How do you log converter slip?
04-01-2015, 04:43 PM
#1
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How do you log converter slip? Im running a vig 3600 3 disc in my 4l60e (level 7 flt with t brake)
I want to see if I can log the slip % to see how efficient it is during a run. Would that just be rpm/output shaft speed in 3rd gear?
I also want to entertain locking it in 3rd going down the track, anyone have any luck doing that? Is it a violent engagment when your wot at 130+mph? 900whp turbo Trans Am.
Thanks
Alex
I want to see if I can log the slip % to see how efficient it is during a run. Would that just be rpm/output shaft speed in 3rd gear?
I also want to entertain locking it in 3rd going down the track, anyone have any luck doing that? Is it a violent engagment when your wot at 130+mph? 900whp turbo Trans Am.
Thanks
Alex
04-02-2015, 02:57 AM
#2
Most people just ball park it as 95% of cars go through the traps in a 1:1 gear in the transmission. Find an online calculator and calculate what your rpm should be at the trap speed and compare to the rpm you logged on the run.
I've never tuned anything with a 4l60, but I do remember there was a way to do it with the 4l80 as there are two vss sensors. One showing input shaft rpm and the other output shaft rpm. I don't think you can do that with the 4l60.
I've never tuned anything with a 4l60, but I do remember there was a way to do it with the 4l80 as there are two vss sensors. One showing input shaft rpm and the other output shaft rpm. I don't think you can do that with the 4l60.
04-02-2015, 08:52 AM
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The HPT scanner has a PID called "TCC Slip %"; I have not used it but suspect it calculates what redtan mentioned.
I have not yet tried my Circle-D triple disk at the track. However Chris suggested re-enabling the PWM converter lockup in the valve body and tune, perhaps to soften the WOT engagement.
I have not yet tried my Circle-D triple disk at the track. However Chris suggested re-enabling the PWM converter lockup in the valve body and tune, perhaps to soften the WOT engagement.
04-02-2015, 01:07 PM
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I do not like the slip%, it is unreliable in my experience.
Bogus numbers type unreliable, not all the time but
enough to bug.
The motor RPM and input shaft RPM are useful, or the
TCC Slip RPM which is the simple difference. I do the
slip ratio figuring in Excel, when interested.
Slip ratio only tells you part of the efficiency story,
because slip always produces "some" torque multiplication
and your efficiency is (RPM_out*TQ_out)/(RPM_in*TQ_in)
but the torque PIDs are calculated, not measured, and
all based on what GM believed about stock converter
attributes for the trans input torque number on top of
the cylinder air mass, timing, fudgery involved in the
delivered torque - engine guesstimate-PID.
About the only way you can get at the torque is to
do back-back, locked-unlocked acceleration pulls and
use some decent fine grained acceleration readings
to assess the acceleration-ratio at equal motor and
input shaft RPM - fly in that ointment being, you do
not get those to line up the same, between locked
and unlocked. And you have to figure what basis
(index, axis) you want as your efficiency reference.
Road speed, input RPM, ...?
Now to me, the only thing that really matters is
acceleration @ road speed but nobody does dyno
tests that way. And on this basis efficiency doesn't
mean d!ck - only the result, and a good converter
(well matched to motor) will give you more of it
unlocked everywhere. But as a basis of comparison
good luck on finding that data.
Bogus numbers type unreliable, not all the time but
enough to bug.
The motor RPM and input shaft RPM are useful, or the
TCC Slip RPM which is the simple difference. I do the
slip ratio figuring in Excel, when interested.
Slip ratio only tells you part of the efficiency story,
because slip always produces "some" torque multiplication
and your efficiency is (RPM_out*TQ_out)/(RPM_in*TQ_in)
but the torque PIDs are calculated, not measured, and
all based on what GM believed about stock converter
attributes for the trans input torque number on top of
the cylinder air mass, timing, fudgery involved in the
delivered torque - engine guesstimate-PID.
About the only way you can get at the torque is to
do back-back, locked-unlocked acceleration pulls and
use some decent fine grained acceleration readings
to assess the acceleration-ratio at equal motor and
input shaft RPM - fly in that ointment being, you do
not get those to line up the same, between locked
and unlocked. And you have to figure what basis
(index, axis) you want as your efficiency reference.
Road speed, input RPM, ...?
Now to me, the only thing that really matters is
acceleration @ road speed but nobody does dyno
tests that way. And on this basis efficiency doesn't
mean d!ck - only the result, and a good converter
(well matched to motor) will give you more of it
unlocked everywhere. But as a basis of comparison
good luck on finding that data.