Infiniti G35 Engine Explained

The Infiniti G35, a popular luxury sport sedan and coupe, has garnered a loyal following for its engaging driving dynamics and potent performance. At the heart of this automotive icon lies its engine, a crucial component that dictates much of the car's character. However, for owners and enthusiasts, navigating the various engine designations and understanding their nuances can be a source of confusion. This article aims to demystify the engine options available for the Infiniti G35, focusing on the widely discussed VQ35DE, the 'Rev-Up' variant, and the later VQ35HR, while also touching upon engine replacement and the concept of a remanufactured engine.

Understanding the Infiniti G35 Engine Lineup

The Infiniti G35 primarily featured variations of Nissan's well-regarded VQ35 engine. This 3.5-litre V6 engine is known for its smooth power delivery and robust build. However, within the G35's production run, Infiniti introduced key updates that resulted in distinct engine versions:

The VQ35DE (Base Engine)

The 'DE' in VQ35DE stands for 'Dual overhead camshafts, Electronic fuel injection'. This was the foundational engine for the early G35 models. It’s celebrated for its reliability and a healthy power output for its time. This engine typically featured a power output in the range of 280-298 horsepower, depending on the specific model year and market. It’s a solid performer, providing the G35 with its signature blend of luxury and sportiness.

The VQ35DE 'Rev-Up' Engine

Later G35 models, particularly some 2005 and 2006 6-speed manual coupes, were equipped with a modified version of the VQ35DE, often referred to as the 'Rev-Up' engine. This iteration received several enhancements aimed at increasing horsepower and improving the engine's ability to rev higher. Key changes included:

• Revised Camshafts: More aggressive camshaft profiles were implemented to allow for greater valve lift and duration, enabling the engine to breathe more freely at higher RPMs.
• Improved Intake and Exhaust Systems: Modifications to the intake manifold and exhaust system were made to optimise airflow and gas flow.
• Increased Redline: The 'Rev-Up' engine typically had a higher redline than the standard VQ35DE, allowing drivers to access more power in the upper rev range.
• Horsepower Increase: This version often produced around 300-305 horsepower.

Identifying the 'Rev-Up' engine can be tricky, as visual cues aren't always obvious. However, specific model year and transmission combinations are strong indicators. For a 2006 G35 Coupe with a 6-speed manual transmission, it is highly likely to be the 'Rev-Up' variant. If you're unsure, consulting your vehicle's VIN or seeking advice from a qualified Infiniti technician is recommended.

The VQ35HR Engine

The 'HR' designation stands for 'High Revolution'. Introduced in the second-generation G35 (starting around 2007 for sedans and the 2008 model year for coupes), the VQ35HR represented a significant evolution of the VQ35 engine. While still a 3.5-litre V6, it was a substantially redesigned unit with over 80% of its components being new or revised. Key features of the VQ35HR include:

• Shorter Stroke: This allowed for higher revving capabilities.
• Improved Cylinder Head Design: Better airflow and combustion efficiency.
• Dual Intake System: Each bank of cylinders had its own intake manifold, contributing to improved performance and a more aggressive engine note.
• Increased Horsepower: The VQ35HR typically produced around 306-309 horsepower, with a notably more responsive feel and a higher redline than previous VQ35 variants.

The VQ35HR is generally considered an improvement in terms of performance and refinement over the earlier VQ35DE and 'Rev-Up' engines.

Engine Swaps and Compatibility

For G35 owners facing engine issues, the question of engine replacement often arises. Understanding the compatibility between different VQ35 variants is crucial, especially when aiming for a cost-effective solution.

Replacing a 'Rev-Up' Engine

As mentioned, a 2006 G35 Coupe with a 6-speed manual transmission likely has the 'Rev-Up' VQ35DE. If this engine has suffered catastrophic failure, as in the case of the user who experienced an engine flush leading to a blown engine, replacement is necessary. The user in the provided information opted for a JDM (Japanese Domestic Market) 350Z engine, which is also a VQ35 variant.

Can an HR engine be swapped into a 'Rev-Up' G35?

While technically possible, swapping a VQ35HR into a car originally equipped with a VQ35DE or 'Rev-Up' engine is a complex undertaking. It often requires significant modifications to the ECU, wiring harness, engine mounts, and potentially other supporting systems. The differences in sensor locations, engine management, and physical dimensions can make this a costly and time-consuming project, often negating the goal of keeping costs down. It's generally more straightforward to replace a VQ35DE or 'Rev-Up' with another VQ35DE or 'Rev-Up' engine, or a JDM equivalent that closely matches the original specifications.

JDM Engine Considerations

JDM engines, such as those from the Nissan Fairlady Z (350Z), are often a popular choice for G35 owners seeking replacement engines. These engines are typically VQ35DE variants, and some may offer slightly different specifications or higher performance levels depending on the specific Japanese market model. As the user's update indicates, fitting a JDM 350Z engine into a G35 can be done, but it requires considerable effort and technical expertise to ensure all the necessary components integrate correctly with the G35's systems.

What is a Remanufactured Engine?

When an engine needs replacement, owners have several options: a new engine, a used engine, or a remanufactured engine. A remanufactured engine offers a compelling middle ground, often providing a balance of cost-effectiveness and reliability.

A remanufactured engine, like the one described, undergoes a rigorous process to be returned to its original factory specifications, or even improved upon. This typically involves:

• Complete Disassembly: The engine is taken apart down to its bare components.
• Cleaning and Inspection: Each part is thoroughly cleaned and inspected for wear, damage, or defects.
• Machining and Resurfacing: Worn or damaged components are machined to precise tolerances or replaced. This can include boring cylinders, grinding crankshafts, and resurfacing cylinder heads.
• Replacement of Wear Items: Critical wear items such as pistons, piston rings, bearings (rod and main), gaskets, seals, and often valve guides are replaced with new OEM (Original Equipment Manufacturer) or high-quality aftermarket parts.
• Reassembly: The engine is meticulously reassembled by skilled technicians.
• Testing: Many remanufactured engines are tested to ensure they meet performance standards.

The description of a remanufactured engine including "all brand new OEM or upgraded internals including pistons, rings, rod bearings, main bearings, cylinder heads rebuilt, valve job and new valve stem seals, new water pump and includes a full gasket set" indicates a high-quality rebuild. Such an engine, being 'zero miles' with a warranty (like the 2-year unlimited mile warranty mentioned), offers significant peace of mind and a reliable solution for a blown or worn-out engine.

Identifying Your G35 Engine

As the user rightly pointed out, definitively identifying which engine version you have can be challenging. Here are some common indicators:

• Model Year and Transmission: As a general rule, 2003-2004 G35s (and some early 2005s) with either transmission typically have the standard VQ35DE. 2005-2006 6-speed manual coupes are strong candidates for the 'Rev-Up' VQ35DE. 2007+ sedans and 2008+ coupes are almost certainly equipped with the VQ35HR.
• VIN Decoder: Some VIN decoders may provide engine information, though this isn't always detailed enough to distinguish between VQ35DE and 'Rev-Up'.
• Engine Cover: While not always definitive, some engine covers might have subtle differences or labels.
• RPM Gauge: The 'Rev-Up' engine has a higher redline, often visible on the tachometer. If your redline is significantly higher (e.g., above 6,500 RPM), it might indicate the 'Rev-Up'. The HR has an even higher redline.
• Consult a Specialist: The most reliable method is to consult an Infiniti dealership or a reputable independent mechanic specializing in Japanese vehicles. They can often identify the engine by its specific markings or by cross-referencing with Infiniti's service databases.

Frequently Asked Questions

Q1: Does my 2006 G35 Coupe have the Rev-up motor?

If your 2006 G35 Coupe is a 6-speed manual transmission model, it is highly probable that it is equipped with the VQ35DE 'Rev-Up' engine. Automatic transmission models from 2006 typically have the standard VQ35DE.

Q2: Will a VQ35HR engine work in place of my 'Rev-Up' engine?

While it's technically possible, swapping a VQ35HR into a 'Rev-Up' G35 is a complex and expensive modification. It requires significant changes to the ECU, wiring harness, engine mounts, and potentially other systems. It's generally not a straightforward or cost-effective replacement.

Q3: What are the main differences between VQ35DE, Rev-Up, and VQ35HR?

The VQ35DE is the base engine. The 'Rev-Up' is an enhanced VQ35DE with higher redline and slightly more power. The VQ35HR is a significantly redesigned engine with improved airflow, dual intakes, and higher overall performance and revving capability.

Q4: What is included in a remanufactured engine?

A quality remanufactured engine typically includes all new or machined internal components, rebuilt cylinder heads, new bearings, pistons, rings, seals, gaskets, and often new auxiliary components like water pumps. It's essentially a fully rebuilt engine with zero miles, usually backed by a warranty.

Q5: Is it cheaper to rebuild my existing engine or buy a remanufactured one?

This depends heavily on the extent of the damage. If only minor components are affected, rebuilding might be cheaper. However, if the engine block or crankshaft is damaged, a remanufactured engine often provides better value and a more predictable outcome, especially considering the warranty offered.

Conclusion

The Infiniti G35's VQ35 engine family offers distinct variations, each with its own characteristics. Understanding the differences between the VQ35DE, the 'Rev-Up', and the VQ35HR is vital for maintenance, repair, and modification decisions. Whether you're identifying your current engine, considering a replacement, or exploring the benefits of a remanufactured unit, this guide provides the foundational knowledge to keep your G35 performing at its best. Always consult with qualified professionals for specific diagnostic and repair advice tailored to your vehicle.