CAROBU’S FIRST STEP WAS TO PULL THE ENGINE from the car, after which Wehr began the rebuild. The 4,943cc flat-12’s stock 82mm bore and 78mm stroke were retained, although the original cast-iron liners were overbored 0.5mm to accommodate new forged pistons that raised the compression ratio to 10.2:1. The crankshaft was balanced, then it and the connecting rods were Magnafluxed to make sure they contained no hidden cracks. “The basic 512 BB bottom end is very strong, so no additional modifications were needed,” says Casey.
Wehr next turned his attention to the Boxer’s cylinder heads. These were tested on a Superflow flow bench, and the flow numbers were analyzed using special software. “Most two-valve Ferrari heads are intake-flow deficient,” notes Casey, and this one was no different. Carobu’s solution was to enlarge the intake ports, raising flow from 160 cubic feet per minute to 180, then port-matching the intake manifolds to the enlarged intake ports.
The exhaust ports remain stock, although the exhaust valves were replaced with one-piece Zanzi items. The head and stem of the original Ferrari valves are welded together, a manufacturing process that can lead to the head snapping off—usually with disastrous results.
To select the proper camshaft profile, Carobu relied on its engine-simulation software. “The goal was good mid-range torque and top-end power with street driveability,” says Casey. The computer recommended the company’s Daytona camshaft profile, which features 247 degrees of duration, and a set of these cams were fitted, along with brand-new Ferrari valve springs.
The warmed-over engine exhales through the stock exhaust headers, which were ceramic coated to contain heat and eliminate rust and corrosion. The stock muffler was replaced with a stainless-steel Tubi unit, which sounds and performs better and weighs 40-plus pounds less. The stock radiator made way for a custom aluminum one, trimming another 35 pounds and improving cooling.
When it was tested on Carobu’s engine dyno, the flat-12 handily exceeded everyone’s expectations, even its builder’s. Before the rebuild, the 4.9-liter mill had delivered 364 crank horsepower at 6,500 rpm and 357 lb-ft of torque at 4,000 rpm. After the rebuild, says Jolley, “It blew us all away by producing 468 horsepower and 392 lb-ft of torque!” That’s practically in 512 BB/LM territory—Ferrari rated that competition car at roughly 480 hp.
WHILE WEHR WAS BUSY WITH THE ENGINE, the 512’s chassis and body were sent to Carobu’s paint and body shop. The Ferrari originally left the factory painted black, and had later endured a sloppy respray in red, at which time it also gained the distinctive black-bottom Boxer trim.
Literally hundreds of hours were spent sanding and prepping the bodywork, improving panel gaps and diligently checking and rechecking everything. “Just painting the rear louvers is a lot of work,” says Casey. “You have to pull them off, sand each louver, primer it, sand it again, paint it and then hand buff each louver.”