Robert Kastle
New Member
- Joined
- Mar 12, 2004
- Messages
- 81
I have been at home the last couple of weeks due to some back/neck surgery and I have been doing some reading,,,,a great deal of it with regards to torqure converters. I would like to post some things that I have noticed.Please correct me if I am mistaken.
Observations:
1) Maximum acceleration accurs when the torque converter is sized to stall at or slightly above peak torque.
2) A properly matched torque converter unlocked will out accelerate a locked torque converter.
3) The stall point changes with load. Example-@15psi the converter may run up to 4100rpm in 3rd gear but @21psi it may run up to 4800rpm 3rd gear. This example would be flooring the car while at a roll in 3rd gear and this would be the rpm's that the engine would jump too.
4) This point kind of goes along with number three,,,the measure % slip changes with load. I have a 3400 9x11 and have read every post I could on this board and others and here is what I have noticed. 1rst @5250rpm about 10% slip,,2nd gear @5250 rpm about 12.5% slip,,3rd gear @5250 rpm 15-17%. Tire size can change this,,,,,,I use 26" some others use 28". The point is that the % slip changes with applied load. I have read of people saying that "X" converter only has 6% slip but when I find posts on this converter it is usually much higher. This is a number that must be taken with a grain of salt.
5) With a typical Buick it appears to be better to be slightly on the tight side due to the limited rpm's of most motors.
6) A Higher stall for a big turbo is a bad match if the engine is done with its power @5000 rpm. Again from what I have noticed the best acceleration happens when the stall is at or slightly above peak torque. The trick it would seem is to get a big turbo to spool at a lower rpm. Ball Bearings,,higher exhaust gas velocity.........Or move the power band up (cam,heads) to match the converter and turbo.
7) It would be best to have some dyno numbers before a converter is purchased.
8) It must be known how the converter is going to be used. If it is going to be at the track more than the street you may want it tighter to keep the stall down at the power level generated at the track.
9) With converters,,,,,,,you get what you pay for. Gosh I can not tell you how many posts I have read about poor performance,,,,only for the problem to be traced back to the converter. I have no idea what causes fins to bend or a converter to balloon but it appears to be not to uncommon a problem among some companies.
Observations:
1) Maximum acceleration accurs when the torque converter is sized to stall at or slightly above peak torque.
2) A properly matched torque converter unlocked will out accelerate a locked torque converter.
3) The stall point changes with load. Example-@15psi the converter may run up to 4100rpm in 3rd gear but @21psi it may run up to 4800rpm 3rd gear. This example would be flooring the car while at a roll in 3rd gear and this would be the rpm's that the engine would jump too.
4) This point kind of goes along with number three,,,the measure % slip changes with load. I have a 3400 9x11 and have read every post I could on this board and others and here is what I have noticed. 1rst @5250rpm about 10% slip,,2nd gear @5250 rpm about 12.5% slip,,3rd gear @5250 rpm 15-17%. Tire size can change this,,,,,,I use 26" some others use 28". The point is that the % slip changes with applied load. I have read of people saying that "X" converter only has 6% slip but when I find posts on this converter it is usually much higher. This is a number that must be taken with a grain of salt.
5) With a typical Buick it appears to be better to be slightly on the tight side due to the limited rpm's of most motors.
6) A Higher stall for a big turbo is a bad match if the engine is done with its power @5000 rpm. Again from what I have noticed the best acceleration happens when the stall is at or slightly above peak torque. The trick it would seem is to get a big turbo to spool at a lower rpm. Ball Bearings,,higher exhaust gas velocity.........Or move the power band up (cam,heads) to match the converter and turbo.
7) It would be best to have some dyno numbers before a converter is purchased.
8) It must be known how the converter is going to be used. If it is going to be at the track more than the street you may want it tighter to keep the stall down at the power level generated at the track.
9) With converters,,,,,,,you get what you pay for. Gosh I can not tell you how many posts I have read about poor performance,,,,only for the problem to be traced back to the converter. I have no idea what causes fins to bend or a converter to balloon but it appears to be not to uncommon a problem among some companies.
