The Datsun 240Z: A Timeless Platform for Performance Upgrades

The Datsun 240Z, produced from 1969 to 1973, remains one of the most iconic Japanese sports cars ever built. Its lightweight body, balanced chassis, and potent L-series inline-six engine make it an ideal candidate for both restoration and modification. For enthusiasts seeking to unlock more power and sharper throttle response, aftermarket components from Japanese tuning legends like HKS and Greddy offer proven solutions.

Modern engine management and forced-induction technology have transformed what is possible with the 240Z. Whether you are building a street-driven tribute to vintage endurance racers or a dedicated track machine, carefully chosen upgrades can elevate performance without sacrificing reliability. Below, we explore five key upgrades from HKS and Greddy that deliver tangible gains in horsepower, torque, and drivability.

Before starting any major modification, consult the factory service manual and consider the condition of your engine. Compression and leak-down tests provide a baseline for how much additional power your engine can safely handle. Upgrading supporting systems—such as cooling, fuel delivery, and brakes—is equally important when adding significant power.

1. HKS Super Sequential Blow Off Valve

Why a Blow Off Valve Matters for Your 240Z

When you install a turbocharger on your Datsun 240Z, the air compressed by the turbo has nowhere to go when you lift off the throttle. Without a blow off valve (BOV), pressure backs up into the compressor wheel, causing compressor surge—a harsh fluttering sound that puts stress on the turbo bearings and reduces its lifespan. The HKS Super Sequential Blow Off Valve vents this excess pressure to the atmosphere, protecting the turbo and improving throttle response between gear changes.

The HKS Super Sequential design uses a two-stage approach. At low boost, only a small piston opens, providing a quiet recirculation effect. At higher boost pressures, a second stage opens fully, producing the signature HKS “whoosh” sound. This staged operation prevents the valve from fully opening during light throttle, which keeps idle quality smooth and reduces the risk of stalling.

Installation Considerations

Mount the BOV as close to the throttle body as possible for the quickest pressure release. Most 240Z turbo kits include a flange on the intercooler piping. HKS offers adapter flanges for common piping diameters. Use a vacuum line from a manifold vacuum source—avoid referencing ported vacuum, which may not provide the signal needed for proper operation. Adjust the spring preload according to your boost level; too loose may cause idle vacuum to draw the valve open, too tight may require excessive boost to open fully.

Performance Gains

  • Reduced turbo lag – faster spool between shifts
  • Increased compressor life – eliminates damaging surge events
  • Improved throttle response – no hesitation when re-applying throttle
  • Distinctive sound – a hallmark of tuned Japanese sports cars

While the HKS Super Sequential BOV is designed for forced induction applications, it can also be used on naturally aspirated engines that have been fitted with a supercharger, though the vacuum signal may differ. For the classic 240Z, this upgrade pairs especially well with the Greddy turbo kit discussed next.

2. Greddy Turbo Kit

Complete Forced Induction for the L-Series Engine

The Greddy Turbo Kit (formerly known as Trust) is one of the most comprehensive and respected bolt-on turbo systems for the Datsun 240Z. It transforms the 2.4-liter inline-six into a potent powerplant capable of 250-350 horsepower on conservative boost levels, with the potential for much more with upgraded internals.

The kit typically includes a Greddy T78 or TD06 series turbocharger, cast-iron or stainless-steel exhaust manifold, intercooler core, intercooler piping, blow off valve flange, wastegate, and all necessary hardware. Many kits also include an oil feed line kit and a drain line for the turbo. The intercooler is efficient enough for street and moderate track use, keeping intake temperatures under control at boost levels up to 15 psi.

Installation and Tuning

Installing a full turbo kit on a 240Z requires some mechanical skill but is within reach of a competent home mechanic. The engine must be removed or the front of the engine compartment cleared to access the exhaust manifold. The factory L-series head may benefit from upgraded valve springs and a metal head gasket to handle increased cylinder pressure. If your engine is stock, limit boost to around 8-10 psi with proper fuel delivery and ignition timing.

Tuning is critical. The Greddy kit usually ships with a pressure-activated rising-rate fuel pressure regulator to enrich the mixture under boost, but for best results use a standalone engine management system such as the Greddy e-Manage Ultimate or a modern ECU like Haltech or MegaSquirt. With proper tuning, the Greddy turbo kit delivers smooth, linear power from 3000 rpm to redline.

What to Expect

  • Significant horsepower gains – 150-200% increase over stock
  • Dramatic torque increase – transforms low-speed drivability
  • Plug-and-play design – no custom fabrication required
  • Proven reliability – decades of use in competition and street cars

For a deeper look at boost levels and engine internals, consult resources like ZCar.com or the hybridZ forum, which have dedicated sections for L-series turbo builds.

3. HKS Exhaust System

Freeing the Engine’s Breath

A stock 240Z exhaust system is restrictive, with narrow piping and a muffler designed for noise control, not performance. Upgrading to an HKS exhaust system—often a Hi-Power or Super Drager model—reduces back pressure and allows the engine to expel exhaust gases more efficiently. This is one of the simplest and most effective bolt-on upgrades, especially when combined with a header and high-flow catalytic converter (where required).

HKS exhausts for the 240Z are typically T-304 stainless steel with mandrel bends, ensuring consistent internal diameter throughout. The muffler uses a straight-through design with fiberglass and steel wool packing, delivering a deep, aggressive tone without excessive drone. The exhaust tip is large (90-115mm usually) and angled to match the rear bumper cutout on the 240Z.

Performance and Sound

On a naturally aspirated L24 engine, an HKS exhaust can free up 8-12 horsepower at the wheels, with a broader torque curve. On a turbocharged car, the gains are even more pronounced because the turbo relies on free-flowing exhaust to spool effectively. A 3-inch diameter system is recommended for turbo applications, while naturally aspirated engines may prefer 2.5-inch to maintain low-end torque.

  • Weight reduction – stainless steel systems are lighter than stock iron
  • Improved engine cooling – quicker exhaust evacuation lowers under-hood temperatures
  • Enhanced sound – a deep, purposeful note that distinguishes a tuned 240Z
  • Easy installation – direct fit with factory hanger locations

HKS exhausts are known for their build quality and long life. If you live in an area with strict noise regulations, consider the optional silencer insert that HKS offers for some models. For more on exhaust system design and tuning, check out EngineLabs.

4. Greddy Fuel Management System

Precision Fuel Control for Modified Engines

Adding forced induction or aggressive camshafts without proper fuel management is a recipe for lean air-fuel ratios, detonation, and engine damage. The Greddy Fuel Management System—typically the e-Manage series or the more advanced Ultimate model—allows comprehensive tuning of fuel and ignition maps. For the 240Z, this enables safe and maximized power from any performance upgrade.

The e-Manage Blue is a fuel-only unit that installs between the stock ECU and injectors, intercepting the injector signals to add or subtract fuel based on throttle position, RPM, and manifold pressure. The e-Manage Ultimate adds ignition timing control, boost control (with optional sensor), and support for larger injectors. Both units come with Windows-based software for real-time tuning.

Tuning Approach for the 240Z

If you retain the original Bosch L-Jetronic fuel injection, the e-Manage series can integrate with that system using a specific harness. Many 240Z owners convert to a more modern engine management system, but the Greddy units offer an affordable middle ground that retains the original look under the hood. For carbureted engines, a different solution—such as the Greddy rising-rate fuel pressure regulator—is more appropriate.

  • Real-time tuning – adjust fuel and timing while the engine runs
  • Ignition control – optimize timing for boost or high compression
  • Boost-dependent fueling – add fuel only under boost, retain stock behavior off boost
  • Data logging – monitor engine parameters to prevent knock

A well-tuned Greddy e-Manage system can deliver a safe air-fuel ratio of 11.5-12.0:1 under full boost on premium pump fuel. Always perform final tuning on a chassis dynamometer or with a wideband oxygen sensor. For guidance, see the tuning tutorials on DailyTuner, which has specific articles for the e-Manage family.

5. HKS Camshafts

Maximizing Airflow Up Top

Stock L24 camshafts are mild, prioritizing smooth idling and low-end torque. HKS camshafts for the 240Z—such as the 256° or 264° duration models—offer increased valve lift and duration, allowing the engine to breathe more effectively at higher RPM. This translates to higher peak horsepower and a broader power band when paired with supporting modifications like a header, exhaust, and fuel management.

HKS manufactures camshafts from chilled cast iron using a billet grinding process for precise lobe profiles. They offer both hydraulic and solid lifter camshafts; for street use, the hydraulic versions work with factory lifters. For race applications, solid lifters with adjustable cam sprockets allow precise valve timing settings. Lobe separation angles are engineered to maintain decent manifold vacuum for carbureted or EFI setups.

Installation and Matching Parts

Installing camshafts on a 240Z requires removing the intake and exhaust manifolds, cam cover, timing chain, and sprocket. Use a quality timing chain tensioner and replace the chain if worn. With aftermarket cams, it is common to upgrade valve springs to prevent valve float at high RPM. HKS recommends their valve springs and titanium retainers for their performance camshafts.

The 256° camshaft is a good street bump, adding 10-15 horsepower without sacrificing idle quality. The 264° camshaft pushes power higher into the rev range, ideal for engines with upgraded intake and exhaust systems. For naturally aspirated engines, higher compression pistons (10.5:1 to 11.5:1) complement these cams well. In turbocharged engines, cam timing can be adjusted to reduce overlap, improving spool.

Expected Results

  • Increased peak power – 15-30 horsepower depending on duration and supporting mods
  • Higher RPM potential – critical for making the most of a turbo kit
  • Improved throttle response – better airflow dynamics
  • Authentic sound – a lumpy idle that signals serious performance

HKS camshafts have been used in countless competition cars, including the legendary JGTC (now Super GT) Datsuns. For reference, see the builds documented on Jalopnik that discuss the performance impact of cam upgrades in classic Japanese sports cars.

Putting It All Together: A Cohesive Upgrade Path

While each of these five upgrades can deliver meaningful performance on its own, they work best as a system. The HKS blow off valve protects the Greddy turbo kit; the HKS exhaust lets the turbo breathe; the Greddy fuel management system ensures safe fueling; and the HKS camshafts maximize air throughput. Together, these parts can push a well-built 240Z to 300+ horsepower while maintaining street manners.

Begin with the exhaust and fuel management if you plan to add boost later. The HKS exhaust system is a reversible modification that immediately improves sound and power. The Greddy fuel management system can be tuned to support future upgrades. When you add the turbo kit, the blow off valve becomes essential, and swapping camshafts last completes the picture. This staged approach spreads costs over time and allows you to enjoy each enhancement.

Reliability must not be overlooked. High-performance cooling—such as a larger aluminum radiator, electric fan, and oil cooler—should accompany any power increase. The 240Z’s factory clutch may slip under increased torque; upgrade to a performance clutch from brands like ACT or Exedy. Stiffer suspension and upgraded brakes (e.g., Toyota S12+4 calipers or Wilwood kit) ensure the car stops and handles as well as it accelerates.

The Datsun 240Z remains a rewarding platform for performance upgrades. With quality components from HKS and Greddy, you can create a car that honors its heritage while delivering modern levels of power and driver engagement. Whether you choose one upgrade or all five, the result will be a more exciting and capable machine. For a comprehensive parts list and current pricing, visit specialty retailers like Z Car Source or The Z Store.