No matter what kind of engine lurks beneath the hood of their car, every driver feels the need for more power at one point or another. Sometimes the morning commute is the wide open road and some blissful canyon corners; other times, the evening commute is stop-and-go traffic and that yellow light that's about to turn red for the fourth time. Sports cars, pickup trucks, economy commuters—it makes no difference because in the world of motoring, more is better. Every automotive manufacturer in the world has spent billions of dollars trying to get their engines to produce more horsepower, more torque, and better fuel economy. Unfortunately, the pressures of research, development, engineering, and sales means that those manufacturers have to bow to the will of the consumer, most of whom can't afford to shell out for million-dollar supercars on a whim.
Updated February 2022: If you're planning to do an engine swap, you'll be happy to know that we've updated this article to provide you with some more inspiration for your own project.
And so, most cars built in the factories around the world feature engines with the smallest displacement, the best fuel economy, and the cheapest materials possible. As a result, the vast array of cars available on the market just don't cut it for the gearheads out there. While some end up struggling with keeping their old clunker alive just to hear that V8 keep roaring, others are lucky enough to have the time, knowledge, and funds to drop serious power into a car that left the factory severely lacking. But not every engine swap is done right. Despite all the mechanical genius some of these jobs require, the overall vision just appears to be lacking. Keep scrolling for 10 awesome engine swaps, and 10 that were awful.
20 Awesome: Mini B16 Honda VTEC
The hot hatch segment continues to balloon these days, if not quite as much in the United States as elsewhere. At the very least, VW's Golf R, Ford's Focus RS, and the Mini Cooper S are attainable these days (though the Focus is on its way out). And while all three models have been around for a long time, the Mini has the dubious honor of being both the oldest, and the one that utilizes front-wheel drive (the Clubman and Countryman don't count, sorry).
Classic Minis may have been fun and cute, and they even enjoyed a tiny moment of rallying and motorsport success, but powerful they are not. Luckily, Honda makes some awesome engines that are small enough to fit into the tiny car's engine bay—although the turbo clearly didn't. The questionable aesthetics are worth it through to get around 360 horsepower, though.
19 Awful: AMG V8 Mercedes-Benz
Classic Mercedes-Benz rides come in two forms; the brand has made some amazing sports cars and a large number of bricks that will run forever. Luxurious cruising was the name of the game for Mercedes, and sometimes eternal life for diesels, though the company has lately been going buck-wild with their AMG products.
After the SLS and SLR brought the original Gullwing's style back to life, AMG has continued to crank out some seriously impressive engines. The only thing holding Mercedes back now is that their cars still weight far too much and never come with stick shifts—so swapping a modern AMG V8 into a classic Mercedes like this one makes no sense, as it's still going to weigh way too much and its transmission almost certainly can't handle all that torque.
18 Awesome: Ford Boss 5.0 E92 M3
BMW broke the hearts of many fans worldwide with the debut of the E90 generation of their M3 sports car. After the legendary E30 and its potent inline-four, then the successful inline-sixes of the E36 and E46, the step up to a V8 did seem a bit unavoidable. And still, the purists cried, "Heresy!" Until they actually drove the car, that is, when they could enjoy a wailing V8 that revved up to 8,400 RPM and produced up to 444 horsepower.
Of course, the M3 has always suffered from a spate of reliability issues, so some maniacal genius decided to remedy the situation by dropping a Ford Boss 5.0 V8 into their car for a bit more good-old Detroit beef.
17 Awful: Porsche 968 Rotary
Porsche's debut of their front-engined, water-cooled touring cars in the late 1970s scared plenty of fans away from the brand. After so many years of rear- and mid-engined sports cars, a touring car from Porshe just didn't seem right. But what's even worse is that someone had the gall to drop a rotary engine into this 968.
Porsche worked for years to make their front-engined cars some of the nimblest on the market—and even hardcore snobs have to admit that cars like the 928 and 944 offer some of the best bang for the buck on the used car market today. But please, no rotaries, these cars have enough trouble staying running on their own.
16 Awesome: Hennessey VelociRaptor V8
No one doubts the supremacy of Ford's F-150 SVT Raptor. Years later, the pickup truck market still hasn't caught up with the Raptor's combination of power, style, and off-road performance. But leave it to the crew over at Hennessey Performance in Texas to take Ford's product and give it a one-up.
Actually, given that Hennessey had already released a souped-up, six-wheel-drive VelociRaptor, perhaps, in this case, their move is a double-up. The only problem with the Raptor was that it had an EcoBoost V6 rather than a solid V8, but Hennessey went ahead and fixed that for all the V8 purists out there who needed 758 horsepower, instead.
15 Awful: M104 Gullwing
The fact that there are wild men out there willing to take a million-dollar car and mod it up enough to enter insane events like hill climbs and salt flat speed runs helps keep a smile on every gearhead's face. Not many will ever get to see a Gullwing in person, much less ever sit in one—and approximately zero percent will ever drive one with a Roush-customized M104 engine putting out 427 horsepower.
Actually, that zero percent is a rounded-down figure because one man is doing it. Bob Sirna has routinely taken this Gullwing to the limit, and his latest team-up with Roush has left this Gullwing in an undeniably bittersweet status of being attractive yet definitely Frankensteined.
14 Awesome: Mid-Engine VR6 VW Pickup
After the Beetle, Volkswagen's most famous car is the Golf. Tuners love the GTI, high-end buyers still clamor after the Golf R, and daily drivers love every iteration of the small hatchback. But Volkswagen also made a Golf-based pickup, known as the Caddy, that offered a bit more utility (if not a single bit more power).
Now, swapping a VW VR6 motor into the tiny Caddy's engine bay would have been quite a feat. But one engineer got around the problem by mounting the larger powerplant in a mid-engine layout. Now, this Caddy has enough power to actually haul more than three sheets of plywood; unfortunately, there's nowhere for the plywood to go anymore.
13 Awful: Chevy Nova turbo 13B Rotary
What was so wrong with the Chevy Nova that one owner couldn't help but drop in a rotary engine and try to up its horsepower while cutting weight? The recipe of increasing output while shaving pounds has been a solid guiding star throughout the history of motoring.
And this Nova looks pretty serious with some wide, wide tires working hard on that dyno—but still, the thought of a rotary engine powering one of Detroit's sweetest muscle cars (if if it has been maligned occasionally through its history) just doesn't seem right, especially given that the car survived this long. After all, its rotary engine certainly won't be about to survive another forty years.
12 Awesome: 8.2-liter V8 Porsche Targa
Porshe fans are perhaps the snobbiest of any car brand's followings. They're perfectly happy to spend the rest of the day (or the rest of a lifetime) explaining why every single engineering decision made in Stuttgart is the best possible choice—just don't mention IMS bearings or trailing throttle understeer.
But to prove that there are still some hilarious P-car fans out there, one owner of a 1981 911 Targa went ahead and did the unthinkable. Hanging off the rear axle of his (formerly) 2,800-pound sports car is an 8.2-liter V8 sourced from a 1970 Cadillac Eldorado. The owner reportedly claims that the car is better balanced, though a quick sprint through a tight canyon curve seems in order.
11 Awful: Jaguar E-Type 20B Rotary
The Jaguar E-Type is so legendary that even fans in the United States don't call it by the XK-E name it was marketed with here. It's the "E-Type Jag" and everyone knows it, everyone wants it, and even Enzo Ferrari called it, "The most beautiful car ever made."
In the ideal spec, it comes in that particular Racing Green hue, with a nice V12 purring under the eternally long hood. Talk about classy cars and the E-Type sits at, or near, the top of the heap. What it doesn't do is brap around with a rotary engine, revving to the stratosphere while burning through gasoline and oil seals til judgment day. (Okay, it might do that even with the Jaguar V12 but still, this is pure automotive heresy.)
10 Awesome: S2000 Tacoma
The long line of Toyota Tacoma pickup trucks has maintained its own cult-like following that happens to include just about every sane gearhead on the planet. What's not to love about a mid-sized pickup truck with perhaps the best reliability of any vehicle ever made—not to mention resale value and depreciation curves that are more like flat lines.
The Tacoma has never been a full-on street sports truck, though, even if Toyota occasionally tries with some TRD upgrades. Cue Honda's S2000, another of Japan's most legendary products, and a sports car that once held the title of highest power output per liter of displacement of any engine in the world. Why not marry the two strong lineages? Perfect.
9 Awful: Twin-turbo LSX Miata
The two snails up above is what's left of the hood on this drag-prepped Mazda Miata just look absurd. There's a good chance the twin-turbo and LSX combo that someone dropped into the tiny car may actually weigh more than the rest of the vehicle in its entirety.
Of course, that nose-heavy V8 isn't going to be causing much of a concern about handling in a straight-line strip, but take this Miata to any canyon curves, where a stock version would be happy as a clam, and the result is likely to be exactly what the front of this car screams at the world, "CARNAGE" for everyone involved.
8 Awesome: Mercury Marine Charger
Every fan of The Fast and the Furious knows that Dom's Charger has never seen a set of taillights. But a particular Charger that was featured on Jay Leno's Garage can probably give the best (even the fictionally built) cars of The Fast and the Furious a serious run for their money.
Built by Wisconsin-based tuners, Speedkore, in 2015, the car has been renamed the Dodge Charger Tantrum and features a 9.0-liter V8 sourced from a speed boat that has a pair of twin-turbos bolted on to crank output up to 1,650 horsepower. Because that clearly wasn't enough to earn the Tantrum moniker, the car's entire body has been constructed out of carbon fiber.
7 Awful: 26B Quad Rotor Gallardo
Lamborghini's Gallardo supercar only just barely makes it into supercar territory. It suffers from the same issue as its sibling, Audi's R8, which even more so begs the question as to why it doesn't have a torque-happy turbo paired with its engine and all-wheel drive?
After all, Audi is legendary for turbocharging and even more legendary for Quattro. And yet, both the R8 and Gallardo hit the streets with a V10 that maxed out below 400 lb-ft of torque. Swapping in a 26B Quad-Rotor Wankel is only going to exacerbate the situation, though, with less low-end torque and even worse fuel economy.
6 Awesome: Top Secret V12 Supra
Probably the most famous Toyota Supra outside of The Fast and the Furious, this car should probably be featured in the franchise's next installment. JDM lovers may have driven values for a stock twin-turbo Supra up into the stratosphere, but those cars have horsepower and price tag numbers that are nothing short of laughable compared to the Top Secret V12-swapped Supra.
Built originally by "Smokey" Nagata, the car features a 1GZ-FE V12 from a Toyota Century (the brand's flagship luxury sedan—not available in the States), plus two HKS GT2835 turbos and two separate ECUs to help modulate up to 930 horsepower and 745 lb-ft of torque. Is it a 10-second car? Does it have a top speed north of 220 miles per hour?
5 Awful: BRZ06
Subaru fanboys—and gearheads collectively—lament that fact that the BRZ (or Scion FRS, Toyota 86, or whatever name it will have next) doesn't have a bit more power and maybe some all-wheel drive. But the decision to keep the car lightweight and tossable apparently overcame the urge to give it a potent drivetrain, so one BRZ owner went ahead and fixed up one of the car's shortcomings.
Namely, this BRZ has a V8 engine sourced from a Corvette Z06 stuffed under the hood—it has some balance issues that might slow it down in the corners, but only time will tell whether the straight line acceleration makes up for it.
4 Awesome: LS3 911 GT3
This famous Porsche 911 GT3 hit the web last year to the dismayed concern of every Porschephile this side of the Atlantic Ocean (and only because its Craigslist ad was location specific). The 911 GT3 is widely considered one of the best driver's cars every built, thanks to weight savings, track-focused details, and a naturally-aspirated version of the famed Mezger flat-six engine that produced a bit over 400 horsepower for its 997 generation.
And sure, the low center of gravity of a flat-six sounds appealing, but how about all those wonderful features paired with a 6.2-liter Chevy LS3 V8 scrunched in behind the rear wheels and producing 525 horsepower and a significant upgrade to 485 lb-ft of torque (compared to around 300 for the Mezger).
3 Awful: Turbo Saab B234 Nissan 300ZX
Nissan and Datsun have had great success with their Z-Cars, a series of sport-tourers that have always paired a smooth inline-six engine with a long hood and rear-wheel drive and stick shift options.
In some ways, they're some of the best driver's cars out there, an inspiration that many manufacturers could follow to this day. Exactly what inspired one 300ZX owner to swap a Saab B234 turbocharged engine up under that long hood remains a mystery, though given the spray-painted tow instructional on the front bumper, it seems like that they don't expect to come close to the finish line of a "LeMons" race.
2 Awesome: RX-7 Beetle
The merits of rotary engines can be debated back-and-forth all day. The best bet is just to acknowledge that the concept is great; after all, who wouldn't love an engine that's simultaneously lighter, simpler, and more powerful than a competitor?
But let's not forget the reliability issues and fuel consumption that have rendered the rotary format all but extinct. And yet, for fans of the Wankel design, there's nothing better than swapping a rotary engine into, well, just about anything. A classic VW Beetle is the perfect candidate for a rotary engine sourced from a Mazda RX-7 simply because both cars are hilarious in their own right.
1 Awful: Twin Rotor 13B Golf
So far, this list has mostly focused on engine swap jobs that haven't done too bad much to the rest of the car additionally. Sure, there's some paintwork and the mechanical necessitates required to perform these engineering feats—but it's important to call out the entire world of high-end work that goes into absolutely ruining cars, all-out 100%.
This Golf has received a rotary engine at its rear end. That, in itself, wouldn't be too bad as the Golf is second only the Beetle in worthiness for rotary power. But the rest of the stance and lowering job makes this an absolute travesty.
Sources: Engine Swap Depot, Wikipedia, Supercar World, and Motor 1.