98redorangeta

iTrader: (10)

I know its someting torque ratio but im pretty sure the s dosent stand for someting. haha Also whats the differance between flash stall and break stall flash is where it jumps to and break is where it stops with both pedals floored right? also flash stall is what torque converters are rated by correct? sorry for so many ?

Yank

iTrader: (181)

this might help you
http://www.converter.cc/faq/faq.htm

98redorangeta

iTrader: (10)

thanks but i didnt see where it said what str stands for it did clear up break stall and flash stall though.

BlackHawk T/A

iTrader: (3)

Stall Torque Ratio

Yank

iTrader: (181)

It is for Stall Torque Ratio it is a number that is telling the amount that engine torque is multiplied by at a set point in the converter at stop. (brake torqued)
but as you brake torque to a higher RPM your engine torque goes up, but the STR goes down!! (a 3500 stall converter rated at 2.0 STR might be rated at 1500 or 3000 RPM brake stall, this number is the call by the maker of the converter)
so that is why each converter, car and engine has a SWEET spot
Yank converters are STR rated at the point that we have tested them to perform best in the style and vehicle the converter is sold for ( SY3500 stall 1.63 STR ) True rating

jay_99z

iTrader: (5)

What point are they tested at? Off idle, 3500, somewhere in between?

Yank

iTrader: (181)

Most of Yank converters like our SS line are rated in the 2400 to 2800 range
but not all!!!!
the SY3500 STR is rated at 3000 to 3300 RPM
and our PT4000 STR is rated at 3400 to 3600
That is why we have so many styles!!
and it is best to talk about your mods
with your converter company before make your final choice

12secSS

iTrader: (30)

To answer your questions:

STR = Stall Torque Ratio (aka: Multiplier)

Flash Stall = The RPMs reached as soon as you floor the throttle from 0% throttle, typically can't be seen with the eyes as it goes by too fast. A log file from a scanner can show you the RPM though.

Break Stall = The point where you broke parts. Typically it is at idle, but the throttle floored.

Brake Stall = The highest RPMs achieved while holding the brake pedal firmly, prior to tire spin. This RPM value varies greatly depending on the condition of the road surface, tire traction and brake pad/rotor quality.

Different companies rate their converters differently. Some companies just blindly guess what the stall speed is based on a test drive, sometimes the test vehicle is not even close to the intended application, resulting in false figures that are not useable. Reputable converter companies will test the converter at similar power output as the intended application, plus zero out the output speed of the converter to achieve the true max Stall RPM (much like a trans brake).

Hope this helps.

98redorangeta

iTrader: (10)

thanks guys for the info

jay_99z

iTrader: (5)

I don't say this to be an ***.....just trying to understand the rating....

I know the higher the STR, the harder it hits the tires but....If the STR is rated at different points on different converters then it is pretty worthless number for comparison (of two converters) right?

OR is it the MAX STR for the converter at any given point........ and that point happens to be in different ranges on different converters? Such as

If this makes no sense I can try to explain my question better. Lol!

Yank

iTrader: (181)

You can use the STR to match converters from the same converter company.
it is useless info to try to match company A to B
That is why we have tested and sell our converters for different market segments.
They are sold for use in that area! this is the REAL world Testing and this is the info performance people need. as we have been drag racers from the late 1960's
We have stopped use of the highest rating of STR at 100 ft lbs! this is what some companys do (that is the info that GM supplied to the aftermarket years ago)
We have found this is useless to the racer as you are over 100 ft lbs by around 2000 RPM

BlackHawk T/A

iTrader: (3)

And this is something I have always wondered, at exactly what point is STR measured, and it's something that as far as I know, has never been discussed on this forum.

So say you have a converter that puts out the same STR as another, let's say 2.5, but it does it around 3500 rpm, while the first does it around 2500 rpm and falls off.

This means the one rated at 3500 rpm is going to put less power to the ground on launch, and a stronger pull afterwards?

Yank

iTrader: (181)

looks like you have to take the engine torque at launch rpm, and times it by the STR at that rpm, this thru the Transmission first gear ratio, times the rear gear, than divide by 2 to give you the Tractive force (torque) at the tire
contact patch, you will also need to know the rolling dia. of the tire setup. this must be a close match for the Max Launch Power and no tire spin.

Now the slope of the STR will effect the rest of the gear range, as this is called shift extention, the point of where STR goes to 0
After that the Efficiency slope takes over and ramps up, as designed into the converter to the stated Max. rpm called out for use.

you will need pick the converter last to blend all your parts together
do not build the car around the converter
Thats why we ask questions about you car it helps us build your converter.

jay_99z

iTrader: (5)

But even yours aren't all the same.....


How are these numbers worth while?

Yank

iTrader: (181)

we give the numbers at the brake stall point the converter responds
to best and most used at the track

BlackHawk T/A

iTrader: (3)

Man this is what I tried telling people here on LS1 tech a few months ago, and all I ended up with was 2 pages of all sorts of people saying I didn't know what the heck I was talking about! I had people rolling their eyes, telling me you should get the converter first. Well, back at them