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Top Engine Swaps - Motivational Therapy
Exploring the possibilities and necessities of Mustang engine swaps
It’s tough to think of anything that says “hot rod” more than an engine swap. Since the very beginning, guys have yanked out old, slow engines and replaced them with the newer and faster variants. It’s an activity that is almost guaranteed to give more speed and personality to the home-brewed vehicle.
Today the impetus to swap engines remains the same. The Coyote V-8 in particular is the popular kid in school. Like slipping Kate Upton into anything from a mud puddle to your hot tub, it has the near magical ability to make almost any Mustang better.
As we’ll belabor in a minute, engine swaps are a lot of work, and can offer more than their share of Excedrin moments, so before getting bogged down in warnings we should say there’s nothing quite like building your own beast. An engine swap has the ability to change the entire personality of a car that may have grown stale or been beaten out by new technology.
But most of all, an engine swap is a really cool way of getting down with a car and making it yours. Such a fundamental change as a different engine means you can really get creative in how you want the car to look and feel. This is especially true with the time-honored tradition of adding cubic inches, such as a 351W in a Fox or a 5.4 in an SN-95. With more displacement comes an inherent torque hit that’s satisfying to drive. There’s little better than putting the pedal down on some serious cubes—stuff happens right now, with no waiting for rpm or boost.
Put a Coyote in a Fox or SN-95, hang a 351W in a Fox or update a V-6 to a V-8
It’s fun going the other way, too. Moving from a slow-turning pushrod engine to a modern revver like the Coyote can be like getting off the tractor and into a sports car. The new engines have a ripping urge that’s a real giggle to tickle, especially when backed up by a little more rear axle gearing. And as an ego stroke, engine swaps are instant credibility wherever car people hang, too. It’s a definite step up from bolt-ons because you earn your technical stripes with a swap.
In the end, we think the lure of an engine swap is putting a different feel or personality into your car. Sometimes it’s all about the performance, but at least as often you can go as fast with a blower or nitrous for much less money and effort. But lots of people have bolted on blowers; you can end up with something completely different with an engine swap. And later on you can add a blower.
So, swaps are cool stuff, but they can be big work. To avoid getting in over your cylinder heads, stick to the beaten path of common engine swaps. This is especially true if you’re a first-time engine swapper. Put a Coyote in a Fox or SN-95, hang a 351W in a Fox or update a V-6 to a V-8. This will give you the guidance and parts you need without sending you too far out into custom car purgatory where every bracket is handmade and all wiring custom.
Be careful when considering the more involved and physically larger engines. The Terminator 4.6s and GT500 5.4s are good examples of fabulous engines with numerous complex systems and heat rejection issues to contend with. Ford had a tough enough time getting all the radiators and coolers in the GT500, and you aren’t going to have it any easier trying to stuff them into the much smaller Fox (We’ve done it and we know). The end results of such big-engine/small-car marriages are stupendous, but they are far too complex and expensive for the neophyte.
If you aren’t a serious enthusiast with a barn full of tools, time, and social lubricant, then at the least consult thoroughly with the shop you will be working with before writing checks or cutting metal. Listen to advice and note that the smart way might be adding a power adder to the car you already have, or possibly even selling your current project for a different car. It may seem more expensive at first, but we’ll bet it isn’t once all the bills are paid.
If you’re intrigued by a swap, have done you homework, and it looks like it will work out, then go for it. There will be a few stumbles along the way, but you’ll learn a lot, and in the end, that’s the best part—oh, and you’ll go faster and have a cool car, too.
Coyote Into Fox/SN-95
Taking top billing on the Ford engine swap scene is the Coyote-to-Fox transformation and there’s no mystery why. The engine is excellent and available, and the classic Fox chassis is many hundreds of pounds lighter than the bloated S197 the Coyote is naturally found in.
Coyote/Fox marriages are excellent performers, with a modern, revvy feel. There’s no immediate need to hot rod the Coyote engine as it has 412-420 horsepower out of the box and plenty of torque (390 lb-ft) to move the sly Fox with authority. Choosing the SN-95 does mean adding around 150 to 200 pounds of extra weight, depending on the cars being compared, but it’s still lighter than the S197 and a little stiffer in the chassis than a Fox.
Adding a power adder makes things better in a straight line, but for an all-around driver, we prefer to preserve the Coyote’s light all-aluminum vibe in naturally aspirated form. But don’t let our tastes stop you! A power-adder Coyote Fox sounds like mega-fun, too.
Three-Valve Into SN-95
If it weren’t for the Coyote, the 300hp Three-Valve ’05-’10 Three-Valve Mustang GT engine would be the hottest Ford swap going. This is still a great engine with far better performance than the ubiquitous Two-Valve fodder in ’96-’04 Mustangs. It’s lighter, more powerful and best of all, nearly a drop-in replacement for aging Two-Valve Mustang GTs.
Three-Valves are an especially good swap for the anemic ’96-’98 Two-Valve GTs because the Three-Valve can add almost 100 hp to these under-powered Mustangs. Even the Performance Improved ’99-’04 GT’s gain about 40 hp with a Three-Valve replacement, which is a bump you can feel. And, if the budget allows, the Three-Valve is a great blower motor; you’ll really enjoy the rowdy torque and top-end charge a simple positive-displacement supercharger puts into these engines. In our September 2009 issue we reported on the ’10 GT Ford Racing built as a demonstrator with a Whipple and just 5 pounds of boost. With 400 hp, 400 lb-ft, and 3.73 gears it was a riot. More importantly, it’s something the average enthusiast can aspire to—and build himself as paychecks allow.
When sourcing a Three-Valve, make sure you get a Mustang GT variant with an aluminum block, and not the iron block version from the Explorer and Explorer Sport Trac. In any case, Ford Racing doesn’t carry these engines, so they are wrecking yard parts these days.
Today Logan Motorsports owns the Three-Valve swap market (see Do The Math, p. 91) with its complete swap kit at $1,499 in standard form or $1,899 with an SCT tune. Logan says ’96-’98 owners need a $499 fuel-rail conversion kit, and because their kit does not support the Charge Motion Runner Control operation you can either buy CMRC delete plates or let Logan modify your CMRC plate for $100 on an exchange basis.
Another resource is Ron Francis Wiring (www.ronfrancis.com), which just released both full-car wiring kits and engine/transmission wiring harnesses for Three-Valves. These harnesses will set you back about $950 to $1,000 depending on the transmission, but they’re a lifesaver if all you have is an engine and no donor car. They also have full Fox-chassis wiring harnesses.
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SOHC 5.4 Into New Edge
Here’s a swap that requires almost nothing from the aftermarket, so there is no kit or shop championing it. Instead, this is a way of adding torque to a ’99-’04 Mustang GT using a wrecking-yard Two-Valve 5.4-liter from an F- or E-Series truck or van or Expedition. Key to this swap is keeping the cost of the 5.4 engine low, as a Three-Valve is likely a better choice because it fits better, is more sporting, and has greater hot-rod potential.
The Two-Valve 4.6 and 5.4 engines are similar enough that the biggest issue is likely hood clearance from the taller and wider 5.4. Items needing attention are to swap the Mustang oil filter/lower radiator hose mount onto the truck 5.4’s block if the truck engine has a remote-mount oil filter. It’s a simple bolt-on swap using stock O-ring gaskets.
The 5.4 oil pan should be replaced by the Mustang’s 4.6 pan to clear the chassis. It may be necessary to bend down one oil control baffle in the pan to clear one of the 5.4’s rod bolts, but otherwise the pan is a bolt-on swap. The dipstick tube will need minor bending and a new hole drilled in its mounting tab to clear the Mustang exhaust manifolds. The H-pipe will also require significant modification to reach up to the manifolds, which will be higher in the chassis.
Flywheels and flexplates are mainly interchangeable (they are not balanced to the crankshaft) as long as you have the eight-bolt pattern (all 5.4s are eight-bolt cranks). Automatic applications must use the 4.6 flexplate as it has a closer torque converter bolt pattern.
Then there is hood clearance. You’ll want to run the Mustang intake manifold to position the throttle body, throttle cable, and so on, and that means fitting intake adapter plates (Professional Products is one source of these) between the 5.4 heads and 4.6 intake. This, and the taller 5.4 engine mean the throttle body ends around 21⁄2 inches taller than stock, necessitating removal of some of the stock hood bracing, or a taller aftermarket hood.
Because you’re swapping in a truck engine with torque cams, don’t expect the 5.4 to be a screamer. It’ll definitely heave harder below 4,250 rpm, but in stock tune it will fall off compared to the 4.6 after that. Tuning and hot rodding the 5.4 has definite potential, but you’d likely do as well for less money/hassle with a freshened and hopped up 4.6, too. Keep it cheap and daily driver easy and this one can be fun.
351W & Clevor Into Fox
Slipping a 351 in the place where a 302 resided is the classic Ford performance engine swap. It offers the big-bicep torque hit that’s fun to drive on the street, and these days 351s can be built big with way over 400 cubic inches if too much is just right. We don’t have the room to detail installing a 351 pushrod in a Fox or SN-95, but that’s OK because this time-tested exchange is one of the best documented, best-supported engine swaps going. It’s an easy to moderate swap depending how crazy you get with the 351 and how many of the 5.0 parts you’re trying to pinch pennies with; 20 years on in the Fox’s life we’re assuming you’re contemplating new everything from engine mounts to a fully dressed 351. So let’s examine the personality of this swap and hit the mechanical highlights as an introduction.
Addressing the 351W, this swap offers cubic inches for either satisfying street torque or big power at the track. It’s also a more durable engine, physically stronger than the 302/5.0 pushrod mill and a less-expensive swap than a Coyote (probably).
Of course, the main Windsor advantage, and the real reason to perform this swap, is to gain displacement. The 351 offers the most cubic inches possible in the light Fox and SN-95, short of the old 460 big-block. The 460 swap had its moment 25 years ago, but it’s too big and heavy to work even at the dragstrip. Besides, a 427ci 351W fitted with a blow-through centrifugal supercharger and carburetor will zoom past 1,100 hp, and we can’t help you if you think you need more than that. Back in the real world, naturally aspirated 392 or 408 Windsors are tough customers and a blast to drive.
Highlights of this swap are the need for a rear-sump oil pan and pickup, 351 swap headers, and a taller hood. We also highly recommend the Maximum Motorsports swap-specific K-member to offset the 351’s weight, give header and starter clearance, and improve the handling.
This is just the beginning of the parts list, as the taller and wider 351 cannot use the 5.0 HO’s intake manifold, fuel rails, A/C and power-steering brackets, distributor, and so on. But assuming you have a dressed 351, the engine mounts fit the Fox/SN-95 chassis and the oil pan, K-member, headers, and hood are the main players. For more details and one of the best explanations of this swap, see www.mustang50magazine.com/techarticles/18818_351w_engine_swap/.
Everything about the 351W swap is applicable to the Clevor (or 351C) swap, except until recently the headers and intake manifold were issues. Now Hedman offers a swap header for 351 2V Clevelands in a ’79-’93 Fox (works with 351W, too), and Trick Flow has an R-Series lower intake for fuel injected Clevors.
Hanging a PS pump on aftermarket Cleveland heads is an issue, and manual steering is the usual solution. Use an all-steel lower steering shaft from Maximum Motorsport. Alternately UPR Products offers an entire front-end kit (K-member, control arms, steering rack and so on) for the Clevor Fox swap.
This is not the least expensive swap—the 351W would cost a little less—but it offers superb high rpm performance for a track car. There’s a bit more information on the Clevor Fox swap at www.mustang50magazine.com/techarticles/m5lp_1206_engine_swap_guide_heavy_rotation/.
Dare to be Different
There are many Ford swaps that make for great bench-racing conversation but aren’t practical for the average guy. Chief of these are putting an ’03-’04 Cobra; ’07-’13 Shelby GT500; or similar hot, heavy, and wide crate engines in anything. We’ve done it in Foxes, and can verify the finished product is a real hoot, but the job is huge and expensive (as in $50,000-plus when done right with some pro help, suspension, paint, electronics, plumbing, and all that).
You can also read about Jerome Shumate’s Fox coupe, which has most of an ’03 Cobra stuffed inside it, at www.mustang50magazine.com/featuredvehicles/m5lp_0604_1992_ford_mustang_lx/viewall.html. If you have Jerome’s skills and a donor Cobra, then you can get the Terminator in a Fox, but it’s a big job and the Coyote option doesn’t look radically different these days yet is far easier and cheaper to accomplish. You can also take a cue from one of the best pro shops that’s done at least two of these swaps and says they won’t do anymore because they are just too involved.
It’s also popular today to consider a 3.5 EcoBoost V-6 swap into a Mustang—we’ve considered it ourselves—and it is sure to be a great all-around performer and a techno wonder. The trouble is the electronics and other support systems, especially a manual transmission, are not enthusiast friendly and those in the know say to wait for the factory to provide something similar in the future.
To date there are some 3.5 EcoBoost engines running in off-road race trucks, but these needed pro-racing aftermarket standalone electronics to function, and that’s far too expensive for any vehicle not making money racing.
Earlier we touched on the 460 big-block. This is one for the displacement fiend (they build nicely to 590 cubes), but today its all-iron construction is too long and heavy even when fitted with aluminum heads. It’s fine for earlier F-Series, but it’s been eclipsed by modern modular’s with power adders.
Decades ago we drove a Ford Ranger with a 5.0 pushrod engine and it was a muscular ride. If you’re a truck guy www.therangerstation.com/tech_library/V8Conversions.html will get you started on this one. We also drove a square Ranger back in the day with a Taurus SHO 3.0-liter V-6 that Ford built as a concept vehicle. Also great fun in an unexpected way, but you’re on your own with everything here, so the pushrod 5.0 is far more practical. There is some buzz and old articles on the SHO Ranger on the web if you’re feeling adventurous.
You might run across a 6.8-liter V-10 modular for cheap and think it’s good swap fodder, but you’ll be happier and faster with a Three-Valve or Coyote, and while it would be a great conversation starter, the physically large 6.2 Raptor engine isn’t factory supported, and again, you’ll go just as fast or faster with a hot Three-Valve or Coyote for a lot less hassle. 5.0
Horse Sense: Because of the automotive doldrums from the mid-’70s to at least the mid-’80s a generation ago the hot swaps were to put old engines in new cars. Thanks to much better engines today the opposite is true. A generation from now will the swaps be pistons for electrons?
Modular to PushrodIt might seem retrograde, but sometimes racers end up putting push-rod 5.0-and 5.8-based engines in ’96-’04 chassis that originally had 4.6 modulars. In that case, Maximum Motorsports says the easy way out is to use its tubular K-members designed for the ’94-’95 Mustang GTs.
In fact, Maximum says when it comes to engine swaps, the K-member is determined by the engine, not the chassis, because the engine mounts are where the biggest changes are. At the chassis end the difference between Fox and SN-95 K-members is in the hole spacing on the two rear-most legs of the K, and Maximum has all the combinations of engine and chassis covered.
Swap Realities- Many first-time swappers find the job more involved than expected, and that’s OK. To be meaningful and provide any growth a challenge has to be a challenge. In no particular order here are some things to keep in mind.
- Physically fitting the engine and transmission is the easy part. The devil is in the electronic and plumbing details.
- Aftermarket parts are a wild card no manufacturer can account for. A kit might fit a stock Mustang, but non-stock parts can change that dynamic.
- Cleaning takes time. When the engine is out is the time to scrub, and you won’t be happy with new, clean engine in an old road-spattered engine compartment. Budget generous time and energy for this.
- Modular V-8s are tall and wide. Moving from vacuum to Hydroboost brakes may be required, especially with Four-Valve engines.
- Steering racks on modular engine cars are 1 inch lower than on pushrod engine Mustangs. You’ll need to lower the steering rack and fit matching spindles when fitting a modular to a Fox or ’94-’95 SN-95.
- Chasing small parts eats up 90 percent of the time. It’s almost always easier to order a complete crate engine, or buy an entire parts car and pick it apart at your leisure
- You’ll need shop space. The car will be apart longer than you think and your significant other will soon get tired of an immovable lump where the Christmas decorations belong, so plan accordingly.
- Custom tuning is necessary for drivability reasons if not also for power. Budget $500-$700 for it.
- Engine swaps commonly occur in higher-mileage cars and what you’re really doing with a swap is restoring and hot rodding. Be realistic when evaluating the brakes, tires and suspension of the recipient vehicle and budget for new gear if necessary.
- New engine accessories are typically needed for older cars. It’s easier to replace the starter, radiator and so on when they’re right in front of you rather than buried in the engine compartment.
- Don’t forget hood clearance.
- A new hood means new paint…
- The 2011 and later Mustangs have more complex computer systems that identify the engine’s VIN number several places throughout the car (notably the instrument cluster module). Swapping computers in these cars can be a no-go proposition or require dealer-only connection to the Detroit mothership.
- So far, EcoBoost engines are a non-starter due to electronic issues. Some of the best pros advise us it can’t be done without factory help at this point.
Ford Racing Control PacksModern engine swapping and hot rod building has quickly come to revolve around Ford Racing Performance Parts collection of electronics, wiring and hardware known as Control Packs. The idea is Ford puts together a package of parts required to get their crate engines up and running in any vehicle. Typically this includes an engine management computer, wiring harness, throttle pedal assembly, oxygen sensors, mass air sensor, and airbox assembly.
The trick is Ford Racing has flashed the computer with slimmed down software and provided a minimal wiring harness to connect the mass air, electronic gas pedal and computer to the engine, so there is little interface with the chassis. That saves many electronic headaches and makes the crate engine/control pack combination portable among chassis.
Control Packs work with FRPP’s crate engines or donor engines from wrecks, and the Control Pack computers can be custom tuned via the usual OBD-II port. They make it easier—or possible in some cases—for folks swapping engines or building street rods, Cobra replicas, and race cars.