The VQ37VHR Engine: A Foundation for Power

The VQ37VHR is a 3.7-liter V6 engine that represents the pinnacle of Nissan’s VQ series. With a DOHC design, variable valve timing on both intake and exhaust (VVEL), and a high 11.0:1 compression ratio, the stock engine delivers 332 horsepower at 7,000 RPM and 270 lb-ft of torque at 5,200 RPM. This naturally aspirated powerplant is known for its smooth power delivery, linear torque curve, and excellent reliability when maintained properly. However, for enthusiasts seeking serious performance gains, the VQ37VHR responds exceptionally well to forced induction and fuel upgrades.

Stock 370Z Performance and Limitations

The stock Nissan 370Z is a capable sports car that provides engaging driving dynamics straight from the factory. With a curb weight of approximately 3,300 pounds and a 6-speed manual or 7-speed automatic transmission, the 370Z delivers respectable acceleration and handling. But when compared to modern rivals, the stock power output feels modest. Key stock metrics include:

  • Horsepower: 332 hp at 7,000 RPM
  • Torque: 270 lb-ft at 5,200 RPM
  • 0-60 mph: 5.0–5.5 seconds (depending on transmission and driver)
  • Quarter-mile: ~13.5 seconds at 104 mph
  • Top Speed: Electronically limited to 155 mph

While these numbers are respectable, tuners quickly discover that the VQ37VHR has significant untapped potential. The factory ECU mapping is conservative, the exhaust system is restrictive, and the intake airflow leaves room for improvement. Moreover, the stock fuel system is optimized for pump gasoline (91–93 octane) and cannot support the fuel flow required for high-boost forced induction on E85 without upgrades. Understanding these limitations is the first step toward building a 600-horsepower monster.

The Path to 600 Horsepower

Reaching 600 horsepower at the crank with a VQ37VHR requires a holistic approach. The most reliable method is to add a centrifugal or twin-screw supercharger, or a properly sized turbocharger system. Running E85 fuel is almost mandatory at this power level because its higher octane rating (around 105–110) and superior latent heat of vaporization allow for higher boost pressures and more aggressive ignition timing without detonation. Below, we break down the essential modifications.

Forced Induction System

For 600 hp, a centrifugal supercharger kit (such as those from Stillen, Vortech, or AAM Competition) or a twin-turbo kit (e.g., from GReddy, CXRacing, or SOHO Motorsports) is necessary. A supercharger provides linear power delivery and easier installation, while turbos offer higher peak numbers and potentially better mid-range torque. At this power level, a supercharger running 8–10 psi with E85 can produce 600 crank hp, while a turbo setup at similar boost will yield slightly more.

  • Supercharger: Stillen Stage 2, AAM S-1, Vortech V3 – all capable of 500–650 whp with proper fueling.
  • Turbocharger: Single 6266 or twin 5858 turbos can hit 600 whp on E85 at 12–15 psi.

Fuel System Upgrades

E85 requires approximately 30–40% more fuel volume than gasoline for the same air mass. The stock fuel injectors, fuel pump, and fuel lines are insufficient. A typical 600 hp E85 fuel system includes:

  • Injectors: 1,000–1,300 cc/min or 96–100 lb/hr high-impedance injectors.
  • Fuel Pump: Walbro 450 or Aeromotive 340 in-tank pump, often with a secondary external pump.
  • Fuel Rails & Lines: High-flow fuel rails and -6AN or -8AN lines to handle E85’s corrosive nature and increased volume.
  • Flex Fuel Sensor: Optional but recommended for tuning flexibility across different ethanol blends.

Engine Internals & Cooling

Surprisingly, the VQ37VHR’s factory internals can handle 600 hp with a conservative tune and good fuel quality. The forged connecting rods, cast pistons, and hardened crankshaft are robust enough for this power level if detonation is avoided. However, upgrading the following is wise for longevity:

  • Head Studs: ARP head studs to prevent head lift under high boost.
  • Oil Cooler: A large setrab or mishimoto oil cooler with thermostat to keep oil temps below 230°F.
  • Intercooler: Air-to-air or air-to-water intercooler sized for 600+ whp.
  • Radiator: High-performance aluminum radiator (e.g., Koyo, Mishimoto) with dual electric fans.

Exhaust System

Stock exhaust manifolds are restrictive. A high-flow exhaust system includes long-tube headers (e.g., Z1, PPE), a high-flow catalytic converter or test pipes, and a 3-inch cat-back exhaust (e.g., from Motordyne, Fast Intentions, or HKS). Free-flowing exhaust reduces backpressure and helps the engine breathe.

ECU Tuning

Proper calibration is the most critical part of the build. For the VQ37VHR, options include:

  • Uprev Osiris: Popular standalone calibration tool with real-time tuning.
  • ECUTek: Professional reflash with advanced features like boost control, launch control, and flex fuel support.
  • Haltech / MoTeC: Full standalone engine management for maximum control (less common on street cars).

A tuner experienced with E85 and VQ engines (e.g., Adam at Z1, or SOHO Motorsports) will dial in the air-fuel ratio (targeting ~11.5:1 for E85), ignition timing (increased ~3–5 degrees over gasoline), and boost pressure to achieve a safe 600 crank hp.

Performance Metrics: Stock vs 600 HP Modified

The transformation from stock to modified is dramatic. The table below compares key performance figures:

  • Horsepower: Stock 332 hp (crank) vs Modified 600 hp (crank) – an 80% increase.
  • Torque: Stock 270 lb-ft vs Modified 500–530 lb-ft (depending on boost and tune).
  • 0-60 mph: Stock 5.0–5.5 sec vs Modified 3.2–3.8 sec (traction limited).
  • Quarter-mile: Stock 13.5 sec @ 104 mph vs Modified 10.8–11.5 sec @ 125–130 mph.
  • Top Speed: Stock 155 mph (electronically limited) vs Modified ~180–190 mph (with gearing).

These numbers represent a properly tuned car on a dyno. Real-world performance depends on traction, ambient conditions, and drivetrain losses. A modified 370Z making 600 crank horsepower will likely put down 480–500 whp on a chassis dyno.

E85 vs Pump Gas: The Fuel Factor

Running E85 rather than pump 93 octane allows for approximately 15–20% more power at the same boost level due to its cooling effect and knock resistance. However, E85 has a lower energy density (about 30% less BTU per gallon), so fuel economy suffers. For a dedicated track car, E85 is ideal; for a daily driver, you may need a flex fuel tune to switch between fuels. Additionally, E85 is corrosive to rubber components, so replacing fuel lines and seals with ethanol-compatible materials is mandatory.

Drivetrain Upgrades for 600 HP

Power is nothing without traction and durability. The stock 370Z drivetrain – clutch, transmission, differential, and axles – will not survive sustained 600 hp abuse. Required upgrades include:

  • Clutch: A twin-disc clutch (e.g., South Bend, Competition Clutch, ACT) rated to 600+ ft-lb of torque.
  • Flywheel: Lightweight or billet steel flywheel for reduced rotational mass.
  • Transmission: The stock CD009 or CD00A manual transmission can handle ~500–550 ft-lb with careful driving. For reliability, consider a built transmission with upgraded synchros and stronger gears (e.g., from Transport Evolved or SOHO). The 7-speed automatic (JR710E) is known to fail above 500 whp; a heavy-duty torque converter and valve body upgrade are essential.
  • Differential: OEM VLSD may overheat; upgrade to a Cusco, Nismo, or Wavetrac limited-slip differential.
  • Axles: Stock half-shafts are a weak point; upgrade to DSS (Drive Shaft Shop) Level 2 or similar.

Cost Breakdown Approximations

Building a 600 hp 370Z on E85 is not cheap. Below are estimated costs (in USD) for parts and labor, assuming you do some work yourself:

  • Supercharger kit + install: $5,000–$8,000
  • Turbo kit + install: $6,500–$11,000
  • Fuel system (injectors, pump, lines, rails): $1,500–$3,000
  • Exhaust system (headers, catback): $2,000–$4,000
  • Intercooler + oil cooler: $1,000–$1,800
  • Clutch + flywheel: $1,200–$2,000
  • Differential + axles: $2,500–$4,500
  • Tuning + ECU reflash: $1,000–$2,500
  • Miscellaneous (gauges, boost controller, flex fuel sensor): $800–$1,500

Total estimated: $15,000–$38,000 depending on choices and labor. This does not include installation costs if you are not DIY-capable.

Reliability and Daily Driveability

A 600 hp VQ37VHR 370Z can be surprisingly reliable if built correctly with conservative tuning and proper cooling. However, it will never be as bulletproof as a stock car. Common issues at this power level include:

  • Heat soak: Requires upgraded radiator, oil cooler, and possibly a larger intercooler.
  • Fuel system corrosion: E85 requires frequent fuel filter changes and inspection of rubber lines.
  • Drivetrain wear: Even with upgraded components, clutches and axles need regular attention.
  • Shortened engine life: Higher cylinder pressures and heat reduce engine longevity. Many tuners recommend an engine rebuild every 50,000–60,000 miles for 600+ hp builds.

For street use, a 600 hp 370Z is a handful. The throttle is jumpy, traction is poor in first and second gears, and the car becomes much louder and stiffer. Most owners reserve this level of modification for weekend track days or drag racing rather than daily driving.

The Driving Experience: Stock vs Modified

Driving a stock 370Z is a pleasant, engaging experience. The power delivery is smooth, the car feels light and responsive, and you can push it to the limit without fear. In contrast, a 600 hp modified 370Z on E85 transforms into a raw, brutal machine. At full throttle, the acceleration pins you to the seat – the 0–60 mph sprint in the low 3-second range is a visceral rush. Cornering demands respect, as the power can easily overwhelm the rear tires. The engine note changes from a refined V6 growl to a thunderous roar, especially with an aggressive exhaust and supercharger whine. It is an experience reserved for experienced drivers who understand the risks of high-horsepower rear-wheel-drive cars.

External Resources for Further Reading

For more detailed information on building and tuning the VQ37VHR, check out these authoritative sources:

Final Thoughts: Is 600 HP Worth It?

The Nissan 370Z VQ37VHR is a fantastic platform for high-horsepower builds. Achieving 600 horsepower on E85 requires a significant investment in forced induction, fuel system, drivetrain, and tuning. The result is a car that can embarrass supercars at the drag strip or on track. However, the cost, reduced reliability, and compromised daily driveability mean that this path is not for everyone. For those who live for extreme performance and are willing to invest the time and money, a fully modified 370Z on E85 delivers an unforgettable driving experience that far surpasses the stock car in every measurable metric. As with any build, proper research and quality components are key to making 600 hp a rewarding reality rather than a frustrating project.