Educate me on converters!
10-19-2011, 01:06 AM
#2
11 Second Club
Torque converters have three basic ratings. Stall, shift extension and STR. The stall is the rpm at which the torque converter will flash to. Flashing a converter is basically just going WOT. The converter "flashes" to the rpm that the stall is set for.
Shift extension is the rpm that the engine falls to after a shift.
STR = stall torque ratio. Basically the higher the number the harder the converter will hit the tires. So higher numbers work better at the track while lower numbers might make it easier to find traction on the street.
So say you have a LS1 F-body with a 4L60E set to shift at 6200 rpm's. Now say you have a 3500 stall torque converter with a 2.5 STR and 4700 shift extension.
You take the car to the track and line up with the engine idling at 700 rpm's. The light goes green and you gun it! The 2.5 STR hits hard, throwing your head back allowing you to get a 1.6 60'. While that is happening the converter flashes from 700 rpm's to 3500 rpm's (the stall speed) and rises till the top of first gear. Once you hit 6200 rpm's the transmission shifts to second and the rpm's drop to 4700 rpm's (the converters shift extension) and you again begin to rise to 6200, where you will shift to third and once again drop to the 4700 rpm's for the final time.
Lockup is a gas saving feature that only applies to street driving at or above approx 40 mph. The higher the stall the higher the rpm's usually are as you cruise around town or on the highway. Say you get on the highway and cruise at 65 mph. When you first get there you might be at 2800 rpm's. Then as you stop accellerating and start to cruise a constant speed the converter locks and the rpm's drop to what they normally would be for whatever gears you have. So you may drop down to 2100 rpm's lets say.
So the lockup is great feature to have as it will save you gas. Also higher stalls cause the transmission temps to run hotter so most people get a transmission cooler.
I'm sure a vendor or mechanic can come in and give you a more technical and indepth explanation of torque converters. But hopefully this gives you the basics.
Shift extension is the rpm that the engine falls to after a shift.
STR = stall torque ratio. Basically the higher the number the harder the converter will hit the tires. So higher numbers work better at the track while lower numbers might make it easier to find traction on the street.
So say you have a LS1 F-body with a 4L60E set to shift at 6200 rpm's. Now say you have a 3500 stall torque converter with a 2.5 STR and 4700 shift extension.
You take the car to the track and line up with the engine idling at 700 rpm's. The light goes green and you gun it! The 2.5 STR hits hard, throwing your head back allowing you to get a 1.6 60'. While that is happening the converter flashes from 700 rpm's to 3500 rpm's (the stall speed) and rises till the top of first gear. Once you hit 6200 rpm's the transmission shifts to second and the rpm's drop to 4700 rpm's (the converters shift extension) and you again begin to rise to 6200, where you will shift to third and once again drop to the 4700 rpm's for the final time.
Lockup is a gas saving feature that only applies to street driving at or above approx 40 mph. The higher the stall the higher the rpm's usually are as you cruise around town or on the highway. Say you get on the highway and cruise at 65 mph. When you first get there you might be at 2800 rpm's. Then as you stop accellerating and start to cruise a constant speed the converter locks and the rpm's drop to what they normally would be for whatever gears you have. So you may drop down to 2100 rpm's lets say.
So the lockup is great feature to have as it will save you gas. Also higher stalls cause the transmission temps to run hotter so most people get a transmission cooler.
I'm sure a vendor or mechanic can come in and give you a more technical and indepth explanation of torque converters. But hopefully this gives you the basics.
Last edited by darrensls1; 10-19-2011 at 01:14 AM.
as much as ive read up on this, this is by far the best explanation ive come across. 
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10-21-2011, 10:47 PM
#9
Torque converters have three basic ratings. Stall, shift extension and STR. The stall is the rpm at which the torque converter will flash to. Flashing a converter is basically just going WOT. The converter "flashes" to the rpm that the stall is set for.
Shift extension is the rpm that the engine falls to after a shift.
STR = stall torque ratio. Basically the higher the number the harder the converter will hit the tires. So higher numbers work better at the track while lower numbers might make it easier to find traction on the street.
So say you have a LS1 F-body with a 4L60E set to shift at 6200 rpm's. Now say you have a 3500 stall torque converter with a 2.5 STR and 4700 shift extension.
You take the car to the track and line up with the engine idling at 700 rpm's. The light goes green and you gun it! The 2.5 STR hits hard, throwing your head back allowing you to get a 1.6 60'. While that is happening the converter flashes from 700 rpm's to 3500 rpm's (the stall speed) and rises till the top of first gear. Once you hit 6200 rpm's the transmission shifts to second and the rpm's drop to 4700 rpm's (the converters shift extension) and you again begin to rise to 6200, where you will shift to third and once again drop to the 4700 rpm's for the final time.
Lockup is a gas saving feature that only applies to street driving at or above approx 40 mph. The higher the stall the higher the rpm's usually are as you cruise around town or on the highway. Say you get on the highway and cruise at 65 mph. When you first get there you might be at 2800 rpm's. Then as you stop accellerating and start to cruise a constant speed the converter locks and the rpm's drop to what they normally would be for whatever gears you have. So you may drop down to 2100 rpm's lets say.
So the lockup is great feature to have as it will save you gas. Also higher stalls cause the transmission temps to run hotter so most people get a transmission cooler.
I'm sure a vendor or mechanic can come in and give you a more technical and indepth explanation of torque converters. But hopefully this gives you the basics.
Shift extension is the rpm that the engine falls to after a shift.
STR = stall torque ratio. Basically the higher the number the harder the converter will hit the tires. So higher numbers work better at the track while lower numbers might make it easier to find traction on the street.
So say you have a LS1 F-body with a 4L60E set to shift at 6200 rpm's. Now say you have a 3500 stall torque converter with a 2.5 STR and 4700 shift extension.
You take the car to the track and line up with the engine idling at 700 rpm's. The light goes green and you gun it! The 2.5 STR hits hard, throwing your head back allowing you to get a 1.6 60'. While that is happening the converter flashes from 700 rpm's to 3500 rpm's (the stall speed) and rises till the top of first gear. Once you hit 6200 rpm's the transmission shifts to second and the rpm's drop to 4700 rpm's (the converters shift extension) and you again begin to rise to 6200, where you will shift to third and once again drop to the 4700 rpm's for the final time.
Lockup is a gas saving feature that only applies to street driving at or above approx 40 mph. The higher the stall the higher the rpm's usually are as you cruise around town or on the highway. Say you get on the highway and cruise at 65 mph. When you first get there you might be at 2800 rpm's. Then as you stop accellerating and start to cruise a constant speed the converter locks and the rpm's drop to what they normally would be for whatever gears you have. So you may drop down to 2100 rpm's lets say.
So the lockup is great feature to have as it will save you gas. Also higher stalls cause the transmission temps to run hotter so most people get a transmission cooler.
I'm sure a vendor or mechanic can come in and give you a more technical and indepth explanation of torque converters. But hopefully this gives you the basics.
10-23-2011, 08:08 PM
#15
11 Second Club
The manufacturers of torque converters do. But for the most part the higher the stall speed the higher the STR.
2.0 or less is generally considered a smaller STR while 2.6 or above is a high STR. So 3000-3200 stalls tend to come with 2.0-2.2 STR while 3400-3800 stalls tend to have a 2.2-2.5 STR's and 4000+ usually have 2.5+ STR.
If you drag race at all with sticky tires then you want a higher STR. The only time you might want a smaller STR is if the car is street driven only or maybe if you spray right out of the hole.
Another point worth mentioning is how "loose" a converter is. This is a term used often to describe how the converter feels under mild acceleration. Lets say you are cruising around town. When you hit the gas lightly a big converter might make the car feel sluggish. At least until you go WOT. This is mostly affected by the stall speed. 3500 and lower will feel tight (when you give moderate gas the car accelerates decently) and 3800+ might feel a little loose (you give it moderate gas and the car accelerates slowly).
But do NOT let this sway you from a larger converter. You can offset the looseness with gears. 3.73's or 4.10's will make a world of difference. You can also get used to the looseness by simply adjusting your driving habits. Instead of 1/4-1/2 throttle off a red light maybe you go 1/2-3/4 throttle instead. You may also find reverse tends to cause your motor to stall. This is normal and can be easily offset with just a little brake stalling anytime you need to be in reverse.
IMO every LS1 on the road should have a 3600+ stall. 3600-4000 for street applications and Nitrous cars. 4200+ for weekend warrior/NA track cars. If you go too small on a converter size then it's just a matter of time before you regret that decision.
The best thing you can do for yourself and your car is buy a good converter brand, match the stall speed to your application/setup and ask the sponsors as many questions as you need to. Don't go cheap on a stall. It's just not worth it. Yank and Circle-D are both great choices. Call them up and tell them what mods you have and what the car is being used for. I guarantee they will recommend the best converter size for your needs.
And thank you all very much for all the kind words in this thread. I am just glad I could be of help.
Darren
2.0 or less is generally considered a smaller STR while 2.6 or above is a high STR. So 3000-3200 stalls tend to come with 2.0-2.2 STR while 3400-3800 stalls tend to have a 2.2-2.5 STR's and 4000+ usually have 2.5+ STR.
If you drag race at all with sticky tires then you want a higher STR. The only time you might want a smaller STR is if the car is street driven only or maybe if you spray right out of the hole.
Another point worth mentioning is how "loose" a converter is. This is a term used often to describe how the converter feels under mild acceleration. Lets say you are cruising around town. When you hit the gas lightly a big converter might make the car feel sluggish. At least until you go WOT. This is mostly affected by the stall speed. 3500 and lower will feel tight (when you give moderate gas the car accelerates decently) and 3800+ might feel a little loose (you give it moderate gas and the car accelerates slowly).
But do NOT let this sway you from a larger converter. You can offset the looseness with gears. 3.73's or 4.10's will make a world of difference. You can also get used to the looseness by simply adjusting your driving habits. Instead of 1/4-1/2 throttle off a red light maybe you go 1/2-3/4 throttle instead. You may also find reverse tends to cause your motor to stall. This is normal and can be easily offset with just a little brake stalling anytime you need to be in reverse.
IMO every LS1 on the road should have a 3600+ stall. 3600-4000 for street applications and Nitrous cars. 4200+ for weekend warrior/NA track cars. If you go too small on a converter size then it's just a matter of time before you regret that decision.
The best thing you can do for yourself and your car is buy a good converter brand, match the stall speed to your application/setup and ask the sponsors as many questions as you need to. Don't go cheap on a stall. It's just not worth it. Yank and Circle-D are both great choices. Call them up and tell them what mods you have and what the car is being used for. I guarantee they will recommend the best converter size for your needs.
And thank you all very much for all the kind words in this thread. I am just glad I could be of help.
Darren
Last edited by darrensls1; 10-23-2011 at 08:16 PM.
10-23-2011, 08:25 PM
#17
Torque converters have three basic ratings. Stall, shift extension and STR. The stall is the rpm at which the torque converter will flash to. Flashing a converter is basically just going WOT. The converter "flashes" to the rpm that the stall is set for.
Shift extension is the rpm that the engine falls to after a shift.
STR = stall torque ratio. Basically the higher the number the harder the converter will hit the tires. So higher numbers work better at the track while lower numbers might make it easier to find traction on the street.
So say you have a LS1 F-body with a 4L60E set to shift at 6200 rpm's. Now say you have a 3500 stall torque converter with a 2.5 STR and 4700 shift extension.
You take the car to the track and line up with the engine idling at 700 rpm's. The light goes green and you gun it! The 2.5 STR hits hard, throwing your head back allowing you to get a 1.6 60'. While that is happening the converter flashes from 700 rpm's to 3500 rpm's (the stall speed) and rises till the top of first gear. Once you hit 6200 rpm's the transmission shifts to second and the rpm's drop to 4700 rpm's (the converters shift extension) and you again begin to rise to 6200, where you will shift to third and once again drop to the 4700 rpm's for the final time.
Lockup is a gas saving feature that only applies to street driving at or above approx 40 mph. The higher the stall the higher the rpm's usually are as you cruise around town or on the highway. Say you get on the highway and cruise at 65 mph. When you first get there you might be at 2800 rpm's. Then as you stop accellerating and start to cruise a constant speed the converter locks and the rpm's drop to what they normally would be for whatever gears you have. So you may drop down to 2100 rpm's lets say.
So the lockup is great feature to have as it will save you gas. Also higher stalls cause the transmission temps to run hotter so most people get a transmission cooler.
I'm sure a vendor or mechanic can come in and give you a more technical and indepth explanation of torque converters. But hopefully this gives you the basics.
Shift extension is the rpm that the engine falls to after a shift.
STR = stall torque ratio. Basically the higher the number the harder the converter will hit the tires. So higher numbers work better at the track while lower numbers might make it easier to find traction on the street.
So say you have a LS1 F-body with a 4L60E set to shift at 6200 rpm's. Now say you have a 3500 stall torque converter with a 2.5 STR and 4700 shift extension.
You take the car to the track and line up with the engine idling at 700 rpm's. The light goes green and you gun it! The 2.5 STR hits hard, throwing your head back allowing you to get a 1.6 60'. While that is happening the converter flashes from 700 rpm's to 3500 rpm's (the stall speed) and rises till the top of first gear. Once you hit 6200 rpm's the transmission shifts to second and the rpm's drop to 4700 rpm's (the converters shift extension) and you again begin to rise to 6200, where you will shift to third and once again drop to the 4700 rpm's for the final time.
Lockup is a gas saving feature that only applies to street driving at or above approx 40 mph. The higher the stall the higher the rpm's usually are as you cruise around town or on the highway. Say you get on the highway and cruise at 65 mph. When you first get there you might be at 2800 rpm's. Then as you stop accellerating and start to cruise a constant speed the converter locks and the rpm's drop to what they normally would be for whatever gears you have. So you may drop down to 2100 rpm's lets say.
So the lockup is great feature to have as it will save you gas. Also higher stalls cause the transmission temps to run hotter so most people get a transmission cooler.
I'm sure a vendor or mechanic can come in and give you a more technical and indepth explanation of torque converters. But hopefully this gives you the basics.
STR is the maximum ratio a torque converter can multiply torque when you launch the car at the converter's stall speed.
Taking the example above, assume you have a 3600 stall speed with a 2.5 STR and you make 300 ft-lb of torque at 3600 RPM. When you launch the car and flash it to 3600 RPM, your 300 ft-lbs will be multiplied by the 2.5 STR. This means at launch you're putting down 750 ft-lbs of torque. This is why a stalled auto kicks *** off the line.
However, torque converters don't multiply torque at every RPM and every speed. STR only really affects the car when you launch from a stand still. After you start moving STR decreases sharply. And the higher the STR, the faster the will STR decreases.
Higher STR - Launches much harder, less efficient over rated stall speed.
Lower STR - Launches softer, more efficient over rated stall speed.
This is how I understand torque converters to work. Hopefully that's as clear as darrensls1's post.
Last edited by Golf&GM; 10-27-2011 at 07:45 AM.
10-29-2011, 06:04 PM
#20
Very good info! All of the LS1 cars I've own have been 6 spd. manuals except my current one which is an auto.
A few days ago while on my way to work I was being paced by a late model Mustang GT maybe a 2010/ 2011. We were going appoximately 70'ish on the freeway when he went WOT on me. Hard to admit defeat but I got spanked trying to keep up.
My car has no bolt ons besides a catback and lid. It's mostly used for cruising but I'm looking to get more out of the car at those speeds without going crazy with bolt ons. So to prevent getting the smack layed down on me what stall converter will give me the best bang for my style of driving?
A few days ago while on my way to work I was being paced by a late model Mustang GT maybe a 2010/ 2011. We were going appoximately 70'ish on the freeway when he went WOT on me. Hard to admit defeat but I got spanked trying to keep up.
My car has no bolt ons besides a catback and lid. It's mostly used for cruising but I'm looking to get more out of the car at those speeds without going crazy with bolt ons. So to prevent getting the smack layed down on me what stall converter will give me the best bang for my style of driving?