The 1978-89 911 SC and Carrera have long enjoyed reputations as the most reliable examples of the 911 lineage. More civilized than their predecessors but still part of an era when driving a 911 at full chat took courage, these models can be very enjoyable and dependable for daily driving. They hold a special place in the hearts of many Porsche enthusiasts, as they are the exclamation points on the first 25 years of the 911's heritage.
With the introduction of the 964 series in 1989, and subsequent 993 and 996 models, many Porschephiles felt the raw feel of their beloved 911 was lost, replaced with a more modern suspension design, extra convenience bits and electronic gadgets that made the purists shudder. Sure, the newer models cars are quicker, brake better and corner faster, but they lost much of the character that appealed to so many since the 911's inception in 1965.
The SC and Carrera were among the world's elite in terms of horsepower and performance during their build years. However, the 15 to 25 years that have elapsed since the SC's introduction in 1978-and the Carrera's demise in 1989-may as well be an eternity with the leaps and bounds in engine technology since then. The SC and Carrera of yesteryear are still forces to be reckoned with for sure, but in stock trim are overmatched by many of today's sport compact and sedan offerings from around the globe. The table on page 79 illustrates the factory-rated horsepower of some of the most powerful and desirable cars in 1988, when a mere 200 bhp appeared to be upper echelon performance. Obviously, times have changed.
The 180-bhp 3.0L SC engine installed in 1978-83 models and the 207-bhp and later 217-bhp 3.2L powerplants for the 1984-89 Carrera are as bulletproof as any 911 engine ever offered by Stuttgart. There are more than a few documented cases of SCs and Carreras with more than 200,000 miles on the odometer without the internals being touched. While these examples should be considered the exception rather than the rule, it is not unreasonable to expect the 3.0L or 3.2L motors to register 150,000 miles before needed a major rebuild. This engine longevity was unheard of during the time period, especially for a high-performance car such as the 911. Unfortunately, as good as these engines are, they do have their share of faults. The 3.0L engines, and to some extent the 3.2Ls, inherited the same cylinder-head stud problems that plagued the earlier 2.7L engines in the mid '70s. The 3.2L engines Achilles' heel appears to be random valve-guide wear, spun rod bearings due to insufficient oiling and rod bolts that can break if the engine is revved upwards of 6800 rpm. All of these issues require at the very least a top-end overhaul to repair.
The 1987-89 Carreras-the last of the "impact-bumper" models originally introduced in 1974-preserve the classic shape and lines that many think of when visualizing a 911. I purchased the 1988 Marine Blue coupe in May 2003. Fitted from Porsche with optional front and rear spoilers, this 911 also had the slick-shifting G50 five-speed transaxle and provided an excellent platform for the host of modifications I was planning.
When purchased, the Carrera had 78,000 miles on the clock and the suspension was tired and feeling its age. The original Boge shocks had lost their damping characteristics and were discarded in favor of Bilstein HDs in the front and Sports in the rear. The stock diameter torsion bars were upgraded to 22mm front and 29mm rear "hollow" units.
Since the Carrera is destined for street use with only limited track time, polyurethane and metal were eschewed in favor of new rubber suspension bushings for the front A-arms, and front and rear swaybar mounting brackets. Neatrix bushings were installed for the rear spring plates, which provide better performance than their rubber counterparts without the vibration and noise commonly associated with polyurethane. A beautiful FFensport 6061-T6 aluminum front strut brace keeps the shocktowers from flexing under hard cornering and rounds out the suspension bits.
A set of original forged 16-in. Fuchs wheels from a 1989 911 Turbo were uncovered, size 7s in front and 9s in rear. Shod with the same 205/55 and 245/45 rubber as the bulbous Turbo, they fill the narrow-body Carrera wheel wells perfectly and contribute to its aggressive stance. Finally, the car was lowered to European ride height, corner balanced and aligned. The net effect is a firm but not harsh suspension that is an ideal compromise for high-performance road use. I won't be setting any track records, but I also won't lose any dental fillings when driving on potholed roads.
A year and 8,000 miles after the purchase, the Carrera began to exhibit symptoms of the infamous valve-guide wear that has afflicted countless others. Intermittent smoke while idling and oil consumption that deteriorated from 1,800 miles/qt to 1,100 miles/qt in a relatively short period of time were telltale signs something was wrong internally. Knowing from the experience of others that the valve guides were likely the culprit and thus a valve job was on the horizon, the tear-down writing was on the wall. It was time to start preparing and saving for performance upgrades.
With only 68.6 hp/liter, the U.S.-spec Carrera motors left a lot to be desired compared to other 911 motors that preceded and followed it. The table on page 77 shows selected specs of Porsche's most powerful street engines. Before rigorous emissions standards became an obstacle in the mid '70s, Porsche's high-performance S motors routinely made over 80 hp/liter. From the mid '70s through the '80s, those numbers dropped as low as 60 hp/liter, as Porsche was forced to redesign the exhaust system and introduce CIS fuel injection to help comply with emissions laws at the expense of horsepower. It wasn't until the mid '90s (with the last 3.6L aircooled motors) where the numbers returned to the good-old-days levels.
The venerable aircooled 911 engine is highly tuneable. It would have been child's play to simply increase the displacement and compression, remove the stock Motronic fuel injection and exhaust system in favor of stand-alone engine management and headers and call it a day. But 80 hp/liter would be disappointing as the magic 100 hp/liter can easily be attained with a blank sheet of paper and open wallet. However, the purpose of this engine project is not to build a high-strung competition engine that needs to rev to insane engine speeds and requires race fuel to make the horsepower I am seeking. California residents are subjected to stringent emissions laws and developing horsepower legally becomes an exercise in careful research and planning, and sometimes is better left to those who have a wealth of experience.
The constraints for this engine build are simple: The engine must run on 91 octane and pass California emissions tests every 2 years. The engine must also be tractable in the low- and mid range and not be finicky for everyday use if the need arises. The final requirement was that the original two-piece engine case, crankshaft and connecting rods be retained to save costs. While 3.6L engine transplants from later 964s and 993s into earlier chassis are fairly common these days, finding a used 3.6L engine in excellent condition at the right price can be a daunting challenge.
While researching for this project, I found many used 3.6L motors with as many miles on them as my 3.2L. Since the 964 and 993 motors have also had head-stud and valve-guide issues (among others), I didn't want to go through the transplant headaches only to end up with the same problem I was attempting to rectify! The 3.6L motors are also not a direct fit into the earlier models and require additional conversion pieces, adding further to the bottom line. Being generally conservative in nature, I wanted the peace of mind of a brand-new engine with all of the best updates available. Moreover, I wanted an engine I could foresee reaching the 150,000-mile mark. The 3.6L transplant remains a viable option for many people, but just didn't fit my criteria for this Carrera.
The name Andial certainly shouldn't require any introduction in this magazine. Many Porsches prepared by Andial over the years have graced the pages of european car. From restoring 917-30s and servicing 959s, to building the all-conquering 962 engines of the IMSA GTP/Group C era, Andial has literally seen and done it all. It was while employed by Andial that I first met Dwain Dement and Steve Becker. Dwain worked as a service technician on the road-car side of Andial's business and Steve was shop foreman on the racing side. Both are excellent mechanics and have a wealth of information with respect to 911 engine building.
Dwain Dement left Andial in the early 1990s and after managing a small independent Porsche and BMW repair shop for a time, decided to open Vision Motorsports in 1995. Initially operating from a tiny 1,775-sq-ft facility with just one hoist, Vision quickly expanded to a 5,000-sq-ft home with three hoists in 1998. Dwain has built a reputation for his 911 Turbo engine-building prowess. Today, Vision Motorsports is one of Southern California's largest independent Porsche service and racing specialists. Its 12,000-sq-ft shop in Laguna Hills, Calif., can provide the finest in general maintenance, performance parts, engine building, suspension tuning, corner balancing and alignments, race-car prep, fabrication and track support.
After toiling 15 years at Andial and Porsche Motorsport North America's racing department in Santa Ana, Calif., Steve Becker took over the daily operation of his Dad's machine shop, also located in Laguna Hills. While he is no longer actively involved in the day-to-day Porsche industry, he continues to build 911- based engines on occasion for local shops and enthusiasts while still finding the time to fabricate sport parts for 911s that are then private labeled by various Porsche tuners. Steve has built the finest Porsche race engines for the highest levels of competition. My high-performance street motor will be in good hands with these guys at the helm.
Since I wanted to have an active role in the build-up of my engine, it would have to be disassembled and rebuilt after hours. Dwain was gracious enough to offer the full use of his facilities. Since I have a regular 40-hour work week like many grassroots enthusiasts, evenings and weekends are my only opportunities to participate. The Vision guys are quite often working late on special projects but weekends are usually devoted to the track. Steve kindly offered to assist and suggested that bringing the motor over a few blocks to his shop would better suit my schedule.
After consulting with Dwain, Steve and a few other knowledgeable professionals, the consensus was that the best way to try and achieve my goal of 80 hp/liter with the constraints was to increase the displacement from 3.2L to 3.5L, utilizing higher-compression 100mm pistons/cylinders and twin-plug ignition as the building blocks. While the SC's fuel injection and ignition systems are different than the Carrera's, the 3.0L and 3.2L engine cases and internals are kissing cousins, which allows for many of the same performance enhancements to have an equivalent result.
Since it was important to see and not just feel the before/after difference between a mildly tuned 3.2L and a high-performance 3.5L, I had Nick run a baseline on Vision's Dynojet 248C chassis dynamometer. The Carrera had previously been chipped with custom software developed by Steve Wong at 911Chips. The exhaust gases were more efficiently shown the exit door with Dansk's stainless-steel pre-muffler and final muffler. While I didn't have a dyno number for the motor in stock configuration, I did expect the 3.2L would make a few more horsepower based on what similarly modified 911s have shown on the dyno.
Two runs were made on the Dynojet and a peak 199.01 SAE-corrected rear-wheel horsepower was measured. With the standard 15% driveline loss many people use to differentiate the factory-quoted flywheel horsepower from rear-wheel horsepower, this equates to approximately 234 flywheel horsepower. More important than the peak horsepower number was the greatly improved throttle response; the run to redline is much quicker and smoother, thanks to Wong's programming skills. The Dansk exhaust looks authoritative with twin 84mm tips out the back and emits a pleasing yet unobtrusive growl at WOT that doesn't overshadow the wonderful fan whine the 911 engine is known and loved for. The Dansk pre-muffler and final muffler are excellent bolt-on upgrades for the SC and Carrera owner who doesn't want or need to go into the engine's internals.
|1988 Horsepower Chart for Selected Makes|
|Porsche||928 S4||5.0L V8||320|
|Porsche||911 Turbo (930)||3.3L Flat-6 Turbo||282|
|Ferrari||328 GTS||3.2L V8||260|
|Ford||Mustang GT||5.0L V8||225|
|Porsche||911 Carrera||3.2L Flat-6||217|
|Porsche||944 Turbo (951)||2.5L Inline-4 Turbo||217|
|Volkswagen||GTI 16V||1.8L Inline-4||123|
|*Many of today's sport compacts and family sedans have much more horsepower than the legends of the past.|
After the Carrera had sufficiently cooled down from the dyno runs, Nick began the task of removing the motor and transaxle. While the entire process of removing the motor is beyond the scope of this article, the procedure is well documented for DIY wrenches in "101 Projects for your Porsche 911" by Wayne Dempsey. Nick expertly disconnected or removed anything and everything needed to safely separate the engine from the chassis, and it was not long before the 3.2L was resting comfortably on a floorjack. Nick then detached the G50 transaxle from the motor and removed the clutch assembly and flywheel. The 3.2L motor was then placed on a pallet and driven over to B. Precise Machining where Steve was waiting with a 911-specific engine yoke and stand.
The best part of the entire process is the teardown. Although you still need to be careful and inspect various components as you are removing them, you have the luxury of knowing that if you happen to break something it probably won't be the end of the world as there is a good chance it will be replaced anyway. "How to Rebuild and Modify Porsche 911 Engines," also written by Wayne Dempsey, is an excellent resource for the DIY mechanic or interested observer and goes into much greater depth than this space allows.
Once the case was securely fastened to the engine stand's yoke, the first order of business was to remove the exhaust system. I removed the Dansk muffler independently as it is the heaviest single component of the exhaust system and then proceeded to remove the heat exchangers, crossover pipes and Dansk pre-muffler as a complete unit. Pre-soaking all of the exhaust nuts with a penetrate like Liquid Wrench can make a potentially frustrating job less stressful. The large metal oil line that runs under the motor was removed.
Next up was the engine sheetmetal, including the motor mount bar. The various pieces were detached individually and sent out to be powdercoated in a semi-gloss black. The sheetmetal will return looking like new and will add a strong visual appeal when the motor is reassembled.
Steve recommended I remove the Motronic injection system as a complete unit for convenience, even though we need to completely disassemble it at a later date. If you are not planning on changing fuel hoses or modifying the intake plenums, the best plan may be to simply clean the exterior parts and then place the entire unit in a large bag to keep dirt and moisture away.
If you will be disassembling the injection system, be sure to take plenty of pictures as it can be confusing trying to figure out where all of the hoses and vacuum lines are routed. In this instance, the intake plenums were sent to Extrude Hone to be flowed, polished and flowed again. The throttle body will be bored out and the aging rubber fuel lines will be replaced with braided stainless-steel pieces. After the injection was off, the fan assembly, alternator (which is located behind the fan) and engine shroud could all be removed, leaving what is known as the long block.
Energized that I was now working on the "meat" of the motor, I eagerly removed the engine oil cooler from the front of the motor and then the cam oil lines and the chain housing covers at the rear of the motor, leaving the pressure-fed chain tensioners (introduced on the Carrera in 1984) chains and camshaft sprockets exposed. The Carrera-style pressure-fed tensioners are a popular update for all earlier 911s as they protect against disastrous chain tensioner failure better than earlier methods.
The upper and lower valve covers were removed, allowing me to see if there were any broken head studs. After unbolting the chain tensioners and removing the chain ramps, the chains can be lifted (but not removed until the case is later split) off the camshaft sprockets. Porsche tool P9191 is needed to hold the cam sprockets steady while removing the large bolts that retain the cams. Since these were on unbelievably tight, Steve held the tool on the three holes of each cam sprocket while I used all the leverage a breaker bar would provide to loosen the 19mm bolts.
The next step is one of the areas where close attention must be paid. When the rocker arms and shafts are removed from the cam towers, it is strongly suggested that each rocker arm and corresponding shaft be marked from where it came out of the motor.
Dwain, Steve and a host of others swear that reinstalling the rocker arms and shafts in their same location can help eliminate oil leaks. If the motor has high mileage and the rocker arms and shafts will be reconditioned or replaced, marking the orientation is not necessary. When the chain housings and rocker arms and shafts are removed, the camshafts should slide out of the cam tower assemblies with a minimum of fuss.
From this point, the motor can generally be stripped down in large chunks. I removed both cam tower assemblies, exposing the cylinder heads. The engine cooling tin that is located on each side of the cylinders must then be removed. Using a breaker bar and some elbow grease, I was able to loosen the cylinder-head stud nuts without incident and the cylinder heads simply slid right off the cylinders.
Unless you are just dying to know what the internals of your cylinder heads look like, there is no need to disassemble them. Most machine shops perform the disassembly as part of the service. If you are planning on reusing your pistons and cylinders, make sure you don't drop the cylinders while trying to separate them from the pistons. They are made from aluminum and are expensive to replace. The cylinders will usually separate from the pistons quite easily, but a few can be stubborn and may require a gentle tap with a rubber mallet.
Removing the pistons from the connecting rods requires a steady hand and safety glasses. A small flat-head screwdriver can be used to pry the circlip free that holds the wrist pin in place. The circlips have quite a bit of tension and if you don't grab onto them as they are being excavated they can-and will-fling to the other side of the room or worse, hit you square in the forehead. Once they are removed, the pistons can be separated from the connecting rods by using the handle end of a small screwdriver or a small punch against the wrist pin and tapping lightly with a rubber mallet. You don't have to completely remove the wrist pin, just tap it out far enough to release the piston from the rod. Remember to keep the pistons with their corresponding cylinders if planning on reusing them.
Almost there! I removed all ancillary pieces on the case exterior, including the ignition distributor, crank pulley, breather cover, oil thermostat and almost too numerous to count case fastening hardware. The case was then deemed ready to be split and after some coaxing with a rubber mallet the case separated and left me with a beautiful view of the crankshaft (with the rods still attached), oil pump and intermediate shaft assembly. The crankshaft will lift right out and the oil pump and intermediate shaft assembly only requires the removal of three nuts and then they come out as a unit. All of the internal parts will be disassembled to receive a thorough cleaning, be reconditioned and brought back to original tolerances, and then cleaned thoroughly again in preparation for reassembly.
Follow along with the build as the next installment will cover in greater depth the various options available to SC and Carrera owners during the course of a standard or high-performance rebuild. I will be relying heavily on the excellent products from industry leaders ARP, AASCO, Andial, Dansk, Extrude Hone, Mahle, Magnecore, Web-Cam and 911Chips along with the talents of Steve and Dwain to help build a powerful, dependable and emissions-friendly motor.
|Horsepower per Displacement Comparison|
|Porsche 911 Street Engines (USA Spec)|
|1967||911S||2.0L, Weber carbs||160 @ 6600 rpm||80.4|
|1969||911S||2.0L, mechanical||170 @ 6500 rpm||85.4|
|1970-71||911S||2.2L, mechanical||180 @ 6500 rpm||82.0|
|1972-73||911S||2.4L, mechanical||190 @ 6500 rpm||81.2|
|1974||911S||2.7L, CIS||175 @ 5800 rpm||65.1|
|1978-83||911 SC||3.0L, CIS||180 @ 5500 rpm||60.1|
|1987-89||911 Carrera||3.2L, Motronic||217 @ 5900 rpm||68.6|
|1989-94||964||3.6L, Motronic||250 @ 6100 rpm||69.4|
|1995||993||3.6L, Motronic||272 @ 6100 rpm||75.6|
|1996-97||993||3.6L, Motronic w/Variocam||285 @ 6100 rpm||79.2|
|The stock U.S. spec 3.2L's output of 68.6 hp/liter leaves plenty of room for improvement when compared to some of Porsche's best street engines.|
|We're hoping to reach the 80 hp/liter mark with the planned modifications while still using 91-octane pump gas and remaining California-emissions compliant.|
|Source: "Porsche 911 Performance Handbook (2nd edition)" by Bruce Anderson|