Calculator
Example Data Table
| Input | Example Value | Meaning |
|---|---|---|
| Engine torque | 300 lb ft | Crankshaft torque entering the converter. |
| Torque ratio | 2.10 | Converter multiplication at the selected condition. |
| Converter efficiency | 92% | Loss allowance inside the converter. |
| Turbine radius | 0.14 m | Effective radius where torque becomes tangential force. |
| Gear and final drive | 3.50 and 3.73 | Drivetrain multiplication before the tire. |
| Tire radius | 0.34 m | Loaded radius used for tractive force. |
Formula Used
Engine torque in N m: Te = entered torque converted to N m.
Turbine torque: Tt = Te × torque ratio × converter efficiency.
Turbine tangential force: Ft = Tt ÷ turbine radius.
Wheel torque: Tw = Tt × gear ratio × final drive ratio × driveline efficiency.
Wheel force: Fw = Tw ÷ tire radius.
Grade force: Fg = mass × 9.80665 × grade ÷ 100.
Rolling force: Fr = mass × 9.80665 × rolling coefficient.
Net force: Fnet = Fw − Fg − Fr.
Acceleration: a = Fnet ÷ mass.
How to Use This Calculator
- Enter engine torque and choose the correct torque unit.
- Add converter torque ratio from converter data or test data.
- Enter converter efficiency to include hydraulic losses.
- Enter turbine radius for local tangential force.
- Add gear ratio, final drive ratio, and driveline efficiency.
- Enter tire radius to estimate wheel thrust.
- Add mass, grade, and rolling resistance for net force.
- Press calculate. Results appear above the form.
- Use CSV or PDF buttons to save the result.
About Torque Converter Force
What the Calculation Means
A torque converter changes engine torque into turbine torque through fluid motion. The engine drives the impeller. The impeller moves oil against the turbine. The stator redirects that oil. This action can multiply torque at low speed. The effect is strongest near stall. It becomes smaller as turbine speed rises. This calculator turns that behavior into useful force values. It estimates turbine force and wheel force. It also checks losses, slip, gear ratios, and vehicle resistance.
Why Radius Matters
Torque is a turning effect. Force is the push at a radius. A larger radius gives less force for the same torque. A smaller radius gives more force. The turbine radius shows the internal tangential force. Tire radius shows road force. Both values matter. They describe different parts of the system.
Using Drivetrain Ratios
Gear ratio and final drive ratio multiply torque. They also reduce speed. This is why first gear gives strong launch force. Driveline efficiency reduces ideal torque. Bearings, gears, oil shear, and joints create losses. The calculator applies those losses before wheel force is found.
Understanding Net Force
Wheel force alone is not the full answer. The vehicle must overcome grade force and rolling force. A steep road needs more push. Soft tires also need more push. Net force is the useful remaining force. Positive net force can accelerate the vehicle. Negative net force means the selected setup cannot overcome resistance.
Best Use Cases
Use this tool for drivetrain checks, converter comparison, launch estimates, and educational physics. It helps compare stall ratios, gear choices, and tire sizes. Use measured values when possible. Real converters change ratio with speed, temperature, and load. Treat results as engineering estimates. Confirm final designs with testing and manufacturer data.
FAQs
What is torque converter force?
It is the tangential force produced when converter output torque acts at an effective radius. This calculator also estimates wheel force after gear and final drive multiplication.
What is torque ratio?
Torque ratio shows how much the converter multiplies engine torque. A value of 2.0 means turbine torque is about twice the input torque before losses.
Why does converter efficiency matter?
Fluid coupling creates heat and losses. Efficiency reduces the ideal multiplied torque so the estimate is closer to a real drivetrain condition.
What radius should I enter?
Use the effective turbine radius for internal converter force. Use loaded tire radius for wheel tractive force. Loaded tire radius is measured under vehicle weight.
Does this calculator include road resistance?
Yes. It subtracts grade force and rolling resistance from wheel force. The result is the net available force for acceleration.
Can I use pound-feet torque?
Yes. Select lb ft in the torque unit field. The calculator converts it to newton meters before applying the formulas.
What does converter slip change?
Slip lowers turbine speed compared with engine speed. This affects the estimated turbine power and power efficiency result.
Is this suitable for final design work?
It is useful for estimates and comparisons. Final drivetrain design should use measured converter maps, temperature data, tire tests, and manufacturer limits.