SuperFlow SF-902 RPM Measurement

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RaceEngineer
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SuperFlow SF-902 RPM Measurement

Post by RaceEngineer » Tue Apr 17, 2018 11:20 am

Hello all,

I am not really sure I can ask this question over here, but I know that there are some (SuperFlow) engine dyno experts on this forum who I already had contact with. However, I would not only bother them with my questions and hope anyone can help me with the following problem I obtained:

I recognized in the raw measurement data of my SuperFlow SF-902 that the engine rpm (channel DynSpd or EngSpd) differs a lot from the engine rpm I received from my datalogger (AIM EVO4). There is no fixed offset between them, but it looks like when the engine is accelerating faster, the difference between them is more. I could post a picture from the real differences tomorrow.

Some information to know:
- The rpm at the dyno is measured with a magnetic pickup sensor on a 60 tooth trigger wheel
- The rpm from the datalogger is obtained from the ECU RPM. The engine has a crankshaft position sensor (I think hall type) and also a trigger wheel.

I am pretty sure the engine rpm the dyno shows is wrong one I wonder how this could happen. Does anyone over here recognize this problem?

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Re: SuperFlow SF-902 RPM Measurement

Post by maxracesoftware » Tue Apr 17, 2018 1:23 pm

RaceEngineer wrote:
Tue Apr 17, 2018 11:20 am
Hello all,

I am not really sure I can ask this question over here, but I know that there are some (SuperFlow) engine dyno experts on this forum who I already had contact with. However, I would not only bother them with my questions and hope anyone can help me with the following problem I obtained:

I recognized in the raw measurement data of my SuperFlow SF-902 that the engine rpm (channel DynSpd or EngSpd) differs a lot from the engine rpm I received from my datalogger (AIM EVO4). There is no fixed offset between them, but it looks like when the engine is accelerating faster, the difference between them is more. I could post a picture from the real differences tomorrow.

Some information to know:
- The rpm at the dyno is measured with a magnetic pickup sensor on a 60 tooth trigger wheel
- The rpm from the datalogger is obtained from the ECU RPM. The engine has a crankshaft position sensor (I think hall type) and also a trigger wheel.

I am pretty sure the engine rpm the dyno shows is wrong one I wonder how this could happen. Does anyone over here recognize this problem?
Please Post ScreenShots

i have noticed the differences in the 2 Channels
and i have a separate Tach on my Dyno , as well as from time to time, Customers bring RacePak Digital Display
and hookup to my Dyno .. we basically show same RPM matchup to one Channel , not the other

DEPAC Dave one time came to my Shop
we had both DEPAC and SF hooked up together , and readings were exactly the same
TQ and HP were within .1 tenth or less, same RPMs , etc
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Re: SuperFlow SF-902 RPM Measurement

Post by RaceEngineer » Wed Apr 18, 2018 7:55 am

maxracesoftware wrote:
Tue Apr 17, 2018 1:23 pm
Please Post ScreenShots

i have noticed the differences in the 2 Channels
and i have a separate Tach on my Dyno , as well as from time to time, Customers bring RacePak Digital Display
and hookup to my Dyno .. we basically show same RPM matchup to one Channel , not the other

DEPAC Dave one time came to my Shop
we had both DEPAC and SF hooked up together , and readings were exactly the same
TQ and HP were within .1 tenth or less, same RPMs , etc
See the picture below for the differences. I would consult some other measurements to see if the differences are always that great..

Image

Very weird that you noticed differences in the channels DynSpd (channel 10) and EngSpd (channel 125). That could not be possible, because EngSpd is calculated from DynSpd with only a gear ratio which could be difference between them. But normally is this one? Let me quote the following from the SuperFlow manual:

"Channel 125 is used to calculate the absorber speed in revolutions per minute (RPM). It uses the frequency from the absorber magnetic pickup, channel 10, divided by the number of pulses per revolution from channel 83. The result is multiplied by 60 to obtain an RPM value. This value is then multiplied by a ratio, channel 81, if one is used between the engine and the absorber."

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Re: SuperFlow SF-902 RPM Measurement

Post by maxracesoftware » Wed Apr 18, 2018 1:22 pm

Very weird that you noticed differences in the channels DynSpd (channel 10) and EngSpd (channel 125).
i see Channel Numbers are different in my WinDyn version from yours
EngSpd = mine channel 13
DynSpd = mine channel 37

i see a maximum difference of 23 RPM between 13 & 37 .... i also have SF871 Brake if that makes a Sensor/Teeth difference ??
Also have 0= Filter setting .. if that too makes a difference ?

What does SuperFlow say about this ??
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Re: SuperFlow SF-902 RPM Measurement

Post by RaceEngineer » Wed Apr 18, 2018 2:10 pm

maxracesoftware wrote:
Wed Apr 18, 2018 1:22 pm

i see Channel Numbers are different in my WinDyn version from yours
EngSpd = mine channel 13
DynSpd = mine channel 37

i see a maximum difference of 23 RPM between 13 & 37 .... i also have SF871 Brake if that makes a Sensor/Teeth difference ??
Also have 0= Filter setting .. if that too makes a difference ?

What does SuperFlow say about this ??
I don't exactly know which absorber I have (SF833 or SF871), where is it displayed?

Yesterday I sent Robert Kwasniewicz (Service manager) a message, but didn't received anything from him today. Hopefully tomorrow.

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Re: SuperFlow SF-902 RPM Measurement

Post by maxracesoftware » Wed Apr 18, 2018 2:56 pm

I don't exactly know which absorber I have (SF833 or SF871), where is it displayed?

Yesterday I sent Robert Kwasniewicz (Service manager) a message, but didn't received anything from him today. Hopefully tomorrow.
checkout your Dyno Data Filter setting
so that you can ask SuperFlow if that makes a difference ?

here's a Pic of the 2 different Absorbers
they should have 2 different combinations of Sensors/Teeth Numbers ??? .. ask about that too .
Attachments
Aborbers.jpg
Aborbers.jpg (171.53 KiB) Viewed 1036 times
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Re: SuperFlow SF-902 RPM Measurement

Post by RaceEngineer » Wed Apr 18, 2018 3:13 pm

maxracesoftware wrote:
Wed Apr 18, 2018 2:56 pm
I don't exactly know which absorber I have (SF833 or SF871), where is it displayed?

Yesterday I sent Robert Kwasniewicz (Service manager) a message, but didn't received anything from him today. Hopefully tomorrow.
checkout your Dyno Data Filter setting
so that you can ask SuperFlow if that makes a difference ?
As I said before. I was analysing the raw measurement data. So without any filter options from SuperFlow (ProFilter they call it in their software).
The data I posted is the real measurement data without any filter.

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Re: SuperFlow SF-902 RPM Measurement

Post by maxracesoftware » Wed Apr 18, 2018 3:37 pm

i just looked at a few Dyno tests comparing 600 RPM/SEC to 200 RPM/SEC

between my 2 Channels : ( stock OEM GM Harmonic Damper + Steel Crank )
200 RPM/SEC = maximum of 14 RPM difference
600 RPM/SEC = maximum of 29 RPM difference
all same engine back-to-back
0 = Data Filter
SF871 Brake

What Name / Brand Harmonic Damper on your test Engine ??

possibly need to realize SuperFlow WinDyn was setup to round-off actual RPM to even numbered 100 RPM increments on the EngSpd Channel
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Re: SuperFlow SF-902 RPM Measurement

Post by maxracesoftware » Fri Apr 27, 2018 6:04 pm

any Info back from SuperFlow ?

:?:
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