Tom Egan from Birmingham, Alabama, has built more than his fair share of LS-powered machines over the years, but his 2004 BMW M3 marks a new chapter. For this build, Egan set out with a specific goal: to tackle a Gen-V LT engine swap. It’s his first time venturing into the modern direct-injection LT architecture, and the M3 platform gave him the perfect canvas. The result is an LT1-swapped M3 that keeps the original German sports car focus with more power and torque.

If you didn’t hear the exhaust note, you could almost classify this as a sleeper.

The Ultimate Driving Machine

In the world of German sports sedans, BMW’s M3 is legendary. In their lineup, the 3-series is their compact sedan, and the M3 version is properly advertised as the ultimate driving machine, with more powerful engines, stiffer suspension, bigger brakes, and larger rubber under wider bodywork. The E46 generation seen here was sold from 2001-2006 in the US and is powered by a 3.2-liter S54 inline-six that produces 333-horsepower. To those of us who love an American V8, that power level might seem a little low for a sports car as popular as this, but these cars still dominate track days across the country.

I didn’t want anything I had to paint or fix a bunch of 40-year-old rust problems. —Tom Egan—

Tom Egan has done a few LS swaps over the years, but this is his first Gen V LT swap.

Under the hood of Tom’s M3, the factory S54 inline-six is long gone. In its place sits a 6.2-liter LT1, mated to a Tremec TR-6060 six-speed manual, which is the same drivetrain combination found in sixth-gen SS Camaros. It’s been upgraded with an LT2 intake manifold and a Texas Speed Stage 1 camshaft, a decision he made to wake up the engine but also eliminate the factory Displacement on Demand (DOD) system, known for its reliability issues in performance applications.

Once the engine and transmission made it into the car, Egan turned to Andrew Borden at Dr. EFI to bring the swap to life with proper tuning. Engine management is handled by a Holley Terminator X, but that alone wasn’t enough to bridge the technological gap between the American drivetrain and the BMW’s German electronics. To get the dash and factory systems functioning properly, Egan sourced a compact Arduino-based interface module from an independent developer online. This custom solution enabled full communication between the Holley system and the factory BMW electronics, restoring functionality to the gauges, warning lights, and other critical systems.

Designed for the Street, Built for Anything

Despite the performance potential of Tom’s LT1-Swapped M3, the car isn’t built to be your typical dragstrip monster. It’s a clean, usable streetcar first and foremost. The LT1 makes more than enough torque to overwhelm the rear tires from a dead stop, but Tom isn’t chasing ET slips. Still, when he took the car to Holley LS Fest in 2022, it managed low 13-second passes in the Kentucky heat and humidity, with street tires and minimal setup. With stickier rubber and more practice, Egan believes low 12s are easily within reach, though that was never the goal.

Other than an aftermarket shift lever and knob for the TR-6060, the interior has been left stock.

Instead, this M3 is a genuine all-rounder: capable of autocross, track days, long-distance cruising, and even running errands. It’s the kind of car you can do everything in and still enjoy the drive. Out of all the cars he’s built, his wife actually likes riding in this one, further proof that a well-sorted swap can win over even the toughest critics.

The rubber is wide, but it’s hard to plant the LT’s torque in a small two-door car.