Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
It seems we go over this multiple times a year. Each time I try to help guys understand how a converter works to try and clear up the confusion but I'm not sure it works. Lol
Let's use some data from a 10.40 car using 2 different lock-ups and the PTC 9.5 NL.
This data is from the most commonly used core to build a Buick lock-up converter. The GM245mm core which is used by every major company including me.
A 3200 1# stall running 10.40 will have 20+ % slip. Way to loose IMO which is why I never use this converter spec unless someone has a large 66+ turbo and only want a great seat of the pants feel. It will feel loose driving. This spec is used by some vendors who sell PTC and have customers who love them. It's to loose for me personally in what I want my converter to feel like.
The 2800 1# stall has about 16% slip at 130+. This is my most common spec lock-up. It spools very well with a 6262 and has been used with 64-66mm turbo's. This converter with a 6466 has been 10.30's. Why do I not prefer it at this level...because I know with a 9.5 this 10.30 car has a good chance of going 9's but the customer wanted a lock-up. The 10" lock-up can slip in the 9-11% range at 130+ mph and retain lock-up but to do so the 1# stall number is closer to 2500 rpm. Most guys want something to spool a little quicker but this converter would still work with up to a 6262. I have found many of the tighter Vigilante's to stall in the 2400-2500 range at 1#.
On a 10.30 car the 9.5 NL is 4% slip while still having a 3000 rpm 1# stall. What you have to pay attention to is the 1# stall number is still 3000, yet the slip is over 10% better. To get this performance out of a lock-up, the converter will be tighter down low.
A car with a 58mm up to a 62mm turbo can run well into the low 11's with slip numbers in the single digits with most of the available lock-ups if the stall speed is kept at 2500-2600 at 1# of boost. I usually stick with the 2800 stall because guys want a much more noticeable spool. This is why a customers needs and intentions is so important to getting the right converter.
Here is an example of what you can expect from any lock-up converter. Let's use a 2800 1# stall converter for example. At 12.00 it will approximately have 4% slip. 11.50---7%, 11.00-----11%, 10.50----14%. You can take the 1# stall number down to 2500-2600 and slip for each power level will also drop. This is why going on slip % alone only tells 20% of the story. Without knowing it's actual 0-1# stall number and the mph it's running you can't compare from one converter to the other.
Let's use some data from a 10.40 car using 2 different lock-ups and the PTC 9.5 NL.
This data is from the most commonly used core to build a Buick lock-up converter. The GM245mm core which is used by every major company including me.
A 3200 1# stall running 10.40 will have 20+ % slip. Way to loose IMO which is why I never use this converter spec unless someone has a large 66+ turbo and only want a great seat of the pants feel. It will feel loose driving. This spec is used by some vendors who sell PTC and have customers who love them. It's to loose for me personally in what I want my converter to feel like.
The 2800 1# stall has about 16% slip at 130+. This is my most common spec lock-up. It spools very well with a 6262 and has been used with 64-66mm turbo's. This converter with a 6466 has been 10.30's. Why do I not prefer it at this level...because I know with a 9.5 this 10.30 car has a good chance of going 9's but the customer wanted a lock-up. The 10" lock-up can slip in the 9-11% range at 130+ mph and retain lock-up but to do so the 1# stall number is closer to 2500 rpm. Most guys want something to spool a little quicker but this converter would still work with up to a 6262. I have found many of the tighter Vigilante's to stall in the 2400-2500 range at 1#.
On a 10.30 car the 9.5 NL is 4% slip while still having a 3000 rpm 1# stall. What you have to pay attention to is the 1# stall number is still 3000, yet the slip is over 10% better. To get this performance out of a lock-up, the converter will be tighter down low.
A car with a 58mm up to a 62mm turbo can run well into the low 11's with slip numbers in the single digits with most of the available lock-ups if the stall speed is kept at 2500-2600 at 1# of boost. I usually stick with the 2800 stall because guys want a much more noticeable spool. This is why a customers needs and intentions is so important to getting the right converter.
Here is an example of what you can expect from any lock-up converter. Let's use a 2800 1# stall converter for example. At 12.00 it will approximately have 4% slip. 11.50---7%, 11.00-----11%, 10.50----14%. You can take the 1# stall number down to 2500-2600 and slip for each power level will also drop. This is why going on slip % alone only tells 20% of the story. Without knowing it's actual 0-1# stall number and the mph it's running you can't compare from one converter to the other.
