EDITOR’S NOTE: What are the top high performance automotive parts of all time? Or in this case, what are the Top 20 most iconic parts that changed hot rodding? We’re talking total game-changers in the annals of our hobby.

We asked a panel of OnAllCylinders staffers, longtime automotive journalists, and veteran members of the Summit Racing technical and marketing departments for their input. The countdown continues with number 4 (you can see numbers 20 through 5 here).

#4. B&M Torque Converter

If you’re racing or driving a performance car with an automatic transmission, you have B&M Racing & Performance Products to thank for making it possible.

“A lot of companies have built high performance torque converters, but it was B&M who really got the ball rolling. When they started building performance automatic parts, the stick was still the king. Not so today. B&M pretty much changed all that.” said OnAllCylinders contributor Wayne Scraba.

In the late 1950s and early ‘60s, when visiting the local dragstrip wasn’t just for hardcore racers, but everybody with a car and heavy foot, manual gearboxes ruled the day.

“B&M started many years ago with perfecting the four-speed Hydramatic transmission which had a type of mechanical converter internally. It was rebuildable and adjustable in certain stall features,” said Frank Marra, B&M’s elite technical service adviser. “They moved onto other transmissions. When automatics came into play in the mid-’60s and ’70s, they took on the role of of modifying converters to change stalls, and increasing multiplications. It made a big impact on street and performance cars.”

If you were at the starting line in a car with an automatic transmission racing a car with a manual shifter and equal power, you were done before the race began.

Don and Bob Spar in the 1950s. (Image courtesy of Car Craft and SEMA archives.)

The engineering evolution that allowed the automatic transmission to be used in performance applications began not in the factory, but at the aftermarket level. B&M’s Don and Bob Spar (Bob is the “B” in B&M) along with high school friend Mort Schuman (the “M”) started the company in 1953 as a general automotive repair shop, but quickly began to specialize in strengthening transmissions to pair with modified engine.

Later, B&M introduced its game-changing torque converter—the first aftermarket converter to produce high stall speeds to dramatically improve torque at launch, allowing auto-shifting cars to get to the engine’s power band more quickly.

Put simply: The B&M torque converter is what made automatic transmissions viable for racing and hotrodding.

“B&M’s release of the first high production, high stall speed torque converter meant that street and strip high performance wasn’t just limited to manual transmissions,”  said Patrick Hill, an OnAllCylinders contributor and “Top 20 Aftermarket Parts” panelist.