I think it’s fair to say that the Chrysler Crossfire was an underappreciated car. Its entire production run lasted only five model years, from 2004 to 2008; just 34,000 people bought it in the United States; and Chrysler never made a successor. Still, it was a handsome, re-bodied Mercedes SLK-Class, owing to the then-partnership between Daimler and Chrysler. It’s only fitting that owner Neil Emiro created the ultimate Crossfire by ditching its lowly V6 for a monster 5.5-liter AMG supercharged V8.
The Crossfire is an unusual place to start a sports car build, but that doesn’t make it a bad one. The Crossfire was largely based on the first-generation R170 Mercedes SLK roadster. Chrysler said at the time that it was only 40% SLK under the skin, but it had the same basic chassis, engine, and transmission options, so we can call that the 40% that mattered most. Since it was based on a car designed as a convertible from the beginning, it had superb torsional rigidity even in soft-top spec. It also weighed just 3,084 pounds, offered an optional manual transmission, and sent power to the rear wheels only.
In other words, it’s perfect for a V8 swap.
An AMG V8 wasn’t actually Emiro’s first choice. He was originally going to use a 2.4-liter turbo-four from a Dodge Neon SRT-4 that he built to make 600 horsepower. He had it all laid out—the fitment was mocked out on a Crossfire parts car and he was halfway through fabricating the engine mounts—when he stumbled upon a 5.5-liter V8 from a Mercedes CL55 AMG on Craigslist. Naturally, he immediately bought the hand-built German lump and changed the project’s direction.
Before the AMG V8, Emiro had never worked on a German engine. That wasn’t much of a problem, though, as it came with all the requisite computers and, as an electrical engineer by trade, he could figure out how to make it work. The holdup was the transmission: it didn’t have one. So he fitted the five-speed automatic previously connected to a Dodge Charger’s 5.7-liter Hemi, albeit a heavily modified example. Emiro replaced and upgraded many of the auto ‘box’s internals before fitting it to the AMG V8.
That’s how much of the build went, though. Emiro borrowed Chrysler parts to pair with the AMG, like the power steering pump and an exhaust system from a Crossfire SRT-6, and custom fabricated others. After plenty of tinkering, he got it all working. And it packed a punch, as you can imagine.
The standard Mercedes CL55 AMG makes 469 hp and 516 lb-ft of torque, which was designed to push 4,327 pounds around. The Crossfire, even with the big V8, is about 1,000 lbs lighter at 3,335 pounds. While Emiro doesn’t have any specific figures, as the car hasn’t been on a dyno, the modifications he made are common for that engine and typically yield about 575 hp. He does, however, have his own indication of speed: the active rear spoiler. The Crossfire’s spoiler deploys at 65 mph and, if it isn’t working by the time the car reaches 90 mph, it will trigger a beep inside the cabin to warn the driver of the potentially dangerous lack of downforce. But with the AMG V8, Emiro’s Crossfire was so rapid during initial testing that he went from 65 to 90 mph faster than the spoiler could deploy, sounding the alarm. He didn’t know the reason behind the alert initially, but he was pretty happy once he did.
Emiro’s first long trip with the AMG Crossfire was a 1,250-mile jaunt on the Tail of the Dragon and its surrounding areas. While the car ran without issue, he did notice a few things that needed tweaking. The massive V8’s power and heft were a bit too much for the Crossfire’s front brakes, front springs, and tires. So he fixed that by swapping in bigger brakes from the SLK55 AMG and new KW coilovers. He also exchanged the five-speed automatic for an AMG Speedshift auto with seven gears for quicker, sharper shifts and more optimal ratios, and tossed in a Wavetrac differential. Emiro can even shift via the paddles on the back of the C-Class steering wheel he installed and wired up.
After years of hard work, trial, and error, Emiro’s Crossfire is exactly where he wants it. Not only does he still own it and drive it today, but he regularly takes it on long trips, where it’s proven itself fun and reliable. He recently used it to travel from his home in Florida to Ashville, North Carolina to attend a Crossfire event—500 miles each way.
I love the irony of stuffing a massive Mercedes-AMG engine designed during the DaimlerChrysler era into a Crossfire that was originally built on a Mercedes platform, long after the two companies split. It’s like reuniting two brands to make the most unsuspectingly kickass version of a forgotten sports car—one that represents the ultimate potential the “merger of equals” never quite realized. And it’ll get even better because Emiro is planning a sequel. He already has another Crossfire ready for an engine swap, but this time he’s going bigger. This time, he’s got his eye on the Mercedes-AMG M156 6.2-liter engine, one of the best-sounding V8s of this century. With the lessons learned from the 5.5-liter Crossfire AMG, the next act should be even better and completed even more quickly.
Got tips? Send ’em to tips@thedrive.com