The Nissan 300zx Twin Turbo (Z32) is a performance icon, and like many enthusiasts, you might be considering injector upgrades to maximize its potential. Understanding the nuances of 300zx injectors is crucial to ensure compatibility and proper engine performance. Let’s break down the injector types and what you need to consider when upgrading your 300zx twin turbo.
Nissan utilized side feed injectors in the Z32, manufactured by JECS. There are two main styles: early and late. Early Z32 models featured a square plug type, while later models transitioned to a square oval shape. The exact date of this change can vary between Twin Turbo (TT) and Naturally Aspirated (NA) models. For most Z32s, especially earlier models, you’ll likely encounter the early type injectors.
Within the early style injectors, there are further distinctions:
- Early NA 300zx: These models came with red square topped injectors, rated at 270cc.
- Early Twin Turbo 300zx: These are equipped with purple square topped injectors, rated at 370cc. Over time and heat exposure, these purple tops often fade to a chocolate brown color.
Later specification injectors maintain the same color codes and sizing as their early counterparts. However, they are not a direct drop-in replacement for early models and require an adapter kit for proper installation.
Regarding R33 Skyline injectors, certain R33 models also used the late-style 370cc side feed injectors, identical to later Z32 injectors. These can be used with the adapter kits in earlier Z32s. However, GTR models and R34 Skylines utilized top feed 440cc injectors, which are significantly more complex and costly to retrofit into a Z32. It’s also worth noting that some factory Subaru vehicles used square oval side feed injectors in 440cc and 550cc sizes, which could be considered with appropriate adapters and tuning.
Crucially, any change to your injector size necessitates recalibrating your engine’s fuel management system. Simply swapping injectors, especially to a larger size like 555cc R33 injectors as mentioned in the original question, without proper tuning will lead to an incorrect fuel mixture and potential engine damage.
To manage the increased fuel flow from larger injectors, you’ll need to remap your ECU. This can be achieved in a couple of ways:
- Chipped and Socketed ECU with Off-the-Shelf EPROM: This involves modifying your factory ECU to accept a chip (EPROM) pre-programmed with a generic tune for larger injectors. While less expensive, this is not ideal for optimal performance.
- Custom ECU Remap (Preferably with Nistune): A custom tune tailored to your specific car and modifications is always the best approach. Nistune boards can be installed into your stock ECU, making it much easier for tuners to adjust the fuel and ignition maps precisely. Many tuners are hesitant to work with the completely stock Z32 ECU, making Nistune a highly recommended upgrade for tuning.
In conclusion, while R33 370cc injectors (late style) can be adapted to fit early 300zx twin turbos, and larger injectors are an option, proper ECU tuning is absolutely essential. For the best results, consider a Nistune setup and a professional tuner to ensure your 300zx twin turbo runs reliably and performs optimally with any injector upgrades.
