stall on 06 GTO
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TECH Apprentice
Joined: Nov 2006
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From: worcester,ma
stall on 06 GTO i plan on putting on a stall in the spring either 3200 or 3600 right now the car is stock but soon after the stall i will be adding the cam so im thinking of really going with a yank 3600 for this reason. But in the mean time how much better will the stall make my a4 perform, i've heard et losses of up to .5 now is this just because of a higher rpm launch or because it keeps it in the power band?? Basically i just need to know if i mash it while i'm cruising will it make a significant difference over stock?
The only reason to be hesitant about going higher with the stall speed is the weight of the GTO. This can tend to make a converter feel looser particularly as you go higher in stall speed. If you know what cam you are going to be going with, it would really help in the decision. Anything above approx 224 and you should start to consider going higher, but with the GTO, and to keep streetability as high as possible without loosing performance, the 3200 range really tends to work much, much better.
As far as what the converter does, yes, a big part of it is the higher RPM launches, but that is not by any means where all of the performance gains come from. There are really three things that are helped with the right converter. The higher RPM launches, higher STR, and lighter weight. The second, STR actually multiplies imput torque on the moment of impact by the rated STR (diminishing as you climb in the powerband). This is a good part of why launches, with the right converter, are so violent. The last should certainly not be forgotten though. The lighter weight of 245mm converters helps the engine climp through the RPMs. This is actually pretty cool to see. If you put the car in neutral and rev the engine before and after the swap, the difference will amaze you. And that is without even moving the car.
-John
As far as what the converter does, yes, a big part of it is the higher RPM launches, but that is not by any means where all of the performance gains come from. There are really three things that are helped with the right converter. The higher RPM launches, higher STR, and lighter weight. The second, STR actually multiplies imput torque on the moment of impact by the rated STR (diminishing as you climb in the powerband). This is a good part of why launches, with the right converter, are so violent. The last should certainly not be forgotten though. The lighter weight of 245mm converters helps the engine climp through the RPMs. This is actually pretty cool to see. If you put the car in neutral and rev the engine before and after the swap, the difference will amaze you. And that is without even moving the car.
-John
I'll agree on the lighter mass, I noticed right away that it falls back to idle much faster after a quick rev, than the stock converter.
One of the biggest things he forgot to mention though, is the shift extension.
One of the biggest things he forgot to mention though, is the shift extension.
Thread Starter
TECH Apprentice
Joined: Nov 2006
Posts: 308
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From: worcester,ma
well to launch at the stalls full potential i take it i would need some upgrades with the rear?? by the way i will eventually go with the hpe c cam which they just recently changed their specs but as far as i can remember its 238/240 112lsa
To take full potential of the amazing power that the stall will give you, of course it is a good idea to beef everything up behind it and get tires that really hook. However, you can really take advantage of amounts of the power without beefing up everything and getting tires. Most people see a half second or more. To not break things, I recommend launching from about 1200-1400 RPMs. This will preload everything behind the converter and cause less shock on parts. The more you trust the parts behind the converter, the closer to idle you should launch. Launches from idle will take full advantage of stall and STR, unlike revving up the engine to close to stall speed and launching from there.
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I have been building performance automatics going on 29 years, and have worked with a few good TC builders, and I would like to know? who coined the idea of the "shift extension"? This is just a euphemism for more slip in the torque converter, which happens with smaller diameter TC's & higher stall TC's. The torque converter does not know what the gear ratio spread on a shift is, or how much torque/horsepower the motor is putting out, so this idea of "shift extension" is hype, and could actually hurt you in terms of a torque converter choice. So I would look at this differently, as how much slip there is in the TC. Ask a good TC builder about this, if you do not agree. I agree with "to keep streetability as high as possible without losing performance, the 3200 stall range really tends to work much, much better."
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Originally Posted by PBA
I have been building performance automatics going on 29 years, and have worked with a few good TC builders, and I would like to know? who coined the idea of the "shift extension"? This is just a euphemism for more slip in the torque converter, which happens with smaller diameter TC's & higher stall TC's. The torque converter does not know what the gear ratio spread on a shift is, or how much torque/horsepower the motor is putting out, so this idea of "shift extension" is hype, and could actually hurt you in terms of a torque converter choice. So I would look at this differently, as how much slip there is in the TC. Ask a good TC builder about this, if you do not agree. I agree with "to keep streetability as high as possible without losing performance, the 3200 stall range really tends to work much, much better."
Sorry, you are wrong the converter adjusts to the torque load it is subject to.
and the coupling point after the torque change can be adjusted up or down it takes many hours of testing and refinement to do this correctly,
Yank has 20 years of dyno testing for this info.
at the shift extention point (that is the place where the torque converter stator will stop making extra torque and start to go into an fluid coupling state ) that input to output converter speed ratio, % of efficiency
at this point will give the determined RPM to keep the engine up or down in the power band.
It is a usefull tuning aid and must be set the the total package as it is most effective after the 2-3 gear change with a 4l60-e wide ratio transmission gear drop
Yank
As a Happy Yank SS3600 owner I can report going from a brown box 2500rpm converter to the Yank SS3600, I gained .5 in the quarter and 3mph. The MPH gain tells you just how efficiant the converter is.
