Frequently Asked Questions

Unsure about the performance or racing torque converter you need? ProTorque provides you with an extensive frequently asked questions directory (FAQs) to answer all of your torque converter questions – a great source for torque converter basics and help in choosing ProTorque!

General Questions

What is the difference between ProTorque and competitors torque converters?

Many of our competitor’s torque converters were designed with only the torque converter in mind. ProTorque converters are designed with the whole vehicle combination in mind, allowing for better torque multiplication rates and are more efficiency. This allows for more power to be transferred and a better overall product.

What is the ProTorque difference?

ProTorque converters will have many differences from the units produced by the factory and other aftermarket rebuilders. Beyond using top quality parts, and parts designed by our own R & D department, we custom build your converter to work with your entire vehicle combination; this results in better durability, performance and efficiency overall.

What is a performance converter?

A regular torque converter is designed for stock engines. A performance torque converter is designed to allow a vehicle to perform beyond the vehicles stock settings. a) The torque converter is strengthened to handle additional power. b) The characteristics of the torque converter are altered in order to transfer additional power. c) The stall is adjusted to more closely match the power curve of a higher performance engine.

Why is a torque converter an important performance upgrade when installing a turbo system?

Theoretically, for maximum acceleration, the stall speed of the torque converter should match the peak torque rpm of the engine. If a high performance engine makes power at a higher rpm, then a higher stall speed torque converter can put more power to the ground quicker. When the same vehicle has a turbo installed you want to make sure that you are transferring power to the ground at the best possible rpm and best boost levels. If the stall speed of the torque converter is too low there can be some associated “turbo lag”, or delay, until the engine rpm comes up and the turbo starts to build boost. The aftermarket performance converter that is properly matched to the turbo system will allow for maximum acceleration. In many cases a performance torque converter will take .4 – .6th’s off of your quarter mile ET with no loss of drivability.

What is stall speed and how do I determine what stall I have now?

Stall speed is a term used to describe the rpm at which the torque converter transfers the power from the engine to the transmission. There are different ways to test stall speed. “Foot brake stall” is when you press the brake pedal and then press the gas pedal. When the engine rpm doesn’t go any higher or the tires start to spin that is “brake stall”. (DO NOT TRY THIS! THIS MEASUREMENT IS MEANINGLESS AND POTENTIALLY DANGEROUS TO YOU, THE TRANSMISSION AND THE TORQUE CONVERTER!) “Flash stall” is when you, from a dead stop, press the gas pedal to wide open throttle (wot). Watch your tach needle, you will see the needle jump to a certain rpm, that is “flash stall”. A drag racing-style trans brake will give you closer to the true stall speed of a torque converter.

How do I determine the best converter for my vehicle?

This can sometimes be a difficult question to give a general answer to. In many cases performance and drivability are somewhat of a trade off. However with a properly matched torque converter and turbo system you can easily achieve the best of both worlds. Because stall speed is dependent on input torque, in a light throttle situation the turbos don’t build a tremendous amount of boost. Therefore the stall speed is really nice and very drivable. In full throttle situations, if the turbo and torque converter are matched properly you will transfer the power at the optimal rpm and boost levels …. and FRY the tires! Generally, with a higher stall speed you loose some of the drivability that you would have with a lower stall speed. The goal is to get a torque converter that will increase performance without sacrificing drivability. The most important thing to keep in mind, when selecting a torque converter, is that you want to match stall speed to the engine’s power band. Many turbo companies will do testing to find out what is the optimum converter for their packages. As a general rule of thumb … when the turbo just starts to build boost is really what should determine what stall speed that you will need. The converter needs to have a high enough stall to enable the turbo to spool. As the turbo spools, it will build boost and more power. This added power will increase the stall speed and continue the spooling process. It is not uncommon for a turbo to pull the stall speed of the converter up an additional 500 rpm. If the converter is sized properly with a turbo application, you will get the best of both worlds; a low stall speed for good drivability in off-boost conditions as well as a higher stall under boosted conditions that will give you great performance. With a properly sized converter combined with a turbocharger, it is possible to have your cake and eat it too.

How do I make a final decision on where to buy a torque converter?

The Dealer/Manufacturer should:
• Be familiar with your type of power package and done testing with similar vehicle combinations.
• Offer you as much technical information and product support as possible.
• Offer you a warranty and free stall adjustments.
• Help you determine what you need from your converter, and then custom build one to your application.

Why a lower stall for diesel applications?

Theoretically, for maximum acceleration, the stall speed of the torque converter should match the peak torque rpm of the engine. Significant gains in throttle response, acceleration, towing and fuel efficiency are possible with a performance diesel torque converter that lowers factory stall speed to where maximum torque is produced. The right torque converter eliminates that “spongy” feel when you step on the accelerator pedal. This reduced converter slippage also results in less heat generation for longer transmission life.

How is the torque converter going to effect the performance of your engine package?

More than likely you have spent an enormous effort making the most amount of power. The torque converter is charged with the job of transferring that power. If you are using inferior OE torque converters with your performance package you are, in essence, wasting that power. A torque converter designed to work in tandem with the engine will put the power back where it belongs – to the wheel.

Why bother with a product that is usually considered an integral part of the drive train not the engine package?

No other component effects the way a motor / vehicle combination makes power like the torque converter. Like every other part of an engine combination the torque converter needs to match the engine curve.

What are the important factors that affect Stall Speed?

• Vehicle Weight
• Vane / Fin Angle
• Horsepower
• Impeller to Turbine Clearance
• Powerband / CamShaft
• Stator Design
• Input Torque
• Converter Diameter
• Gear Ratio

What’s the most important factor in selecting the right converter?

First, make sure the converter you are considering comes from a quality company that has experience with your vehicle application. The company should be able to help determine the proper product based on your combination. The most important factor in the converter is ensuring it will handle the power you are trying to put through it.

Converter Selection Questions

What’s the most important factor in selecting the right converter?

First, make sure the converter you are considering comes from a quality company that has experience with your vehicle application. The company should be able to help determine the proper product based on your combination. The most important factor in the converter is ensuring it will handle the power you are trying to put through it.

How do I determine what stator I need?

Years of experience and practical knowledge as well as thousands of dyno and datalogging exposure has led our techs to being able to help you determine the right stator for your application.  In addition, many notable tuners that have used our products and had consistent results know exactly what stator they want to tune the entire combination.  When in doubt, speak to a professional and let them guide you. The stator will affect the stall range.

When should I have an extra stator on hand?

If you have a bolt-together converter, the answer is always!  One of the major benefits of having a bolt-together converter is the ability to tune the converter for different power levels and conditions. We would recommend having one tighter and one looser stator for ultimate control of your race car.

Why should I consider a billet cover?

Horsepower and torque will determine the strength of the features needed on your torque converter. We have painstakingly taken the hard work determining what you need to have by using our experience and engineering department to match the product levels with the appropriate power levels.

When should I get a rebuild kit or replacement sprag for my converter?

Ideally you should have a service kit on hand at all times.  It is our recommendation to buy the service kit when you buy your bolt-together converter.  It will already be too late if you are at the track and have to service your converter and not have simple parts on hand.  Plus, we can throw it in the converter box and you will save on the shipping cost. 

Converter Installation Questions
See this link for the appropriate tech help.

What bolts do I need to bolt the converter to the flexplate?

All of the following series use 7/16-20:

  • EV
  • UX
  • BR


The below series units will vary depending on the type of unit and part number.  Usually, it will take the same as the factory torque converter it is replaced with.  For example, the GM LSXT will take the same bolt as what came out, M10x1.5 metric.

  • Prodrive
  • Street muscle
  • LSXT
How often should I have my converter serviced?

This really depends on how much usage and abuse you are introducing the converter.  Generally, any time you are servicing the transmission you should be servicing the converter.  We have had many of our torque converters handle several years and several thousand “passes” on them.  Ideally, once a year in your down time of the season would be the most prudent plan.

What signs indicate I need to have my converter inspected for damage?

The answer to this question can be complicated.  If the vehicle is no longer consistent and is losing Et and MPH this could be an indication that there is something going on.  When reading the datalogs, you can sometimes determine that there is some anomaly that needs to be diagnosed. 

What services do you offer and what is the turn-around time?

We offer full-service converter repairs.  This includes inspections which are complimentary, stall adjustments, stator changes, pump or turbine replacements, spline changes, and freshen ups. Turn-around time really depends on what unit it is and what needs to be done to the converter, as well as the time of year.  We try to operate a “first in” and “first out” service program but sometimes the service work needs to be done in a time-sensitive manner.  Please call one of our techs and let them know if you have a time-sensitive service.


Please use this online form to send your unit in for inspection.

What are the important data points to consider when honing in my converter?

Look at this page to see the important channels we use:

How can I determine if I’m having a transmission issue or a converter issue?

This is a little harder to answer with a simple response.  There are many factors and we recommend that you speak to one of our techs to try and help you figure out what may be causing the issue.

Will adding rear gear loosen or tighten my converter?

In general, going up numerically will tighten the overall finish line efficiency.

What is the right converter charge pressure?

This can be a tricky question, but in general 80-90 lbs of charge pressure seems to net the best results.  Further discussion should be explored with one of our technical experts.

What do I torque the bolt-together converter bolts to?

Bolt-together units that use our “D-bolt” technology will need to be torque to 27Ft lbs.  All others that are allen bolt are torqued to 24 ft lbs. See our tech documents for more information.


How much distance between converter and flexplate do I need?

Due to variances in overall converter heights and flexplate thicknesses, be sure to check clearances between the torque converter mounting pads and the flexplate after the transmission is bolted to the motor. After installation be sure to check that the flexplate and torque converter spin freely and that they are not binding. Clearance between the flexplate and the converter should be between 1/8″ and

3/16.” Any more than this should be shimmed properly with the appropriate shim kit. A good rule of thumb is to use a 1/8″ drill bit as a feeler gauge and make sure it slides in with little clearance. If shims have been provided with your torque converter, more than likely you will need to use them. See our tech documents for more information.

How far should the pilot go in crank?

Ideally with the converter pads touching the flexplate, there should be .250” of pilot engagement into the crank. There should also be at least .250” distance between the end of the torque converter pilot and the bottom of the crank.

Choose the best converter for yourself using our formula

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