Ferrari is without a doubt one of the most universally loved car companies on the planet. The Italian firm's history is rich in competition heritage and it uses track dominating engineering that can be traced directly from its racecars to use on its street cars. Really, there’s very little to not like about its creations, whether it’s a vintage 12-cylinder classic or the latest turbocharged V8-powered 488 GTB. However, the company has produced cars that have not been as universally loved as others.
One example that springs to mind is the ‘70s-era 308 GT4. Personally, we've always been fans of the GT4’s sharp, angular styling that flies in the face of more curvaceous Ferraris like the swoopy Dino of the early ‘70s and the lithe and pretty 308 GTS and GTB that came later. Thanks to a relative lack of appreciation by the majority of Ferrari buyers, for decades the GT4 was one of the biggest bargains around and one of the easiest ways to get into Ferrari ownership on a budget. For a long time, even the best GT4s had a hard time cracking the $30,000 or $40,000 barrier. Of course, those days are over. The red hot classic car market means that GT4s are going up in value along with all of the other vintage, V8 Ferraris. As the saying, goes, a high tide lifts all ships.
Like all cult classics, if you ask a GT4 owner about their car you will hear nothing but praise for the edgy-looking GT4. “I’ve always liked the styling,” says Ed Brown, who owned the GT4 pictured here until 2014, when it sold for a record amount at auction. “A lot of people seem to think that they’re ugly but I love the big windshield and the great visibility. It’s a smooth, fast car and with the carbs makes really good sounds.”
Of course, the reason it’s here on Retromod is because this is no ordinary GT4, but rather one that has been thoroughly upgraded by Carobu Engineering. Carobu specializes in hot-rodding Ferrari’s and Brown’s old GT4 is a perfect illustration of what can result when they upgrade an entry level model like this one.
Brown had owned several Ferraris and numerous other obscure classics before he finally bought a GT4 in 2009, a model that he had coveted for years but had never actually owned. While it was in good shape when he first got it, it started having issues shortly after he got it home. It started with carburetor issues and spiraled from their, culminating in a blown motor that was caused by a snapped valve in one of the heads. The pieces of broken valve ended up punching a hole in the adjacent piston, necessitating a costly engine rebuild.
Carobu’s engine specialist Bert Wehr gave Ed a range of options, from a basic rebuild to the other end of the spectrum, which was rebuilding the motor into a larger displacement and far more powerful3.5-liter. The allure of added performance and drivability was more than Ed could resist, so he went with the more powerful 3.5-liter.
The heart of the conversion is a 78-mm billet stroker crank designed by Carobu that mimics the design of the factory Ferrari crankshafts. It’s 10-lbs lighter than the original GT4 crank. Stock connecting rods are bolted to 85-mm Razzo Rosso pistons contained inside Razzo Rosso liners, all of which produce a compression ratio of 10:1. The heads were fully rebuilt and then ported and polished for better airflow. Higher revving Carobu camshafts were also installed, increasing the engine’s power and willingness to rev.
The standard exhaust headers were retained, the catalytic converters were deleted and an X-Ost Maranello sport muffler was installed. With additional power now on the menu, Ed also upgraded the Ferrari’s suspension for better roadholding. The stock Koni shocks were rebuilt and converted to a threaded body, which allows the ride height to be easily adjusted. The rear swaybar was replaced with a larger bar that reduces understeer and makes handling more neutral.
With a full mechanical rebuild underway, Ed also decided to have the Ferrari resprayed in its original shade of Rosso Corsa. “I thought when my bodyman got into it, he would find all sorts of rust,” admits Ed. “When we sanded it to bare metal though, there was only one, dime-sized bit of rust.” The exterior of the 308 has been sharpened up by tucking the large, U.S.-spec bumper closer to the body. Initially, Ed considered installing much slimmer Euro bumper, but the but the high price steered him away.
In order to tuck the bumpers, small holes were drilled in the hydraulic rams of the bumpers so that the oil inside could be drained out. The bumpers were pushed back 4 or 5 inches with small screws inserted into the rams to keep them in place. The original 14-inch wheels were replaced with more performance oriented 16x7-inch front and 16x8-inch rear wheels from a 308 Quattrovalve. The wheels roll on sticky Bridgestone Potenza RE70 Sport tires.
The GT4’s immaculate interior has an airy and spacious feel that belies the the car's relatively compact dimensions. The instrument binnacle is wide and horizontally laid out, while outward visibility is superior to a 308 GTS or GTB from the same era. Ed had the leather red-dyed and the front seats reupholstered and the results look and feel virtually new. Keeping with the period correct theme is a functioning Blaupunkt Stalk stereo controlling that sticks up next to the driver’s seat. It’s kitschy now, but was state of the art back in the late ‘70s and early ‘80s.
There is also a vintage-looking MOMO steering wheel, drilled alloy pedals and a titanium shift knob. Ed even had a company fabricate a new metal surround for the sunroof handle, as the old, plastic one had crumbled into pieces: “I found a company in Idaho that CNC-machined an aluminum copy of the piece. It took four or five months of back and forth with the company but the results are perfect.”
At idle the 308's engine sounds like most 3.0-liter Ferrari V8s, though there is a slightly deeper tone burbling from the chrome muffler tips. When I blip the throttle I can hear the downdraught Weber carbs brap-brapping as they deliver a cocktail of air and fuel to the motor. The shift action in Ed’s GT4 is particularly nice, snicking into the dog-leg first gear smoothly and lightly. It’s a nice mechanical action that continues for the rest of out drive as we click the metal shift lever up and down through the gears. With 280-hp and 240 ft/lbs of torque at the crank, Ed's GT4 is considerably quicker than a stock example. Peak horsepower arrives at a lofty 6600-rpm, but the generous torque delivered by the additional displacement is one of the party tricks that makes this Ferrari such a beguiling car to drive.
By 3800-rpm, the engine is pumping out over 230 ft/lbs of torque, which peaks at 240 ft/lbs until it begins to taper off a bit at 5400-rpm.. Rather than having to work the engine in the upper reaches of the rev-range for maximum speed, the car is effortlessly quick, all the while producing a soundtrack that is absolutely glorious. The bigger displacement means a deeper sounding engine note, in this case magnified by the sport muffler, which sharpens up the exhaust note. The Weber carbs snort in fresh air as RPMs rise, adding another layer to the mechanical song coming from the tailpipes. Frankly, the motor feels like it will sail happily past redline, so smoothly and eagerly does it pick up revs. Thanks to the Ferrari’s flat, wide windshield the road comes at you in Cinemascope, rushing up to the car as the Ferrari surges forward.
The well-chosen upgrades to the suspension transform the Ferrari’s handling and road holding when the going gets windy. The lower ride height and re-valved shocks along with the stiffer springs reduce body roll as well as squat under acceleration and dive under hard braking. Thanks to their longer wheelbase, GT4’s boast more more predictable handling than the slightly twitchy 308 GTB and GTS models, a trait that has been enhanced in this example. The larger rear sway bar reduces understeer and also encourages the back end to rotate around as we nail the apex and then shriek out of corners on a wave of torque. The plentiful torque makes it easy to steer the car with the throttle, and the chassis’ setup seems to encourage a tail-out style of driving. Combine that with a powerful, high-revving V8 that sounds like a racecar, and well, the results are predictably exhilarating. Ed's investment in the 308 was substantial, but the results were well worth the effort. This really is a vintage supercar in disguise.
Carobu Engineering •www.carobu.com • (949) 378-3226