Ok I'll show my ignorance, but please educate. What is a loose converter and how does that effect performance? I have been told that my loose converter is better for street driving but with a tighter converter I will pick up rwhp. So what's up?

 

Loose is genrally the term used to describe just that a converter that feels sloppy in the bottom alot of rev at light throttle but not moving much. Gneraly this type converter will give more bottom end kick at WOT throttle however. Now the tight converter generally feelsmuch more like stock in the bottom dosent give a much of a kick when launching but does provide torque multiplication over a broader RPM range and tends to be more efficent on the dyno for hp loss.

 

Thanks, so is one better for daily driving vs. strip/drag racing, if so which one? and why? Does the rated "stall" have anything to do with "looseness" or is that a different measurement.

 

I spec'd my converter with a pretty low STR (by "performance"
converter standards, though somewhat higher than stock) in
order to get better coupling at the low pedal, low RPM end.
This makes it, not "loose", but "stretchy" (my term). A high STR
swings you from no coupling, to high coupling, in a shorter span
of RPM which ends about the nominal stall speed, so low STR
designs "reach down" further but less firm, torque modulates
more with pedal and some people will call -that- loose. It's one
of those words that have "loose" definitions / usage. Heh.

The rated stall contributes to "looseness" at the low end, you
moved the coupling-point away from where you drive on the
street. High STRs are usually part of the performance converter
deal, part by necessity but part because "that's what they all
want". Great if you can hook it up, useless if you can't, for
launch. Hitting the tires hard but fading early for multiplication
may not be your ideal recipe but it sells, people like to feel that
kick in the *** when they bolt in a new piece. Whether ot not
it's any better across the whole distance, depends on the setup,
balance between tires and motor and efficiency and "powerband
management". Track only, put the slicks on, make it wail at 5500
to 6500RPM all the way, and trailer it home when the trans lets
go; buy the 4400RPM, 2.8STR and rock it. But it will want 3000
RPM just to climb a hill in 2nd.

For a low mods, street tires car you could be happy with a 3000
stall, 2.0 STR high efficiency converter. Though most of these
broncos will tell you to go big. When you don't have a ton of power
efficiency and torque multiplication that persists a good ways out,
helps a lot.

3500, 2.5 is where a lot of "street performance" converters seem
to be positioned, +/-500RPM. I've been at 3000 and 3500 and won't
be going any higher; 3500 was a little big until the cam went in, by
my standards. Which don't have too much to do with the track and
more to do with "enthusiastic" street & highway driving.

 

Perfect!! And I quoted your entire post. Maybe some people will read it twice. Folks also need to honestly assess their driving usage before choosing a converter. 80% street/20% strip or 80% strip / 20% street. Application matters as much as combination.

 

Really great post... The "milder" 3500 stall car will murder the 4400/2.8str car 9 times out of 10 on the street (unless you drive slicks on the street). And from a roll, forget it.... the 2.8STR car will be looking at taillights all day. Seen it a million times.