Building the Ultimate E46 M3 with Turner Motorsport
The BMW E46 M3 is BMW’s last naturally-aspirated straight six powered coupe from the M-GmbH division before they decided the only way to achieve more power was through more cylinders or adding turbochargers. The E46 M3 is perhaps the most commonly owned, raced, and modified of all the models Turner Motorsport supporters choose, and for good reason. It offers a rigid chassis, incredible weight distribution, surprising power from the 3.2-liter S54, and is contemporary enough to be a reliable choice for daily commuting. However, with all the benefits the E46 M3 provides, it is far from perfect. We see tons of examples sporting different build directions and modification choices, which demonstrates just how flexible the E46 M3 is as a platform for creativity. That begs the question we would like to answer today: if our budget was unlimited, how would we build an E46 M3 to be the perfect version it could be?
| |  | | Engine
The S54 that powers the E46 M3 is phenomenal in its own right. With 333hp on tap, this rev-happy straight-six makes tons of power and sucks in air through individual throttle bodies for a snappy throttle response and gorgeous intake noise. However, it does have two ‘weaker’ points that would need attention before we can focus on putting down more power. Namely, the rod bearings need to be replaced with WPC Treated Rod Bearings and the VANOS needs to be serviced as well as adding the ECS Exact-Fit stainless steel VANOS line to prevent future leaks. We would tackle those two maintenance concerns, along with an overall refresh. Oil pan gasket, rear main seal, valve cover gasket, Bav Auto upgraded coil packs, NGK spark plugs, and a LIQUI MOLY engine flush, oil service, Hengst filter, and CERATEC treatment.
After the engine is brought back up to snuff, we would begin to throw more power at the already impressive S54. That, and a little extra security. To prevent any oil consumption issues and to keep the intake air as clean as we can, we would opt for the Turner Motorsport Catch Can Kit, which you can read about in our previous article covering the function and importance of such devices.
With oil consumption handled, we could comfortably add our new CSL-Style Turner Motorsport Carbon Fiber Intake for a 23% increase in airflow and modest power increase (plus insanely good looks) to the intake system and know it won’t be coated in any crank case vent particles thanks to the catch can.
For a more mechanical solution to power, the Schrick camshaft upgrades are necessary. With longer duration, higher lift, more aggressive camshafts, our valves can stay open longer and open more fully for better airflow and more power. Remember, engines are basically air pumps. The faster you can move air through and the greater the volume it can handle, the more power you make. That’s the gist of engines, anyway.
To further assist the engine’s ability to access power it already has, our Turner Motorsport Power Pulleys will under drive the accessories and allow the S54 to divert more power to the ground rather than spend it on useless things like AC and power steering. Of course, those accessories will still work, they just won’t rob as much power through parasitic loss to driving them with the rotation of the engine.
Lastly, in the engine department, we need a way to tie it all together. While we didn’t go crazy with the engine work, it still needs a way for the computer to know what’s up. That’s where the Shark Injector Software upgrade comes into play. With a plug-and-play setup, this is the easiest solution to maximize the engine’s potential and work with the mods we’ve installed and will install to squeeze every bit from the S54 that it has to give us. Naturally, the tune will wake the S54 up on its own, but it is critical when you have upgraded camshafts, an intake, and the exhaust we will install so the computer can compensate with more fuel for the increased flow rate and volume of air that will be pumped through the system. Plus, it removes the speed governor and increases the red line, which is always good for those of us with a bit of a heavy right foot.
| | Cooling
To prevent any future issues and to handle the already notoriously weak factory cooling system, a full overhaul would happen in our Ultimate E46 M3. This would include a new water pump, like a GEBA unit, for reliability and longevity, a Mishimoto low-temp thermostat to reduce the temperature at which coolant begins to circulate, and an electric fan upgrade with Mishimoto electric fans to help keep temperatures down during the hardest and hottest driving conditions. The importance of keeping everything cool is critical: we don’t want to have to bust back into the engine to replace a blown head gasket or find ourselves out of a track day because we burst something.
Speaking of bursting, replacing all the hoses with reinforced silicone hoses from ECS is a must as well. These hoses resist wear and damage due to heat along with holding high pressure. They will ensure we don’t have a premature failure if we see increased temperatures while chasing lap times on a hot day.
For the radiator itself, a CSF aluminum radiator will both increase coolant capacity for more temperature control and reduce weight over the factory versions for a bit of additional savings on the scales. To take it a step further, the CSF upgraded oil cooler will further tackle heat issues by providing a larger heat exchanger over the factory unit to prevent oil emulsification. This will give us the peace of mind that even under the hardest driving conditions, our LIQUI MOLY oil is able to provide exceptional lubrication that will prevent any premature wear on our new bearings.
| | Exhaust
To help with all the additional airflow into the engine, provide increased power, and give us a glorious exhaust note, we’re going with Supersprint headers and a full exhaust system including a muffler. Supersprint offers the absolute highest quality, hand-built, most attractive sounding exhausts, so that would be our pick. There really isn’t much to say about exhaust; it’s just all about scavenging, increasing volume, and increasing pulse flow rate. That’s it. Which Supersprint does incredibly well.
| | Brakes
Now that we have a good bit more power, we’re going to want a way to keep it all in check for the Ultimate E46 M3 to remain safe and drivable. Additionally, we need better brakes with more heat dispersion efficiency, greater size with more surface area, and higher clamp force for improved cornering. The less time we can be on the brakes, the more time we can spend on the throttle, which means further improved lap times. In this case, stopping is going faster. For that, we’d turn to StopTech for their Trophy Big Brake Kit in the front and rear. With upgraded pads, bigger diameter rotors with more cooling ability, and beefier six piston front calipers, four piston rear calipers, and some hefty braided steel lines from StopTech as well, our middle pedal (yeah, no SMG here) will do a much better job bringing the Ultimate E46 M3 to a stop and offer better pedal feel for improved communication between car and driver. To top it off, a full brake fluid flush with racing fluid that has a higher wet/dry boiling point with some help from the Schwaben brake pressure bleeder will ensure that our brakes work as they should, even under track conditions.
| | Drivetrain
With more power, better stopping ability, and the improved handling we will have in our M3 after the suspension upgrades we will discuss momentarily, we will need to tackle all the probably old, worn out, soft bushings that BMW equipped the M3 with from the factory. Even with brand new rubber OEM bushings, the amount of deflection they allow is unacceptable when we want the rawest, best-performing, and most direct M3 we can make. That’s why we’d go with solid aluminum engine and transmission mounts as well as Turner Motorsport Solid Aluminum differential mounts to eliminate as much drivetrain slop as possible. That means more power goes to the ground rather than to those bushings that will give way under load for comfort. Who needs comfort when you can drive at the limit?
Speaking of mounts, the rear subframe is a particularly weak point in the E46. It is known to crack the chassis, even under normal driving conditions. So, we’d address that with the Turner Motorsport subframe reinforcement plate kit as well as replace the soft OEM subframe bushings with solid aluminum versions for greater rigidity and less deflection.
While we’re back there, an LSD upgrade with a Turner Motorsport Custom LSD as well as a diff (and transmission) fluid service would certainly need to happen. Changing up the final drive ratio and internals for a track setup would be ideal. You can read about why LSDs are important in one of our old Turner Motorsport Weekly articles that will take you through everything you need to know about ramp angles, lockup, and the differences between LSD types, so check that out if you need some pointers with an LSD upgrade of your own.
Back towards the front, the transmission needs some attention in the form of an ACT Lightweight single mass flywheel, upgraded clutch, and sturdier pressure plate. This will help improve throttle response times, make it easier to rev-match, and will hold the extra power better for an improved driving experience.
Speaking of experience, the shifting experience in the M3 is phenomenal but can be improved. The Turner Motorsport Double Adjustable Shift Kit will give us a tighter shift feeling as well as allow us to adjust the height and throw length of our shifter for quick, tight, and precise shifts.
Farther forward, we would also add Turner Motorsport Monoball FCABs to improve turn in response, braking response, and eliminate suspension deflection. These are basically lifetime parts, too, since you can re-grease them as they age and keep the spherical bearings inside nice and lubed.
| | Suspension
Bilstein PSS-10 adjustable coilovers would sit on all four corners of the Ultimate E46 M3, making sure the car stays planted in the corners and has a nice, low, ride height while maintaining a proper ride thanks to the adjustable dampers. To further reduce body roll, Turner Motorsport sway bars and bushings mounted with Whiteline adjustable end links would help keep the M3 flat through the twisties, which means more contact patch and more traction around the corners from the tires. Lastly, for proper rear-end alignment, the Turner Motorsport Adjustable Rear Suspension Arms would help keep everything in proper spec, even with a lowered ride height. | | Chassis
For safety and improved rigidity, nothing but a custom roll cage can offer the correct solution. A NASA-spec full cage with SCHROTH racing harnesses would encase the interior with a safe and attractive cage that both protects us when we drive on the track and improves the already stiff chassis further with multiple points of connections thanks to the full cage setup. | | Interior
Beyond the cage, we would certainly need racing seats to help keep us planted and safe while also reducing weight. Being the Ultimate E46 M3, no expense shall be spared. I have always wanted a set of Sparco Evo seats, which is what we will put in the M3. For a steering solution, the MOMO Mod.07 wheel with a MOMO hub adapter will eliminate the airbag and bring the wheel closer to me, which is nice, because I am rather tall. If this car were built for someone of average or shorter than average height, a wheel with a lower offset (flatter) design would work better. | | Wrapping Up
With that, almost everything would be complete. I would probably choose to wrap the car with 3M wrap in a color as close to Laguna Seca Blue as possible, just to make the car a single color and hide all the fancy carbon fiber bits. I don’t like seeing bare carbon, so that’s the only reason. However, with that, the car would be finished. An M3 with a modest increase in power, that focuses on chassis rigidity, suspension capability, and reduced deflection with improved stopping, cornering, and shifting as well as a hearty exhaust note that leaves no stone unturned would make this the Ultimate E46 M3, at least, in my eyes.
Would you do it differently? Have you done it differently? We’d love to hear from you. Let us know at [email protected] what you would choose to do with your E46 M3 or show us what you’ve done. Maybe you’ll see your build in another edition of Turner Motorsport Weekly.
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