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Ford Mustang GT 1996-2004: Engine Swap Information

The Ford Mustang with its modular engine has been a popular platform for enthusiasts and tuners alike. In recent years, various Mustang engine swaps have become a proven and often cost-effective way to increase power levels without sacrificing reliability.

By Joseph Coelho - November 2, 2015

This article applies to the Ford Mustang GT (1996-2004).

The last iteration of the SN95 Mustang GT produced 260 horsepower and 305 lb-ft of torque. While it packed a punch, these power numbers are pretty anemic by today's standards. With the Mustang platform being hugely popular, the aftermarket is thriving with performance upgrades, especially for older models. Although bolt-on mods can allow for a few extra Ponies, anyone looking for moderate to large horsepower gains should consider heavy reworking and strengthening of the engine internals, or an entire engine swap. When adding up costs, most individuals find that an engine swap turns out to be the most cost-effective solution to livening up performance. Fortunately, many aftermarket companies have kits available with all the necessary components to make the swap as easy as possible. This article will give an overview of several popular engines that can be swapped into the SN95 Mustang chassis.

Component Breakdown

PI (Power Improved) Engine

Geared towards the pre-1999 Mustang GT owners, the "Power-Improved" engine can provide a noticeable increase in performance for less than the cost of rebuilding the original motor. For the 1999 Mustang GT, Ford made revisions to the intake manifold and cylinder heads to greatly improve flow and slightly raise the compression ratio. The result was an engine that produced a whopping 55 horsepower more than the Non-PI engine fitted in the 1996 Mustang GT model. While the PI cylinder heads, cams, and intake manifold can be fitted to an older engine, many individuals choose to swap the entire engine instead of sourcing the parts, especially if the original engine has a lot of miles or is due for a rebuild.

Figure 1. 4.6L "PI" engines can be had for $1,000 or less.

3-Valve 4.6L Engine

Another popular engine swap option without breaking the bank is the 3-valve 4.6L V8 engine from the fifth generation Mustang. This all aluminum engine boasts 300 horsepower and 320 lb-ft of torque, which many argue will allow the SN95 Mustang to easily outperform the SN197 Mustang, due to a better power to weight ratio. The popularity of this swap stems from the ability to use the stock headers and all engine accessories. This biggest hurdle is the variable valve timing, which will not function with the stock PCM; however, companies like Logan Motorsports offer a kit to lock the cams in place to allow for trouble-free engine operation. Similarly, a newer model PCM and wiring can be installed to retain the function of the VVT.

Figure 2. 3-Valve V8 for budget minded enthusiasts.

'03-'04 Cobra Engine

Perhaps the favorite engine swap for the Mustang GT is the '03 to '04 Mustang Cobra engine. Coined "The Terminator," this dual overhead cam engine is fitted with an Eaton roots style supercharger, producing nearly 400 horsepower. The best part is that the engine internals, such as the forged pistons and Manley H-beam connecting rods, were heavily strengthened to cope with the forced-induction. With these factory upgrades, larger superchargers have been fitted for increased performance with little effect on reliability. This swap is much more in-depth and typically requires changes be made to the wiring, cooling, air conditioning, and suspension.

Figure 3. Supercharged Cobra engine.

5.0 Coyote Engine

The hot new setup is Ford Racing's 5.0L "Coyote" V8. This normally aspirated monster is the latest from Ford that is meant to compete with GM's LS series engines. While it shares much of the same physical dimensions as Ford modular V8 line, heavy reinforcement of key areas coupled with numerous intake and valvetrain improvements has the output rated at a healthy 420 horsepower and 400 lb-ft of torque. Although it is the most costly, and perhaps most rigorous swap, this new crate engine features a 2-year/24,000 mile warranty and can be bought as a complete kit, which includes a new PCM and wiring harness to aid in making this swap easy as possible.

Figure 4. 5.0L Coyote engine.

Common Questions

How much does an engine swap cost?

The cost of an engine swap greatly varies depending on what level of performance is desired. PI and 3-Valve engines can be found at salvage yards with low mileage for relatively low prices. A swap with one of these engines is fairly straightforward and requires little to no modifications to work. It is not uncommon for owners to spend in the neighborhood of $500 to $2,500 on the swap. This is quite reasonable for engines that can easily support 300 to 350 horsepower with a few bolt-on mods. With higher levels of technology and greater horsepower comes increased costs; thus, the Cobra and Coyote engine swaps are much more expensive. While the engines run approximately $7,500, it is the additional accessories and electronics that drives costs upward. Several owners who have recently converted to the 5.0L Coyote engine claim the entire swap can be completed for approximately $15,000. As the old adage goes, "horsepower costs money, so how fast do you want to spend?"

Can I use my stock PCM?

The PI, 3-Valve, and Cobra engines are all able to utilize the stock Mustang GT PCM for correct operation. While the PI and 3-Vavle engines are nearly "plug-n-play," the Cobra engine may require a a few changes depending on the model year of your car. For an increased cost, plug-n-play Cobra kits are available for owners not wanting to fiddle with any wiring changes. With any of these engines, an aftermarket tune is recommended to dial in the dirvability and increase reliability. The Coyote motor is much more advanced and needs the Ford factory PCM and wiring harness to function correctly. Fortunately, any place that offers the crate engine will typically offer everything needed for the engine to operate.

Do I need to change my transmission?

The PI and 3-Valve engines can utilize the stock transmissions with no problems. The Cobra and Coyote engines can accept a variety of automatic and manual transmissions, including the stock transmissions. If planning any type of performance driving, especially drag racing, it is highly recommended that the transmission/clutch be upgraded to one capable of withstanding the increased power levels that the Cobra and Coyote engines produce.

Do any changes need to be made to the fuel system?

Depending on the power level, stock fuel injectors can be used on PI, 3-Valve, and Cobra engines. It is important to keep an eye on the injector duty cycles for modded Cobra engines and upgrade if necessary. Similarly, the stock fuel rails can be used with little modification to cut costs. The fuel pump will need upgrading in Cobra and Coyote applications. Besides a new fuel pump, a Coyote crate motor will come with the correct fuel injectors and fuel rails, so all that is needed is correct fuel line routing.

I want to go all out with a Coyote swap. How much needs to be changed?

Besides the crate motor, the main components needed for the swap include: wiring harness, PCM, oil pan conversion, alternator kit, power steering pump bracket, exhaust headers, exhaust mid-pipe, engine cover kit, pedal bracket, K-frame, and coilovers. Also, depending on the transmission, a new clutch and proper bell housing may be required. Late Model Restoration claims the swap can be done for as little as $10,000 if you are handy at fabrication and can shop on a budget; however $15,000 to $20,000 is usually the norm.

Figure 5. Coyote engine being swapped into SN95 Mustang.

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