STR Question.
04-01-2004, 04:01 PM
#1
STR Question. Means Stall Torque Ratio right? I was looking at the TC's and the STR ranges from 1.61 to 2.55 from what ive seen. Im sure there are some that are higher and lower but what is a good STR for drag/street?. Does the higher or lower in the STR help the "looseness" in a gentle take off as it is referred to.
04-01-2004, 04:14 PM
#2
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A low STR will multiply torque over a wider
band of RPM preceding stall than a higher
STR. I'm a bit fuzzy on what other people
mean when they say "tight" or "loose" so I'll
try to explain it another way. If you have
(say) a 3000RPM/2.0STR and a 3000RPM/2.5
the 2.0 would give you more "pavement
thrust" at 1500RPM than the 2.5 would;
the 2.5 is not coupled up as much. But
at 2500RPM the 2.5 would be giving you
more torque out the back than the 2.0
as they are both well into the stall range
but the 2.5 has more torque multiplication.
I think this makes the lower STR the more
streetable, there is more multiplication
"further out" (lower RPM) to give you some
pedal-proportional acceleratiion while a
very high STR will be more of an abrupt
coupling-up followed more closely by more
torque output.
It appears to me that higher STRs give up
top end efficiency relative to lower ones of
the same rated stall speed. However there
are some stator design advances which
might make this not entirely true, mfr to
mfr or product line to product line.
band of RPM preceding stall than a higher
STR. I'm a bit fuzzy on what other people
mean when they say "tight" or "loose" so I'll
try to explain it another way. If you have
(say) a 3000RPM/2.0STR and a 3000RPM/2.5
the 2.0 would give you more "pavement
thrust" at 1500RPM than the 2.5 would;
the 2.5 is not coupled up as much. But
at 2500RPM the 2.5 would be giving you
more torque out the back than the 2.0
as they are both well into the stall range
but the 2.5 has more torque multiplication.
I think this makes the lower STR the more
streetable, there is more multiplication
"further out" (lower RPM) to give you some
pedal-proportional acceleratiion while a
very high STR will be more of an abrupt
coupling-up followed more closely by more
torque output.
It appears to me that higher STRs give up
top end efficiency relative to lower ones of
the same rated stall speed. However there
are some stator design advances which
might make this not entirely true, mfr to
mfr or product line to product line.
04-01-2004, 09:28 PM
#3
I may be wrong, but I thought the higher the STR - the less pedal it took to get the car moving. And the lower the STR - the higher the 1/4 mile trap speed and the more pedal effort required to get the car rolling. 
Take for instance my stock TC w/ the low stall speed and 1.8 STR, it traps higher than a lot of cars running close to, or the same ET. Coincedentally, most of the said cars have converters with higher than stock STR's. Just an obsevation. Again... someone more knowledgeable please step in and correct me if I'm wrong, but be prepared to explain why I am wrong.
Take for instance my stock TC w/ the low stall speed and 1.8 STR, it traps higher than a lot of cars running close to, or the same ET. Coincedentally, most of the said cars have converters with higher than stock STR's. Just an obsevation. Again... someone more knowledgeable please step in and correct me if I'm wrong, but be prepared to explain why I am wrong.
04-01-2004, 09:33 PM
#4
Just want to get a TC installed(was going to go with a 3000 or so but everyone says to get higher) with a 3500-4000 stall. But i have found some with different STR's. Just trying to figure out what is the advantage and disadvantage in a high or lower STR for a street car and a drag every know and then. KNow what i mean? 
04-02-2004, 07:38 AM
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No nitto DR's on street = lower STR & STALL = less fun
Nitto's (with your power) at track = higher STR & STALL = more fun
ET's at track +more mods = higher STR & Even bigger stall = way more fun
Nitrous = Lesser stall (more use of low end torque) special nitrous converter.
4000 Stall proably cams/all boltons since it will keep you up in the 6000 rpm range down the 1/4 mile.
The tci ssf 3500 i have can do a 6100rpm shift and 4600 SE which might be good your current mod level, running nitto DR's all the time.
Apparently after putting ET's on my car i have come to the mistake of having too little stall. I should got the TCI 3800 or even 4000. but i have some mods that make more torque.
Don't bother with 2.5STR verter if you plan to run street tires, you will be babying the car way too much. It will not be fun to get smoked by a honda because you are sitting at the light spinning tires. The TCI SSF 3500 takes a good bit of thought at the track at my mod level to launch on DR's at 13psi. Otherwise i'll blow the **** out of them and get a crappy 2.0 60'. Take's some finesse or just slapping ET's on (no finesse necessary).
you will need to deal with higher fluid temps, they are very real starting bout this time o the year.
I am going to try: (have cooler), fan override switch, and +3QT fluid pan for trans, and an extra fan on the trans cooler.
Nitto's (with your power) at track = higher STR & STALL = more fun
ET's at track +more mods = higher STR & Even bigger stall = way more fun
Nitrous = Lesser stall (more use of low end torque) special nitrous converter.
4000 Stall proably cams/all boltons since it will keep you up in the 6000 rpm range down the 1/4 mile.
The tci ssf 3500 i have can do a 6100rpm shift and 4600 SE which might be good your current mod level, running nitto DR's all the time.
Apparently after putting ET's on my car i have come to the mistake of having too little stall. I should got the TCI 3800 or even 4000. but i have some mods that make more torque.
Don't bother with 2.5STR verter if you plan to run street tires, you will be babying the car way too much. It will not be fun to get smoked by a honda because you are sitting at the light spinning tires. The TCI SSF 3500 takes a good bit of thought at the track at my mod level to launch on DR's at 13psi. Otherwise i'll blow the **** out of them and get a crappy 2.0 60'. Take's some finesse or just slapping ET's on (no finesse necessary).
you will need to deal with higher fluid temps, they are very real starting bout this time o the year.
I am going to try: (have cooler), fan override switch, and +3QT fluid pan for trans, and an extra fan on the trans cooler.
04-02-2004, 08:25 AM
#7
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Originally Posted by 86 IROC
I may be wrong, but I thought the higher the STR - the less pedal it took to get the car moving. And the lower the STR - the higher the 1/4 mile trap speed and the more pedal effort required to get the car rolling. Take for instance my stock TC w/ the low stall speed and 1.8 STR, it traps higher than a lot of cars running close to, or the same ET. Coincedentally, most of the said cars have converters with higher than stock STR's. Just an obsevation. Again... someone more knowledgeable please step in and correct me if I'm wrong, but be prepared to explain why I am wrong.
Take for instance my stock TC w/ the low stall speed and 1.8 STR, it traps higher than a lot of cars running close to, or the same ET. Coincedentally, most of the said cars have converters with higher than stock STR's. Just an obsevation. Again... someone more knowledgeable please step in and correct me if I'm wrong, but be prepared to explain why I am wrong.the low stall, means efficiency further below top end), which is
"free" RWHP which is trap speed.
Higher STR multiples torque more, but does it "closer in" to the
stall point. So it probably takes less pedal to go, hard, but
relative to a smaller-STR converter the high-STR takes more
pedal, to go "just a little" like the old bag in front of you.
Yank's web site is the best I've found for explaining this stuff.
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04-02-2004, 05:32 PM
#8
Originally Posted by jimmyblue
The low STR trades for higher efficiency at the top end (and also
the low stall, means efficiency further below top end), which is
"free" RWHP which is trap speed.
Higher STR multiples torque more, but does it "closer in" to the
stall point. So it probably takes less pedal to go, hard, but
relative to a smaller-STR converter the high-STR takes more
pedal, to go "just a little" like the old bag in front of you.
Yank's web site is the best I've found for explaining this stuff.
the low stall, means efficiency further below top end), which is
"free" RWHP which is trap speed.
Higher STR multiples torque more, but does it "closer in" to the
stall point. So it probably takes less pedal to go, hard, but
relative to a smaller-STR converter the high-STR takes more
pedal, to go "just a little" like the old bag in front of you.
Yank's web site is the best I've found for explaining this stuff.
, and be reliable for my intents and purposes. I might not get quite the gain of per se` a 3500+ stall 2.5+ STR verter, but this car isn't an all out race car.
04-02-2004, 05:43 PM
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well once you lockup at 30-40mph all converters are basically the same, actually a 9" converter would be more efficient maybe due to less reciprocating mass (like the ASP pulley). So base your verter choice on your power output. If your shift extension doesn't match your ultimate goals, then you will re-stall the verter.
and yeah i picked a too small verter (tci ssf 3500 2.5str). the 3800 or a 4000 would have been a better choice.
The looseness is all 0-40mph(or 30) and your tcc lockup speeds. Efficiency locked up shouldn't matter if the clutches are worth a ****.
remember my mods + tci ssf 3500 = shift extension of 4600 with shift point of 6100rpm. You want to really think out your peak whp (go baseline dyno your car) before you pick a converter, i think thats a VERY important idea.
Then choose a converter that will meet your short term future mods. Because $500 verter isn't something you want to take out in 6 months when you do the cams/lt/ls6 intake/dr's because you want more speed.
I was able to pull (365whp) on my bro's 384whp m6 but he had +100lbs for t/a and another 150lbs (extra rider). Started out neck and neck and i started to pull away at 100mph. Not bad given the lack of hp and the obvious gains the m6 has in gearing on a roll..
(plus his tranny was just rebuilt, and mine has 70.5K miles on it!)
and yeah i picked a too small verter (tci ssf 3500 2.5str). the 3800 or a 4000 would have been a better choice.
The looseness is all 0-40mph(or 30) and your tcc lockup speeds. Efficiency locked up shouldn't matter if the clutches are worth a ****.
remember my mods + tci ssf 3500 = shift extension of 4600 with shift point of 6100rpm. You want to really think out your peak whp (go baseline dyno your car) before you pick a converter, i think thats a VERY important idea.
Then choose a converter that will meet your short term future mods. Because $500 verter isn't something you want to take out in 6 months when you do the cams/lt/ls6 intake/dr's because you want more speed.
I was able to pull (365whp) on my bro's 384whp m6 but he had +100lbs for t/a and another 150lbs (extra rider). Started out neck and neck and i started to pull away at 100mph. Not bad given the lack of hp and the obvious gains the m6 has in gearing on a roll..
(plus his tranny was just rebuilt, and mine has 70.5K miles on it!)
04-02-2004, 05:49 PM
#10
Originally Posted by samz28
well once you lockup at 30-40mph all converters are basically the same, actually a 9" converter would be more efficient maybe due to less reciprocating mass (like the ASP pulley). So base your verter choice on your power output. If your shift extension doesn't match your ultimate goals, then you will re-stall the verter.
and yeah i picked a too small verter (tci ssf 3500 2.5str). the 3800 or a 4000 would have been a better choice.
The looseness is all 0-40mph(or 30) and your tcc lockup speeds. Efficiency locked up shouldn't matter if the clutches are worth a ****.
remember my mods + tci ssf 3500 = shift extension of 4600 with shift point of 6100rpm. You want to really think out your peak whp (go baseline dyno your car) before you pick a converter, i think thats a VERY important idea.
Then choose a converter that will meet your short term future mods. Because $500 verter isn't something you want to take out in 6 months when you do the cams/lt/ls6 intake/dr's because you want more speed.
I was able to pull (365whp) on my bro's 384whp m6 but he had +100lbs for t/a and another 150lbs (extra rider). Started out neck and neck and i started to pull away at 100mph. Not bad given the lack of hp and the obvious gains the m6 has in gearing on a roll..
(plus his tranny was just rebuilt, and mine has 70.5K miles on it!)
and yeah i picked a too small verter (tci ssf 3500 2.5str). the 3800 or a 4000 would have been a better choice.
The looseness is all 0-40mph(or 30) and your tcc lockup speeds. Efficiency locked up shouldn't matter if the clutches are worth a ****.
remember my mods + tci ssf 3500 = shift extension of 4600 with shift point of 6100rpm. You want to really think out your peak whp (go baseline dyno your car) before you pick a converter, i think thats a VERY important idea.
Then choose a converter that will meet your short term future mods. Because $500 verter isn't something you want to take out in 6 months when you do the cams/lt/ls6 intake/dr's because you want more speed.
I was able to pull (365whp) on my bro's 384whp m6 but he had +100lbs for t/a and another 150lbs (extra rider). Started out neck and neck and i started to pull away at 100mph. Not bad given the lack of hp and the obvious gains the m6 has in gearing on a roll..
(plus his tranny was just rebuilt, and mine has 70.5K miles on it!)
04-02-2004, 06:05 PM
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Look at my dyno #'s. I run nitto's on street. They are annihilated on strip without very careful launch technique. Now when i got my bro's ET's on. I had too much tire and not enough power. Either way i dont have enough shift extension (shift at 6100 and drop to 4600). I Think by removing more TQ MGMT and raising shift points this will help, but the idea to keep your SE (on a roll or in the 1/4 mile) so you spend the maximum amount of time in peak whp range. I could run my motor to 7200rpm if i wanted to trash it (as i was told thats too high for the ls1) shift extension wise ... and that might solve the problem, but buying the right converter would be easier on the motor.
Also read my thread on overheating. These converters make alot of heat. If you plan to drag race or do alot of city unlocked driving i suggest a very competent cooling system, great fluid, and maybe even a larger trans fluid pan.
80F out, after 5 runs, i was at 225ECT and 225 trans fluid. 225 trans fluid is not big enough. My 24K cooler is not big enough. Now i get to spend more money, on a bigger cooler or rig up a fan, a bigger fluid pan, and more fluid.
I wish this kind of "REAL WORLD" info was in a FAQ, it would have helped me understand my selection better. Mind you i love the tci SSF 3500, its awesome for the $$ especially when folks do the 10% off deal (look), but now i think the 3800 or 4000 would have been even better that i've had the TASTE of ET's.
I think the 3500 with 2.5STR would be a good idea for you right now, why? you have 2.73's. The higher STR will bring on more torque when you peddle it than the lower STR. Your shiz is gonna be loose regardless till you get some better gears. I did 3.42's they are okay. I dont freeway alot, I bought them for strength (GM real 3.42's) and no whine, but now i think 3.73's would be better.
I can't afford heads/cam and dont wanna do nitrous(wife said no). So i gotta live with what i got. Hope i can tune it better, and spend little as possible to keep my 70K mile tranny together.
good luck, and hopefully other will chime in. The rule is REAL, do 500-800 more stall than you think is right, 3500-3800, otherwise you'll be like me saying hmm. this sux, i can't afford to pull the tranny, be down for a restall (Daily driver) and pay for all that jazz.
I'd say tci 3800 if you wanna run 12.0's (no cage) is a great cheap verter. If you got big cash go with those Yank SS4000 i hear they drive superbly well too. But i spent 500 bucks on my tci ssf 3500 and spent the diff on the longtubes/ory..
Also read my thread on overheating. These converters make alot of heat. If you plan to drag race or do alot of city unlocked driving i suggest a very competent cooling system, great fluid, and maybe even a larger trans fluid pan.
80F out, after 5 runs, i was at 225ECT and 225 trans fluid. 225 trans fluid is not big enough. My 24K cooler is not big enough. Now i get to spend more money, on a bigger cooler or rig up a fan, a bigger fluid pan, and more fluid.
I wish this kind of "REAL WORLD" info was in a FAQ, it would have helped me understand my selection better. Mind you i love the tci SSF 3500, its awesome for the $$ especially when folks do the 10% off deal (look), but now i think the 3800 or 4000 would have been even better that i've had the TASTE of ET's.
I think the 3500 with 2.5STR would be a good idea for you right now, why? you have 2.73's. The higher STR will bring on more torque when you peddle it than the lower STR. Your shiz is gonna be loose regardless till you get some better gears. I did 3.42's they are okay. I dont freeway alot, I bought them for strength (GM real 3.42's) and no whine, but now i think 3.73's would be better.
I can't afford heads/cam and dont wanna do nitrous(wife said no). So i gotta live with what i got. Hope i can tune it better, and spend little as possible to keep my 70K mile tranny together.
good luck, and hopefully other will chime in. The rule is REAL, do 500-800 more stall than you think is right, 3500-3800, otherwise you'll be like me saying hmm. this sux, i can't afford to pull the tranny, be down for a restall (Daily driver) and pay for all that jazz.
I'd say tci 3800 if you wanna run 12.0's (no cage) is a great cheap verter. If you got big cash go with those Yank SS4000 i hear they drive superbly well too. But i spent 500 bucks on my tci ssf 3500 and spent the diff on the longtubes/ory..
04-02-2004, 06:18 PM
#12
Originally Posted by samz28
Look at my dyno #'s. I run nitto's on street. They are annihilated on strip without very careful launch technique. Now when i got my bro's ET's on. I had too much tire and not enough power. Either way i dont have enough shift extension (shift at 6100 and drop to 4600). I Think by removing more TQ MGMT and raising shift points this will help, but the idea to keep your SE (on a roll or in the 1/4 mile) so you spend the maximum amount of time in peak whp range. I could run my motor to 7200rpm if i wanted to trash it (as i was told thats too high for the ls1) shift extension wise ... and that might solve the problem, but buying the right converter would be easier on the motor.
Also read my thread on overheating. These converters make alot of heat. If you plan to drag race or do alot of city unlocked driving i suggest a very competent cooling system, great fluid, and maybe even a larger trans fluid pan.
80F out, after 5 runs, i was at 225ECT and 225 trans fluid. 225 trans fluid is not big enough. My 24K cooler is not big enough. Now i get to spend more money, on a bigger cooler or rig up a fan, a bigger fluid pan, and more fluid.
I wish this kind of "REAL WORLD" info was in a FAQ, it would have helped me understand my selection better. Mind you i love the tci SSF 3500, its awesome for the $$ especially when folks do the 10% off deal (look), but now i think the 3800 or 4000 would have been even better that i've had the TASTE of ET's.
I think the 3500 with 2.5STR would be a good idea for you right now, why? you have 2.73's. The higher STR will bring on more torque when you peddle it than the lower STR. Your shiz is gonna be loose regardless till you get some better gears. I did 3.42's they are okay. I dont freeway alot, I bought them for strength (GM real 3.42's) and no whine, but now i think 3.73's would be better.
I can't afford heads/cam and dont wanna do nitrous(wife said no). So i gotta live with what i got. Hope i can tune it better, and spend little as possible to keep my 70K mile tranny together.
good luck, and hopefully other will chime in. The rule is REAL, do 500-800 more stall than you think is right, 3500-3800, otherwise you'll be like me saying hmm. this sux, i can't afford to pull the tranny, be down for a restall (Daily driver) and pay for all that jazz.
I'd say tci 3800 if you wanna run 12.0's (no cage) is a great cheap verter. If you got big cash go with those Yank SS4000 i hear they drive superbly well too. But i spent 500 bucks on my tci ssf 3500 and spent the diff on the longtubes/ory..
Also read my thread on overheating. These converters make alot of heat. If you plan to drag race or do alot of city unlocked driving i suggest a very competent cooling system, great fluid, and maybe even a larger trans fluid pan.
80F out, after 5 runs, i was at 225ECT and 225 trans fluid. 225 trans fluid is not big enough. My 24K cooler is not big enough. Now i get to spend more money, on a bigger cooler or rig up a fan, a bigger fluid pan, and more fluid.
I wish this kind of "REAL WORLD" info was in a FAQ, it would have helped me understand my selection better. Mind you i love the tci SSF 3500, its awesome for the $$ especially when folks do the 10% off deal (look), but now i think the 3800 or 4000 would have been even better that i've had the TASTE of ET's.
I think the 3500 with 2.5STR would be a good idea for you right now, why? you have 2.73's. The higher STR will bring on more torque when you peddle it than the lower STR. Your shiz is gonna be loose regardless till you get some better gears. I did 3.42's they are okay. I dont freeway alot, I bought them for strength (GM real 3.42's) and no whine, but now i think 3.73's would be better.
I can't afford heads/cam and dont wanna do nitrous(wife said no). So i gotta live with what i got. Hope i can tune it better, and spend little as possible to keep my 70K mile tranny together.
good luck, and hopefully other will chime in. The rule is REAL, do 500-800 more stall than you think is right, 3500-3800, otherwise you'll be like me saying hmm. this sux, i can't afford to pull the tranny, be down for a restall (Daily driver) and pay for all that jazz.
I'd say tci 3800 if you wanna run 12.0's (no cage) is a great cheap verter. If you got big cash go with those Yank SS4000 i hear they drive superbly well too. But i spent 500 bucks on my tci ssf 3500 and spent the diff on the longtubes/ory..
04-02-2004, 07:05 PM
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my 4th run was 12.163@112.60mph with 1.80 60 on dr's. The track hooked, it wasn't hot out that night. I was quite happy. With the day time racing and i guess crappier track prep i had to put on et's to get that 12.28 with a 1.757 60'. Trans temps as i said were 225 (& ECT). so i guess the cooler temps helped alot.
I have about 20 passes under my belt total, maybe 14 after the mods put on the z28 so by all means i have no idea what im doing yet
i dont want to put a cage in my car, the closer track likes to ban 11 second cars, but a consistent 12.0 day/night would be perfect. And maybe fun for bracket racing too.
Thats my goal.
I have about 20 passes under my belt total, maybe 14 after the mods put on the z28 so by all means i have no idea what im doing yet
i dont want to put a cage in my car, the closer track likes to ban 11 second cars, but a consistent 12.0 day/night would be perfect. And maybe fun for bracket racing too.
Thats my goal.
