Bracket Talk
RPM QUESTION ON GRAPH!

This topic can be found at:
https://drr.infopop.cc/eve/forums/a/tpc/f/80760912/m/5887052186

June 17, 2018, 07:53 PM
Kutsick
RPM QUESTION ON GRAPH!
What is your opinion on the change in direction of the rpm`s just before the shift?




June 17, 2018, 08:05 PM
imakehp
Are you talking about the sharp rise in RPM leading up to the shift?


.
Dave



F J B

June 17, 2018, 08:11 PM
Kutsick
Yes.




June 17, 2018, 08:27 PM
undacuva67
Overlay the driveshaft rpm
June 17, 2018, 08:37 PM
Kutsick
I can not do that. I dont have a racepack with a driveshaft sensor only the grid that just gives me the rpm graph.




June 17, 2018, 09:27 PM
imakehp
So many things it could be....
It really starts to rpm/pull @7000rpm
"Driving through the convertor"
Tires start spinning
etc etc

You need more data to interpret the graph correctly....


.
Dave



F J B

June 17, 2018, 09:47 PM
Kutsick
If you listen to this video interview with Marty Chance at about 30.00 into it he addresses it and says it is a converter problem.




June 17, 2018, 09:52 PM
Curly1
With limited information we have I would say the converter is too tight and where it ramps up is where motor really gets into powerband.


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June 17, 2018, 10:35 PM
Kutsick
Yes I do believe it is a converter issue, that is why I have already contacted two different converter company's about a new one. Just waiting on a response at the moment.




June 17, 2018, 10:43 PM
markemark
From the graph display, it looks like you are using a distributor to trigger the ignition.
June 17, 2018, 11:48 PM
Scott Smith
Logging data without a drive shaft sensor is like evaluating a time slip without sixty foot times.
June 18, 2018, 09:49 AM
Greg Kelley
What's your combo?

You are not getting a flat spot indicative stall.

I see this sometimes with Nitrous or blown cars running their "small" tune-up but the "big" converter:


typical Powerglide bracket car:




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609-265-2110 GKelley@MotorSportsInnovations.com


June 18, 2018, 11:35 AM
TOP38
Most that I see the rpm in low has two curves, your first one is much steeper than most for sure! Most tend to flatten out before the normal steep rise in rpm. How does the Accel curve look? How is it performing on track?

Not a lot to go on here.
June 18, 2018, 12:13 PM
Kutsick
The best explanation for it that I have heard is in this video at about the 30:00 mark on, where Marty Chance says your losing torque multiplication in the converter. Basically it becomes to efficient/equal. If you have facebook go listen to the explanation here.... https://www.facebook.com/dragi...s/10156383230473588/