Torque Convertor question
02-22-2007, 07:23 AM
#1
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Torque Convertor question This is probably a really dumb question but, If I put a bigger stall on my car, say 3500, does that mean that everytime I leave a red light the car wont go unless it is at 3500 rpms? And when I am driving around town will it have to be at 3500 rpms the whole time? Thanks fellas
02-22-2007, 08:19 AM
#2
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yes and no.
Essentially the TC will feel like it's slipping so it will need more throttle to get moving however unless you hold it on the brake or stab the throttle it shouldn't always go to 3500rpm.
It's like with the stock TC if you are parked on a steepish slope (this affectivly makes the car heavier from the TC's point of view) you have to give it more power and high rpms before it will start and move.
Essentially the TC will feel like it's slipping so it will need more throttle to get moving however unless you hold it on the brake or stab the throttle it shouldn't always go to 3500rpm.
It's like with the stock TC if you are parked on a steepish slope (this affectivly makes the car heavier from the TC's point of view) you have to give it more power and high rpms before it will start and move.
02-22-2007, 09:12 AM
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^so if you stab the gas, RPM shoots immediatley to 3500? and when you try to roll forward normally, the car will begin to move at a slightly higher than normal RPM then a stock TC?
02-22-2007, 09:39 AM
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No, 3500 is only a rating, under specific conditions.
There are differences between same-rating models
and brands in how they couple up below rated stall
and how efficiently above it.
The STR number has a lot to do with it within a set
style of construction, and construction has to do
with it between vendors. Not very well spec'd or
often discussed. But as a rule a low STR will be more
"elastic" (or "loose", RPM sliding more with torque),
begin to couple early and take longer to transition.
For example I have a 3500 with a 2.0 STR and I
cruise level at 30MPH at 1500RPM and still creep at
a 700RPM idle. I climb a hill at about 2000RPM same
speed. A 3500/2.5 like the TCI SSF3500 is going to
creep less or none and motor slightly higher; my
cruise RPM is the same as my prior TCI 3000/2.2 and
the hill-climb slightly higher by 100-200 RPM or so.
When I nail it I'm up over 4000 right off.
There are like eleventy-zillion threads like this in the
Automatic section for your reading enjoyment.
There are differences between same-rating models
and brands in how they couple up below rated stall
and how efficiently above it.
The STR number has a lot to do with it within a set
style of construction, and construction has to do
with it between vendors. Not very well spec'd or
often discussed. But as a rule a low STR will be more
"elastic" (or "loose", RPM sliding more with torque),
begin to couple early and take longer to transition.
For example I have a 3500 with a 2.0 STR and I
cruise level at 30MPH at 1500RPM and still creep at
a 700RPM idle. I climb a hill at about 2000RPM same
speed. A 3500/2.5 like the TCI SSF3500 is going to
creep less or none and motor slightly higher; my
cruise RPM is the same as my prior TCI 3000/2.2 and
the hill-climb slightly higher by 100-200 RPM or so.
When I nail it I'm up over 4000 right off.
There are like eleventy-zillion threads like this in the
Automatic section for your reading enjoyment.
02-22-2007, 10:15 AM
#6
Ive got a PTC 3500 stall in my car and it will start moving at like 1100 rpm not moving fast but still moving. Its when you give it like 75% throttle where you feel the converter flash up in the high rpms. Awesome feeling, but you will lose your top end with it.
