Don Terrill’s Speed-Talk

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?

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

Very weird that you noticed differences in the channels DynSpd (channel 10) and EngSpd (channel 125).

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.

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 ?