The aftermarket auto parts industry is, according to SEMA, a $31 billion (with a B) a year industry. That’s a lot of carburetors and coil-overs, among other items, that are built and sold on a daily basis. Yet these days money is tight for many people, and a shiny new crate engine is just out of reach for a lot of folks. But there is another way.

Can a dedicated gearhead convert an old, anemic car to a V8-powered monster without spending a dime? That’s what we’re going to find out, as I attempt to swap a V8 engine into my 4-cylinder Mustang…for zero ($0) dollars.

Crazy? Impossible? Dumb? Yes, that sounds about right. And yet if you think about it, it’s not that crazy of an idea. For decades, shade tree mechanics have been repurposing engines, drivetrains, and chassis’s and churning out some amazing hot rods and street machines, often based on what they had lying around.

The proverbial "little old lady" garage-kept Mustang - no dents, no rust and nary a scratch when I first bought it

My Little Pony

What I had lying around was a 1989 Ford Mustang with the 2.3 liter four-cylinder engine under the hood. I bought this 4-banger and immediately drove it across the United States for six-weeks last summer, racking up over 12,000 miles. Since then, it has served as a reliable, if slow, daily driver. The plan has always been to drop a V8 engine into the car when funds allowed for it, which got me to thinking; how little can I spend on an engine swap? Can I do it for the price of free?

To even begin considering the idea of a no-dollars engine swap, I’d have to come up with an entire donor car because, as it turns out, there are a lot of differences between a four and eight-cylinder Fox-body Mustang. Just how different are they? Let’s find out…

The Differences Between the Four-Cylinder and 5.0

While you would think dropping a V8 into a car designed to hold such an engine would be an easy feat, there are a ton of small parts that all add up to make a big difference between the two vehicles, and depending on how involved you want to get, you can swap a whole lot more than just the engine and transmission.

To start with, the four-cylinder and V8 engines have different wiring harnesses and computers, and while they both must be completely removed, swapping these out is no small task even with the engine and transmission out of the way. The wiring is, for many the most intimidating aspect of the swap, but there are other factors to take into consideration too, including the brakes. For example, the four-cylinder Mustang (depending on the year) wears smaller front brakes, usually 8-inch or 9-inch rotors, compared with the 11-inch rotors on the Mustang GT, though the rear drum brakes are 9-inches in diameter for four-cylinder and V8 Mustangs.

That’s not all. The four-cylinder Mustang makes due with a smaller rear-end too, with a 7.5-inch pumpkin versus the V8’s bigger 8.8-inch rear. While the four-cylinder Mustang’s rear end can hold up to a stock 5.0 (at least for a little while), the four-cylinder Mustang’s lack the studs for the V8 Mustang’s quad-shock suspension setup. The spring rates are different as well, to keep the ride height the same between the two different Mustangs.

The only modification to my 4-cylinder Mustang; a chalkboard-covered hood that people *REALLY* like to draw on

What else is different? Glad you asked. While both Mustangs came with the option of a four-speed automatic or five-speed manual, there were actually four different transmission options; a four-cylinder/four-speed auto, four-cylinder/five-speed manual, V8/four speed auto and V8/five-speed manual. To further complicate things, there are three different length driveshafts to account for too. My four-banger Mustang has the terrible A4LD four-speed automatic transmission, and even though I paid almost $2,000 to have it rebuilt a week into my cross country adventure, the transmission is already slipping and acting up again.

This is just the tip of the iceberg too; the fuel lines are on opposite sides of each car (four-cylinder passenger’s side, V8 driver’s side) and the exhaust system setups are a lot different too. Even the speedometer gauge cluster is different, and then there is the body kit, badging, the wheels, shocks, springs, and plenty more. There’s a whole lot of work to be done here before this swap is a done deal.

The 2.3 liter four-banger is a stout motor, all 92 horsepower of it.

Carburetor or Fuel Injection

Faced with the daunting realization that there are a lot of parts that require replacing, I started considering whether or not it might be easier to just ditch the fuel injection altogether and go with a carbureted setup.  There are a lot of ways to go about this swap, the easiest is by putting in a carbureted 302 engine with an automatic transmission. If you’ve got an old 302 engine, the most that’s required is an oil pan, harmonic balancer and dipstick swap. If you’ve got a modern 5.0 with fuel injection, then you need the carburetor, intake, throttle linkage and air cleaner. That’s pretty cut and dried stuff, if you’re not the fuel injection type.

However, I am trying to do this swap for as few dollars as possible, and this is one of those rare circumstances where fuel injection is the cheaper option. Why? A couple hundred bucks for a used carb, a couple of hundred bucks for an intake manifold, and suddenly I am spending money when I really don’t have to. Sure, I could recover some of that money selling off the fuel injection system, but I am also making more work for myself, even though I already have plenty of work to do. So, for now, I will be sticking with the fuel injected setup, which means I need a whole donor car for not a lot of money.

That’s what friends are for.

The deranged donor Mustang that will make the swap work

The Bad Side of Good – My Donor 5.0

While the prices for a complete, running and driving Fox-body V8 Mustang with 100,000+ miles is around $8,000 in my neck of the woods (New England), I was able to find a mostly-complete rusted-out wreck of a Mustang for $500. Amazingly, even with well over 15,000 miles on the (broken) odometer the engine still starts and runs on the first try, and it sounds great through the true dual exhaust setup. The five-speed transmission works pretty damn well too. What’s left of the rest of the car though is in, well, let’s just call it “rough” condition.

The seller liked to regale me with the many times he drove this car drunk, or high, at speeds far in excess of the speed limit, and I’ve no reason to disbelieve him as his friends all have their own stories of beating on this poor abused Mustang. If you look at this car from just the right angle, you can see that it sits at a funky angle, supposedly from some Dukes of Hazzard-style jumping in an effort to elude the local authorities. Proof enough to me that the engine in this car is still pretty stout.

There should be a driver's seat here

Normally, a car like this would only be worth the engine and transmission, and that’d be it, as this Mustang is currently more rust and rot than anything else. For starters, there is a gaping hole where the driver’s side seat should be. Gaping as in, I could stand there, and the car could be lifted up over me and I’d still be standing on the ground. Then there is the rest of the interior, or lack thereof, which was ruined by a leaky sunroof. However, the car did come with a leather backseat that might be sellable, for maybe $50. The dashboard is also in a good way, and that could fetch another $50 on the open market.

The real prize though are the GT-style taillights, which are in mint condition and worth upwards of $150 for the pair on eBay…if they are the right color. Seeing as how black has always been a popular color, I think I’m in good shape there. The only other high-dollar items I can see selling from the donor car though would be the hatchback itself, which could bring around $100 on the open market. Beyond that, you’re talking about nickel and dime stuff, like inner door panels, the steering wheel, and perhaps even the seatbelts.

Real clean work there, Captain.

Unfortunately, most of the fenders and body panels are too rusted, dinged, and dented to be worth much on the market, save for the front fascia, which I will be taking to replace my own crinkled front end. The rear fascia though has been ruined by a (poor) attempt to make exhaust cutouts, the driver’s side door no longer closes, neither the power windows nor locks work, and even the 5.0 badges have seen better days. All that is really left is the scrap value of the car, which should pull in a couple of hundred bucks.

As for my little four-cylinder Mustang, the only items of any worth are likely to be the engine/transmission combo, which will probably be worth no more than $400. I might be able to get $100 for the 7.5″ rear end on a good day as well, though I wouldn’t count on it. The wiring harness and computer might fetch another $100 if I am lucky.

So, on paper at least, this project now looks quite doable. However, as we all know, little things can add up pretty quickly, and I plan on keeping tabs for every nickel and dime I spend on this project, including beer money, nuts and bolts, engine degreaser, WD-40 to remove those stubborn bolts, the cost of towing whatever is left to the scrapyard, etc. etc. And at the end of the day I will (hopefully) be left with a V8 Mustang that cost me nothing more than a few headaches and lots of trips to the liquor store.