based on your results I'm not sure it will be different.

I need those small probes that Bruce makes. I had a Dwyer J bend that I gave to Bruce about 5 or 6 years ago to have for checking his as he built them. It wouldn't work in the heads I do....too large to get a centerline reading..

Pitots are a double edge sword. Make it large enought to react instantly and deal with it affecting the flow in the port...make it more ideal for the port size and deal with slow reaction time.... Frustating

I still have my FP1. I'm going to do a heads up on my bench. I'll get back to you with findings. What I know at this point is I've seen numbers from PTSDM that have corresponded will to what I previously got with FP and SF110...

I think one thing that affects what I see vs what you see is your orifice size. I use a 2.035" orifice in my bench. As such, the sensors are likely to track better than on the size of orifices you require for car heads... The nature of orifice measurement again

If you're running XP for OS, I'll send you something...

I did notice a difference in the flow curve from the FP to the PTSDM on the PTS bench. Like I told Bruce, it must be in the orifice plate. I used a 2.504 in the bench for EVERYTHING up to 440cfm with the FP. I was out of air at 320cfm with the PTSDM. I have a 3.200 in the PTS currently with the PTSDM.

Again, big ole can of worms and I'm just stupid anal!

That makes no sense...

[1960FL]

Thanks Chad

When I spoke to Bruce about the lag in response with my PTS J bend pitot, he said the USB version of the DM is much quicker to respond. I was going to upgrade for that but based on your results I'm not sure it will be different.

I need those small probes that Bruce makes. I had a Dwyer J bend that I gave to Bruce about 5 or 6 years ago to have for checking his as he built them. It wouldn't work in the heads I do....too large to get a centerline reading..

Pitots are a double edge sword. Make it large enought to react instantly and deal with it affecting the flow in the port...make it more ideal for the port size and deal with slow reaction time.... Frustating

I still have my FP1. I'm going to do a heads up on my bench. I'll get back to you with findings. What I know at this point is I've seen numbers from PTSDM that have corresponded will to what I previously got with FP and SF110...

I think one thing that affects what I see vs what you see is your orifice size. I use a 2.035" orifice in my bench. As such, the sensors are likely to track better than on the size of orifices you require for car heads... The nature of orifice measurement again

If you're running XP for OS, I'll send you something...

I did notice a difference in the flow curve from the FP to the PTSDM on the PTS bench. Like I told Bruce, it must be in the orifice plate. I used a 2.504 in the bench for EVERYTHING up to 440cfm with the FP. I was out of air at 320cfm with the PTSDM. I have a 3.200 in the PTS currently with the PTSDM.

Again, big ole can of worms and I'm just stupid anal!

That makes no sense...

Please remember the FP uses a 40” sensor on the DP and we use a 16” so with the smaller orifice you can over drive the DP on the FP1 on the PTS once you reach 16” of DP Flow stops (You are at 100% of the scale).

Advantage At 10 bits of ADC on the FP (That is saying they have 10) you have 40/2024 or .039” increment. Same as our base Depression scale.

On the PTSDM for Delta P we use 16” at 10 Bits or 16/1024 that is .0156” or more than twice the resolution. With this as an example if your sampling is set to 100 and your averaging is set to 100 you are taking the average of 100 samples and outputting it each second. Bruce tells me I am splitting hairs but you can tune this thing to be dead nuts accurate.

All that said in the prior posts if audie is putting in a CD correction factor for the SF application I would be more than glad to look at programming this but it will take the end user a lot of flow time and a good span of calibration plates to determine the corrections for each calibration I/E orifice.

Rick

[Chad Speier]

you can tune this thing to be dead nuts accurate.

That is exactly what I want.... can you tell?

[larrycavan]

I forgot about the sensor difference Rick... now it makes sense. Thanks for that