The No-Stone-Unturned BMW Build That Rewrote What an E90 M3 Could Be

The E46 M3 gets a lot of praise for offering the best of old and new. Just beside that junction where the analog and digital eras meet, its successor offers a slightly more compromised solution. It is a plush, tech-heavy GT meant to waft along at highway speeds, but, in a way that only M-cars of a certain vintage can. It has real athletic prowess that can be called upon at the right moment.

That versatility doesn’t make it a racing car, though. When you have committed to turning an E90 M3 into the lightest, most efficient, least compromised racing car a man on a moderate budget can manage, sometimes sophistication gets in the way. That was the case with Ralph Warren, who had to dig deep to render this cruiser a stripped and simplified club racer and realize its sporting potential.

Ralph Warren’s love affair with the brand began in the mid-90s with an E30 M3 street car with which he became a regular at track days in his home state of Massachusetts. After relocating to Southern California in ’97, he started racing Peter Cunningham’s RealTime Racing BMW E36 to run a handful of World Challenge events.

“It’s a very expensive way to wind up going home 12th with a bunch of bent body panels,” he sighed. “I preferred the camaraderie of club racing anyway,” he declared. He sold the car and moved on to an E46 M3 car, then a 135i. By this time, Ralph was racing more and more with NASA.

The BMW 135i was wrecked in the middle of developing it, sending the team looking for a replacement platform.

Deciding On The Platform

“We got a call from a friend who’d found a wrecked E90 M3 street car at an auction,” Warren said. “The left rear had been hit badly, but it ran and drove so we went for it. After we confirmed the frame was straight, we started the overhaul.

“Crevier BMW, one of our older partners, were instrumental then. They gave us all the OEM parts to repair it for free,” Warren added. “Sparco gave us the needed safety gear and StopTech provided us with huge 380mm Trophy Brakes. We also got a lot of help from Maxxis Tires. John Wu gave us a tire allocation, wrapped the car, and provided support for travel expenses.

Steve Pavlov of Pavlov Racing did the cage, headers, exhaust, solid rear subframe mounts, seat mounts, window net and fire extinguisher mount. Pavlov cuts no corners, and is an artist when it comes to metal fabrication.

When the car was finally race-ready, it was far from light. During tech inspection the first race weekend, Warren asked to roll on and off the scales multiple times – the tech couldn’t believe the car weighed almost 3,800 pounds with Warren in it. If the car was going to make a stir, it had to be svelte.

Stringent Diet

To assist in the weight loss regimen, Warren brought on two rocket scientists; Scott Cary and Craig Arnold. The team had trouble finding carbon fiber doors for the four-door M3 variant, so they teamed with four other E90 owners and had DTM FiberWerkz make five custom sets. The trunk is from DTM FiberWerkz, too.

The carbon roof from Lang Racing Development came cheap because it was blemished with some bubbles in it – fine for a race car. Bimmerworld carbon headlight blanks replaced the heavy factory headlights. Even the fire bottle and battery were the lightest they could find.

The front windshield came from Racingshields.com, and Warren made the rest of the Lexan windows himself.

During the most stringent phase of diet, Warren would obsess on a nightly basis. “I’d stand in the garage late at night and find four ounces to pull from the car – could be a couple wires, could be trimming some metal. By making and accomplishing these small steps regularly, I was able to trim a lot of weight from the car – it all adds up,” Warren reminisced.

Teething Problems

Making it a true middleweight would require delving into the often confusing side of electronics. “It’s a challenge to take a modern car and make it light and still have all the factory ergonomics, DME, and other electrical issues work as they should. You need to try to isolate each step as much as possible to not get caught in a snag,” Warren began.

“For example, we tried a lighter battery and lighter battery cable ground and to the starter, but inadvertently removed the BMW Intelligent Battery Sensor. The system monitors battery voltage, current, and temperature; communicates with the DME; and regulates charging for efficiency and longevity. After replacing the IBS, that still wasn’t enough. Using a factory computer, we had to change the charging setting for a smaller battery.

“The entertainment harness came out in one piece, but somehow we disrupted a CAN bus and caused a host of issues. We had eliminated the CAN bus termination resistor. It only took a couple hours to diagnose and resolve, but it taught us how important it was to move slowly and carefully.”

Some issues weren’t electrical in nature, but equally hard to pinpoint. “We had an OEM water pump with a plastic impeller go bad, but it didn’t give any symptoms until we took the car on track. It would flow enough water in the paddock, but wouldn’t move enough water at speed causing the engine to run hot. A simple all-steel water pump fixed everything and the car runs cool now.

When these issues were addressed, they set about maximizing efficiency where possible. “We incorporated a self-contained 997 GT3 Cup car power steering unit. It sits in the passenger floor and it’s driven by 12-volt power,” Warren said. “It pressurizes the hydraulic hose that drives the power steering, and there’s no longer any parasitic loss coming off the engine. No more belt or pump on the engine – it’s all off campus, so to speak.

“It works fantastic. It’s light, responsive, gives lots of feedback, and when you’re on the straights, the pump actually slows down a bit,” Warren added.

After adding a lighter, more efficient aftermarket fan and a manual fan switch, we decided to get rid of the fan relay,” he said. “However, that’s controlled by the CAN bus from the DME, so when I took that out, thankfully, the CAN bus didn’t react too badly.”

“We wanted reliability, so we left the internals of the engine completely stock,” Warren began, “and with modern motors, the intakes and heads are pretty much maximized from factory. The headers and exhaust are usually choke-points,” he said.

For a few thousand in total, including materials, Steve Pavlov built Warren a set of headers and an exhaust with steel from Burns Stainless. “We spent every evening for a month bending, cutting, and timing until everything was perfect. Now, it puts 414 to the ground 291 pound-feet of torque. More than enough to push around a 2,800-pound (dry) car,” he added.

Prior to NASA competition, the car was forced to retain certain interior panels. Once they moved into NASA, gutting the interior to the last ounce was paramount. “I started cutting pieces out of the carbon doors – excess material around the frame, if it meant saving some weight.”

Once they’d gotten power and weight comfortably in the middle of the NASA Super Touring 2 window, ballast became the focus, and finally their meticulous obsession with weight could come to an end, and their reduced running costs helped them understand why it was worth the effort. The car now tips the scales at 2,800 pounds.

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Scant Running Costs

“When I got the Strom Motorsports E9X Precision Series uprights, I was able to lower the front spring rates and we immediately started noticing better tire wear. They also helped with braking performance and tire wear, since I could get away with less camber,” Warren explained.

“With these uprights, the roll center is moved back up to the center of the car instead of being underground, so the arm is flat instead of being at an upward angle. This keeps the car from rolling as much, and thus you can run softer springs and maintain the same amount of body roll as you would with stiffer springs with incorrect geometry,” Brett Strom explained.

“I set the front camber at a pretty mild -3.8 degrees. If we get the wear evenly at the end of the weekend, then we don’t change the camber – and most of the time, they wear evenly, ” Warren added.

Stoptech Trophy brakes help keep the running costs low, too. Rotors last seasons and seasons and they are just $400 each. I’ve changed the fronts twice and the rear only once in the past twelve years.” He said with a smile.

The team has been able to score used Alcon-Brembo 7700-shape pads for peanuts. “These brakes use the same shape as some NASCAR brakes. We get them after they’ve been lightly used, at 28MM – about 2MM shy or their original thickness – for $100 a set. Best of all, they last an entire season. Our annual brake pad budget is less than a Spec Miata,” he laughed.

“Tires are similarly priced – heat-cycled Yokohama 300-section A005 slicks off a Porsche Cup Car – after a couple laps. Some of the tires still have the nubs on them.”

With all the money he saved on consumables, spending a major sum on shocks was a little easier. “The modification that made the most change overnight was the MCS three-way damper. That was the one item we didn’t get a discount on, I just bit the bullet. It wasn’t easy, but the car handles amazingly now.”

Further Refinement

It’s nice to know that a modern car can still be tweaked using basic backyard solutions. “I turned TC off by disconnecting a yaw sensor, which turns off the TC, but the ABS still works,” Warren explained.

“To fine tune the brake bias, we installed a pair of brake bias levers by my left knee which I can adjust independently during the race. I can dial in a bit of free rotation under braking. For example, I can dial in more right rear brake bias so the car will start rotating right slightly under braking. On Willow’s front straight, I dial in the left rear to get rotation for the upcoming left of Turn 1, then back to neutral for Turn 3.”

It’s designed to run long races – to be beaten hard for 40 minutes straight. Last time Warren ran it, the day went like this: unload the trailer, run every session, keep the same tires and same suspension settings, and just adjust tire pressures a bit throughout the weekend. We never had to open the hood, and the tires lasted the entire weekend. It’s extremely reliable – the only thing to fail on us in recent months is an ABS controller, which we replaced with another off eBay for $150. We thought about rebuilding it, but it would be a more efficient use of time to buy one used.

The obsessive pursuit of efficiency is why this no-stone-unturned ST2 build can runs so quickly with a moderate amount of power. It’s also why it’s able to handle whatever the team throws at it, and why it doesn’t strain their wallet as much as it could. This minimal-strain, maximal-satisfaction approach to racing is something everyone would want – but it’s not easy to come by. That may be a masterpiece of understatement, because it took a brilliant team 12 years to realize.

The car is currently for sale on RacingJunk.com.