Which stall
Thread Starter
TECH Fanatic
Joined: Oct 2002
Posts: 1,068
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From: Seattle,Wa.
Which stall Which stall for my T/A. Stock motor, 3800 lbs.car?
Shaun said a 3200 might be a bit much for my car. I would like your opinions, I want to keep the car streetable. Mods are in my sig.
Thanks in advance.
Shaun said a 3200 might be a bit much for my car. I would like your opinions, I want to keep the car streetable. Mods are in my sig.
Thanks in advance.
Well, looking at Yanks menu, you have the Stealth Thruster in the mild corner. Supposed to act a lot like the stock unit until you nail it. Moving up a notch there is the one I bought, the SuperStock3200. Very efficient, adds a tad more punch than the Stealth for the launch, and yet is tight for hiway driving. Or you can go big like one Pro Yank 4400 if all you want to do is crank out 1.5 60' times all day.
I would personally not go over 3500 is this is a daily driver. itchygomey98 cruises around with a 3800 stall but that's a little too much for my taste. A 3200 seems about perfect with your application.
Do you plan to cam the car?
Nate
Do you plan to cam the car?
Nate
Thread Starter
TECH Fanatic
Joined: Oct 2002
Posts: 1,068
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From: Seattle,Wa.
I don't think a cam & heads is in the budget for 2005. Eventually I am going to H/C but not sure when. That's why I need all of your assistance in choosing the right stall. When I do H/C maybe I will have to change the stall size. If there is a stall that would work for my car whether I have H/C or not, let me know.
I'm thinking a stall would give me the biggest bang for my buck at this point of modding, except for a bottle of juice.I'm more interested in a stall right now. I've heard good things about Yank.
I'm thinking a stall would give me the biggest bang for my buck at this point of modding, except for a bottle of juice.I'm more interested in a stall right now. I've heard good things about Yank.
Thread Starter
TECH Fanatic
Joined: Oct 2002
Posts: 1,068
Likes: 0
From: Seattle,Wa.
Thanks Wahusker,
I've been looking at the Yank Stealth Thruster 3000, not sure what 2.25 STR means though. The price is $700. I wonder if they have them in stock?
What type of tranny cooler do I need? Where should I look?
I've been looking at the Yank Stealth Thruster 3000, not sure what 2.25 STR means though. The price is $700. I wonder if they have them in stock?
What type of tranny cooler do I need? Where should I look?
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This is off the Yank site. Makes me re-think my 3.0str.
Stall Torque Ratio is one of the most misunderstood aspects of torque converter construction. Our competitors often call stall torque ratio: torque multiplier. The stall torque ratio is the amount of engine torque that the torque converter can multiply at a particular rpm level. By definition, stall torque ratio is when the turbine is at 0 RPMs and the converter is at maximum designed stall. This will produce a positive push on the turbine to increase the torque to the input shaft of the transmission, multiplied by the designed stall torque ratio of the torque converter. For example, a stall torque ratio of 2.0 would multiply 200 lb. ft. of engine torque to 400 lb. ft. of torque at the transmission input-shaft.
The misconception of stall torque ratio is that more must be better. This is not always the case. High stall torque ratio applications, typically are for industrial equipment or engines with limited low rpm engine torque. With high stall toque ratio converters, there are important trade-offs. What you take at one end you give up on the other. Typically, a torque converter with a very high stall torque ratio, such as 2.0-2.5, will be much less efficient above its rated stall speed. There is a sacrifice in higher rpm efficiency to achieve high stall torque ratios. That lower efficiency translates into less horsepower transmitted to the tires over an RPM range.
The problem with a high stall torque ratio converter is that it is only high while the car is not moving. Maximum stall torque ratio occurs at wide open throttle with no rotation of the transmission input shaft. As the input shaft starts to rotate with vehicle forward movement, the stall torque ratio will become non-existent much sooner than a converter of the same stall, with a lower stall torque ratio. A converter with a stall torque ratio of 2.2 for example, would display that at the starting line, but it would drop off much sooner than a converter with a lower stall torque ratio. See graph:
For example: A competitor's converter with a claimed stall torque ratio of 2.5 (red graph line) would typically have an efficiency of around 90% at high RPMs (5,000 plus). That means 300 flywheel horsepower would translate to 270 horsepower at the transmission input-shaft. A Super Yank Converter with a stall torque ratio of 1.6 (green graph line) has efficiency in the 97% range. That means a 300 horsepower engine would transmit 291 horsepower to the transmission input-shaft: A gain of 21 horsepower! For an LS-1 customer dyno sheet showing 97% efficiency press here.
As you can see, the converter with the lower stall torque ratio will multiply torque for a longer period of time than the converter with a higher stall torque ratio. As most of you know, most racing occurs above 3,000 RPMs. That's why the lower stall torque ratio often wins the race:
*Lower stall torque ratio is gentler on the tires at the initial launch, but it will pull harder for the remaining 1,305 ft. of the 1/4 mile. Less races will be lost at the starting line from excessive wheelspin.
- Lower stall torque ratio will be more efficient and transmit more torque and horsepower to the tires. This translates into lower ETs and higher trap speeds! Brake Stall vs. Flash Stall:
Flash stall is the maximum your engine's torque can stall a torque converter. In essence flash stall and full stall are nearly identical. If you had a transbrake, you could find full stall by putting your foot to the floor and reading your tach. For argument sake, let's say we're testing a 3500 stall Yank ST 3500. If you had a transbrake, you would see around 3500 rpms. If your motor was at idle and then you suddenly floored the throttle, you might see slightly more (maybe 100 rpm more) stall for a half second as the momentum of the motor's internals "flashed" the converter a small bit above its true stall rating.
Brake stall, on the other hand is a very subjective thing. For most, it's the highest stall you can achieve before your tires spin. This varies greatly based on many factors: Traction, gearing, brake clamping force, and engine torque. With a ST3500, I may only be able to get 2200rpm "brake stall" on the street with street tires...any higher rpm and the motor torque would overwhelm the tires. But if I was at the track with racing slicks on the starting line, I might be able to get 3200 brake stall before the motor torque overwhelmed the tires. See...brake stall is very subjective.
Yank rates their converters based on their intended application. A ST 3500 will stall 3500 rpms in a stock LS1. If you had a 422 and wanted a ST 3500, the converter you received would still stall 3500 because it would be built around the torque of a 422, not a stock displacement LS1. Yank checks the stall of their converters and their competitors by using either a trasmission dyno or a "tranny tricker" in the vehicle tested. With the tranny tricker, you can place the vehicle in 2nd or 3rd gear and stab the throttle to the floor...making it easy to read both flash stall and full stall.
How a 12" converter can have the same stall speed as a 9.5" converter:
Two different sized converters can have the same stall speed, but the efficiencies will vary greatly. A converter pump will tend to have a higher efficiency when its blades have a positive angle to them. The positive angle feeds the most amount of fluid to the turbine. The more fluid you feed the turbine, the harder it pushes on it. The harder the turbine is pushed, the more torque is transferred to the transmission.
For a 12" converter that normally stalls at 1600, to be converted to a 2600 stall, most converter builders will bend the pump blades back to a negative angle to feed less fluid to the turbine. This means the pump will have to turn more rpms to force the turbine with the same amount of fluid as before. As you can imagine, the efficiency starts to drop off rapidly as you bend the blades more and more negative. You will lose rwhp.
A 9.5" converter stalls higher because it generates less fluid by virtue of it's smaller size. It takes more stall to achieve the same amount of hydraulic force of a larger 12" converter. Good thing about a 9.5" converter is that you can achieve very high efficiency in higher stall applications because the pump blades still maintain a very forward pitch to them (positive angle). So in essence, by bending the blades negative on a 12" converter, you are turning it into a heavy, inefficient, higher stall converter in comparison to a smaller diameter converter. This is the very reason why Yank Converters uses a special pump and stator combination to achieve high efficiency along with high stall in its Stealth line of 12" converters.
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Verdad Gallardo Good info Rokko! Seems like every time I read about stalls I see something new. The one thing I didn't see there was the "higher str converters will feel tighter under normal driving conditions" statement.
On a side note, the SS3200 that I bought is supposed to be more efficient than most with a high str due to the 21 blade stator thats used in the SS series. Dave & Mike @ Yank recommended it for me, knowing I am going to be running an open road race where I WILL be running higher rpms & will be concerned about heat. So I'm thinkin the str is not the end-all for top end consideration.
Obviously I do not know much tho, right Rick? Eric? Doug? Shut-up Ellis!
On a side note, the SS3200 that I bought is supposed to be more efficient than most with a high str due to the 21 blade stator thats used in the SS series. Dave & Mike @ Yank recommended it for me, knowing I am going to be running an open road race where I WILL be running higher rpms & will be concerned about heat. So I'm thinkin the str is not the end-all for top end consideration.
Obviously I do not know much tho, right Rick? Eric? Doug? Shut-up Ellis!
Heh. Well, I was a member of "the higher the str the better" which I see is not good for upper end efficiency. Now the way I read it, the lower the str, the more it will pull on the mid to top end. 2.2-2.5 is what I'm going to go for now. Probably a ST or SS series verter.
That SS series has the efficient 21 blade stator. GM is planning on using that style stator in the new caddy's.
That SS series has the efficient 21 blade stator. GM is planning on using that style stator in the new caddy's.
to each his own, but i'm telling you that if you go with a small stall, you'll be kicking yourself in the *** later. bobby can chime in about my car anytime he wants to. when he rode in it i still had the 2.73's. ultimately the decision is yours. keep in mind that vig offers 1 free re-stall when you buy a new converter. that way when you buy the tiny stall, you can get a real one later.
Originally Posted by Rokko
That SS series has the efficient 21 blade stator. GM is planning on using that style stator in the new caddy's.
Launching!
Joined: Nov 2003
Posts: 235
Likes: 0
From: White Salmon, WA.
basic rule of thumb... Get a TC with a stall rating about 500 RPMs below your max torque rating as read off your dyno sheet!
IE: 358 ft/lb torque at 4000 RPM get a 3500 stall TC.
You might look up Frank Lupo who can build you a TC based on your specs and needs. Won't cost you $700.00 either!
Ken
IE: 358 ft/lb torque at 4000 RPM get a 3500 stall TC.
You might look up Frank Lupo who can build you a TC based on your specs and needs. Won't cost you $700.00 either!
Ken
Originally Posted by kickassT/A
thats what converter yank starts with. they use caddy cores
It all depends on what you are after. If all you want to do is to drag race, get a BIG stall with a medium str. Something in the 4k range with about 2.0 str that will maximize the torque of the LS1. If however you want to drive it daily, or run road races, then maybe something smaller is better. And if your exhaust is loud & the local police are ****, then one with a higher str is better too. Hence my choice of the SS3200.
That's the nice part about calling Dave & Mike @ Yank, or talking to Ellis & telling them what you want to do with your car. They can help take the guesswork out of it so you make an informed decision.
