Understanding Turbocharging and the Greddy Kit

Turbocharging is a form of forced induction that compresses air entering the engine, allowing more fuel to be burned per cycle. This directly increases horsepower and torque without needing a larger displacement engine. The Greddy Turbo Kit for the Nissan 370Z is a complete, bolt-on system that delivers this forced induction in a reliable, track-tested package. Unlike custom one-off setups, the Greddy kit includes all necessary components—turbocharger, intercooler, exhaust manifold, wastegate, blow-off valve, and all piping—designed to work together as a system. When tuned to 18 PSI of boost, the power gains are substantial, often pushing the 370Z from a stock 332 horsepower to between 450 and 500 wheel horsepower. This article examines real-world dyno results, the engineering behind the kit, and the factors that influence final output.

What the Greddy Turbo Kit Includes

The Greddy kit is engineered for a straightforward installation on the 370Z's VQ37VHR engine. Key components include:

  • GT2860RS or GTX3071R turbocharger – Depending on the specific kit variant, these turbos are selected for quick spool and high flow capacity.
  • Cast iron exhaust manifold – Designed for strength and heat retention, reducing backpressure and improving turbine response.
  • Air-to-air intercooler – Core size is matched to the power target, keeping intake air temperatures low even under sustained load.
  • Wastegate and blow-off valve – Factory-calibrated to maintain stable boost pressure; adjustable for fine-tuning.
  • Mandrel-bent piping – All charge pipes and intake tubing are powder-coated or polished for durability and flow efficiency.
  • Oil feed and drain lines – Essential for turbocharger lubrication; kits often include banjo fittings and braided stainless steel lines.
  • Hardware and gaskets – Everything needed for a complete install is included, reducing the need for additional purchases.

This all-inclusive approach means the installer does not need to source individual parts, which minimizes compatibility issues and simplifies the build process.

Power Gains at 18 PSI – Real Dyno Results

At 18 PSI, the Greddy kit consistently delivers impressive power on the 370Z. Below are representative dyno results from independent shops and owner-reported data:

Stock vs. Tuned Comparison

  • Stock 370Z (crank): ~332 hp and ~270 lb-ft torque (factory rated)
  • Greddy kit at 18 PSI (wheel): 450–500 hp and 400–425 lb-ft torque
  • Dynojet correction factor: Wheel horsepower on a Dynojet typically reads 12–15% lower than crank. So 480 whp equates to roughly 550–560 crank horsepower.

Real-World Owner Reports

  • Case 1: A 2013 370Z with the Greddy GTX3071R kit, tuned by a reputable shop, produced 488 whp and 418 lb-ft torque at 18 PSI on a Dynojet. Fuel used was 93 octane with water-methanol injection for added knock protection.
  • Case 2: A 2015 370Z Nismo, using the GT2860RS kit, recorded 452 whp and 395 lb-ft torque at 17.8 PSI with pump gas only. The slightly lower output was attributed to the smaller turbo sacrificing top-end flow for faster spool.
  • Case 3: An owner with full bolt-ons (headers, exhaust, intake) plus the Greddy kit achieved 512 whp and 435 lb-ft torque at 18.5 PSI, using a flex-fuel setup with E85.

These examples demonstrate that the kit's power ceiling is high, and final numbers depend on fuel quality, tuning precision, and supporting modifications.

Factors That Influence Power Output

No two builds are identical. Several variables affect how much power a Greddy-equipped 370Z will make at 18 PSI:

Engine Condition and Compression

The VQ37VHR has a factory compression ratio of 11.0:1. For forced induction, this is relatively high. A healthy engine with good compression and leak-down test results will tolerate boost better. Engines with high mileage or carbon buildup may detonate more easily, limiting timing advance and thus power.

Fuel Quality and Octane

Higher octane fuel resists knock and allows more aggressive timing. Most dyno results at 18 PSI are achieved with:

  • 93 octane pump gas: Typically yields 450–480 whp
  • E85 (85% ethanol): Can add 30–50 whp due to its cooling effect and knock resistance, enabling higher boost or more timing
  • Race fuel (100+ octane): Allows even more aggressive calibration, potentially exceeding 520 whp

If you plan to run 18 PSI on 91 octane (common in some regions), expect power on the lower end of the range, as the tuner will need to pull timing to prevent detonation.

Supporting Modifications

The Greddy kit is designed to work with the stock engine and fueling, but upgrading other systems can unlock additional power:

  • Fuel system: Larger fuel injectors (e.g., 600–850 cc/min) and a higher-flow fuel pump are recommended for sustained high boost. The stock injectors max out around 480–500 whp.
  • Exhaust system: A free-flowing cat-back exhaust (3-inch diameter is ideal) reduces backpressure and helps the turbo spool more quickly. Test pipes or high-flow cats also improve flow.
  • Intake system: While the Greddy kit includes its own intake, upgrading to a cold air intake with a larger air filter can reduce inlet restriction.
  • Intercooler upgrade: Although the supplied intercooler is adequate for 18 PSI, a larger core (such as from Z1 Motorsports) can reduce intake air temperatures further, especially in hot climates.
  • Cooling system: An upgraded radiator and oil cooler help maintain consistent temperatures during back-to-back pulls, preventing power loss from heat soak.

Tuning Quality and ECU Calibration

The tuner's skill is arguably the most important factor. A conservative tune may leave 20–40 whp on the table, while an aggressive but safe tune extracts the maximum. Common tuning platforms for the 370Z include:

  • UpRev – Widely used, allows full control of fuel, timing, and boost maps
  • ECUTek – Offers additional features like boost-by-gear and launch control
  • Haltech or Motec standalone ECU – For extreme builds with fully custom engine management

A professional street or dyno tune is essential. Relying on a generic "off-the-shelf" map is not recommended for 18 PSI.

Installation Considerations and Challenges

While the Greddy kit is designed as a bolt-on, installation is not trivial. It typically takes a skilled mechanic 10–15 hours to complete. Key points to be aware of:

  • Oil return line routing – The oil drain must be positioned above the oil pan level to prevent gravity from forcing oil into the turbo seals. Some kits require drilling and tapping the oil pan.
  • Coolant lines – The GT2860RS variant is water-cooled, requiring connection to the engine's coolant system. Air bleeding is critical to prevent steam pockets.
  • Wastegate adjustment – The internal wastegate arm must be adjusted to achieve the target boost pressure without boost creep.
  • Intercooler piping clearance – In some installs, piping may contact the radiator shroud or fan. Minor trimming may be necessary.
  • Accessories – The power steering pump and AC compressor may need slight repositioning on certain kit versions.

Careful attention to these details during installation prevents oil leaks, boost leaks, and cooling issues that could limit power or cause damage.

Reliability and Longevity at 18 PSI

The VQ37VHR is a robust engine, but adding 150–180 whp over stock places increased stress on internal components. Here is what you should know:

  • Rod bolts: The factory rod bolts are a weak point above 500 whp. At 18 PSI (450–500 whp), they are near their limit. Many owners upgrade to ARP rod bolts for safety.
  • Pistons and rings: Stock pistons can handle 500 whp on conservative timing and good fuel. However, pre-ignition can crack ring lands quickly. A good tune is your safety net.
  • Clutch: The stock clutch is inadequate for 450+ whp. Expect slippage on the first hard pull. A stage 2 or stage 3 clutch (e.g., from ACT Clutch) is a required upgrade.
  • Differential: The VLSD can handle the power, but aggressive launches may cause the differential to overheat. An aftermarket cooler or upgraded differential is recommended for track use.

If the engine is healthy and the tune is safe, a Greddy kit at 18 PSI can be reliable for daily driving with occasional track use. Frequent oil changes (every 3,000–5,000 miles) and careful monitoring of oil temperatures are strongly advised.

Cost Breakdown and Value

Understanding the total investment helps set expectations:

  • Greddy Turbo Kit: $4,500–$6,000 depending on vendor and turbo size
  • Installation labor: $1,200–$2,000 (if professionally installed)
  • Tuning (dyno time): $500–$1,000
  • Supporting mods (clutch, injectors, fuel pump, exhaust): $2,000–$3,500
  • Total estimated budget: $8,200–$12,500

For the power gain (roughly 150–180 whp), this is competitive with other forced induction options like Stillen supercharger kits or single-turbo custom setups. The Greddy kit offers a proven track record and well-documented tuning information.

Comparison with Other Boost Options

How does the Greddy kit stack up against alternatives?

  • Stillen Supercharger Kit: Produces similar peak power (450–500 whp) but delivers it linearly across the rev range. Superchargers have less complexity and no turbo lag, but they draw parasitic power from the engine. The Greddy kit often feels more aggressive on top-end.
  • APS Twin Turbo Kit: More expensive ($6,000–$8,000) and more complex to install, but capable of slightly higher peak numbers (500–550 whp). Reliability depends heavily on supporting mods.
  • Custom single turbo: Can be cheaper if sourcing used parts, but lacks the engineering validation and easy support of a packaged kit. Build quality and tune consistency vary wildly.

The Greddy kit strikes a balance between cost, power, and reliability, making it a strong choice for enthusiasts who want a proven package without the headaches of a custom build.

To safely and consistently achieve the highest power at 18 PSI, consider these upgrades:

  • Upgraded fuel injectors – ID850 or DeatschWerks 725 cc/min for E85 compatibility
  • High-flow fuel pump – Walbro 450 or AEM 340 lph
  • Boost controller – Electronic boost controller (e.g., Greddy Profec or AEM) for precise boost regulation
  • Wideband O2 sensor – Required for tuning and fuel mixture monitoring
  • Oil cooler – Setrab or Mishimoto 19-row core to keep oil temps below 230°F
  • Clutch upgrade – ACT Heavy Duty or Competition Clutch Stage 3
  • Cat-back exhaust – 3-inch system from Fast Intentions, Stillen, or Greddy

For track or road racing use, a fuel surge tank and baffled oil pan are also recommended to prevent fuel starvation and oil starvation under high lateral G.

Final Thoughts – Is the Greddy Kit Right for You?

The Greddy Turbo Kit transforms the 370Z from a respectable sports car into a serious performance machine. At 18 PSI, the power gain is dramatic, seat-of-the-pants thrilling, and measurable on the dyno. Real-world results consistently show 450–500 wheel horsepower, which is a 35–50% increase over stock. However, this level of power demands respect for the engine's limitations, proper fueling, and a high-quality tune.

If you are looking for a complete, engineer-approved kit that delivers proven results with a large community of owners and tuners, the Greddy kit is an excellent investment. The power is accessible, the installation is well-documented, and the upgrade path to even more power (via larger turbos or E85) is straightforward. For additional technical information, owner experiences, and installation guides, refer to resources like The370Z.com Forum and Z1 Motorsports, which offer extensive user reports and product support.