Just wondering if someone could explain exactly what STR is and what it does at different levels?

 

search, john fuddle has a great explanation on his website

 

Stall Torque Ratio - the amount your verter multiplies the torque from your engine.

Higher STR=car feels tighter + leaves harder out of the hole=less traction on street tires

for eg. a verter with STR of 2.4 multiplies the torque your engine is supplying by 2.4X

-Jay-

 

I believe this is all true, except the part about the higher the STR the tighter the converter. There was a recent thread with an explanation of this and I'll see if I can find it. As I recall, it had to do with converter design and tolerances, rather than STR.
Ed

 

Checked with the Fuddle site FAQ's - his info agrees with mine for what it's worth...

 

No it's been discussed here before on how higher STR's will help tighten up the feel of a converter. This is mostly for cars still running on stock gears (like me). If the converter hits harder then it will feel less sluggish then one that has a much lower STR. But the higher the STR the less traction you will find (especially on the street).

But there has to be a fair comparison. A 3000 stall with a 2.0 STR will definately feel tighter then a 3800 stall with a 2.7 STR due to the far more streetable stall speed. But a 3500 stall with a 2.5 STR will feel tighter (on stock gears) then a 3500 stall with a 2.0 STR.

 

The faq info on our site is highly simplified. It is how the converter is designed that determines stall and STR. The components used to create a 3600/2.2 will feel much better on the road than the components used to create a 3600/1.8. While the higher str variant in that (and most) situation will feel tighter, it is not because of the STR. It is tighter because the components used to achieve that stall and STR provide better street feel.
One key to remember is that as components used to increase stall are used, the STR will also be raised. For example, a 4000/2.4 will be looser on the street than a 3600/2.2 despite the higher STR.
Basically what I am saying is that you are both correct. There are so many factors that play into the feel of the converter that boiling it down to the level I have on Fuddleracing.com may be misleading. I will consider changing the wording or adding an advanced tech section on the site.

 

No fair. You beat me to it and said it perhaps better.
Well put.

 

Lurk.

 

My ST3500 (2.5 STR) & 2.73 gears will literally boil the tires with the largest (street) tires I can get on stock wheels.
Torque x is fantastic from a stop or low rpms, but the torque x runs out fairly quick.
A well designed TC with a lower STR will pick up and roll better from a higher speed, while mine kicks *** from low rpms (mine is a a better 1/4 mile as opposed to running from a highway roll).

 

I see. I'm looking at going with a bigger cam and possibly steeper gears so I want to fully unstand stalls before I upgrade to another one. John, I'll give ya a call when I get money for the upgrades, I'm looking at going with one of yours. Thanks guys.