Choosing the RIGHT Converter... is it voodoo or science?
By Jok Nicholson
Actually it might involve a little voodoo and a lot of science (experience).
I want to make it perfectly clear that I AM NOT an expert on converters
by any means. I don't even want to know why or how they work. I actually
only want them to do a few things: react the same every lap, provide
deadly consistent 60-ft times, last for a couple of hundred runs before
needing a rebuild, and not cost an arm and a leg. See, I don't ask for
When I started the search for a torque converter, I started not with
a converter / transmission builder but rather I consulted with my engine
builder. Ken Lazerri, the master engine builder at Indy Cylinder Head,
showed me how to use the dyno sheet to have a converter built that matched
the torque and horsepower the engine developed. His recommendation was
a 5600 rpm stall, 8-inch converter. He suggested a launch rpm of 4200-4800
rpm and recommended that if I was trying for the fastest possible setup
I should stay away from both the "soft hit" converters and 9-inch converters.
Since I had no experience with this type of car (a 235-inch, four-link,
1800-lb dragster) or an engine with this type of power (817 hp and 723
ft/lbs torque), it was time to make some calls to torque converter specialists.
are dozens of them out there and I am sure they all do their best to
provide racers with the best product they can. I decided to call one
of our Drag Racing Online tech experts, Mike Stewart of Mike's Transmission
in Lancaster, CA and also Jim Hughes of Hughes Performance in Phoenix,
The first thing I noticed when I talked to both guys was their attention
to detail. Each one asked me about the engine, gear ratios, tire size
and what I expected to do with car. My only input on the converter was
that I thought I should have a 9-inch converter. I was planning on a
lot of Quick Rod / Super Comp racing and the 9-inch I had in my trusty
old Dart worked like a champ.