Please explain torque conveter stall speed effect
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
"My" combo likes to footbrake to approx 2k. "
My setup ('87 w/zz4 cam and LTs, 2K convertor ) just goes up in smoke if I footbrake it.Any more than 1000rpm on line ,bye ,bye tyres!
Best launches; at idle , hit it ,digs in and goes ;
1.84s /60ft with Falken street tyres on good track.
As said above , every combo different
My setup ('87 w/zz4 cam and LTs, 2K convertor ) just goes up in smoke if I footbrake it.Any more than 1000rpm on line ,bye ,bye tyres!
Best launches; at idle , hit it ,digs in and goes ;
1.84s /60ft with Falken street tyres on good track.
As said above , every combo different
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Originally Posted by rodj
"My" combo likes to footbrake to approx 2k. "
My setup ('87 w/zz4 cam and LTs, 2K convertor ) just goes up in smoke if I footbrake it.Any more than 1000rpm on line ,bye ,bye tyres!
Best launches; at idle , hit it ,digs in and goes ;
1.84s /60ft with Falken street tyres on good track.
As said above , every combo different
My setup ('87 w/zz4 cam and LTs, 2K convertor ) just goes up in smoke if I footbrake it.Any more than 1000rpm on line ,bye ,bye tyres!
Best launches; at idle , hit it ,digs in and goes ;
1.84s /60ft with Falken street tyres on good track.
As said above , every combo different
On the street 2k is like driving on ice. 
My combo could probably use 500 more rpm on the stall speed. I just do not want the problems that go with it. Compromise is sometimes the key. 
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by Pete K
It depends. It will flash to a higher rpm when you floor it from idle. .
The reason I ask is I am supposed to have a 3000 converter and I cant get it to rev past 1400-1500 without shoving it through the lights. I never tried to look at the actual flash rpm when leaving. If I am understanding you correctly I may be better off leaving at idle. Traction has never been a problem. With slicks Im not making that much power.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Originally Posted by 93 ragtop
Pete, are you saying the actuall stall will be higher from idle, vs say a 1400 rpm foot brake and then going full throttle?
The reason I ask is I am supposed to have a 3000 converter and I cant get it to rev past 1400-1500 without shoving it through the lights. I never tried to look at the actual flash rpm when leaving. If I am understanding you correctly I may be better off leaving at idle. Traction has never been a problem. With slicks Im not making that much power.
The reason I ask is I am supposed to have a 3000 converter and I cant get it to rev past 1400-1500 without shoving it through the lights. I never tried to look at the actual flash rpm when leaving. If I am understanding you correctly I may be better off leaving at idle. Traction has never been a problem. With slicks Im not making that much power.
Drifting
Joined: May 2004
Posts: 1,648
Likes: 0
From: Thornton Colorado
Very interesting thread 
, what does a stock 93 lt1 with auto have for stall speed and is there a good way to determine what you want for certain mods. ie added headers and exhaust for example, added maybe 25 horse's. is there a rule of thumb guide or just more trial and error
Thanks guys
, what does a stock 93 lt1 with auto have for stall speed and is there a good way to determine what you want for certain mods. ie added headers and exhaust for example, added maybe 25 horse's. is there a rule of thumb guide or just more trial and errorThanks guys
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Originally Posted by arrow322
Very interesting thread , what does a stock 93 lt1 with auto have for stall speed and is there a good way to determine what you want for certain mods. ie added headers and exhaust for example, added maybe 25 horse's. is there a rule of thumb guide or just more trial and error
Thanks guys
, what does a stock 93 lt1 with auto have for stall speed and is there a good way to determine what you want for certain mods. ie added headers and exhaust for example, added maybe 25 horse's. is there a rule of thumb guide or just more trial and errorThanks guys
Race Director
Joined: Oct 2001
Posts: 19,653
Likes: 428
From: Melbourne Florida
Cruise-In IV Veteran
When I wanted to up my stall I called GM and found out the stock stall on my 93 was 1397 rpm...I went with a TCI 2200-2400 stall converter...I flash from idle at the drag strip...
I should tell you that when I put in the higher stall I also had the tranny rebuilt and beefed up, a full race Transgo installed, a complete driveline swap to a Dana 44, new 3:73 gears and all new u-joints...
Oh yeah, I'm about to up my stall to 3000..he he
I should tell you that when I put in the higher stall I also had the tranny rebuilt and beefed up, a full race Transgo installed, a complete driveline swap to a Dana 44, new 3:73 gears and all new u-joints...
Oh yeah, I'm about to up my stall to 3000..he he
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Michael S. Palmer
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
The early C4 had a 2,000rpm TC; the later, including my '88, had about a 1,500rpm TC.
When stock I could not power brake above 1,200rpm and short times were around 2.0x sec. At the first rebuild I had a 2,000rpm modified GN TC installed and would power brake to around 1,700rpm for best ETs, with a short time in the 1.8x-1.9x range.
During the recent rebuild I had a low $$ 2,000rpm TC installed and, though it will flash to 2,000rpm, I cannot power brake much above 1,200rpm or it pushes through the beams. Now short times are back in the low 2.0x sec range and ETs have dropped off.
I prefer to power brake as high as possible to preload the drive train. If the track is slick or on the street I have to "press" the accelerator to avoid wheel spin. If I hammer it the tires go up in smoke.
I was told by Pat Barrett of Level-10 that with a stall of 2,400 rpm or less and a 12" lockup TC an additional tranny cooler is not required. But I suppose that depends on driving style. For example, if you auto cross it would be a good idea to install an additional tranny cooler as you are doing a lot of driving with the TCC unlocked while putting a lot of torque to the A4.
When stock I could not power brake above 1,200rpm and short times were around 2.0x sec. At the first rebuild I had a 2,000rpm modified GN TC installed and would power brake to around 1,700rpm for best ETs, with a short time in the 1.8x-1.9x range.
During the recent rebuild I had a low $$ 2,000rpm TC installed and, though it will flash to 2,000rpm, I cannot power brake much above 1,200rpm or it pushes through the beams. Now short times are back in the low 2.0x sec range and ETs have dropped off.
I prefer to power brake as high as possible to preload the drive train. If the track is slick or on the street I have to "press" the accelerator to avoid wheel spin. If I hammer it the tires go up in smoke.
I was told by Pat Barrett of Level-10 that with a stall of 2,400 rpm or less and a 12" lockup TC an additional tranny cooler is not required. But I suppose that depends on driving style. For example, if you auto cross it would be a good idea to install an additional tranny cooler as you are doing a lot of driving with the TCC unlocked while putting a lot of torque to the A4.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Yes our stock TC has an internal clutch that "locks up" when commanded by the ECM. There are three internal switches for 2nd-4th gears that allow the TCC to be locked.
After lockup occurs the drive train is very similar to a stick shift with no fluid coupling; before lockup there is slippage and torque multiplication of the TC.
When I accelerate slowly up to around 50mph I can see the RPM drop at TCC lockup; it looks and feels like a gear change. In fact when it happened on the dyno at ~120mph in 3rd gear, the dyno operator thought it was a gear change.
After lockup occurs the drive train is very similar to a stick shift with no fluid coupling; before lockup there is slippage and torque multiplication of the TC.
When I accelerate slowly up to around 50mph I can see the RPM drop at TCC lockup; it looks and feels like a gear change. In fact when it happened on the dyno at ~120mph in 3rd gear, the dyno operator thought it was a gear change.
Race Director
Joined: Feb 2004
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There is a lining, similar to clutch lining, that is bonded to the rear of the turbine. When engaged, it applies and grips the rear converter shell. This causes all internal guts to lock up and spin together at a 1:1 ratio. If the friction surface wears off, or the torque converter balloons,The friction surface will not apply, therefore no lockup. This causes vibrations and chattering.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by Pete K
There is a lining, similar to clutch lining, that is bonded to the rear of the turbine. When engaged, it applies and grips the rear converter shell. This causes all internal guts to lock up and spin together at a 1:1 ratio. If the friction surface wears off, or the torque converter balloons,The friction surface will not apply, therefore no lockup. This causes vibrations and chattering.
In my case since the TC change it is gone so what you just said was the source of my vibration
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Originally Posted by Redeasysport
Gee Pete where were you a few months ago when I was tryin to figure out my intermittant vibration In my case since the TC change it is gone so what you just said was the source of my vibration
In my case since the TC change it is gone so what you just said was the source of my vibration I will not let you down again 
Le Mans Master
Joined: Feb 1999
Posts: 6,470
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From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
Originally Posted by CFI-EFI
Do WHAT in neutral??? Neutral drops went out before zits.
RACE ON!!!
RACE ON!!!
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
OK I will admit to tossing my mom's car in reverse and then slamming it into drive and hammering it at the same time.It was the only way to get that 6 banger tempest to spin the tires.Forgive me for I have sinned.
Burning Brakes
Joined: Jun 2003
Posts: 937
Likes: 0
From: Bedford Tx
at 'stall' rpm, what happens?
is there a torque number, associated with a TC,
at a stall rpm?
does stall RPM mean, engine RPM, or
the difference between the input and output shaft
speeds, in RPM.
I am retarded.
I am missing something basic.
is there a torque number, associated with a TC,
at a stall rpm?
does stall RPM mean, engine RPM, or
the difference between the input and output shaft
speeds, in RPM.
I am retarded.
I am missing something basic.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
The way I understand it , the"stall" speed is the engine rpm where both shafts are at the same speed as 1:1.Up to the stall speed you are getting torque multiplcation and the engine rpm are higher then the trans.
Like starting in top gear with a stick and slipping the clutch until the car gets up to speed.
The stated stall speed for a given convertor will be different dependent apon engine torque and car weight.
From memory , lighter car / more torque will give higher "actual" stall speed
Like starting in top gear with a stick and slipping the clutch until the car gets up to speed.
The stated stall speed for a given convertor will be different dependent apon engine torque and car weight.
From memory , lighter car / more torque will give higher "actual" stall speed
