Developing the Magic in an E46 Sedan

It was though the planets aligned. Larry Moore’s Spec E46 had proven itself in Northern California, and after the hailstorm of COVID hit, he and his builder Justin Ross of Magic Developed were stuck indoors with big plans and plenty of time to realize them. After a year-long build aimed at optimizing the Spec E46, they ended up shifting classes and making it into one of the most competitive Super Touring 5 machines on the West Coast.

The trusted E46 chassis is well developed and, for some, a straightforward build recipe, but the S54 engine has only gotten costlier in recent years. The answer for NASA racer Larry Moore was to take the Spec E46 route and focus on improving as a driver — something every spec series tries to provide. This variant uses the cheaper, more plentiful M54 motor, which is less costly to build, and with less power than the M-car counterparts, it’s easier on consumables, too.

The MooreWood Creative 2001 E46 sedan was originally built to run in the 2017 25 Hours of Thunderhill. After consulting the rulebook, they found there were a few modifications they could make to fit E1 at the time, but it would still be, by and large, a Spec E46. They attached a wing and a splitter, and to improve the car’s functionality, grabbed a few friends and went full throttle into the longest race in North America. The team finished second in E1 that year, and took P1 the following year.

Then, having understood some of the finer elements of endurance racing by that point, they took the car to the 2019 25 Hours of Thunderhill with one new addition. For a few functions that would simplify their lives in the 25, they added an MaxxECU for functions like a pit lane speed limiter, for instance. Additionally, the ECU helped simplify the tech process when running on different dynos.

“It was too much to keep reflashing the stock ECU to suit each dyno, which all read differently,” said Magic Developed owner Justin Ross. “If we dyno’d a few horsepower over what we were allowed, the aftermarket ECU made it much easier to trim those and fit within the window.”

At the 25 that year, they were leading the race at hour six by more than two laps. The car was hit while trying to enter pit lane, breaking both tie rods and the left front control arm. Even though the team got the car back on track within 35 minutes, they weren’t able to recover, and finished sixth in class.

It was less than what they wanted that year, but their initial success in an endurance setting jump-started their imaginations and drove their plans for the car in a new direction. When the lockdown began several months later, the project snowballed.

“The new rules set for 2020 stated we’d have to build the car to the Super Touring guidelines, and since we were stuck in the shop, Larry and I decided to try and turn the car into a ‘full kill’ build for ST5,” Ross said.

The ST5 project began with the motor, which needed to be replaced. After slogging it out for 25 hours, the engine had ingested so much dirt and mud that it was no longer sealed, and so they installed a replacement stock M54B30.

The M54 has always been a torquey engine, but in stock trim, it was still a little agricultural. With this particular motor, they added a set of carefully chosen-bolt on modifications and optimized the engine for greater techability, response, and power — all without compromising its fantastic reliability. While this would remain OE internally, they planned a series of bolt-on modifications that would give the agricultural M54B30 the zest and liveliness of one of its S-series siblings.

MODIFYING THE M54

The inspiration for the powerplant modifications came from studying an M54-powered E46 that ran in the World Touring Car Championship. “We saw that they’d picked VW coil packs, which got us thinking about what easy changes we could make within the rules while keeping the budget in mind. Then we started making the incremental improvements one makes when tuning a normally-aspirated engine,” Ross explained.

They copied the touring car and tried a few different brands of plugs, and then replaced their factory intake manifold with one from an M50B30 out of an E36 328i. This non-DISA intake lacks the variable length runners found in the M54’s intake, and while its simpler design reduces low-end power, it livens up the top-end considerably. Along with the intake, they paired a set of eBay headers to the Spec E46 exhaust to make use of the improved airflow.

They retained the M54’s throttle body to run a drive-by-wire setup, which would simplify the tuning process and make certain features like auto-blip possible. They also fitted a Dinan E36 cold air intake tube and began making a few changes to improve airflow into the filter unit.

Rather than mount it behind the headlight, they decided to relocate the air filter behind the kidney grilles, and cordoned this off from the hot engine bay with a custom enclosure. This was easy enough, but the cramped confines of the bay required they use a miniature radiator originally intended for a Volkswagen to give the new intake enough room to breathe.

The Pro Mod from Northern Radiator is a modified Scirocco radiator, which measures 22 inches wide, 13 inches tall, and 3 inches thick. It hasn’t compromised the cooling beyond control, but to manage heat soak, they had to fit an electric water pump. To do this, they had to modify the front timing chain cover to allow complete control of the water flow. This removed the factory thermostat and sealed up the extra water ports in the housing so the water would only go where they wanted it to go.

“The cooling is only marginal at places like Willow Springs. We ran an enduro there last summer when it was something like 103 degrees Fahrenheit, and we couldn’t sit behind another car for too long. We’d have to jump out of the tow to get fresh air on the straights. If the ambient temperature is anything under 95F, we have no problems at all,” Moore said.

Finding the right application for bolt-on modifications has yielded some serious gains. Fully uncorked, the engine produces 249 to the tires at 6,400 rpm. Where it once fell flat on its face in stock trim — around 5,900 rpm — the M50 intake has done wonders. It keeps that curve climbing toward the redline. “We’ll usually shift around 6,400 rpm, but if it saves time to avoid a shift, we can rev it to 6,800 and bounce off the rev limiter for a second,” Ross elaborated.

Like a good M54 should, it makes a healthy shove in its mid-range — 228 lb-ft at 4,500, but that torque now arrives in scintillating style thanks to the extensive mapping changes made.

FINE TUNING

The M54 has never been gutless, but in stock trim, it’s fair to describe it as lazy. It is a little on the dull side, but it works well enough — read: generates enough torque — to get a Spec E46 around a track quickly. While punchy enough, it lacks the sharp-edged response to agitate the rear when desired. “I find that, because of the way the power is delivered, it doesn’t rotate the car with the throttle. It will tend to push if you lean on the gas too hard,” Moore said.

By altering the VANOS system through the ECU, they’ve been able to advance the cams — just the basic M54 camshafts, not the hotter versions found in the ZHP models — within the general window of application, thus making the motor much more eager.

Changing the final drive has helped make the most of the moderate power without any drawbacks. The shorter 3.64:1 rear end does not hinder them at California tracks where 130 mph is the most they’ll ever see.

More than just fattening up the midrange through cam control, they’ve improved the drivability and response of the motor by tuning the throttle map. “Most DBW engines don’t offer a linear, intuitive sort of relationship between the throttle pedal and the throttle plate. We were trying to improve the general response of the engine without making it jerky or unmanageable,” Ross said.

To do this, they first aimed at delivering power somewhat sweetly at tip-in. The reason for this is easy to understand: it would be too easy to overdrive the car if they combined a generous power delivery at the point in the corner when the weight is first shifted longitudinally. Once the car has taken a set and a little more oomph is needed in the power-down phase, they increase the throttle response to provide more in the middle travel of the pedal, if you will. This urgency, combined with the fatter midrange torque, makes it possible to rotate the car consistently.

All this is done with proportionality in mind. Movement through the range of throttle travel must correspond with an intuitive power delivery. There are no lulls, no flat spots, or no rapid upticks that leave the drivers second-guessing themselves. The clarified connection between the throttle and the power delivery helps put the driver at the nexus of control, and with a higher spring rate at the rear, this ST5 car feels much more eager and willing to turn through careful manipulation of the loud pedal.

CHASSIS CHANGES

Little has been done to the car’s body since it was a true Spec E46 — a testament to the E46 platform and Justin’s expertise. However, they made several ST-specific alterations where they could. The Spec E46’s MCS one-ways are retained, albeit with stiffer rates at the rear. This change supports the aero loading and helps induce some rotation under throttle. To keep aero loading safe and consistent, they mounted the wing to the frame rails.

The interior has had some bits stripped, too — the dash and the spare tire well, namely. “Removing the dash gives the cabin an airy feeling. There’s a lot of space now,” Ross added. With some additional weight reduction from body panels and the good ol’ “every ounce counts” approach, they were able to bring the weight down to 2,550 pounds without driver.

Interior room was further expanded by an alteration to the cage. This car being a sedan, they had the option of extending the door bars slightly by notching the b-pillars. This allows for easier ingress and egress without compromising the car’s safety. The idea here is that faster driver changes improve their chances of winning an enduro. They also added a few more cage attachment points as per the rulebook.

The aim of the car, as mentioned earlier, was to excel in endurance settings. For that reason, they upgraded from the factory calipers up front to a custom brake package consisting of NASCAR-spec AP Racing four-pots mated to a 325 x 32mm rotors — roughly 9mm thicker than the OE rotors.

This wasn’t done so much for improvements in outright braking performance, but instead to avoid time-consuming brake changes. “We’ve seen these pads last 35 and 38 hours, and the rotors will go for 80 to 90 hours,” Ross added. When combined with their go-to Hawk ER-1 pads, which are used in sprint races, too, the setup is dependable and provides consistent performance. The only catch with the current configuration is that the driver needs to be aggressive getting brake temperatures up on their sprint race outlaps as these pads take a little extra before they’re in their window.

“The car is way overbuilt, but that’s how an endurance car ought to be,” Ross declared. It ran its first few years of Spec E46 without any engine issues, and since it’s been converted to ST5 spec, it’s been equally reliable: two-plus consecutive years of racing amounting to more than 200 hours on one motor is a remarkable feat of engineering.

Reliability means a lot in such a competitive class, but so does improved techability, a moderate increase in power, a more intuitive power delivery, and a slightly pointier car. This holistic approach to tuning has made it the ST5 record holder at all Northern Californian tracks. On top of that, Ross took it to the NASA Championships in 2022 and won TT5. And, as expected, it excelled at the 25: three wins in class and second overall at the 2022 event. Apparently, taking a big-picture approach to building an involving, responsive, and reliable race car gives it a broad enough scope to win sprints, Time Trial and enduros.