animuL

iTrader: (3)

I bought a Vigilante 3600 stall. From what I have read its about a 2.5 str. Someone is telling me that the lower the str the "tighter" it feels for regular street driving. Is there any truth in this? I have read that the converter I bought does feel very tight and is much better than others for a DD.

06 SS

exactly the opposite. Lower STR means it will feel looser. Better for a track launch, less usefull for true street car use.

LS1curious

Hmm loaded question.

animuL

iTrader: (3)

How bout this.... is how tight the converter feels always directly related to the str value or can you have two converters: say one's a Yank, the other a TCI, both with the same rated stall, both with the same str, and one feels tighter for regular driving?

GregWS6&z28

iTrader: (8)

doesnt affect a whole lot on the street. it's when you flash it WOT that the different STR is really felt. it affects the converters efficiency on the top end also.

edit: most people say the Yanks feel tighter driving around town

RICEETER

iTrader: (49)

im still kinda lost on how the str works also but fwiw, i had the yank ss4000 with 2.6str and it was loose as a goose. i was asked on more than one occasion if i was running a t-brake.

...and LMAO at animuL's sig

animuL

iTrader: (3)

I have found a few articles on Yank's and PI's websites. Basically they say str means nothing for how the car daily drives. PI says advertised str numbers are BS: http://www.converter.com/torqueration.htm

The info I have found so far says the lower the str the softer the hit and the more efficient at high rpms (above 5000).

I went to Neal Chance's website and they dont even bother to mention str. A friend of mine has a Chance converter, they are local to us and he actually talked to the owner who said the str number is nothing to be concerned about.

Funny that so many people are concerned about this number yet all the top converter companies play it down so much. Either way, I can't wait to replace my stock converter with the Vig 3600!!

LS1curious

Loaded question. STR can change even with the same theoretical stall speed depending on what pump,turbine,stator combo is in the unit.

animuL

iTrader: (3)

"Loaded question" <- love the pun, thanks for the info.

performabuilt

iTrader: (25)

SOME INFORMATION COPIED FROM YANKS WEB SITE OF INTEREST CONCERNING STR
Stall Torque Ratio is one of the most misunderstood aspects of torque converter construction. Our competitors often call stall torque ratio: torque multiplier. The stall torque ratio is the amount of engine torque that the torque converter can multiply at a particular rpm level. By definition, stall torque ratio is when the turbine is at 0 RPMs and the converter is at maximum designed stall. This will produce a positive push on the turbine to increase the torque to the input shaft of the transmission, multiplied by the designed stall torque ratio of the torque converter. For example, a stall torque ratio of 2.0 would multiply 200 lb. ft. of engine torque to 400 lb. ft. of torque at the transmission input-shaft.
The misconception of stall torque ratio is that more must be better. This is not always the case. High stall torque ratio applications, typically are for industrial equipment or engines with limited low rpm engine torque. With high stall toque ratio converters, there are important trade-offs. What you take at one end you give up on the other. Typically, a torque converter with a very high stall torque ratio, such as 2.0-2.5, will be much less efficient above its rated stall speed. There is a sacrifice in higher rpm efficiency to achieve high stall torque ratios. That lower efficiency translates into less horsepower transmitted to the tires over an RPM range.

The problem with a high stall torque ratio converter is that it is only high while the car is not moving. Maximum stall torque ratio occurs at wide open throttle with no rotation of the transmission input shaft. As the input shaft starts to rotate with vehicle forward movement, the stall torque ratio will become non-existent much sooner than a converter of the same stall, with a lower stall torque ratio. A converter with a stall torque ratio of 2.2 for example, would display that at the starting line, but it would drop off much sooner than a converter with a lower stall torque ratio. See graph:



As you can see, the converter with the lower stall torque ratio will multiply torque for a longer period of time than the converter with a higher stall torque ratio. As most of you know, most racing occurs above 3,000 RPMs. That's why the lower stall torque ratio often wins the race:

*Lower stall torque ratio is gentler on the tires at the initial launch, but it will pull harder for the remaining 1,305 ft. of the 1/4 mile. Less races will be lost at the starting line from excessive wheelspin.
Lower stall torque ratio will be more efficient and transmit more torque and horsepower to the tires. This translates into lower ETs and higher trap speeds!

youguessit

So i have been reading up on this and from what i gather str is very important. The more str the faster off the line or better for drag strip. Lower str is good for highway use because they tend to be more efficient high end. So for a street strip car you would want the most str (at the proper stall speed for your application) with the best high end efficiency for street use as well. Well since more of one of these tends to negetively effect the other it seems you have to choose between slow low end, good high end efficiency or fast low end and bad high end efficiency. so here is the real question: is there a converter out there that can stall 3000+rpms with a high str to propel the low end, with a high efficiency ratio that wont sacrafice high end? I have read that they take the converter size down from 298mm to 245 in order to help this dilema.... someone please put there 2cents in !

MuscleCarZ28

iTrader: (11)

damn i was thinking about going with a 3600, but since i race a lot from a roll the 3200 and its lower STR is better for me. correct??

firefighter813x

iTrader: (6)

I'm restalling my Vig 3600 for the tighter 3200. When I install it I'll make a post soon.

BubaGumpShrimp

iTrader: (1)

str isnt the only thing that will get you off the line quicker. Stall speed is important as well. You will have to decide what your goals are as far as what str you pick. The lower the str (ex 1.6) the more top end pull you'll get cause its a more efficient converter. Higher str helps to launch the car off the line quicker but is less efficient over all. Since the 1/4 mile is a short distance and you need to get that car up and going as fast as possiable you would need more str but you also have to take in account what kind of tires you plan on running. If your going to use street tires then it makes no sense to get a high str, drag radials will get you more hook so a little higher str could be used and of course slicks would allow more hooking potential and allow you to use more str. Also--gears can play a role as to how much str will affect a car and how loose it feals..

jetlag

iTrader: (32)

The SS3600 in my car almost feels stock.