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BMW M57 Air & Turbocharging

The BMW M57 air and boost system — turbocharger(s) including variable-geometry, intake, intercooling, boost control, EGR and exhaust after-treatment.

System structure (single-turbo): unfiltered air intake, intake silencer, exhaust turbocharger, intercooler, intake manifold (plenum), exhaust manifold, EGR, exhaust system — Original M57D30 (E38/E39), DDE 4.0
Unfiltered air intake — draw point: Below kidney grille, in front of radiator; positioned so no warm engine-bay air is drawn in
Unfiltered air intake — snorkel construction: Two components: fresh air duct + unfiltered air snorkel (body duct to engine-mounted intake silencer)
Intake silencer / intake module: Silencer integrated in the intake module; three main components: cylinder head cover, intake manifold, intake silencer with air cleaner. Head cover & manifold are glassfibre-reinforced polyamide (plastic), acoustically isolated by rubber elements on the head
Air cleaner change interval: approx. 100,000 km — Normal conditions. Original M57 only; S2 gives no interval for relocated TU1-TOP air cleaner
Intake module tasks: Cover for camshaft chamber; damping of intake noise; filtering of intake air; engine ventilation & oil separating; air guide/distribution to inlet ports (tangential and swirl ports)
Exhaust turbocharger (single-turbo) — type: Exhaust turbocharger with variable nozzle turbine (VNT), same as M47, thermodynamics adapted to power output
Single-turbo VNT — boost & vane control: Boost control by boost-pressure-activated pressure cell; turbine vanes controlled by electropneumatic pressure converter; control integrated in DDE control unit
Single-turbo VNT — assembly components: control cell, control rod, turbine wheel, compressor housing, bearing housing, adjustment ring, guide vanes, turbine housing, compressor wheel — Fig. 87
Single-turbo (TU) — improved-efficiency VNT: Single VNT with improved efficiency (changed compressor + turbine blade geometry, turbine housing adapted); compressor-outlet charge-air line now a flange coupling (as M47TU); vacuum unit repositioned higher. Still single VNT — NOT two-stage
Intercooler (single-turbo): Adapted vs M51 to increased volume; integrated in cooling assembly; supported by engine fan / electric fan
Cooling-assembly stack (rear view): power steering cooling loop, gear oil cooler, assembly frame, A/C condenser, intercooler
Charge-air cooler (TU): All-aluminium intercooler (no plastic parts); charge-air duct uses quick-release couplings
Intake manifold (intake plenum, single-turbo): Plastic manifold, two-shell weld technology; guide to swirl/filler port separated from intake volume
Exhaust manifold (single-turbo, original): Single-fluted; sheet-metal beaded gasket to cylinder head and turbocharger
Exhaust manifold (TU): Air-gap-insulated welded sheet-steel (was cast). Advantages: -1.7 kg, higher gas temp at cat, better turbo response, faster cat light-off after cold start
EGR (single-turbo): Corrugated EGR pipe (compensator); one valve mounted at inlet to air manifold; aluminium valve housing
EGR cooling (single-turbo): Added later for EU-3 compliance; cools recirculated gas by approx. 100 °C
Exhaust backpressure (single-turbo): < 200 mbar — Distinctly reduced. Single-turbo M57 E38/E39 only; S2 gives no equivalent for twin-turbo
Catalytic converter volume — primary (M57 E38): 1.7 litres — M57 E38: 1x primary cat
Catalytic converter volume — primary (M57 E39): 2.17 litres — M57 E39: 2x primary cats, total
Catalytic converter volume — main (M57 E38/E39): 2.66 litres — 2x main cats, total (both E38 and E39)
Catalytic converter volume (TU): 2.26 litres — Oxidation type. TU has only ONE catalytic converter (2nd-gen CR reduces treatment needed)
Central silencer volume (TU): 5.4 (E60) / 5.8 (E65) litres — Absorption type
Rear silencer volume (TU): 23 (E60) / 32 (E65) litres — Reflection type
Exhaust system & after-treatment (TU): Stainless-steel system; intermediate pipes + central + rear silencers form one component; only ONE catalytic converter (oxidation type), no DPF
Two-stage twin-turbo — principle: Two series-connected turbochargers, both with rigid turbine geometry (no adjustable blades). HP = small turbo for high torque & good response at low engine speed; LP = larger turbo for high power output — M57D30TU1-TOP, E60 535d from 09/04, DDE 606, EU-4
Twin-turbo — max system boost pressure: 2.85 bar — Overall system. M57TU single-turbo = max. 2.5 bar
Twin-turbo — max turbine speed, HP stage: 230,000 rpm
Twin-turbo — max turbine speed, LP stage: 170,000 rpm
Twin-turbo — control element: turbine control valve: Exhaust side; diaphragm unit, vacuum via high-speed EPDW; routes exhaust through bypass duct past the HP stage to the LP stage; variably adjustable
Twin-turbo — control element: wastegate: Exhaust side; diaphragm unit, vacuum via EPDW; opens at nominal output to cap boost/turbine pressure; part of exhaust bypasses the LP turbine; variably adjustable
Twin-turbo — control element: compressor bypass valve: Air-intake side; diaphragm unit, vacuum via EUV (electric changeover valve); bypasses the HP stage on the air side; fully open or fully closed only
Twin-turbo — control signals: EPDW driven by DDE with PWM signal (300 Hz), nominal 12 V; EUV controlled by DDE, nominal 12 V
Twin-turbo — switching regime: up to 1500 rpm: Turbine control valve closed, compressor bypass valve closed, wastegate closed; both stages driven, primarily HP stage
Twin-turbo — switching regime: 1500–3250 rpm: Turbine control valve opens continuously (exhaust increasingly bypasses HP turbine), compressor bypass valve closed, wastegate closed; increasingly the LP stage
Twin-turbo — switching regime: 3250–4200 rpm: Turbine control valve fully open, compressor bypass valve open, wastegate closed; LP stage only (HP bypassed both sides)
Twin-turbo — switching regime: from 4200 rpm (nominal output): Turbine control valve fully open, compressor bypass valve open, wastegate opens as speed rises (bleeds exhaust past LP turbine to limit turbine speed); LP stage — Switching points stored in a characteristic map, transition smoothly with hysteresis
Twin-turbo — vacuum system: Vacuum routed from vacuum pump via distributor to a near-engine vacuum accumulator; from there to both EPDWs (turbine control valve, wastegate) and the EUV (compressor bypass valve)
Twin-turbo — vacuum hose identification: Turbine control valve = short blue braided-sheath hose; wastegate = long blue braided-sheath hose; compressor bypass valve = black braided-sheath hose with red stripes — Colour + length prevents interchange; confusion causes acute power loss
Twin-turbo — distributor throttles: Four connections; three use a 0.8 mm throttle; only the connection to the EUVs for engine mounts + swirl flaps uses a 0.5 mm throttle and is made shorter to avoid confusion mm
Twin-turbo — exhaust system: Adapted to higher volumetric throughput; designed as a dual-flow system between the diesel particle filter and the rear silencer
Twin-turbo — exhaust after-treatment: Oxidation catalytic converter + diesel particle filter (DPF)
Twin-turbo — air-cleaner relocation: Near-engine intake silencer no longer possible (space taken by two turbos + higher air demand); intake silencer + air cleaner relocated from engine to right-hand wheel arch. Includes intake snorkel, hot-film air mass meter, engine-breather line, filtered-air gaiter
Twin-turbo — no air flap control (LKS) on E60 TOP: No air flap control (LKS) on E60 M57TU1-TOP
Oxidation catalytic converter — volume: 2.26 litres — Oxidation-type catalytic converter (M57TU).
Central silencer — volume: 5.4 L (E60) / 5.8 L (E65) — Absorption principle.
Rear silencer — volume: 23 L (E60) / 32 L (E65) — Reflection principle.
Intercooler (charge-air cooler): Re-engineered with turbo; improved compressor/turbine blade geometry & efficiency — 2nd-gen turbo — better response and efficiency.
VNT actuator - stroke & vacuum: 10 mm rod stroke; fully retracted at > 650 mbar vacuum, fully extended with no vacuum — Vacuum-operated VNT vane actuator (single-turbo M57)
Swirl flaps - stuck-closed power loss: ~10% power loss at higher engine speed if the swirl flaps stick closed — Swirl-flap changeover valve (EPDW) closes the flaps when activated by the DDE
EGR valve - EPDW duty range: 5% (min = DDE wants it closed) to 80% (max = DDE wants it open) — Pulse-duty of the EGR pressure-converter (EPDW); a diagnostic of EGR / vacuum faults
Boost pressure - EPDW max duty: 80% maximum — At max charge-air-control duty the DDE is doing all it can to raise boost - points a low-boost fault to mechanics, not the ECU