








3600 or 4000 - now with poll feature
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My advice is to select the one that meets your long-term needs or wait until you determine what those are.
The guys at Yank are quite sharp on converter selection, make a clear request and get a clear answer.
SS4000 ;D
Are you looking for the fastest times on the track with ET streets? Go high stall.
Are you looking to take off like a rocket from a stoplight on drag radials? Trim the stall down some, and keep the STR flatter.
Do you want to retain more highway power? Drop the tq multiplication (STR) way down and keep the stall high for shift extension (especially on taller gears, i.e. 2.73, 3.23).
If you're keeping 3.23's, you can afford a higher stall and higher STR.
If you're swapping to 3.73's later, you'd better have slicks if you want to hook up with something high STR/high stall.
Cam selection plays a big role as well. You can make use of massive shift extension with a high stall if your cam spins 6700+. If you're shifting a lot lower, it won't help as much.
A lot of people have a great deal of fun on the street with a high stall/high STR, but that's partially because they like blowing their street tires off at will, which may be fun, but it's not fast.... so again, depends on what you're looking for. The most "fun" combo for you may not be the fastest.
Above all, don't go overboard with STR. Extremely high STR tends to be very 'peaky', meaning the multiplication hits in a spike, which will brake the tires loose, leaving you spinning even after it drops off.
As far as 4000+ being the only way to go.... that's preference. A 4000+ car will be a blast to drive, but line up next to a guy with a 3600 at a stoplight while you're both on street tires or DR's, and he'll have a very big edge in terms of consistency. But it boils down to what's more enjoyable for you?
Blowing the tires off at will, I admit, is pretty cool but it isn't going to help me be any quicker when I do hit the occasional street race. So a lower stall with a moderate STR would be better?
Blowing the tires off at will, I admit, is pretty cool but it isn't going to help me be any quicker when I do hit the occasional street race. So a lower stall with a moderate STR would be better?
For something that's purely street... you have 2 ways to balance it. You want to make sure your overall applied torque (the amount that hits the tires) is in the realm of what a street tire can handle. To achieve that, you have to decide if you want to lean more towards stall, or more towards STR. For a lot of people that comes down to feel. The higher stall/lower STR will feel "looser", while the lower stall/higher STR will have a tighter feel, but... too much STR is no good.
With 3.23's on an A4, you still have a big gap between gears, so you want enough stall to keep the engine in the powerband after a shift, so anything 3000+ will be a big help for that. In terms of STR, remember that more STR directly reduces efficiency, and thus, less rwhp.
It's pretty much a big equation... engine torque at launch rpm x STR ratio at launch rpm x 1st gear ratio x rear end ratio.
Bumping up stall speed will increase launch rpm and thus have your engine putting out more torque when you launch. You can achieve the same applied torque by lowering launch rpm (or lowering stall) and increasing STR. Just remember not to overdo it on STR.... it's just like any part selection, if you go with more than you can use, you're giving up a little elsewhere (in this case, top end rwhp and trap speed).
So don't just settle on stall speed, look around at different STR's. Stall is a good place to start since it will determine your launch rpm, shift extension, and overall converter feel.


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