Understanding the VQ37VHR Engine and the 500 HP Goal

The Nissan 370Z’s VQ37VHR is one of the most refined naturally aspirated V6 engines ever produced by Nissan. With a 3.7-liter displacement, aluminum construction, and Nissan’s Variable Valve Event and Lift (VVEL) system, it delivers a strong 332 horsepower from the factory. However, reaching 500 wheel horsepower on this engine – a gain of roughly 50% – requires a methodical combination of airflow, fuel delivery, and tuning. While many enthusiasts turn to forced induction for such numbers, a well-chosen camshaft upgrade paired with professional ECU flashing can push the VQ37VHR close to that mark while maintaining excellent drivability.

This article details the specific upgrades needed to achieve 500 hp on a 370Z VQ37VHR, focusing on camshaft modifications and ECU tuning using Stillen components. We’ll also cover supporting modifications that become critical as power levels rise.

The VQ37VHR’s Strengths and Limitations for High Horsepower

The VQ37VHR features a high compression ratio (11.0:1), dual intake and exhaust variable valve timing, and the VVEL system that adjusts valve lift continuously. These traits give it excellent low-end torque and throttle response right from the factory. However, at high rpm, the stock camshaft profile limits airflow. The VVEL system is also not infinitely adjustable – its lobe profile is fixed, meaning the maximum lift and duration are predetermined. To overcome this, aftermarket camshafts with more aggressive profiles are needed.

Another limitation is the fuel system. The stock fuel pump and injectors are sufficient for roughly 400-420 wheel horsepower. Above that, you’ll need upgraded injectors and a higher-flow fuel pump. The same applies to the intake and exhaust: the stock airbox and Y-pipe become restrictions as airflow demands increase.

Camshaft Upgrades: The Foundation for High RPM Power

Choosing the right camshaft is the single most important mechanical change for a naturally aspirated VQ37VHR aiming for 500 hp. Aftermarket cams increase both lift and duration, allowing more air into the cylinders at high engine speeds. For the VQ37VHR, camshafts are available with lifts ranging from 0.500” to 0.550” and durations from 270° to 290° (at 0.050” lift). A moderate cam (e.g., 0.520” lift, 280° duration) pairs well with the VVEL system and can support 470-500 wheel horsepower with proper tuning.

Stillen Camshaft Options

Stillen offers a direct camshaft upgrade for the VQ37VHR. Their Street Performance camshafts are designed to work with the factory VVEL system and stock valve springs up to a certain rev limit. For 500 hp goals, Stillen’s Stage 2 camshafts are a popular choice. They increase lift by approximately 0.030” over stock and extend duration by about 15°, shifting the power band higher. Stillen provides detailed specifications and dyno charts showing gains of 30-40 wheel horsepower when combined with their ECU tune.

Installation and Valvetrain Considerations

Installing camshafts on a VQ37VHR involves significant labor: removal of the front timing cover, timing chain, VVEL actuators, and camshafts themselves. Because the engine is an interference design, careful attention to piston-to-valve clearance is mandatory, especially with larger cams. It is highly recommended to upgrade valve springs to dual springs if you intend to rev beyond 7,200 rpm. Many builders also install titanium retainers and hardened valve keepers for safety. Stillen’s installation guide notes that their camshafts can be installed with factory springs up to 7,000 rpm, but for 500 hp you’ll likely want to rev higher, so upgraded springs are advisable.

ECU Flashing with Stillen: Optimizing the Tune

After swapping camshafts, the engine’s volumetric efficiency changes dramatically. The stock ECU maps will be far from optimal: fuel ratios will be lean at certain points, ignition timing will be too conservative, and the VVEL target angles need recalibration. This is where Stillen’s ECU flashing solution comes in. Stillen offers a handheld UpRev-based tuner that can read and write the factory ECU. They provide pre-loaded tunes for various camshaft combinations, or you can opt for a custom dyno tune by an authorized Stillen dealer.

What the Stillen Flash Adjusts

The Stillen ECU flash makes critical changes to several parameters:

  • Fuel maps: The air/fuel ratio is targeted around 12.8:1 for maximum power under full throttle, with richer mixtures at peak torque.
  • Ignition timing: More aggressive timing is added at mid-range and high-rpm to exploit the increased airflow.
  • VVEL target angles: Because the camshaft profile changed, the VVEL system must be re-mapped to maintain smooth transitions and proper valve overlap.
  • Rev limit: The rev limiter can be raised to 7,400-7,500 rpm, which is necessary to take advantage of the camshaft’s top-end power.

Stillen’s base tunes are developed on their own dyno and have proven reliable on hundreds of cars. For maximum power, a custom dyno session is recommended because each engine’s tolerances vary. A good tuner will also adjust cold start enrichment, throttle mapping, and disable post-catalyst oxygen sensor error codes if a high-flow exhaust is used.

Supporting Modifications for 500 HP

Camshafts and tuning alone won’t get you to 500 wheel horsepower. The following upgrades are essential to keep the engine breathing and fueled correctly.

Intake System

A high-flow cold air intake (CAI) with a large filter and smooth piping reduces intake restriction. Stillen offers a CAI kit that drops intake air temperature and flows well over 400 CFM. Alternatively, some tuners prefer a short-ram intake with a heat shield, but for 500 hp, a CAI that draws air from the front bumper is superior.

Exhaust System

The stock exhaust has restrictive catalysts and small-diameter tubing. To support 500 hp, you need at least a cat-back exhaust with 3-inch piping and high-flow or catless test pipes. Stillen’s cat-back exhaust system features a true dual design with mandrel-bent tubes and straight-through mufflers. It reduces backpressure significantly and adds a noticeable top-end pull. Be aware that removing catalytic converters will trigger a check engine light unless the ECU flash disables the related monitors.

Fuel System

At 500 wheel horsepower, the VQ37VHR consumes roughly 650-700 cc of fuel per minute at peak power. The stock injectors (approx. 320 cc/min at 43.5 psi) run out of flow around 420 whp. You will need upgraded fuel injectors in the 600-700 cc/min range (often from Deatschwerks or Injector Dynamics). The stock fuel pump also reaches its limit; a Walbro 450 or equivalent high-flow in-tank pump is a must. Some tuners also upgrade the fuel pressure regulator to maintain consistent pressure under high demand.

Cooling and Oil Systems

With increased power comes more heat. A larger radiator, upgraded oil cooler, and perhaps an auxiliary transmission cooler (for automatic cars) are strongly recommended. The VQ37VHR can suffer from oil temperature spikes during sustained high-rpm driving, which can thin the oil and reduce engine life. Stillen offers an oil cooler kit with a thermostat and a 19-row cooler core that drops oil temps by 20-30°C.

Dyno Tuning and Optimization

Even with the best parts, the final tuning step occurs on a dynamometer. A typical dyno session for a cammed 370Z aiming for 500 hp involves:

  • Baseline pull to evaluate the current air/fuel ratio and power curve.
  • Multiple wide-open throttle pulls while adjusting fuel, timing, and VVEL targets.
  • Partial-throttle and cruise mapping to maintain drivability and fuel economy.
  • Verification of knock control and safety limits.

A professional tuner will also test for spark knock (detonation) by monitoring knock sensors and will add ignition timing only as far as the fuel octane allows. For 500 hp, 93 octane pump fuel is generally sufficient, but many tuners recommend a small amount of ethanol (e.g., E30 blend) for added knock resistance.

Stillen’s network of certified tuners uses Dynojet or Mustang dynamometers and has years of experience with the VQ37VHR. Expect to pay $500-$800 for a custom tune, which is money well spent to avoid engine damage and to maximize power.

Reliability at the 500 HP Level

The VQ37VHR is a stout engine, but 500 wheel horsepower is near the limit for a naturally aspirated build. Long-term reliability depends on meticulous maintenance: oil changes every 3,000 miles with a high-quality 5W-30 synthetic, spark plug replacement every 30,000 miles, and regular checks of valve clearances. The camshaft itself wears faster than stock, so using zinc-additive oil (ZDDP) is beneficial. Engine mounts should be upgraded to polyurethane to control motion and reduce stress on the drivetrain.

Many owners report that a well-tuned 500 hp VQ37VHR can last 50,000-70,000 miles of street driving, but track use will accelerate wear. It is not a “set and forget” setup; regular datalogging and attention to oil pressure, temperature, and knock counts are required.

Alternative Route: Forced Induction with Stillen

For those who want 500 hp with less stress on the engine, Stillen also offers a supercharger kit that produces around 500-520 wheel horsepower on a stock engine. While this article focuses on the naturally aspirated path, it’s worth noting that a properly installed supercharger can achieve the same numbers with simpler installation (no cam swap) and lower maintenance. The downside is cost: the Stillen supercharger kit retails for around $7,000, whereas a cam upgrade plus ECU flash is roughly $3,500-$4,500.

However, many purists prefer the linear power delivery and signature sound of a cammed VQ, and the naturally aspirated build can be more thrilling to drive on a track. Both approaches are valid, and Stillen supports both.

Conclusion

Reaching 500 horsepower on a Nissan 370Z VQ37VHR with camshaft upgrades and Stillen ECU flashing is an ambitious but achievable goal. The combination of a performance camshaft that increases airflow and a custom tune that optimizes the VVEL system and fuel maps can unlock the engine’s hidden potential. Supporting modifications – especially a high-flow intake, free-flowing exhaust, upgraded fuel system, and improved cooling – are non-negotiable at this power level.

Whether you choose the naturally aspirated path described here or opt for forced induction, the key is a thorough, well-planned build and professional tuning. Stillen’s components have proven themselves in countless 370Z builds, and their technical support can guide you through the process. With proper care, a 500 hp VQ37VHR is not only possible but also a reliable and exhilarating daily driver or track weapon.

For more information, see Stillen’s product pages for 370Z camshafts and ECU tuning options. Also check out the technical write-ups on My350Z.com’s 370Z forum for real-world build threads.