I will be installing a Th350 soon, so since 2.5 STR converters are good for launch purposes but aren't very efficent up top, wouldn't they be best for 1/8th mile races since your top speed won't be near as high as a 1/4 mile race?

In other words as long as you hook on take off 2.5 STR should 95% of the time get the best E.T. in the 1/8h compared to a lower STR, when in the 1/4 mile race this might not be the case. Sound about right?

 

The term "stall torque ratio" is pretty much meaningless. There is no standardized way to measure it. Basically, ignore it. I have never heard a serious racer talk about it.

Rich

 

So there is no difference between a 1.6 STR and 2.5 STR??

 

If there is, we would love to see results and data.

 

Below is according to Performabuilt. So I assume this is full of crap.

"To help you choose, here is some additional information about Stall Torque Ratio. Stall torque ratio is the multiplier for torque for a short time when the car is launching. Higher STR will give a much higher torque multiplication for a very short time right at launch, but with an overall cost in efficiency at the top end. In other words, higher STR will increase your 60 ft times, but it may be at the expense of MPH at the top end. Lower STR, while it will not deliver the punch at the bottom like a higher STR, will give torque multiplication for a longer period of time and may allow you to place more power to the ground with less spinning. Additionally, the over all efficiency is much better. Where a 2.5 STR might be only 90 percent efficient above rated stall, a 1.69 would be 96 percent efficient above rated stall (both these numbers based on converter not locked). This means you put more power to the ground throughout the run down the track."

 

So, tell me how you measure it?

Rich

 

Measure what? Effeciency or amount of torque???

 

maybe making paases with both converters of the same stall speed but changing the STR?..

 

Sounds about right to me.

 

You realize that even transbrake equipped cars usually do not launch at stall speed? And if you are not using a brake, it's not possible to launch at the stall speed? Take a look at the websites or catalog of leading converter manufacturers (Coan, ATI, Neal, etc.). They sure don't sell converters based on "STR".

Anyway, if I haven't made my point, go ahead and do what you want. It will probably work fine but not because of some mythical "Stall Torque Ratio".

Rich