Understanding the VQ37 Engine

The VQ37VHR, a 3.7-liter V6 introduced by Nissan in 2008, is the final evolution of the storied VQ engine family before the VR30. Found in the 370Z, G37, Q50/Q60 (early models), and Z34, it is revered for its smooth high-revving character and the advanced Variable Valve Event and Lift (VVEL) system that eliminates the need for a traditional throttle body at part throttle. Stock, it produces around 330–350 horsepower, but its cast-aluminum block, forged steel crankshaft, and robust bottom end have made it a favorite for forced-induction builds.

However, pushing the VQ37 beyond 500–600 wheel horsepower exposes common weak points: the factory oil pump drive collar (prone to snapping), ringlands on cast pistons, and inadequate cooling under sustained load. Without a systematic approach to reliability, even a perfectly tuned car can suffer catastrophic failure. The following sections cover the modifications, maintenance habits, and monitoring strategies that separate a high-power VQ37 that lasts from one that grenades prematurely.

Foundational Reliability Strategies for High-Power VQ37 Builds

1. Oiling System Overhaul

The VQ37’s oiling system is its Achilles’ heel at high RPM and high boost. The stock oil pump uses a pressed-on drive collar that can shear off under increased harmonic stress, causing immediate loss of oil pressure. Upgrading to a billet oil pump gear set (available from Z1 Motorsports or similar vendors) or a complete aftermarket pump eliminates this failure mode. Additionally, a baffled oil pan is essential to prevent oil starvation during hard cornering or launch events. Be aware that the factory oil pickup tube can also crack; a welded or reinforced pickup is a cheap insurance policy.

  • Billet oil pump gears – replace factory pressed-on collar with a keyed or splined design.
  • Baffled oil pan – add windage tray and trap doors to keep oil near the pickup.
  • High-volume oil pump – only if needed; excessive flow can aerate oil at high RPM.
  • Oil cooler – thermostatic plate + large core (e.g., 25-row or 34-row) to keep oil below 220°F under track conditions. Concept Z Performance offers complete kits.

2. Cooling System Upgrades

Factory cooling on the VQ37 is marginal for sustained high-power driving. The plastic end-tank radiator can fatigue, and the stock fan clutch may not pull enough air at idle. For builds above 500 whp, start with a full aluminum radiator (Koyo, Mishimoto, or CSF) with a high-flow thermostat (160–170°F). Upgrade to an electric fan conversion or a heavy-duty clutch fan. A coolant reroute kit that eliminates the rear heater-core bypass improves flow distribution to the rear cylinders, which often run hotter. Do not overlook water pump condition—a high-flow mechanical or electric water pump (by Meziere or Davies Craig) can be justified for extreme setups.

  • Full aluminum radiator – core thickness of at least 2 inches, preferably triple-pass.
  • Oil cooler + transmission cooler – separate thermostatic circuits for each.
  • Vented hood or lower grille opening modifications to reduce underhood heat soak.
  • High-performance coolant – water + Water Wetter for track use, or Evans waterless for street cars.

3. Forged Internal Components

The stock VQ37 pistons are hypereutectic cast aluminum and will fail under sustained knock or power levels above 550–600 whp. For builds targeting 700+ whp, forged pistons (CP, JE, Mahle, Ross) and forged connecting rods (Manley, Carrillo, Oliver) are mandatory. The factory VQ37 connecting rods are sintered powdered metal and can stretch or break under detonation. For street-driven cars aiming for 500–600 whp, the stock rods with ARP rod bolts often survive if the tune is conservative, but forged rods with a 2000-series wrist pin offer peace of mind.

  • Piston choice – aim for a compression ratio between 8.5:1 and 9.0:1 for forced induction; higher for naturally aspirated builds.
  • Rod bolt upgrade – ARP 2000 bolts are a minimum requirement for any boosted VQ37, even with stock rods.
  • Main bearing clearances – set to 0.0020–0.0025 inches for boost; use a high-performance oil like 5W-40 or 10W-40 (Motul 300V or Red Line).
  • Head studs – ARP head studs replace factory torque-to-yield bolts to prevent head lift at high boost.

4. Tuning and Engine Management

A reliable high-power VQ37 relies on a professional tune from a shop experienced with the platform (e.g., Specialty Z, Admin Tuning, or Z1 Motorsports). The stock ECU can be reflashed via ECUTek or UpRev, but standalone options (MoTeC, Haltech, or AEM Infinity) offer superior safety features like dual fuel maps, boost-by-gear, and real-time knock monitoring. Regardless of the system, the fuel map must target an air/fuel ratio no leaner than 11.5:1 under boost, and ignition timing must respect the knock threshold of the fuel used. Use high-octane fuel (93 AKI minimum, or E85 for its knock resistance and cooling effect).

  • Professional dyno tune – never use a generic “off-the-shelf” map on a heavily modified engine.
  • Knock sensor monitoring – log knock activity on every pull; disable knock control only after verifying timing is safe.
  • Tailored boost curve – taper boost at high RPM to maintain safe cylinder pressures.
  • Fuel system – 600–1000 cc injectors (Denso or Injector Dynamics) and a fuel pump capable of supporting the target power (AEM 340 LPH or inline Bosch 044).

5. Valvetrain and VVEL Considerations

VVEL is a marvel of engineering but introduces complexity. At high RPM (above 7,500), the VVEL actuator and linkages can wear, leading to abnormal valve events. For builds that extend the redline beyond 7,500 RPM, upgrade the VVEL actuator gear with a billet unit, and consider converting to a fixed cam profile (deleting VVEL) for ultimate reliability—though this sacrifices idle quality and low-end torque. Stock valvetrain components (valves, springs, retainers) are adequate up to 7,500 RPM with mild boost; above that, upgrade to dual valve springs and titanium retainers to prevent valve float. A complete port and polish of the cylinder heads is optional but helps flow without increasing boost.

  • VVEL actuator brace – reduces slop in the system.
  • VVEL delete kit (available from companies like Soho Motor Sports or custom grind cams) – for extreme builds only.
  • Valve spring upgrade – PAC, Supertech, or Ferrea dual springs with retainers.
  • Cam timing – verify with adjustable cam gears and degree to spec during assembly.

6. Drivetrain and Clutch

Power is meaningless if it breaks the gearbox or axles. The factory CD009 or CD00A manual transmission is strong but has a known weakness: the synchros on 3rd and 4th gear become notchy under high power. Upgrade to a carbon synchro kit or a built transmission from Z1 Motorsports or ZSpeed. The stock 370Z/G37 aluminum driveshaft can vibrate at high speeds; a one-piece carbon fiber driveshaft is a worthwhile investment for builds over 600 whp. For the clutch, a twin-disc or triple-disc unit (Competition Clutch, ACT, or OS Giken) with a lightweight flywheel is essential to handle the torque without slipping. Do not forget the slave cylinder—the CSC (concentric slave cylinder) is prone to failure; replace with an external slave conversion or a heavy-duty internal unit.

  • Transmission coolers – for automatic cars, a standalone cooler is mandatory.
  • Axle upgrade – Factory axles can twist at 600+ whp; upgrade to chromoly axles from DSS or GTM.
  • Differential – the stock viscous limited-slip diff is weak; install a clutch-type or Torsen diff with solid mounts.

7. Boost Management and Data Logging

Monitor boost with an electronic boost controller (e.g., Turbosmart, AEM, or GFB) that supports boost-by-gear and boost-over-boost protection. Install a wideband oxygen sensor gauge (AEM or Innovate) and a boost gauge. More importantly, data log every parameter—boost, AFR, oil pressure, coolant temp, intake air temp, knock voltage—using software like ECUTek data log or a dedicated logger (Racepak, AiM). Review logs after every aggressive driving session. Detonation can occur in milliseconds; real-time knock monitoring via the ECU should be coupled with a mechanical knock sensor listening device (e.g., Phantom or a piezo transducer) for piece of mind.

  • Boost controller with safety map (reduce boost if knock is detected).
  • Catch can – PCV system can push oil into the intake under high boost; a quality catch can prevents detonation from oil ingestion.
  • Blow-off valve – recirculating type to avoid compressor surge; vent-to-atmosphere can cause rich spikes on MAF-based systems.

Long-Term Maintenance Habits

Even the best-built VQ37 will fail if neglected. Establish a strict schedule: oil changes every 2,000–3,000 miles (or every track weekend) using high-zinc oil; coolant flush annually; spark plugs (NGK LFR7AIX or colder) replaced every 20,000 miles for boosted setups. Inspect the serpentine belt, accessory pulleys, and all rubber hoses frequently—the factory cooling system hoses can rupture under 20+ psi of boost pressure. Keep the engine bay clean and look for fluid leaks at the turbo oil feed/drain, oil pan gasket, and timing cover.

Additionally, let the engine cool down before shutting off after a hard run. A turbo timer (or an electronic coolant pump that circulates fluid after shutdown) will prevent heat soak from cooking the oil pump drive collar and turbo bearings. Annual compression and leak-down tests provide early warning of ring or valve seat wear.

Conclusion

Building a reliable high-power VQ37 is not about a single magical part—it requires a holistic approach that starts with understanding the engine’s weak points and systematically addressing them. Upgrade the oiling system first, then address cooling, internal strength, and tuning simultaneously. Invest in quality components from trusted vendors, and never cut corners on installation tolerances. With proper planning, a VQ37 can deliver 600–800 reliable wheel horsepower and still start, idle, and drive daily. As with any performance build, the key is prudent boost management, meticulous assembly, and vigilant data logging. If you respect the limits of the platform and the physics involved, your high-power VQ37 will reward you with thousands of miles of excitement.