PTS Flowbench Forum

Chad Speier wrote: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.

larrycavan wrote: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 wrote: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!!!!!

Chad Speier wrote:

larrycavan wrote: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!

larrycavan wrote:

Chad Speier wrote:

larrycavan wrote: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...

you can tune this thing to be dead nuts accurate.