Yank

iTrader: (181)

Any converter company can make a converter stall higher, however, it takes real extensive design work and testing to make a converter produce high efficiencies and accurate STR in relationship to each customers' required application.

Yank Converters depends on designing and prototyping converters with the lastest technology. It is not just a tranny shop or an assembly site. Building a true performance converter is like building a race engine. It requires a lot of special parts, quality control, and computer designing as well as manufacturing.

Yank Converters are often dubbed as overpriced. However; the hours, engineering time, and extreme quality control put into each converter are shown through extreme performance and accurate results.

blkZ28spt

I might have a Yank converter, if I could more easily afford it and/or you guys did a better job answering the phone and replying to emails/phone messages. The PT4000 looks pretty good to me...that or the SS4000. Yank does build a good converter.

chris718

here is an except from our 200 page gm 2004r transmission technical manual that some may find usefull

11-D. TORQUE CONVERTER SELECTION
In order to increase the power output of the internal combustion engine the operating speed of the engine is increased. By increasing the operating speed of the engine we allow a higher volume of air and fuel to be enter the combustion chamber to be compressed, ignited and transferred into a rotary motion to drive the crankshaft, transmission and ultimately the vehicle. This phenomenon of the internal combustion engines ability to increase air and fuel ingestion may appear quite complex even to those who believe they understand its operating principles. Although it may be simply viewed as atmospheric pressure filling a vacuum, it should also be seen in some respects as a runaway condition of momentum at speeds that cannot be registered by the human eye or understood completely by a human being. We can all agree that the more the throttle is opened the more air and fuel the engine ingests and with this comes a corresponding increase in engine speed and power output. With this comes a corresponding increase in the rpm range where the engine makes its peak torque .In order for a vehicle to accelerate from a dead stop with maximum efficiency, the engine must be able to freely enter its rpm range just below peak torque to produce the quickest “launch”. Each vehicle and engine combination will require a converter with a specific stall speed and torque multiplication ratio if maximum performance is to be achieved To accomplish this the torque converters coupling efficiency is reduced at speeds below peak torque to allow the engine to enter its rev range without allowing engine torque to push through the transmission, final drive, brake system and tires. Stall speed should be understood as the maximum engine speed the engine can reach with the throttle plate wide open, the transmission in gear, the transmission turbine shaft held stationary and the vehicles brake system applied. In most cases there will come a point when the engine will overcome the tires because energy stored in the driveline is sufficient enough to overcome the final drive and brake system. Vehicles with numerically low final drives, increased vehicle weight or with upgraded brake systems will achieve higher stall speeds than their counterparts. The use of a transmission brake takes this one step further by allowing the transmission to be internally locked by simultaneously applying reverse and drive ranges thereby not allowing engine torque to enter the driveline allowing the maximum stall speed to be reached. In order to select or profile the characteristics of a specific converter the intended usage, power output, operating range, final drive ratio, must be known as well as if you plan on using a lock up or non lock converter or a transmission brake. Most vehicles that will use the 2004r transmission with its specific planetary gear set ratio and performance final drive ratios will exhibit a general pattern of acceleration behavior based on these factors. Most normally aspirated and mild turbocharged application will require the engine to use 2000 to 2800 rpm’s in first gear to accelerate them with maximum efficiency. If the engine will see a maximum of 5600 rpms than it should become apparent that most maximum effort performance applications within this operating range will require stall speeds of 2800 to 3600 rpm’s .Inside this window all the small details about the combination will produce the specific stall speed that will work properly. Vehicles with intricate or large turbocharger configurations pose many obstacles when selecting a converter. For example, if you have a turbocharger that needs an exhaust volume that is produced at 3800 rpms in order to enter its power curve coupled with an engine that reaches its mechanical limitations at 5600 rpm’s selection becomes difficult for the novice. This is because in order to stage the car and get the turbo to spool properly converter efficiency above this rpm is compromised due to the maximum operating range of the engine and the converters response to the rapid build up of torque entering boost with the car stationary. In this case we would use a 3600 rpm stall lock up converter so that at high engine speeds we could physically 100% couple the engine and transmission eliminating the inefficiency of the fluid coupling associated with this unique set of circumstances Most converters will also produce an additional 200 rpm’s in engine speed the instant the brake pedal or transmission brake is released ...It should also be understood that a torque converter will also multiply engine torque at a specific ratio based on its design as well as input torque. This principle as well as many others can be better understood by studying chapter 11 A. Always make your selection based on the data you compile that is specific to your combination. If you are unsure you may contact us for additional help in making your selection. In most high horsepower applications (beyond 550 horsepower) the car will run down the quarter mile faster with a properly selected non lock-up converter. Always remember that there are exceptions to this rule and every combination is unique in its own way requiring special attention.

rufretic

iTrader: (37)

Heres the thing, your comparing a high stalled car to a low stalled car with gears and better traction and saying the car would 60' just as good but trap higher. Ok that may be true but you take that high stalled car and do the same with gears and tires and its now going to be an even comparison of the high stall vs low stall and we all know whos going to have the better ET. High mph doesn't win races low et does.

Last time I was at the track a m6 supercharged lt1 corvette was trapping 114 almost every time. I was trapping 107-109 and I beat him by .3-.5 every time. I'll take a win over a high mph any day.

BadAssFast

iTrader: (2)

I agree with the above...If I have a motor which makes power between 2000 - 4500 and I have a stall a 3800, my torque (which launches me...not hp which finishes the run) will be spent real fast (60ft or...) ...am I, in this power range, not better with a stall at say 2800? A 3800 or 4000 is great if my power band is higher? What am I missing if I'm incorrect?

josh99ta

iTrader: (1)

Some people wont though. Some people want both (like me). I want the lower ET, but I also want a good trap speed and awesome performance from a roll. The discussion came up on our board if smaller stalls were more efficient and thus better suited for racing from a roll or if bigger stalls with higher shift extensions were better suited for this.

Good discussion guys, keep it up.

rufretic

iTrader: (37)

The closest your going to get to both is a stall that will keep you in your power range. This could mean a lower stall if you don't make any power up top but there arn't many cars making more power at 3000rpms than 4000rpms. A stall is going to help an A4 no matter where you are racing from a stop or a roll. As soon as you punch it with a stall it will flash to where you want to be. That is if you have the right stall for your combination. In most cars case, this is higher in the rpm range. If you have a 4000 stall on a close to stock car it is still going to perform better than a 3000 because even stock, you are making more power past 4000. When your racing from a roll, you want to get in your power band the quickest, a 4000 stall is goin to be that much closer.

The only reason I can see to go with a lower stall is driveability, there are no performance advantages.

RevGTO

iTrader: (12)

I can say that almost all of the gain I've gotten from my TC has been in the 60'. I've been disappointed in the effect of shift extension getting me down the track quicker. In fact, I've wondered if I would have had the same gains putting Nittos on with the stock converter. But my converter is small, and there are a lot of variables - including weather - and I've got to get to the track some more to get it dialed in.

jimmyblue

iTrader: (11)

From what little I've been able to collect, there are
some pretty big differences in the efficiency profile
between converters that aren't all that far apart in
nominal stall speed.

I'm not talking about the "rated" efficiency. There's
no standard for that and a single number is irrelevant.
I'm talking about, over how much of your powerband is
the converter coupling efficiently? Does it cost you 10%
or more until you get above 5000? Or is it flat and over
95% efficient from 4000 up?

If you're using the converter to keep your RPMs up
(shift extension) then the HP "bonus" you get from
being at that higher RPM has to be more than what
you'd get by reclaiming the lost efficiency from the
converter slip, by being on a tighter@RPM one at
the lower RPM. Power is basically RPM in the midband.
You could figure that hanging at 4000RPM gives you
33% more crank HP than being at 3000.

Now, my 3000 stalls at about 3000 at mid throttle
but if I'm on it the car shifts at 6000 and drops to
3700 or so, just by gearing in the A4. A 4000 stall
might let the RPM stay up at 5000. 35% more HP.

The converter would have to be ~70% efficient to
make this a wash. 3000-3500RPM range converters
look to be 80% efficient at 4000RPM by my data /
analysis. They hit 90% 5000, 95% at 6000. or so
(roughly speaking).

So net gain on a 4000 looks likely unless it's one sloppy
piece. More so on a car that has more room at the top
end than the stock powerband and doesn't quit pulling
just when the converter starts getting efficient.

strokedls1

iTrader: (1)

This is why I bought a 3400 vig with a 5 disc clutch. I can get the good sixty and lock it up in 3rd to get some extra efficency. I smoke m6's all the time from a roll and my car is a 4k lb tank. lol I am not caught up on dyno numbers or mph. I am just looking for better et's. The m6 shift time is a big factor in the et. It doesn't compare to my .350 second shifts. If shift extension keeps you in your power band you will go faster. I know this from racing experience.

XTrooper

Exactly. My converter keeps my engine speed at ~5000 rpm between WOT shifts. How in hell can dropping down to ~3500 with a stock converter somehow be "better." Same 60' times with a stock converter car vs. mine? I'll whip it every time. The fact is, with 97% efficiency, my Yank SY3500 is more efficient than the stock converter.

With a high-stall converter when your transmission shifts at WOT, instead of the engine speed dropping down to 3000-3500 rpm, it will stay at 4000-5000+ rpm (depending on the converter) and you'll be right back up to redline again for your next shift. This results in your motor staying in the meat of its power band for the whole run and that translates into improved ETs. There is no way this can be bad for performance and, all else being equal, you will crush a car with a stock converter whose motor drops below 4000 rpm between shifts. If keeping your motor in the heart of its power band were unimportant, it would be unnecessary for manual tranny drivers to powershift to accomplish the same thing shift extension does for us. They could lazily make their shifts unconcerned about how low their engine speed dropped between them. This is not the case.

The “shift extension” factor will help even if you never visit a drag strip, as it will eliminate the “dead spot” that stock converter cars suffer from. Now, when you accelerate and your transmission kicks down into passing gear, instead of your engine having to build up speed from the 3000 rpm range, you'll be starting at that higher engine speed which translates into better acceleration, better performance, and safer passing.

PonchoFan

You have to drive a car with a high shift extension to appreciate it. With the stock converter, the car bogged at the 1-2 shift until the rpms came up. With the current high stall converter, the 'bog' is gone due to the shift extension increase.
The best way to verify this would be with a plot of the acceleration value through the entire run with both converters. I'm sure you'll find that all the gains are not in the first 60 ft.

RevGTO

iTrader: (12)

Your shift extension is 3700? Is that a typo? We have the same converter and same gears, and mine is 4700.

Fenster

iTrader: (3)

Great thread guys... Looking forward to seeing where this goes!!! Maybe this should be a sticky!!!

jay_99z

iTrader: (5)

Here is the problem with your argument.....in the real world a 2800 will not 60' the same as a 4400. If it does you need to throw the 4400 in the trash because it's junk.

Whether or not you gain at the top because of shift extension (I believe you do) you will gain overall ET because of the high stall. There is a reason the "top dogs" don't swap back to a 3600 stall. Some of these guys have a race only car and have tried many different setups. Don't you think they would swap back if there was something to gain?

As far as trap speed....I don't really care too much about it. Back when the car had a stock converter it ran 12.78@110mph. The next week I only changed the converter (Yank3600). It ran 12.38@110. Sooo .4 drop with no trap speed change. Who cares?


I guess what I'm getting at is.....does it matter if a 4400 slips more than a 2800? Nope. To me it's all about the ET. I think shift extension helps a lot but like I said....having a 2800 to 60' the same as a 4400 for comparison purposes shouldn't happen.

XTrooper

An excellent point and right on the money.

Yank

iTrader: (181)

Check out this attached graph. This is a time of accl. of converters from dead stop to red line in 3rd gear with max work load applied.

josh99ta

iTrader: (1)

The point isn't which one will 60' better or run quicker at the track. The point is efficiency, and which converter would be better from a roll. A converter that is less efficient, higher shift extension or a converter that is more efficient, but without as much shift extension. We're not talking track times here, just using trap speed as a marker for how fast a car is from a roll. Cars that trap higher will almost always be faster from a roll. We're talking maximizing efficiency. A lower stall and higher numerical gearing might be the ticket. That is the point Chris is arguing (I believe).

Yank

iTrader: (181)

this might show you that there is more power at the top rpm"s

B T

That's some good info Yank thanks!
Now I can see how each one changes things, it will help make my decision when I buy a Yank converter.

A4 cars use 3 gears in the 1/4?

My car is at the top of 2nd gear when it breaks the beams.

If my auto was using 4 gears like the M6 car then I would finally have the ET and MPH I've been looking for.

Lets change things a little and give the M6 car an M2 trans with the same % drive train loss as the M6( i know what you guys are thinking ).

Everything else being equal from the driver down to gearing on both cars.
The auto car gets an A2, ( A2 = 1st and 2nd ratio's from the 4L60-E trans with the same % drive train loss as the 4L60-E trans ).

The M2 car gets the same trans gear ratios as the A2 car has. 1st and 2nd 4L60-E ratios.

Final drive gear is going to be 2:73 for both the M2 and A2 cars.

What happens when we run these two cars if they both 60 ft the same?

What will be the main difference other than the M2 car will shift slower?

Will both the MPH be the same???

What about ET???

Just thought I'd throw this into the mix...

This thread has some great information, keeping it coming guys!

BT