The S58 Engine: A Powerhouse Platform

BMW’s S58 engine, introduced in 2019, is a 3.0-liter inline-six twin-turbo powerplant that underpins the G80 M3, G82 M4, and the X3 M/X4 M. It shares its architecture with the B58 but features a closed-deck block, forged internals, and a dual-branch exhaust manifold, all designed to handle substantial boost. In stock form, it delivers 473 hp (Competition) or 503 hp (M xDrive), but the aftermarket quickly identified opportunities for far more. The Pure Turbos S58 Upgrade Kit targets this potential, offering a complete replacement of the factory turbochargers and supporting hardware to push the engine well beyond 700 hp on pump fuel.

What Is the Pure Turbos S58 Upgrade Kit?

Pure Turbos, a leader in high-performance turbocharger upgrades for BMW applications, designed the S58 kit as a drop-in solution that maintains factory mounting points and plumbing. Unlike some competitors that require custom fabrication, Pure’s kit uses billet compressor wheels, upgraded wastegates, and a revised intercooler core to deliver higher flow without excessive lag. The kit is often bundled with tuning support from established calibrators like BootMod3, MHD, or EcuTek.

Kit Components

  • High-flow turbochargers: Billet CNC-machined compressor wheels with extended tip technology for improved surge margin and flow capacity.
  • Upgraded wastegates: Larger diameter or reinforced actuators to prevent boost creep at elevated targets (22–28 psi).
  • Enhanced intercooler: A bar-and-plate core with >30% greater volume than stock, reducing intake air temperatures (IATs) during sustained pulls.
  • Intake and charge-pipe upgrades: Larger-diameter aluminum pipes with reinforced couplers to minimize pressure drop.
  • Gasket and hardware kit: All necessary seals, O-rings, and bolts for a factory-like installation.

Pure Turbos offers several variants: the Stage 1 (ceramic ball‑bearing, 700–750 hp), Stage 2 (dual ball‑bearing, 780–830 hp), and Stage 2+ (with 10mm larger turbine housing, 850+ hp). The article focuses on the Stage 2 kit, which is the most popular for street/track dual use.

Cost Breakdown: What You’ll Really Spend

The base price of the Pure Turbos S58 Upgrade Kit (Stage 2) sits between $3,500 and $5,000, depending on retailer and whether you purchase direct from Pure or through a distributor like ECS Tuning or Turner Motorsport. However, the total investment for a turnkey installation often exceeds $6,500 when labor, supporting mods, and tuning are included.

Kit Price

Most online stores list the Pure Turbos S58 Stage 2 kit at $4,200–$4,800. Sales or holiday discounts can drop it to ~$3,800. Always verify if the kit includes the intercooler; some retailers sell the turbos alone for ~$3,200, with the intercooler as an optional add.

Additional Costs

  • Labor: Professional installation at a reputable shop runs 12–20 hours at $100–$175/hour, totaling $1,200–$3,500.
  • Fuel system upgrades: The S58’s high-pressure fuel pump (HPFP) and low-pressure pump are often insufficient above 700 hp. A port-injection kit or upgraded turbos can require $1,000–$2,500 for a fuel lobe upgrade or supplemental injectors.
  • Tuning: A custom remote or dyno tune from a Pure Turbos–familiar calibrator like BootMod3 costs $500–$1,200, including license fees.
  • Intake and exhaust: While the kit includes charge pipes, a full 3.5-inch downpipe (required for high boost) and cold-air intake add ~$800–$1,500.

Total estimate: $6,500–$9,000 for a safe, reliable 780 hp setup.

Installation Process: Not a Weekend DIY for Beginners

Installing the Pure Turbos S58 kit demands intermediate-to-advanced mechanical skill. The S58 engine is tightly packaged in the G80/G82 chassis, and access to the rear turbocharger is particularly challenging. Pure Turbos provides a comprehensive instruction manual, but even experienced DIYers should budget 2–3 full days. Below is an expanded step-by-step guide.

Pre-Installation Preparation

  • Disconnect the 12V battery (negative terminal) and relieve fuel rail pressure via the diagnostic port.
  • Drain coolant and engine oil to prevent spills during turbo removal.
  • Remove the front bumper, crash bar, and intercooler assembly to access the turbochargers from above and below.
  • Disconnect all vacuum lines, coolant hoses, and electrical connectors to the turbos and wastegates.

Removal of Factory Turbos

  • Oil and coolant lines: Unbolt the banjo fittings and crush washers. Have new copper or aluminum washers ready.
  • Exhaust manifold bolts: Use a long-reach 10mm triple-square socket. Apply penetrating oil to the six nuts holding each manifold to the head.
  • Turbocharger removal: Lifting each turbo out requires rotating the engine slightly (crank pulley tool) to clear the block. The rear turbo requires removing the wastegate actuator bracket first.
  • Clean mating surfaces: Scrape old gasket material; do not let debris fall into the turbo oil feed holes.

Installation of Pure Turbos Kit

  • Turbochargers: Mount the new turbos with new gaskets. Torque manifold bolts to 25 Nm + 90° (refer to factory specs).
  • Wastegates: Install the upgraded wastegates with new locking clips and adjust preload so the actuator arm just closes the flapper (no slack).
  • Oil and coolant lines: Replace all crush washers and use a thin layer of thread sealant on the banjo bolts. Pre-fill the turbo oil feed ports with clean engine oil to prevent dry startup.
  • Intercooler: The larger Pure intercooler bolts directly to the factory bracket but may require minor trimming of the lower bumper ducting. Fit the intercooler, then reinstall the bumper.
  • Intake system: Install the included charge pipes and couplers. Ensure all clamps are oriented for easy access.

Post-Installation Checks

  • Pressure test: Use a boost leak tester (30–40 psi) to check all connections before adding coolant.
  • Prime the oil system: Pull the fuel pump fuse, crank the engine for 10–15 seconds in three 5-second intervals. Reconnect the fuse.
  • Start and inspect: Run the engine at idle until coolant temperature reaches 90°C. Check for oil leaks at turbo fittings and wastegate vacuum lines.

Professional vs. DIY: Most owners choose a shop due to the risk of snapping manifold studs or damaging nearby sensors. A typical shop charge of $2,000–$3,500 is often well worth the peace of mind. If you do attempt it yourself, have a BMW ISTA diagnostic tool handy to reset adaptations and run the turbo break-in procedure.

Real-World Performance: Dyno Sheets and Seat-of-the-Pants Results

The most compelling evidence for the Pure Turbos S58 kit comes from independent dyno runs. On a G80 M3 Competition (stock 503 hp), a Stage 2 Pure kit with 93-octane pump fuel and a conservative 22 psi tune produced 704 whp and 670 lb-ft at the wheels on a Mustang AWD dyno. On E85 or race ethanol blends, the numbers climb to 795 whp (approx. 920 crank hp) with a zero-drivability tune. These results align with Pure Turbos’ claims of 150–200 hp gains over stock at the crank.

Driving Impressions

Users report several key improvements beyond raw power:

  • Spool: The billet compressor wheels reach full boost (22 psi) by 3,200 RPM, only 200 RPM later than stock. The larger turbine housing on Stage 2+ shifts spool to 3,500 RPM but offers top-end extension to 7,200 RPM.
  • Throttle response: The electronic wastegate control (EWG) adaptation is seamless. Pure supplies a calibration file that reduces WGDC overshoot; owners describe it as “crisp” with no lag in DCT kickdown.
  • IAT management: The upgraded intercooler keeps intake temperatures within 15°F of ambient during repeated 0–130 mph pulls, compared to 40°F+ rises with the stock unit.
  • Sound: The kit produces a distinct whistle under part throttle, transitioning to a deep roar above 4,500 RPM. The OEM twin-scroll characteristics are preserved.

Reliability Considerations

Pure Turbos uses 4340 alloy shafts and double ball bearings (on Stage 2) that are rated for sustained 28 psi. However, the S58’s closed-deck block can handle the power, but the connecting rods are a weak point above 800 whp. Most owners stay at Stage 2 levels (700–780 whp) without internal engine modifications, and several have reported over 15,000 miles of daily driving and multiple track events with zero turbo failures.

Common issues to monitor:

  • Check wastegate preload every 5,000 miles; some kits require re-tensioning after thermal cycling.
  • Upgraded PCV or catch can recommended (blow-by increases above 700 whp).
  • Transmission cooling: The ZF 8HP75 can slip on hard launches above 680 whp; an external ATF cooler is wise for track use.

Comparing the Pure Turbos Kit with Competitors

Two main alternatives exist: Bimmerworld’s S58 turbo upgrade (which uses a larger compressor wheel but retains MHI’s original cartridge) and Vargas Turbo Technologies (VTT) S58 billet wheels. Pure Turbos differentiates itself through its complete re-engineering of the compressor housing and wastegate base, leading to more consistent boost curve and faster spool. The VTT kit is about 10% cheaper (~$3,600), but Pure’s support network and proven reliability on European vehicles often justify the premium. For owners targeting 800+ whp reliably, the Pure Stage 2+ is the current benchmark.

Final Thoughts: Is It Worth the Investment?

The Pure Turbos S58 Upgrade Kit transforms an already formidable M3 or M4 into a legitimate competitor to supercars. The installation is not for the faint-hearted, but with professional help, the process is straightforward, and the results are repeatable. The cost, while significant, is competitive in the high-performance BMW world, and the modularity of the kit allows owners to later add port injection, WMI, or even pure ethanol without changing turbos. For anyone who wants a 700+ hp street car that retains factory drivability and longevity, this kit delivers the highest value proposition on the market today.