Converter stall speed vs spool up
09-22-2009, 09:28 PM
#1
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Converter stall speed vs spool up
I have used the search feature and have found members with many different thoughts in rule or theory on stall speed vs spool up. None decisive as to rule of thumb! OH! By the way, sorry this is a long post but I did not know how to get answers otherwise. I am no expert by any imagination. Just trying to learn!
First, I would like to assume the subject vehicle will be 650 -750 hp & 95% street driven low compression turbo 408. The goal is to maximize performance via Torque Converter (spool up).
I am naturally interested in optimizing my own vehicle (setup as in sig below) but also in others opinion from real world experience with their own setups. I will post this in LSI TECH forum also.
Further let’s assume all things being equal as far as set up, exhaust, fairly aggressive cam, 4l80e, turbo, triple disk same manufacturer converter where lock up will not be a problem, weight, etc. Also assume flash and brake stall to be equal in rpm.
And most importantly, NO TRACTION ISSUES to deal with.
To over exaggerate the scenario assume stock 4l80e converter @1800 vs. a quality after maket 4000 rpm stall converter.
I have always believed as rpm increases so does torque output to a point of max. ie. Lower RPM less HP, higher RPM more HP as a generalization.
Even though you may be able to get 3-5 lbs boost on the stock unit @ 1800 RPMs heck even double the engines output with 15 lbs. My thinking is the overall power output at this relatively low RPM should be MUCH less than that obtained from the same engine at 4000 RPMs at the same boost level. Is this correct or is there a bust in my thinking?
Also assume the time it takes to reach each stall RPM is equal, (1,800 vs. 4,000)
Some members of the Truck Performance forum indicate success with the low stall stock 4l80e converter and their theory of LOADING the turbo sooner to expedite boost as opposed to a converter with a higher RPM flash or stall level.
I am probably wrong but the time in mil seconds to reach the 1,800 rpm lockup VS time it takes to reach 4,000 rpm lockup of the higher stall converter would not be measurable. Please guide me in the right direction or share your knowledge.
First, I would like to assume the subject vehicle will be 650 -750 hp & 95% street driven low compression turbo 408. The goal is to maximize performance via Torque Converter (spool up).
I am naturally interested in optimizing my own vehicle (setup as in sig below) but also in others opinion from real world experience with their own setups. I will post this in LSI TECH forum also.
Further let’s assume all things being equal as far as set up, exhaust, fairly aggressive cam, 4l80e, turbo, triple disk same manufacturer converter where lock up will not be a problem, weight, etc. Also assume flash and brake stall to be equal in rpm.
And most importantly, NO TRACTION ISSUES to deal with.
To over exaggerate the scenario assume stock 4l80e converter @1800 vs. a quality after maket 4000 rpm stall converter.
I have always believed as rpm increases so does torque output to a point of max. ie. Lower RPM less HP, higher RPM more HP as a generalization.
Even though you may be able to get 3-5 lbs boost on the stock unit @ 1800 RPMs heck even double the engines output with 15 lbs. My thinking is the overall power output at this relatively low RPM should be MUCH less than that obtained from the same engine at 4000 RPMs at the same boost level. Is this correct or is there a bust in my thinking?
Also assume the time it takes to reach each stall RPM is equal, (1,800 vs. 4,000)
Some members of the Truck Performance forum indicate success with the low stall stock 4l80e converter and their theory of LOADING the turbo sooner to expedite boost as opposed to a converter with a higher RPM flash or stall level.
I am probably wrong but the time in mil seconds to reach the 1,800 rpm lockup VS time it takes to reach 4,000 rpm lockup of the higher stall converter would not be measurable. Please guide me in the right direction or share your knowledge.
09-22-2009, 09:37 PM
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Run a larger converter and a higher gear then with a super charged set up.. The gears will alow the turbo to build boost, stay loaded while the biger verter will let you get it into boost, stay there.. 
That is my out look on things..
That is my out look on things..
09-22-2009, 09:42 PM
#3
stall/ spool
Its hard to talk about " spool up" with someone when you have a stall converter... because when your in "stall" even if the trucks making power its not being felt... I have run over 20 .. Yes i said 20 different stall converters in my truck over the last 2 years depends on what your wanting to do with the truck?h2?... If i remeber right this thing was built with a PI 3 disc but it was 9.5" ??... with the weight of yours i would think it would pull alot better with something in the 10.25+ range.... what are you wanting? red light racing?... wanting it to footbrake 10psi?... or change lanes at 60mph??...
09-22-2009, 10:10 PM
#4
Its hard to talk about " spool up" with someone when you have a stall converter... because when your in "stall" even if the trucks making power its not being felt... I have run over 20 .. Yes i said 20 different stall converters in my truck over the last 2 years depends on what your wanting to do with the truck?h2?... If i remeber right this thing was built with a PI 3 disc but it was 9.5" ??... with the weight of yours i would think it would pull alot better with something in the 10.25+ range.... what are you wanting? red light racing?... wanting it to footbrake 10psi?... or change lanes at 60mph??...
09-22-2009, 11:19 PM
#5
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Casey 2323
I am looking for the best all around performance that I can get. Not specifically red light to red light or changing lanes. My current stall flashes at approx. 2400-2500. When I read about others on this forum with 5000+lb turbocharged trucks and they are seeing good results with a stock 4l80e converter and then others with 3000 rpm+ stalls and both are daily drivers, I tend to question if I could do better. Will I do better raising my stall a few hundred RPMs or trying one with less stall capabilities? Will either one give me more acceleration and or quicker spool over what I have been using? Again I am only concerned with the performance increase made possible by the optimum stall converter and not with other tuning, setup or modification that are possible. My current converter feels and drives very similar to stock even though it has a slightly higher stall capability when throttled. I have not had the opportunity to experience different converters as you. This is why I ask questions on this forum. If I elect to up my stall a few hundred RPMs what negative performance issues will I find?
I am looking for the best all around performance that I can get. Not specifically red light to red light or changing lanes. My current stall flashes at approx. 2400-2500. When I read about others on this forum with 5000+lb turbocharged trucks and they are seeing good results with a stock 4l80e converter and then others with 3000 rpm+ stalls and both are daily drivers, I tend to question if I could do better. Will I do better raising my stall a few hundred RPMs or trying one with less stall capabilities? Will either one give me more acceleration and or quicker spool over what I have been using? Again I am only concerned with the performance increase made possible by the optimum stall converter and not with other tuning, setup or modification that are possible. My current converter feels and drives very similar to stock even though it has a slightly higher stall capability when throttled. I have not had the opportunity to experience different converters as you. This is why I ask questions on this forum. If I elect to up my stall a few hundred RPMs what negative performance issues will I find?
09-23-2009, 07:26 PM
#6
a higher stall will definitely get the turbo/s spinning up sooner(going by time).
the problem is a higher stall converter will have a difficult time holding the power back once the boost/tq builds.
getting the right converter on a turbo car is tuff. too tight and you are waiting. too loose and you get off the line well but the rpms may never fall below 5500+rpms where your peek tq might be at 4900rpm.
then if you do get just the right converter you decide you want more power so you turn the **** a little and bam, now the converter is stalling 500rpm higher then it was before.
i like the idea of going loose and then locking it up after the 2-3 shift. 1st gear goes by so fast you dont loose anything but gain a quick spool and a good 60'. 2nd gear is hurt a little by being too high in the rpms but then after the 2-3 shift you lock it up and get to enjoy your peek tq.
the problem is a higher stall converter will have a difficult time holding the power back once the boost/tq builds.
getting the right converter on a turbo car is tuff. too tight and you are waiting. too loose and you get off the line well but the rpms may never fall below 5500+rpms where your peek tq might be at 4900rpm.
then if you do get just the right converter you decide you want more power so you turn the **** a little and bam, now the converter is stalling 500rpm higher then it was before.
i like the idea of going loose and then locking it up after the 2-3 shift. 1st gear goes by so fast you dont loose anything but gain a quick spool and a good 60'. 2nd gear is hurt a little by being too high in the rpms but then after the 2-3 shift you lock it up and get to enjoy your peek tq.
09-23-2009, 08:25 PM
#7
I dont know my exact specs anymore... I call the Circle D Magic model 
... Chris knows me very well and knows exactly what he was done with my setup to make it work so well..... Feel free to call and ask him ... But on a side note I have used everything else on the market by anyone else that would sell me one... Let me save you alot of trouble and 
..... He has some GREAT ideas and Combos that work VERY well with turbos amd trucks ! With his help I have been able to make the impossible happen with my Large Frame Rear mount Truck ... Just wish I would have made this choice months ago when he made me an offer to end all my problems and build me one of his bad *** units 
. Made in the USA 
... Chris knows me very well and knows exactly what he was done with my setup to make it work so well..... Feel free to call and ask him ... But on a side note I have used everything else on the market by anyone else that would sell me one... Let me save you alot of trouble and ..... He has some GREAT ideas and Combos that work VERY well with turbos amd trucks ! With his help I have been able to make the impossible happen with my Large Frame Rear mount Truck ... Just wish I would have made this choice months ago when he made me an offer to end all my problems and build me one of his bad *** units . Made in the USA
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09-23-2009, 08:38 PM
#8
a higher stall will definitely get the turbo/s spinning up sooner(going by time).
the problem is a higher stall converter will have a difficult time holding the power back once the boost/tq builds.
getting the right converter on a turbo car is tuff. too tight and you are waiting. too loose and you get off the line well but the rpms may never fall below 5500+rpms where your peek tq might be at 4900rpm.
then if you do get just the right converter you decide you want more power so you turn the **** a little and bam, now the converter is stalling 500rpm higher then it was before.
i like the idea of going loose and then locking it up after the 2-3 shift. 1st gear goes by so fast you dont loose anything but gain a quick spool and a good 60'. 2nd gear is hurt a little by being too high in the rpms but then after the 2-3 shift you lock it up and get to enjoy your peek tq.
the problem is a higher stall converter will have a difficult time holding the power back once the boost/tq builds.
getting the right converter on a turbo car is tuff. too tight and you are waiting. too loose and you get off the line well but the rpms may never fall below 5500+rpms where your peek tq might be at 4900rpm.
then if you do get just the right converter you decide you want more power so you turn the **** a little and bam, now the converter is stalling 500rpm higher then it was before.
i like the idea of going loose and then locking it up after the 2-3 shift. 1st gear goes by so fast you dont loose anything but gain a quick spool and a good 60'. 2nd gear is hurt a little by being too high in the rpms but then after the 2-3 shift you lock it up and get to enjoy your peek tq.
09-24-2009, 05:47 PM
#9
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Thanks Casey2323 & Parish8
I will be running approx. 16 lbs boost and not any higher. Probably near limit on pump 93 no meth.
Questions about converter was because my current PI Vigilantly just wiped out all input splines and is getting rebuilt. I thought about raising stall 200-300 RPMs. But from what I read on this forum, I am not sure if going in right direction. Some have commented on good success in retaining a lower stall to allow greater load on engine ie spooling sooner. My general thought would lead me to believe that increased Rpms would provide for more torque/hp at equal boost levels.
I was told my converter is already a 10.25” But previously flashed at approx. 2400-2500. I have little experience in different stalls and not wanting to make bad choice.
I will be running approx. 16 lbs boost and not any higher. Probably near limit on pump 93 no meth.
Questions about converter was because my current PI Vigilantly just wiped out all input splines and is getting rebuilt. I thought about raising stall 200-300 RPMs. But from what I read on this forum, I am not sure if going in right direction. Some have commented on good success in retaining a lower stall to allow greater load on engine ie spooling sooner. My general thought would lead me to believe that increased Rpms would provide for more torque/hp at equal boost levels.
I was told my converter is already a 10.25” But previously flashed at approx. 2400-2500. I have little experience in different stalls and not wanting to make bad choice.
