Torque converter and top end
efficiency for bigger STR and higher stall speed, or a
higher necessary RPM to get into efficient coupling.
The best converters for efficiency top out around 97%
and a lot of race types are well less. There's always a
tradeoff. I have never, ever seen converter makers
publish an efficiency vs RPM curve and I surely wish
one of the mags like, say, Chevy High Performance
would take on a dyno test of popular converters
(say, two models apiece from PI, TCI and Yank - and
bought from distribution, not cherry-picked) and show
real RWT/RWHP vs RPM dyno curves. That would be
hot. But it would be guaranteed to **** off at least
two of the three advertisers, so don't hold your breath
waiting for those kind of facts.


