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What Cars Have GT40 Heads? Everything You Need to Know

Published by Dustin Babich on

The GT40 and GT40P cylinder heads are known for their performance improvements in Ford’s lineup, primarily found on certain models of the Ford Mustang, Ford Explorer, and some Ford small block engines in the 1990s. Here’s a comprehensive exploration of these heads, the cars equipped with them, and the impact they have on performance.


The GT40 and GT40P heads became a hallmark of Ford performance in the 1990s, known for their improved airflow and higher performance over standard factory heads. These cylinder heads were part of Ford’s strategy to enhance the power output and efficiency of their V8 engines, particularly in the Mustang and Explorer models. The GT40 heads were initially used in the Ford Mustang SVT Cobra and later found their way into other models, while the GT40P heads were a more refined version with slightly better airflow characteristics and were commonly found on the Explorer.

Key Takeaways

  • GT40 and GT40P heads are sought after for their performance improvements.
  • Originally featured on the Ford Mustang SVT Cobra and later used in other models.
  • GT40P heads are an improved version with better airflow, commonly found on the Ford Explorer.
  • These heads are compatible with various Ford small block engines, enhancing power and efficiency.
  • They are popular among enthusiasts for engine upgrades and swaps.
  • Recognizing these heads involves specific casting numbers and visual features.

Understanding GT40 and GT40P Heads

History and Development

The GT40 heads were developed as part of Ford’s Special Vehicle Team (SVT) Cobra Mustang project in the early 1990s. Their goal was to increase the power output of the 5.0L V8 engine without significantly increasing production costs. These heads offered better airflow, larger valves, and improved combustion chamber design compared to standard heads.

Technical Specifications

The GT40 heads are identifiable by their three-bar casting mark and feature larger intake and exhaust ports and valves. They were made of iron, with some versions in aluminum for the Cobra R models. GT40P heads, marked by a four-bar casting, introduced slightly smaller but more efficiently designed ports and a different spark plug angle for better combustion.

Performance Improvements

Both GT40 and GT40P heads are known for their ability to significantly improve horsepower and torque figures on the 5.0L V8 engines. They are a popular choice among enthusiasts for engine builds and upgrades due to their bolt-on performance benefits.

Cars Equipped with GT40 Heads

Ford Mustang SVT Cobra

The early 1990s SVT Cobra models were among the first to benefit from the GT40 heads. These models saw a noticeable performance improvement, solidifying the GT40’s reputation.

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Ford Mustang GT

Some late model Mustang GTs, particularly from the mid-90s, were equipped with GT40 heads, often as part of a factory upgrade or performance package.

Ford Explorer

The GT40P heads were more commonly found on the Ford Explorer models equipped with the 5.0L V8 engine, especially from 1996 to 2001. These SUVs enjoyed improved engine performance thanks to the heads’ enhanced airflow characteristics.

Performance and Tuning

Enhancements and Modifications

Both GT40 and GT40P heads are popular bases for further modifications, including porting and polishing, to maximize airflow and performance. Enthusiasts and tuners often choose these heads for engine swaps and upgrades.

Compatibility and Swaps

These heads are compatible with a wide range of Ford small block engines, making them a versatile choice for various projects. They are particularly popular in the Mustang community for engine upgrades.

Recognizing GT40 and GT40P Heads

Identification is crucial for enthusiasts. GT40 heads have three vertical casting bars, while GT40P heads have four. Other distinguishing features include casting numbers and the unique spark plug angle in GT40P heads.

The Original GT40 Iron Heads

Ford first introduced GT40 heads on the 1993-1995 Mustang SVT Cobra. This special edition Mustang needed a power boost, and the GT40 heads provided a significant improvement over the standard 5.0L Mustang cylinder heads. You can spot a set of original GT40 heads by the “GT40” casting and the three vertical bars on the front.

In terms of performance, GT40 heads delivered a noticeable increase in power and torque. Their improved airflow characteristics were a substantial upgrade at the time. However, they would later be slightly surpassed in flow potential by their successors, the GT40P heads.

GT40P – The Explorer Variant

In 1996, Ford introduced a revised GT40 head known as the “GT40P.” These were primarily fitted to the 5.0L V8-equipped Ford Explorer and its Mercury Mountaineer sibling until mid-1997. Visually, they have “GT40P” cast in and feature four vertical bars on the front.

Performance-wise, GT40P heads are a fantastic budget option for power gains. They offer a sizeable boost compared to stock 5.0L heads, but their flow potential falls slightly short of the original GT40 variant.

Identifying GT40 and GT40P Heads

Identifying GT40 and GT40P Heads

Telling GT40 and GT40P heads apart is crucial for enthusiasts. Luckily, they have distinct markings:

  • GT40: “GT40” casting + three vertical bars
  • GT40P: “GT40P” casting + four vertical bars

If you’re browsing junkyards or online listings, these visual cues are vital for identifying these performance gems.

GT40 Heads as a Performance Upgrade

Swapping GT40 or GT40P heads onto older 5.0L Ford Mustangs (particularly the Fox Body generation) is a popular performance modification. Remember that you’ll usually need a compatible intake manifold, upgraded exhaust, and potentially other supporting upgrades to fully reap the benefits. With the right setup, you can experience substantial gains in horsepower and torque.

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Are GT40 Heads Worth the Effort?

The value of GT40 heads in today’s world is debatable. With readily available and affordable aftermarket cylinder heads, they might not always be the top-performance choice. However, if you’re operating on a budget or enjoy the thrill of using OEM Ford performance parts, they still hold appeal.


GT40 and GT40P heads offered a noteworthy boost in performance in their era, connecting production cars to a racing legend. While they might not always be the ultimate power solution, they remain interesting pieces of Ford performance history and can be a viable upgrade path for budget-minded enthusiasts.

FAQ: All About GT40 Heads

What’s the difference between GT40 and GT40P heads?

  • GT40 heads were the original version, found on 1993-1995 Mustang Cobras. They generally have slightly better flow potential than GT40Ps.
  • GT40P heads came on some Ford Explorers and Mercury Mountaineers. They are a great budget performance option, but fall slightly short of the original GT40s in terms of maximum flow.

How do I tell if a set of heads are genuine GT40 or GT40P?

Look for the casting marks: GT40 heads will say “GT40” and have three vertical bars on the front. GT40P heads will say “GT40P” and have four vertical bars.

Can I put GT40 heads on any Ford 5.0L engine?

Technically, yes, with the right modifications. Older Fox Body Mustangs are popular candidates for GT40 head swaps, but you’ll likely need a compatible intake manifold, exhaust upgrades, and potentially other supporting parts.

How much power will GT40 heads add to my car?

Gains depend on your specific car and supporting modifications. However, expect a noticeable increase in horsepower and torque compared to stock 5.0L heads, especially on older Mustangs.

Are GT40 heads still a good upgrade option today?

It depends. If you’re on a tight budget, GT40/GT40P heads can offer decent performance gains. However, many affordable aftermarket cylinder heads now outperform them for a slightly higher price point.

Where can I find GT40 or GT40P heads?

Junkyards, online forums, and marketplaces are your best bet. Look specifically for the Mustang Cobra (GT40) or ’96-’97 Explorer/Mountaineer 5.0L (GT40P).

Dustin Babich

Dustin Babich

Dustin Babich

As the passionate author behind, Dustin Babich is a knowledgeable expert in all things automotive. With a deep understanding of car tools, equipment, engines, and troubleshooting techniques, Dustin Babich shares invaluable insights, practical tips, and effective solutions to empower readers in overcoming car-related challenges.

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