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When it comes to fuelling your Nissan GT-R in New Zealand, you’re faced with an important decision that can significantly impact your vehicle’s performance, reliability, and running costs. The choice between running premium 98 octane petrol or converting to E85 ethanol fuel is one that many GT-R owners in Auckland and across New Zealand grapple with. This article will explore both fuel options in detail, examining the benefits, drawbacks, and practical considerations of each to help you make an informed decision for your high-performance vehicle.
98 Octane Petrol: The Standard Choice for GT-Rs
Premium 98 octane petrol remains the most common fuel choice for GT-R owners throughout New Zealand. This high-octane unleaded fuel is readily available at most petrol stations across Auckland and provides reliable performance for your GT-R straight from the factory. The fuel’s high octane rating helps prevent engine knock and pre-ignition, which is crucial for the GT-R’s twin-turbocharged VR38DETT engine that operates under high compression and boost pressures.
Running 98 octane in your GT-R offers several advantages that make it the go-to choice for many owners. First and foremost is convenience – you can fill up at virtually any petrol station in New Zealand without planning your routes around fuel availability. The fuel quality is consistently regulated and monitored, ensuring your engine receives clean, reliable fuel every time you fill up. Additionally, your GT-R’s engine management system is factory-tuned for 98 octane, meaning you’ll achieve optimal performance without any modifications required.
From a maintenance perspective, 98 octane petrol is gentler on your engine’s internals compared to ethanol-based fuels. It doesn’t have the corrosive properties of ethanol, which means fuel system components like injectors, fuel pumps, and fuel lines will typically last longer. This translates to lower maintenance costs over the long term and fewer unexpected repairs related to fuel system degradation.
E85 Conversions: Unlocking Extra Performance
E85, a fuel blend containing approximately 85% ethanol and 15% petrol, has gained popularity among performance car enthusiasts in Auckland and throughout New Zealand. For GT-R owners seeking to extract maximum performance from their vehicles, E85 conversions offer compelling advantages. The fuel’s inherently high octane rating (typically around 105-108) allows for more aggressive ignition timing and increased boost pressure, resulting in significant power gains.
The cooling properties of E85 are particularly beneficial for turbocharged engines like the GT-R’s VR38DETT. As ethanol evaporates, it absorbs more heat than petrol, leading to lower intake air temperatures and reduced engine temperatures overall. This cooling effect can help prevent detonation and allows tuners to push the engine harder while maintaining safe operating temperatures. Many GT-R owners who’ve converted to E85 report power gains of 50-100 horsepower or more, depending on supporting modifications.
However, converting your GT-R to run E85 isn’t as simple as just filling up with the different fuel. The conversion requires several modifications to ensure proper operation. You’ll need larger fuel injectors to accommodate E85’s lower energy density – typically 30-40% more fuel flow is required compared to petrol. The fuel pump may also need upgrading to handle the increased fuel demand. Most importantly, a proper ECU retune is essential to adjust fuel maps, ignition timing, and boost control strategies for E85’s unique properties.
Cost Considerations and Fuel Economy
When evaluating fuel choices for your GT-R, cost is often a major factor. While E85 is typically cheaper per litre than 98 octane petrol in New Zealand, the overall running costs tell a different story. E85 contains less energy per litre than petrol, meaning your GT-R will consume approximately 25-30% more fuel when running E85. This increased consumption can offset the per-litre savings, especially if you do a lot of daily driving.
The initial conversion cost for E85 can be substantial. Quality fuel injectors suitable for E85 use can cost several thousand dollars, and a professional retune from a reputable tuner in Auckland will add to the expense. You’ll also need to factor in more frequent oil changes, as E85 can dilute engine oil more readily than petrol, potentially requiring oil changes every 5,000 kilometres instead of the standard 10,000-kilometre intervals.
For GT-R owners who primarily use their vehicles for weekend drives or track days, the performance benefits of E85 might justify the increased running costs. However, if your GT-R serves as a daily driver covering significant distances around Auckland, the fuel economy penalty could result in substantially higher annual fuel costs compared to running 98 octane.
Availability and Practical Concerns in New Zealand
One of the biggest challenges facing GT-R owners considering E85 conversion in New Zealand is fuel availability. Unlike 98 octane petrol, which is available at virtually every petrol station, E85 availability is limited to select Gull stations and a handful of other suppliers. In Auckland, you’ll find several E85 pumps, but availability becomes scarce as you venture outside major urban areas. This limited availability can significantly impact your driving experience and travel plans.
The inconsistent ethanol content in New Zealand’s E85 supply presents another challenge. Unlike some countries where E85 maintains a consistent 85% ethanol blend year-round, New Zealand’s E85 can vary seasonally, with ethanol content sometimes dropping to 70% or lower during winter months. This variation requires either frequent fuel testing and ECU adjustments or a conservative tune that sacrifices some performance to maintain safety across different ethanol concentrations.
Storage considerations also come into play with E85. Ethanol is hygroscopic, meaning it absorbs moisture from the air. If your GT-R sits for extended periods without being driven, the E85 in your tank can absorb water, leading to phase separation and potential engine damage. This makes E85 less suitable for GT-Rs that aren’t driven regularly or are stored during winter months.
Long-term Engine Health and Reliability
The impact of fuel choice on your GT-R’s long-term reliability is a crucial consideration. While 98 octane petrol is proven to be safe for extended use in the VR38DETT engine, E85’s effects on engine longevity are more complex. The increased cooling and knock resistance of E85 can actually improve engine reliability when the tune is conservative and the fuel system is properly upgraded. Many motorsport teams successfully run E85 in competition environments where reliability is paramount.
However, E85’s corrosive nature can accelerate wear on certain components. Fuel pumps, injectors, and rubber fuel lines not specifically designed for ethanol use may degrade faster. The fuel’s tendency to wash oil from cylinder walls can increase wear on piston rings and cylinder bores, particularly during cold starts. Regular oil analysis and more frequent maintenance intervals become essential when running E85 to monitor and mitigate these potential issues.
For GT-R owners planning to keep their vehicles long-term, sticking with 98 octane petrol might be the more prudent choice. The proven reliability, lower maintenance requirements, and widespread parts compatibility make it easier to maintain your GT-R’s value and reliability over many years of ownership.
Making the Right Choice for Your Driving Needs
The decision between 98 octane and E85 ultimately depends on your specific needs and priorities as a GT-R owner. If you primarily use your GT-R for daily driving, value convenience, and prefer minimal modifications, 98 octane petrol is likely your best option. It provides excellent performance, widespread availability, and proven reliability without the need for expensive conversions or frequent maintenance.
Conversely, if you’re chasing maximum performance for track days or motorsport events, and you’re willing to invest in proper modifications and increased maintenance, E85 conversion can unlock significant power gains. The key is ensuring the conversion is done properly with quality components and professional tuning to maintain reliability while extracting the performance benefits.
Some GT-R owners in Auckland have found a middle ground by setting up flex-fuel systems that can run both 98 octane and E85. These systems use ethanol content sensors to automatically adjust tuning parameters based on the fuel in the tank, offering the flexibility to use whatever fuel is available. While more complex and expensive initially, flex-fuel setups provide the best of both worlds for owners who want performance when needed but convenience for daily use.
Need Help With Your GT-R Fuel System and Tuning?
Choosing the right fuel for your GT-R is just the beginning – proper servicing and maintenance are essential regardless of whether you run 98 octane or E85. At Dodson Motorsport in Auckland, we specialise in servicing high-performance Nissan GT-Rs and can help you make the best fuel choice for your needs. Our experienced technicians understand the unique requirements of both fuel systems and can ensure your GT-R performs at its best while maintaining long-term reliability. Contact our team today by calling 09 441 3635 to discuss your GT-R’s fuel system needs and book a comprehensive service.