Shop Rebuild Kits →
The single most common mistake on a mild truck build is buying too much converter. Someone drops a small cam and a tune into a 5.3 or a 6.0, reads a forum thread, and orders a 3,000-stall converter. Then they tow with it, the converter never fully couples under load, and the transmission cooks itself in two summers. Stall converters are not a horsepower part. They are a load-matching part, and on a truck the load is weight, not RPM.
A mild truck build — bolt-ons, a small cam, maybe a 3.73 or 4.10 rear — usually wants only a small bump in stall, if any. The job of this page is to keep you from overshooting.
What Stall Speed Actually Means
Stall speed is the RPM the converter lets the engine spin to against the brake before the truck starts to move. A higher-stall converter lets the engine climb further into its powerband before it hooks up. That helps a peaky, big-cam engine launch. It hurts a torquey truck engine that already makes its grunt down low, because all you have done is added slip, and slip becomes heat.
Two numbers matter for a truck: your engine's torque peak RPM, and how much weight you tow. You want the converter to flash to stall just below where your engine starts pulling hard, and you want it to lock up tight at cruise so you are not generating heat at 70 mph with a trailer.
Stall-Speed Targets by Build
Stock truck converters flash somewhere around 1,600-2,000 RPM depending on the platform. Here is a realistic target range for common mild combinations. These assume an automatic like a 4L60E, 4L80E, 6L80, 68RFE, or 6R80.
| Build | Recommended Stall | Why |
|---|---|---|
| Stock/bolt-ons, daily + tow | Stock to 2,200 | Stock converter is fine; tighter is better for heat |
| Small cam, 3.73-4.10 gears, street | 2,400-2,800 | Brings the converter up to meet the cam's idle quality |
| Small cam + tow heavy | 2,200-2,500 lockup | Keep it tight; prioritize lockup over flash |
| Bigger cam, mostly street/strip | 2,800-3,200 | Cam needs RPM to make power; do not tow on this |
If you tow, never let stall creep above about 2,800 unless the truck is a dedicated toy. Every 200 RPM of extra stall is more heat into the fluid when the converter is unlocked under load.
Lockup vs Non-Lockup — Always Lockup for a Truck
A lockup converter has a clutch inside that mechanically couples the engine to the transmission at cruise, eliminating slip. Every modern automatic truck converter is lockup, and you must keep it that way. A non-lockup converter slips constantly, runs hot, and tanks your fuel economy. The only reason to run non-lockup is a dedicated drag car. For a truck, the lockup clutch is what saves the fluid from cooking on the highway.
On a mild build, the quality of the lockup clutch matters more than the stall number. Look for a multi-disc (triple-disc) lockup if you tow or tune. A single-disc lockup clutch on a tuned, heavy truck will slip and burn. Triple-disc converters hold far more clamping load.
We break this comparison down further in our triple-disc vs single-disc torque converter guide.
Billet vs Stamped Cover
The front cover is where a converter fails under boost or load. A stamped-steel cover can balloon (flex outward) under pressure, which kills the lockup clutch and can throw the converter out of balance. A billet cover is machined from a solid steel disc and does not flex. For a naturally aspirated mild build, a quality stamped converter is usually fine. The moment you add a tune, a power-adder, or serious tow weight, step up to a billet cover. It is cheap insurance against a converter that fails and contaminates the whole transmission.
- Stock-ish, no tune, light tow: quality stamped lockup converter
- Tuned, regular towing: billet cover, triple-disc lockup
- Diesel (Cummins/Duramax/Power Stroke): billet, full stop — the torque demands it
Price Ranges — What You Actually Pay
| Converter Type | Typical Price | Best For |
|---|---|---|
| OE-replacement stock-stall | $130-$260 | Stock truck, tow, want it reliable |
| Mild custom-stall, single-disc | $300-$500 | Small cam, street truck |
| Triple-disc, custom stall, stamped | $450-$700 | Tuned street/tow truck |
| Billet, triple-disc | $700-$1,200 | Diesel, heavy tow, power-adder |
When you buy a custom-stall converter, the builder will ask for your engine combo, cam specs, gear ratio, tire size, and intended use. Answer honestly. A converter built around a fantasy of how you drive will run hot in the real world.
Browse lockup torque converters
Building the Trans Too? Ships Same-Day
If the converter is going in alongside a rebuild, our companion shop gearboxinsider.com stocks the rebuild kits, billet input shafts, clutch packs, and shift kits to handle the extra load. Same-day ship before 2pm Eastern, free shipping.
Shop Gearbox Insider →FAQ
Will a higher stall converter give me more power?
No. It does not add power. It changes the RPM where the converter couples, which can help a peaky engine use the power it already has. On a torquey truck engine it usually just adds heat.
Can I tow with a 3,000-stall converter?
You can, but you should not on a mild build. Above ~2,800 stall, an unlocked converter under tow load generates a lot of heat. Keep stall down and prioritize a strong lockup clutch instead.
Do I need a transmission cooler if I add a stall converter?
Yes, especially if you raised the stall at all. More slip means more heat. A good auxiliary cooler is mandatory on any tow truck with a custom converter. See our transmission cooler for towing guide.
Will a stall converter hurt my fuel economy?
A loose converter that never locks up cleanly will. A properly matched lockup converter that clamps tight at cruise barely moves the needle. The lockup clutch is the whole game for economy.