This engine in this 1971 Ferrari Daytona 365 GTB/4 was rebuilt to Dayton Competition specs and has about 450-hp. Most other mechanical areas were gone through as well, including new brakes and suspension. This is a very well-used car that is driven on track and in road rallies by its owner.
Ferrari 512BBi that packs a punch.
Read MoreEngine Specs:
313 lb-ft of torque @4100-rpm, 325-hp @6700-rpm
Type: V12 DOHC 2v/cylinder
Bore: 82mm Razzo Rosso forged pistons
Stroke: stock crankshaft
Compression ratio: 10.3:1
Cylinder heads: intake ported and matched, nitrided exhaust valves
Camshafts: stock Ferrari camshafts
Induction: 3 Weber 40 DFI carbuetors., rejetted
Exhaust: standard Ferrari headers
Ignition: Pertronix electronic ignition
Suspension: stock rebuilt
Brakes: stock rebuilt
Wheels: stock alloys
Tires:
This 1969 Ferrari 365 GTC was a comprehensive project of restoration and improvement that was performed by Carobu. While historically speaking, Ferrari may be most often associated with sports and racing cars, the company also has a illustrious tradition of designing and manufacturing powerful, high-speed GT cars. The 365 GTC is one such model. Designed for touring more than sport oriented driving, in its day the GTC was just the Ferrari to whisk its occupants down the Autostrada in speed and style, or maybe to a nice dinner or to take in an opera.
This Argento Silver, 1969 example was acquired by its owner in 2005 after a long search for the right vintage Ferrari. The owner had been searching for a 330 GTC, the 365's less powerful predecessor, and had also comparison shopped the later Daytona, also powered by a front-mounted V12. He decided he liked the 330, but wanted a little more power, so decided to locate a 365 GTC. As the 330's replacement, the 365 shared virtually identical bodywork but had more power. It's also far more rare. While there were around 600 production 330s, it's estimated that were a scant 168 365s made in 1968 and 1969.
After driving the car for a period after acquiring it, the owner decided to have the motor rebuilt. It was soon sent off to a well-known mid-western Ferrari restoration shop, where it stayed for longer than was expected. When it was returned, the "new" engine smoked, the transaxle whined and there were a few other alarming issues with the car.
This is where Carobu comes into the picture. In January 2010, the 365's owner approached us about having the poorly running motor looked at. Once the Ferrari was shipped to Carobu, engine builder Bert Wehr ran a compression and leak-down test, the latter of which determines how much air is escaping through the rings and valves. The results showed that neither of these parameters were within spec. The compression was 115-125 psi (should be 150+ psi) and the hot leak-down showed 4-12% (5% is acceptable, over 10% indicates the need for a refresh).
Making matters worse, when the engine was run on our engine dyno, it was well down on power. Once he got over the bad news, the owner instructed Carobu to rebuild the 365's engine, with an eye towards better street performance. This is after all a Ferrari that gets regularly used, so more power and torque would make it an even better driver.
ENGINE BLOCK AND BOTTOM END
The first step was completely disassembling the Ferrari's V12. Since the engine had supposedly been recently rebuilt, the block was closely inspected and then cleaned and honed to clean up the bores. The stock crankshaft and connecting rods, already quite robust in this particular motor, were retained as well. New small end bushings were slipped into the rods as the originals showed signs of wear.
One of the ways that the motor would make more power was by increasing the displacement. In this case, the engine's bore was enlarged, which was accomplished by using Carobu's proprietary 82-mm Razzo Rosso pistons. The custom pistons ensure that the motor's compression ratio is bumped up to 10.3:1, while the displacement is now 4.5-liters, 110-cc over the stock 365's displacement of 4,390-cc. During the previous rebuild, the compression was supposed to have been raised up, but when measured, showed to be only 8.5:1; another reason for the poor performance. To further ensure that the motor would stay tightly bolted together for years to come, Razzo Rosso/ARP hardware was used to bolt the connecting rods to the crank.
HEADS, IGNITION AND FUEL SYSTEM
Once the bottom end of the 365's motor was reassembled, we turned our attention to the remaining mechanical systems. In the process of rebuilding the heads, they were ported for increased airflow (see accompanying chart), which equates to more power and better throttle response from the motor.
The valves were replaced with the correct nitrided type. The valve tips on the cheaper stainless steel replacement valves become damaged by the hardened adjuster tips used on the rocker arms. The use of hardened valve stems greatly reduces the chances of this occurring.
While the motor still uses the stock exhaust manifolds, these were port matched to the heads to ensure optimal flow as spent exhaust gasses leave the engine. In stock form, the 365 utilizes a trio of 40 DFI Weber downdraught carburetors, which in this case were rejetted on the dyno to work with the improvements to the engine. Lastly, both of the 365's distributors were upgraded by replacing the antiquated points setup with a far more reliable Pertronics electronic ignition.
DYNO TESTING
With the engine buttoned up, it was taken into Carobu's engine dyno room, where its increased performance could be verified and fine tuned before it was bolted back into the GTC's engine bay. The changes didn't disappoint, with the newly rebuilt motor putting out 325-bhp (see accompanying dyno graph) at 6,700-rpm and 313 ft-lbs of torque at 4,100- rpm, as measured at the crankshaft.
Engine Specs:
385 lb-ft of torque @4500-rpm, 410-hp @6400-rpm
Type: V12, 365 C/4-412i hybrid
Bore: 82mm
Stroke: 78mm
Compression ratio: 10:1
Cylinder heads: intake ported and matched to manifold
Camshafts: Razzo Rosso "hot street" grind
Induction: 6 Weber 38 DCOE carburetors with 32mm venturis
Exhaust: Razzo Rosso custom headers
Ignition: Black Stallion programmable ignition
Suspension: stock Koni shocks rebuilt for ride height adjustment, 300-lb front, 200-lb rear springs
Brakes: Brembo GT Big Brake Kit
Wheels: 17x8-inch front and 17x10-inch rear Razzo Rosso wheels
Tires: 235/50-17 front and 285/40-17 rear tires
This Ferrari 365 GTC/4 has been specially modified by Carobu Engineering. The modifications include a 5.0 liter C/4-412i hybrid engine, Brembo GT "Big Brake" kit, 17" Razzo Rosso wheels and height adjustable suspension. 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 engine/transmission Ferrari 365GTC/4 was introduced to the world at the 1971 Geneva Auto Salon as the replacement of the 365 GT 2+2. The C/4, as it is commonly known, had a distinctive flowing 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 plan included rebuilding the engine with a "balanced" combination of parts and modifications to produce a strong yet flexible power curve combined with street reliability. The paint/bodywork needed attention too; the front spoiler was smashed and the front and rear lids had bad fits on the right side. The paint was a quickie re-spray over the original factory black color and it looked tacky with various masking errors. Additionally, the "blackout" on the rear deck and door jams was done incorrectly.
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 basic block with raised deck height 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. The 412 engine was rated at 340 hp at 6000 rpm in the original configuration. For this project, the stock C/4 Weber carburetors and air boxes were retained.
Heads and Camshaft
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. 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 @ 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 not improve the low speed torque of the engine. The exhaust port flowed 127.9 cfm at 28" of water.
Induction and Ignition System
Since the K-Jetronic Bosch injection of the 412i would not be adequate for the modifications of the project engine, and to keep with the original character of the C/4, it was decided to keep the 38 DCOE side-draft Weber carburetors, fitted with larger 32 mm venturis. This required some modification of the 412i heads to accommodate the C/4 intake manifolds including plugging the injection ports in the heads. It was also necessary to modify the heads to accommodate the C/4 distributor drives. A Black Stallion solid state electronic ignition kit with programmable ignition timing was fitted. This kit includes a special stock-appearing distributor with Hall-sensor trigger, ignition coil, wiring harness, spark plug wires and a programmable ignition module. The kit allows for a reliable ignition upgrade while retaining a completely OEM-look. Some of the features of the ignition include extreme accuracy in ignition firing, live ignition curve adjustment, in-car switching between two preprogrammed curves, and "soft" engagement rev limiter. With these modifications, the engine has actually become a 365GTC/4 – 412i hybrid.
Short Block
The 82mm bore and 78 mm stroke of the 412i engine was retained resulting in a 4942 cc displacement. Based on the engine simulation modeling, it was decided to increase the compression ratio to 10:1. This would provide increased power and allow for the use of premium pump gas. The engine was equipped with Razzo Rosso forged aluminum pistons. The stock connecting rods were replaced with steel Carrillo rods. The stock Ferrari crankshaft was retained.
Headers and Exhaust
The plan included rebuilding the engine with a "balanced" combination of parts and modifications to produce a strong yet flexible power curve combined with street reliability. The paint/bodywork needed attention too; the front spoiler was smashed and the front and rear lids had bad fits on the right side. The paint was a quickie re-spray over the original factory black color and it looked tacky with various masking errors. Additionally, the "blackout" on the rear deck and door jams was done incorrectly.
The car was also fitted with a Tubi Style under-car stainless steel exhaust , also ceramic coated to match the original parts. It is interesting to note that this particular car was equipped with a modified exhaust system installed by another shop. This modified system eliminated the center muffler/resonators. The muffler/resonator in the OE system and the Tubi system provide additional exhaust tuning resulting in a broader torque band for the engine. Testing of both systems would be done as part of this project. Further discussion of exhaust testing will follow
Dynamometer Testing
Upon completion of the engine build, the engine was tested on the CAROBU Engineering DTS dynamometer in order to break-in the engine, tune the carburetors and set the optimum ignition timing/advance curve and to test the engine performance. Running the engine on an engine dyno is also helpful in that small issues such as oil, and water-leaks can be located and corrected while the engine is out of the car. The CAROBU dyno facility was also designed with the capability of running the complete under car exhaust system to insure proper tuning. Following break-in and tuning, this engine produced maximum power of 410 HP at 6,400 rpm and maximum torque of an amazing 385 lb-ft at 4,500 rpm. This engine makes 90% of maximum Torque by 3,800 rpm. No one can say that this Ferrari lacks low-end torque! By comparison, the original C/4 engine, dyno tested in the "as-received" condition, made 291 HP at 5,300 rpm and 300 lb-ft at 4,900 rpm. Admittedly, the original engine was weak.
As mentioned earlier, this car was fitted with a non original, custom, stainless steel exhaust system. The original Ferrari exhaust, and the Tubi-Style system include a center resonator section that "connect" the front three cylinder with the rear three cylinder exhaust on each side of the motor. This provides a secondary tuning effect providing for a broader power band and increased horsepower and torque. The original "modified" system had deleted the center resonators, thus isolating the header branches. Both systems were tested on the dyno. The Tubi system made nearly 5 HP more at maximum power and 8 more lb-ft of maximum torque. But what is really evident is the improvement in mid-range torque. At 4,100 rpm, the Tubi system produced nearly 45 more lb-ft of torque!
Additional Powertrain Modifications
The additional power of the engine required improved cooling. To increase the cooling capacity, an aluminum radiator was installed. The thermal conductivity of aluminum is almost double that of brass, greatly increasing the ability of the radiator to reject heat. This is a direct replacement aluminum radiator, 100% TIG welded with multi-louvered fins and billet machined fittings. The aluminum radiator also saves 35 pounds due to the lightweight aluminum construction. To improve the responsiveness, the engine was also fitted with a custom lightweight aluminum flywheel mated to a modified Kevlar-lined clutch to take the extra power.
Suspension and Brake Modifications
The guiding design principle at Carobu Engineering is to make modifications that keep the original character and intent of the Ferrari automobile intact, and to make a "balanced" car. In keeping with this principle, CAROBU chooses to use high performance parts from Ferrari O.E. suppliers such as Koni, Brembo or from specialty suppliers such as Tubi-Style that build high-performance exhausts for the Ferrari Racing department. To design a "balanced" car, CAROBU prefers to make improvements in the three aspects of performance - engine, handling and braking.
The engine modifications have been discussed above. In order to address the handling of the C/4, CAROBU upgraded the shocks and wheel/tire combination. CAROBU Engineering in consultation with the owner chose to convert the OEM Koni shocks to height-adjustable shocks. This conversion allowed us to lower the ride height of the car and adjust the spring rates. The stock Konis have adjustable rebound settings allowing for suspension tuning. The conversion utilizes 2.5" diameter racing springs that are available in a variety of spring rates. By choosing the proper spring rate and shock-valving combination for the desired ride-height, the handling of the car could be optimized. Since this car was to be used primarily as a street car, moderate spring rates of 300 lb/in front and 200 lb/in rear rates were used. The car was lowered approximately 1" from stock. The stock shock-valving was retained. Additionally, the stock leveling shocks were cleaned, tested and re-used.
The Razzo Rosso 17" racing wheels were used to provide a good selection of modern high-performance tires and clearance for the Brembo GT brakes. Due to body clearance issues, the wheel sizes were restricted to 7.5" on the front and 8" on the rear. The owner wanted larger wheels sizes, so after driving the modified C/4 for over a year, decided to change the body work to accommodate larger wheel sizes. In the new wide-body version, the wheels sizes are 8" front and 10" rear using 235/50-17 and 285/40-17 Pirelli P-Zero tires respectively. The rear spring rates were also increased to 225 lbs/in to re-balance the handling.
Body and Styling Modifications
In addition to allowing room for the wider wheels by tasteful flaring of the front and rear fenders, the nose of the C/4 was substantially modified. The ungainly rubber front bumper was completely removed. The headlights and turn-signals were repositioned in a new front grill and the headlight doors eliminated for a cleaner look. The hood strakes remained from a previous modification. A "C" shaped accent was added right behind the front wheel arch to break-up the flat sheet metal there. Modern electric mirrors helped with better rearward vision and look surprisingly well integrated. The rear of the C/4 was also substantially modified. The rear bumper was completely removed, the tailpipes shortened and the center panel modified. A small rear kick-up was molded into the trunk lid and rear quarter panels and the body accent lines sharpened. The overall effect is to transform the 365 GTC/4 into a more muscular looking Ferrari.
The interior was previously changed by adding 550 Maranello seats and removing the rear seats altogether. A rear package shelf was created to fill the rear seat area. This makes the C/4 into a true 2-seat sports car like the Daytona. A more modern steering wheel and a larger shift ball add to the enhanced driving experience.
Driving this modified C/4 is very revealing. The steering, while already power assisted, has a lively feel and the turn-in is instant. City street 90º corners are dispatched with ease belying the bulk of this car. The great low end torque seems to pick the car up when the accelerator pedal is floored and hurl the car forward. The engine seems to rev with a new found eagerness not present in the standard engine. Too much speed is easily erased by the large Brembo cross-drilled rotors. No more high-speed fade as was evident in the stock system with this heavy car.
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425-hp @7,000-rpm, 338 lb-ft of torque @6100-rpm
Type: V12, 365 GTB/4 Daytona
Bore: 82mm Razzo Rosso forged pistons
Stroke: 71mm
Compression ratio: 10.25:1
Cylinder heads: intake ported and tested on flow bench, intake and exhaust manifolds matched
Camshafts: Special Carobu grind, 272/263-degree with 10.6/10.4-mm lift
Induction: 6x40 DCN Webers with custom Daytona Comp style air box
Exhaust: Euro-spec Tubi headers, Tubi stainless steel mufflers and pipes
Ignition: Electronic with optical sensor conversion
Suspension: fully adjustable Koni aluminum racing shocks with stiffer 2.5-inch diameter racing springs, lower ride height, larger front anti-roll bar
Brakes: Brembo GT big brake kit with F50 4-piston calipers, 332-mm front and 328-mm rear rotors, stainless steel brake lines.
Wheels: 17x7.5-inch front and 17x8.5-inch rear Razzo Rosso 3-piece alloy wheels
Tires: Michelin Pilot Sport
The engine was completely rebuilt to "Comp Daytona" specification. CAROBU Engineering utilizing a methodical approach of measurement, engine simulation modeling and testing, developed the engine modifications. The cylinder heads were ported and port-matched to the intake and exhaust manifolds. The engine was then bored to 82-mm and equipped with aluminum forged pistons, proprietary camshafts, Carrillo rods, electronic ignition with optical distributor sensors and custom fabricated "Comp-style" air box. The engine produces over 425 hp at 7000 rpm and 338 lb-ft at 6100 rpm. A special-ratio rear-end gear was also fitted to further improve acceleration times. The car is equipped with European-spec headers fabricated in stainless steel and stainless steel exhaust by Tubi Style.
The increase in engine performance required that the stock brakes be upgraded in order to bring the 3600 lb car to a stop within a reasonable distance. CAROBU Engineering equipped this Daytona with its exclusive Brembo GT kit including "F50" 4-piston calipers with 332 mm rotors in front and 328 mm rotors and stainless steel brake lines.
To improve the handling, CAROBU Engineering fitted the Daytona with Koni racing shocks with stiffer 2-1/2" diameter racing springs, and lowered the ride. The shocks are all-aluminum construction for light weight and fully adjustable for ride height, compression and rebound. The spring rates were specially chosen for this application to produce neutral handling. This Ferrari is also shod with Razzo Rosso 17x7.5-inch front and 17x8.5-inch rear, 3-piece wheels with Michelin Pilot tires. Additionally, a stiffer front anti-roll bar was installed.
The interior was redone in black leather with red accents in the Daytona style, which compliments the exterior aesthetics very nicely.
The Ferrari F40 was the last new Ferrari model introduced by Enzo Ferrari before his death in August of 1988. As the fastest production car of it's time, the F40 quickly became the ultimate super car of the 1980's and put an end to the adage that a true Ferrari had CAROBU Ferrari F40 engine had to have 12 cylinders. Michelotto and Pozzi Ferrari France (the French Ferrari importer) developed racing versions of the F40 known as the F40LM, and the F40 GTE, that were campaigned with some success in the US IMSA race series. F40s were actively campaigned in professional endurance racing up until 1996 and many of these super-Ferraris continue to be raced in many gentlemen racing series even today. After 17 years since it's debut in June of 1987, the F40 has retained legendary status and the purposeful lines originally penned by Pininfarina still remain fresh and passionate.
The 81.9 mm bore and 69.5 mm stroke of the 2936 cc turbocharged engine, known as the Tipo 120A, was a direct derivative of the Ferrari V-8 first debuted in the Dino 308 GT/4 nearly 14 years earlier. The addition of twin water-cooled IHI RHB 53LW turbochargers combined with twin Behr intercoolers allowed for forced-induction of 1.1 bar (16.1 psig) resulting in factory quoted power output of 478 bhp at 7000 rpm and peak torques of 425 lb-ft at 4500 rpm. Twin Weber/Marelli IAW units, one for each bank, control the fuel injection and ignition systems insuring efficient and safe operation of the engine with 7.7:1 compression ratio. The single wastegate, controlled by one of the IAW units, discharges directly to atmosphere resulting in the characteristic 3-pipe exhaust exiting in the center of the car. Later, for the F40 GTE, Michelotto developed the even more radical Tipo F 120B engine with up to 3.6 liter displacement and power outputs of nearly 800 hp.
Performance Figures by Road and Track (October 1989) claim a 0-60 mph time of 4.5 seconds with 100 mph after only 8.2 seconds. The F40 completes the ¼ mile in 11.6 seconds and reaches a top-speed of 198 mph. These performance claims result in a calculated horsepower of approximately 440 bhp, a little shy of the factory claims (Click here for a discussion of calculated power figures). Carobu Engineering dyno results for a stock, non-freshened F40 engine are 468 bhp @ 7200 rpm and 390 lb-ft @ 4500 rpm utilizing the stock engine management system. Forza magazine (December 2002) reported chassis dyno test results of 455 bhp at 6,650 rpm at the rear wheels for an F40 equipped with Carobu Engineering's Razzo Rosso LM computer chip and a Tubi Competition exhaust .
The mighty Michelotto F40 LMs campaigned by Pozzi and other Ferrari racing customers were equipped with larger turbos (running up to 38 psig of boost), a large radiator air outlet in the center of the front lid for improved cooling, a front spoiler, and adjustable rear wing and larger diameter wheels. Upgrading the stock F40 with "LM turbos" has become a popular upgrade with Carobu Engineering's F40 customers. The "LM turbos," have larger IHI compressors mated to the stock F40 turbines.
In order to fully exploit the power available from the LM turbos, it is necessary upgrade the computer-code of the Weber/Marelli management system. Carobu Engineering developed the Razzo Rosso computer chips for the F40 LM kit in order to optimize the boost control, fuel delivery and ignition timing. The result of the F40 LM turbo upgrade is considerable. Running only 20 psig boost, peak power increased to 511 bhp @ 6700 rpm and peak torque of 422 lb-ft @ 5900 rpm for the Carobu development engine. This is an increase of nearly 10% in peak power and peak torque over the baseline engine results. More remarkable is that the engine now has over 400 lb-ft of torque between 4200 rpm and 6700 rpm.
Since most customer F40s, even on track days, seldom require the nearly 200 mph terminal speed of the F40. Carobu Engineering developed the Razzo Rosso F40 Drop Gear set in order to improve the acceleration and drivability of our customer F40s. The gear set is forged and machined exclusively for Carobu Engineering by one of the finest European gear manufacturers and reduces the final drive ratio by 9%. For the race F40, or serious street F40, Carobu has developed the Razzo Rosso aluminum flywheel with multi-disc racing clutch package that reduces rotating mass by 45%, improving both the throttle response and acceleration of the car.
The customer F40, shown in these pictures, was upgraded extensively by Carobu Engineering and includes:
· Razzo Rosso LM Turbo upgrade including computer chip-set
· Razzo Rosso Drop Gear-Set
· Tubi-Style Sport stainless steel exhaust
During the upgrade, the F40 engine underwent a complete out-of-the-car engine and transmission service including a full inspection, replacement of belts, rollers, fuel line upgrade, valve adjustment, spark plug replacement, complete cleaning and resealing of the engine. As this F40 is intended for street use, Carobu replaced the original worn clutch with an OEM replacement. In addition, Carobu replaced the worn, leather upholstery of the Kevlar two-piece bucket seats with original specification Ferrari-Red Nomex cloth. The cockpit was also modified with a smaller diameter steering wheel and a modified under-dash knee-bar for more comfortable seating for the new owner. The job was complete with two 335/35-17 Goodyear Eagle GS-A rear tires and a set of new Razzo Rosso A810R4S brake-pads for street use. The clearly excited customer and his family are shown below taking delivery of the modified F40. The car is also to be featured in European Car Magazine.
The mighty Michelotto F40 LMs campaigned by Pozzi and other Ferrari racing customers were equipped with larger turbos (running up to 38 psig of boost), a large radiator air outlet in the center of the front lid for improved cooling, a front spoiler, and adjustable rear wing and larger diameter wheels. Upgrading the stock F40 with "LM turbos" has become a popular upgrade with Carobu Engineering's F40 customers. The "LM turbos," have larger IHI compressors mated to the stock F40 turbines.
Carobu Engineering
Physical Shop:
130 Solomon Road, Estancia, NM 87016
505-384-2783
Email US:
Carobu Engineering • Ferrari Retro Tuning • (505) 384-2783
