365 GTC/4 Project Car
This Ferrari 365 GTC/4 has been modified by CAROBU Engineering LLC. The modifications include a 5.0 litre C/4-412i hybrid engine, Brembo GT “Big Brake” kit, 17” “Speedline-style” wheels and height adjustable suspension. As the resale prices show, the C/4 is a “sleeper” Ferrari whose image was outshined by the popular “Daytona.” However, the elegant Pininfarina styling, and the steady road manners of the car made it an excellent basis for modification.
365 GTC/4 Background
The front-engined Ferrari 365GTC/4 was introduced to the world at the 1971 Geneva Auto Salon as the replacement of the 356 GT 2+2. The C/4, as it is commonly known, had a distinctive wedge-profiled body designed and built by Pininfarina in Turin. The C/4 body was comprised of welded steel panels and aluminum trunk and hood over a steel frame. The car was in production for 18 months with a production of a mere 500 cars.
The car was powered with a Columbo-based, 4390 cc, 60 degree V-12 engine rated at 320 bhp (DIN) at 7,000 rpm and 318 lb-ft of torque at 4,000 rpm. The engine has an 81mm bore and 71 mm stroke and runs at an 8.8:1 compression ratio. The 4-cam motor is similar to that of the 365GTB/4 Daytona except that it uses a wet-sump lubrication system and fed through 6 side-draft Weber carburetors (38-DCOE-59/60). The wet-sump system utilizes an oil gear-pump sharing its housing with twin water pumps at the front of the engine. The pumps are chain-driven off the crankshaft. Twin oil-filters are mounted in the in the center of the vee. The carburetors are connected to the cylinders through inlet ports positioned between the inlet and exhaust camshafts in order to reduce the height of the engine for fitment under the low-profile hood. Euro-spec C/4s had a single Marelli distributor mounted in the rear of the engine and driven off the right exhaust camshaft. US-spec cars were equipped with dual Marelli distributors on each bank. The engine configuration gives the C/4 engine a beautiful and stately appearance both under the hood and when on an engine stand.
C/4 – 412i Hybrid Engine
The goal of this project was to increase the power and torque of the engine while retaining the balanced character and stock appearance of the C/4. In order to accomplish this, it was elected to install the 5.0 liter engine from the later 412i. The 412i engine is based on the same Columbo block and made an excellent basis for the C/4 project. In stock form, the 82mm bore and 78 mm stroke results in a 4942 cc displacement operating at a 9.6:1 compression. The higher compression of the 412 was possible through the use of Bosch K-Jetronic fuel injection. The 412 engine was rated at 340 hp at 6000 rpm in the original configuration. For this project, the stock carburetors and air boxes were retained.
Heads and Camshaft
In order to design and build a high performance street engine fitting for the grand touring nature of the C/4, CAROBU elected to use its proprietary “hot-street-grind” camshaft, used successfully in the 365 GTB Daytona project car, to control the engine breathing. The lift and duration of the intake and exhaust lobes are the same measuring 0.363” maximum lift and 247 degrees of duration at 0.050”. The camshaft grind provides good torque and power without the drivability issues associated with more radical grinds such as
the “P6” race-grind.
To properly utilize the additional lift and duration provided by the CAROBU camshaft, the intake and exhaust ports were massaged to match the port flows with the camshaft. Computer simulation modeling was used in order to determine the ideal intake and exhaust flow profiles. Figure 1 illustrates the head flow, in cfm at 28” of water, of the intake and exhaust ports for the original 412i heads and for the “ported” 412i heads. The original heads flowed 127.2 cfm at 0.350” valve lift. After porting, the intake port flowed 144.7 cfm, and increase of 17.5 cfm or 13.8% increase over stock. As mentioned above, in order to reduce the height of the engine, the intake port positioned between the intake and exhaust cams and manifold configuration of the C/4 is less than ideal for engine breathing. For comparison, the 365 GTB/4 Daytona project engine, with a more advantageous intake port design, had an intake port flow at 0.350” lift of 168.4 cfm at 28” of water. The exhaust ports of the heads were not ported as the computer simulation predicted that additional exhaust port flow would actually hurt the performance of the engine. The exhaust port flowed 127.9 cfm at 28” of water.
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CAROBU Engineering LLC
130 Solomon Road North
Estancia, NM 87016
Phone
(949) 722-9307
FAX
(949) 722-9013
Email:
tate@carobu.com
