What will a higher stall torque converter do for my car?
1. A higher stall torque converter will multiply the torque of your engine to put more power and torque to the tires! The high stall torque converter will "slip" the engine into a higher rpm range where there is more torque and horsepower. This will make your car haul ass!
What kind of performance gains will I see with a high stall torque converter?
2. Our customers typically see a .5 reduction in quarter mile times, traction permitting. Highly modified cars with ported heads and bigger cams have seen gains of over 1 second!
What is the difference between "brake stall" and "flash stall"?
3. 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.
What will happen to my fuel economy?
4. Very little. If your vehicle originally came with a lock-up clutch, your Yank Performance Converter would also have a lock-up clutch. You may need to apply slightly more throttle for driving around town, but you should not see a noticeable drop in fuel economy.
How can a 12" torque converter and a 9.5" torque converter both achieve the same stall speed?
5. 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.
Will the Yank Converter affect my warranty?
6. That depends on the dealer. All Yank Performance Converters exceed the manufactures specifications for strength and durability. A dealer should not deny warranty coverage for your converter. If however, you have further concerns, the Stealth Yank Converter is housed in the factory converter case and left the factory color...making it indistinguishable from your stock converter...at least in appearance!
Which converter should I choose for my application?
7. Typically, you want to choose a torque converter with a stall speed 500-700 rpms below the engine's torque peak. For example, an engine making peak torque at 5000 rpms, a 3800-4000 converter would give maximum ET. In choosing your torque converter, understand that there is no one best converter for all situations. A converter that produces very good results at the track may have reduced drivability in town. Key factors are your planned usage, current and future modifications, and drivability. If your primary goal is increased performance at the track, you will want to select from the higher stall converters, 3500 rpm and up. For mostly street driving, you will want to select from the converters with a stall of 3500 rpm or less. A higher stall converter will be "looser" than a stock converter. Looseness refers to the fact that the converter slips the engine into a higher rpm. The use of higher rpms helps provide greater torque during full throttle acceleration, but it also causes the engine to use higher rpms at part throttle too. Looseness can be demonstrated by comparing the typical in town rpms used by a stock converter and a performance converter.
The table below demonstrates the range of looseness. Stock 1600 1600 - 2000 part throttle rpm range Thruster 2800 1800 - 2200 part throttle rpm range SuperYank 3500 2000 - 2500 part throttle rpm range Pro Thruster 4000/4400 2500 - 3000 part throttle rpm range The stock converter requires the least amount of throttle input and will accelerate at lower rpms. The Thruster 2800 is nearly as tight as stock, requiring only slightly higher rpms. The SuperYank 3500 is looser. While under light throttle the car can be driven at below 2,000 rpms, most drivers will be using 2,000+ rpm until lock up. Once the converter locks up (typically 35 - 40 mph), the rpms will drop off to the exact same rpms as the stock unit. The 9" Thruster Pro is the loosest, but provides tremendous gains at the track. Note that the rpm range used in the above example was for a car with 3.23 gears.
A car with 2.73s would use higher rpms, while 3.73s would require lower rpms. Looseness is mostly a perception issue. Because the car uses higher rpms, the exhaust note is more pronounced. Cars with loud aftermarket exhausts will definitely notice the increase in exhaust volume, while cars with quiet systems will notice only a small change. Looseness can reduce the feeling of snappy part throttle acceleration. This sensation is primarily due to the fact that a larger throttle input is required. Most people adjust quickly to a looser converter. If you are unsure of whether looseness will be a concern, consider test driving a friend's car before buying a converter. The Stealth Yank 2600/ SLP 2600 is for those who want a low-cost increase in performance without raising a "red flag" with your dealer. The Stealth provides most of its gain below 2600 rpm, ideal for someone looking for a nice boost in 0 - 30 mph acceleration with street tires. The Stealth has great drivability, but offers the least performance gain, typically a .2 - .3 second decrease in the 1/4 mile time. The all-new Yank Truck Thruster 2600/Stealth Thruster 2800 converters are not re-tooled or re-stalled versions of the stock GM converters, but a brand new design that is a Yank exclusive! The 278mm (11 inches) size is slightly smaller than the stock 300mm (12 inches) and has substantially different driving characteristics. The maximum stall on a factory GM 5.3L torque converter is 1,600 rpms and the shifts drop approximately 2,200 rpms between shifts. With the new Yank Truck Thruster 2600 torque converter, your 5.3 engine will now stall 2,600 rpms and the 2.1 stall toque ratio will multiply more starting line torque than the factory 1.9 STR. 0-60 acceleration times will drop from .3-.4 seconds! To keep the engine more in the sweet spot of its power-band, the Truck Thruster 2600 converter only allows the shifts to drop 1900 rpms between gear changes. For example, an engine that shifts from 1st gear at 5500 rpms will drop to 3,300 rpms in 2nd gear with the stock torque converter.
With the Truck Thruster 2600, the rpms would only drop to 3,600...a nice boost! The Yank Torque Thruster 3.0 is a series of converters for individuals who want maximum thrust off the line without going to excessive stall. The extremely high stall torque ratio of 3.0 multiplies engine torque 3.0 times at the transmission input shaft at launch. This converter is recommended for individuals who want to "roast the tires" while still remaining streetable. The converter is the best choice for individuals who's primary consideration is drivability and who plan to go to the track rarely. The Thruster 2800 provides very good part throttle responsiveness and will provide a significant boost in the 2500 - 3500 rpm range compared with either stock or the Stealth. This converter works best in cars with a mild motor (e.g., lid & cat-back) and 2.73 gears. For 3.23 gears, drag radials are recommended unless the converter is ordered with a 2.5 STR, which is available for $100. The Yank 3000 is the converter for those individuals who want to have the best of both worlds. You will get a dramatic increase in off-the-line torque, but the streetability is very high too. The Yank 3000 provides less torque off the line compared to the Thruster, but provides increased performance in the 2500 - 4000 range. This is an excellent choice for street and strip use. High torque and high top-end efficiency are trademarks of the 3000 converter. You can see why these converters were the first sold for the LS1 and still remain a popular choice. The Super Yank 3500 is a breakthrough in street/strip converters. By using 21st Century materials and CNC manufacturing, the Super Yank provides a superior launch, without blowing the tires off the line.
Our customers typically will pull 60' times on drag radials comparable to their competitor's cars on slicks. Although a SuperYank 3500 can easily roast the tires, you can launch nearly as hard on the street as you could at the strip. The SuperYank 3500 provides great midrange torque. The converter will increase torque out to 5000 rpm on an LS1. This eliminates the flat spots after upshifts and makes second gear a monster even at lower speeds. Because of its lower STR and strong midrange, the SuperYank 3500 teams with 3.73s to form a very hot street set-up. As an additional bonus, the Super Yank is the world leader in efficiency...that means your Super Yank will transform engine torque into rear wheel torque almost as efficiently as a manual transmission! All this in a converter that retains good drivability. The Yank Super Thruster 3500 is a hard hitting version of the Super Yank 3500. We take the competition-bred 9" converter housing and bring the efficiency up to Super Yank standards with a proprietary stator. This means you'll get a 3500 stall converter with high efficiency, but with a much harder hit to the tires at the starting line. This converter is a logical step up for individuals wanting something a little more aggressive than the traditional Yank 3000, but don't want to go to a full race converter. The Super Yank 4000 converter is a step up in performance for vehicles modified with ported cylinder heads and long duration camshafts. The 9" Pro Thruster 4000 converter is for racers looking for maximum launch off the starting line. With over a 4000 stall and a 2.70 stall torque ratio, the 9" Thruster Pro is recommended only for enthusiasts running ET Streets or Slicks.
Drag Radials have no hope of hooking up with this converter...it hits that hard! Despite its high STR, the converter maintains very good efficiency. It will hold 5000+ rpms on upshifts, ensuring high hp to the rear wheels throughout the entire 1/4 mile run. This is a serious performance converter for those willing to trade some drivability for true high performance. The Ultra Yank utilizes an industry-exclusive 225mm billet housing, custom clutch assembly, extremely low weight and very high efficiency. Stall speeds from 4200 and up. See us to custom tailor for your specific needs. A must for the maximum effort racer or extreme street racer. For Nitrous and Blown applications, the Pro Yank 3600 Extreme takes the breakthrough design of the Super Yank and modifies the stall characteristics and shift extension to perfectly match the unique torque curve when using a "power adder". The Pro Yank 3600 Extreme incorporates our exclusive Posi Lock-Up kevlar clutches and 6 bolt mounting lugs to make the most of each nitrous run. Off the bottle, the Pro Yank 3600 Extreme provides similar gains to the Super Yank 3500, giving a solid performance increase on the street while maintaining outstanding drivability.
How am I able to reduce my ET while at the same time, increase my finish line mph and rear wheel horsepower?
8. The superior design of the Yank Performance Converter adds a great deal of efficiency over the stock converter and our competitor's offerings. Our 265mm and 258mm converter housings are based on 1990's General Motors torque converters. These converters have come light years ahead in efficiency compared to those used so often by our competition. The tight tolerances between the pump, turbine, and stator are critical to maintaining a high degree of efficiency and reducing internal heat buildup.
Is a transmission cooler needed with my Yank high stall converter?
9. Not typically with the street strip converters below 3000 stall. The superior efficient design of the Yank converters generate less heat than our competitor's offerings, making trans coolers unnecessary in street/strip applications. For more hard-core racing applications (or converters over 3000 stall speed), a trans cooler is always cheap insurance to protect the transmission when "hot-lapping" the car.
Is a shift kit required or recommended?
10. Yank Performance Converters can achieve maximum performance and efficiency without the use of shift kits. Shift kits dramatically raise transmission line pressure to increase shift firmness. Increased shift firmness will not increase performance, but create unnecessary stress on the transmission and other drive-line components.
Where did the name "Yank" Converters come from?
11. Back in the 1980s, many Australian drag racers had come to the United States to hone their skills and borrow some of the latest technology. After seeing how our cars consistently ran below the national records, they just had to get their hands on one of those "Yank" converters...the name kinda' stuck!