12secSS

iTrader: (30)

Those of you who think a high STR will feel looser, versus a low STR (which should feel tighter), you need to read what I posted about what STR is. If you have more available power to the rear wheels, the vehicle will accelerate with less throttle effort, if you have less power to the wheels, the vehicle will require more throttle effort. Simple physics! STR multiplies the torque at the rear wheels from idle up. So a 1.6 STR will feel looser because it is making less torque multiplication from idle, versus a 2.5 STR. The reason the stock stall of 1600 STR ~1.7 feels very tight is due to the low stall and larger diameter (in basic terms). I could explain in more detail, but I would lose most everyone on the fluid dynamics of the Stator, Impeller and Turbine roles in regard to "looseness" and "Tightness".

mike13

iTrader: (27)

wouldn't a higher STR have more torque multiplication because it takes more engine rpm to turn the driveshaft the same amount of rpm as a lower STR? Wouldn't that mean a higher STR is less efficient at torque converter coupling at lower rpm?

9000th01ss

iTrader: (10)

HEY! read what I said carefully.

Yea, well it's a big mystery unless you have a torque converter dyno. And my own opinion on that is that a company can build a converter for a peticular application and driving characteristic and not "pick" a STR.

Companies that pick specific STR's usually build converters based on what a machine says, not an actual vehicle.

9000th01ss

iTrader: (10)

No, I think thats a problem. Dumbing it down never works for me.
When people make something easy to explain, and easy for a "regular" person to understand, it usually ends up making less sense IMO.

9000th01ss

iTrader: (10)

The thread is about STR. What you just typed above doesn't give your opinion or even say anything about STR.

Are you saying str doesn't matter?

All I got out of it is that you just did a bunch of testing, good to know. But the question is about STR.

12secSS

iTrader: (30)

No, just the opposite. Think of it like this, STR is how many buddies you have to push a 3000lb weight. The more buddies you have the less effort you need to push that weight. The less buddies you have, then more effort you need. Now you are bringing in something most people mislabel: Torque converter coupling (aka: locking up). This happens when the Stator is pretty much at the same speed as the turbine, where TQ multiplication is no longer produced. The converter doesn't get locked up, but rather it is at the most efficient point, then it starts to generate heat and looses efficiency. I am going off on a tangent here, so not to digress. Think of STR like the torque from an LS1 versus a Honda. The higher STR is the LS1 and the lower STR is the Honda engine. Simple! Lower STRs is better for street tires because it doesn't hit the tires hard. The higher STR is great on slicks and the track, because ti hit the tires harders, which results in great 60' launches that are usually wheelies.

9000th01ss

iTrader: (10)

So this thread is a big mass of confusion.
I ordered a converter, not from FTI. (no offense I just chose a different company)
I talked to someone on the phone, I didn't even say a word about STR.
I don't care what my STR is, how the car drives is what I care about and I think the converter I ordered is going to be what I want.

So I'll talk about my converter when I get it, hopefully this thread will just disappear.

12secSS

iTrader: (30)

I was referring to a typical consumer. Unfortunately, most of what I know is from spending hours in front of the converter dyno and doing testing. It is much easier to understand by experience, rather then explain via verbage. For me at least. Although I can refer you to SAE papers from G. Wallace.

mike13

iTrader: (27)

12secss OK I think I'm starting to grasp the concept, so in theory a higher STR would also allow a larger difference in engine rpm vs driveshaft rotation on the top end? So if just going by STR and not taking into account the other factors in building converters in theory a stock converter will be closer to 1 to 1 at maximum rpm and mph.

matthewjosh

iTrader: (7)

This has to be the dumbest thread I have read! STR means one thing and one thing only!!!! If you want a good launch go with a 2.5 if you want a good all around converter go with a 2.0 or lower!!!! Thats all nothing more nothing less!!!!

12secSS

iTrader: (30)

There is more to efficiency then that, but basically yes.

If it was that easy, there wouldn't be so many different Stall, STR and size combinations to achieve different setup goals. You need to remember that gear ratios, vehicle weight, power band , etc ... all affect how a conevrter will act. Simply saying a 2.5 will work for this group, where as a 2.0 will work for the others is an ignorant statement.

matthewjosh

iTrader: (7)

Not sure what group you are talking about, but what I was saying is that a 2.5 str will hit hard off the line and a 2.0 will too but will be better on top end as well due to efficiency!

This is true no matter what horsepower you have no matter what stall or weight car you have. I think you looked into what I was saying to much.

mike13

iTrader: (27)

Wow that's it? We should tell all the converter manufacturers that's how to build converters. How dare they take 2.5 STR's and make them great street converters. Yes it's a dumb thread if you just want someone to tell you what to buy. It's interesting to me because it's not that simple, you have high stall cars that dyno 50-100rwhp less then they should but when you check their et's they're actually making the power.

9000th01ss

iTrader: (10)

In a way yes, but YOUR converter. (not converters in general)
My final thoughts on this are--- 12secSS has done a lot of time on a converter dyno gathering results of different combinations of parts (correct me if I'm wrong)
FTI said they just got done doing a bunch of tests (that did not require any special machines like TC dynos)

After certain vehicles have been around for a while, these companies have enough info gathered (and a few of their own secrets) that they can build you a converter for YOUR car.

Thats the key, talk to them. It shouldn't be the customer that determines STR. That decision should be made by the converter manufacturer based on your SPECIFIC information. (vehicle specs, goals, etc)

CarsandWomen

iTrader: (19)

man i read through alota bullshit for a little info

WHPLASH

iTrader: (22)

Going back to the Yank quote, I think they need to chime in and clarify their statement. Quite confusing why they don't even offer that low of STR's on their website.

And I just went with a higher STR and stall from them.

9000th01ss

iTrader: (10)

I asked them in one of their threads and they said call for questions. So if I did that I'd be the only one who knows. Or I could relay the info and type it up here, but I don't see why I have to be their secretary. They should step up and type a bit here, or update their now useless info on their site.

Seems like they don't care, so I took my money elsewhere. Why should they care, I'm only one sale they lost.

koolaid_kid

iTrader: (21)

A short tandem repeat (STR) in DNA is a class of polymorphisms that occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 10 base pairs (bp) (for example (CATG)n in a genomic region) and is typically in the non-coding intron region, making it junk DNA. By examining enough STR loci and counting how many repeats of a specific STR sequence there are at a given locus, it is possible to create a unique genetic profile of an individual. There are currently over 10,000 published STR sequences in the human genome. STR analysis has become the prevalent analysis method for determining genetic profiles in forensic cases.

Heck, I thought everyone knew.

WHPLASH

iTrader: (22)

Exactly what you said. Couldn't of said it better. lol

WHPLASH

iTrader: (22)

They told me the same thing. Call them.

I bought one of their converters a few years ago off the chart they have on the website. I bought a PY3400 Extreme. 3.23 gears and a supercharger. When I called them up a couple months back......... no, no, no. Thats not the right converter for your app. I told them I went off their chart. So now I have a SS3600 that I'm waiting till spring and this damn snow to dissapear to try it out.