Right now I have a SY3500 from Yank. STR is 1.61. 97% efficient. Yank touts this as one of the best converters they have as well as one of the best available ANYWHERE.



My question is... for as much daily around town driving as I do, wouldn't I be better off with a higher STR for all the stop and go? As the converter doesn't get locked too often except ont he highway.



OR... should I just go with a steeper gear? I have 3.42 now.



Going by Yanks converter selection chart, they show a SS3600 or SS3800 is the way I should go. They both have a 2.5 STR.



Yet they claim this SY3500 is the best all around.



What do you guys think? I know the lower STR is easier on the launch, but they say it carries the power longer. The STR is supposed to only really make a difference in the first 60' or so, and after that the converter efficiency is what puts the power to the wheels.



I'm only putting down 1.9 60' times with a 12.9 ET and 104.5mph. The SS converter has only 2% less efficiency, but it puts down 50% more torque on launch. With better 60' times, my ET's can only improve, right? Assuming I am putting down 325hp to the wheels, then the difference in the efficiency of the two converters is only 7hp (325/.97=335hp, 325/.95=342hp).



Seems to me the 7hp is not enough difference to make up for the 50% more torque hitting the tires at the line. And I can't see going to 3.73 gears making enough of a mechanical advantage to make up for the difference.



thoughts?

 

You are leaving something pretty basic out of your thought process, and that is the torque curve of the motor. That is the prime determinate of the optimal stall speed. STR is a somewhat controversial area, I would not chosse a converter based on the STR to any great extent.

Rich

 

Stall's have more to do with cam duration then anything.. steeper gears will just up the rpm throughout the band..