Porsche 911: A Performance Legacy is Born
This article was originally published in HPBooks' Porsche 911 Performance: Building the Ultimate 911 for High Performance Street or Road Racing, by . Rossi is a contributor to European Car, Road & Track, Sport Compact Car and Los Angeles Times. As part of our selection of vintage 911 must-reads, this book provides a comprehensive look into the high-performance modification of 911's for the street and track. Covering topics ranging from engine building to chassis strengthening, this 144-page guide will certainly take your venerable 911 to the next level of performance. Click here to order this book.
1965. The Vietnam War rages, Sony and Cher rattle the pop charts and the Dow Jones sets a record at 969.26 points. At the same moment, America was being invaded by a sleek new sports car, the 911.
Figure 1: A well-traveled 1967 911.
Figure 2: A 1973 2.7-liter Carrera RS.
When Butzi Porsche put pencil to paper and sketched the swooping lines of the replacement to the revered 356, he could not have imagined the automotive passion he would ignite or the longevity his artistic hand would sustain. Like Cher, the shape of the 911, in all its sensuous forms, has proven timeless.
The focus of this book is to restore and upgrade an early 911 to be as competitive on the track as it is thrilling to drive on the road. And then, if the enthusiasm overrides common sense, to take the next step and construct a dedicated race car.
But which 911 does one choose to create their ultimate Porsche? Aside from the major body changes in 1974, 1989, and 1994, the evolution of the 911 can be difficult to discern. To make a complete and comprehensive analysis of the air-cooled 911, from the prototypes to its demise in 1998, is an ambitious endeavor and beyond the scope of this text. Volumes have been written about these celebrated cars, about their unique engineering, the rear-mounted, flat-six power plant and, of course, about their illustrious racing career. Owning a library of these books is a prerequisite for being a true Porsche fan and that includes planting an edition of Karl Ludvigsen's hefty Excellence Was Expected on your night stand.
As with anything that fuels zealous devotion, it is impossible to get a consensus on the best 911. Each model displays strengths and weaknesses. Some were light on their feet, others toted creature comforts of a Cadillac. A few were not as reliable as expected, and an elite group could puddle the blood into the back of your skull with turbo-charged thrust.
Figure 3: A 1979 930 Turbo.
Walk the tarmac of any Porsche club racing event and you will find an example of every street model that ever rolled out of Zuffenhausen. Whether your interest lays with slaloms, time trials or highly-competitive bouts of wheel-to-wheel racing, these 911s offer the most adaptable foundation on which to construct a club racer.
Figure 4: A pair of highly modified 911 racers.
Figure 5: The "Softer" 911E.
Early on, Porsche understood that their sports cars were bought with the intent of being driven hard. On the amateur level, the 911 was track ready out of the box. Improvements in design and mechanics were continuously transferred to the road cars as the factory learned from its successes and failures on the racing circuit. Only one model, the 911E, deviated from this philosophy. Yet even this "comfortable" riding 911 sustained sportiness when compared to other marques of the time.
The early '70s was the dawn of Porsche's racing dynasty. While the world knew the manufacturer from their many championship titles and the famed 356, it was the formidable 917s and their complete domination of international competition that forever placed the German automaker in the annals of endurance racing and automotive folklore. To gain kinship with this royal family, a customer needed only to walk into a Porsche showroom and place his order for the latest 911.
Thus, for this project I focus on the 911s built from 1969-1973. Lightweight, powerful and less government-regulated cars from a period many consider Porsche's Golden Era.
The decision on exactly which model to buy may fall to your pocket book or to the luck of finding that not-quite-so perfect coupe. But this is not so much a buyer's guide as it is an overview of the mechanical distinctions between these models. While some of these 911s were delivered with better components than others, any one of them can be made into an excellent street performer and club racer.
Figure 6: A 1969 Long Wheelbase 911.
1969: The B-Series
The earliest cars, 1965-1967, were designated at the factory as the Type 911 while the 1968 units were internally identified as the A-series and began Porsche's alphabet soup of model identification. These first cars were fun, spry automobiles with a respectable power-to-weight ratio. But again, unless your intent is vintage racing or spot-on restoration, the next series of 911s are better choices on which to build your racer.
By 1969, the B-series 911s were the most powerful road cars ever offered by Porsche. Built on the same unit-body chassis, the series was divided into three models primarily by engine output. The entry level car was designated the T, denoting Touring. The luxury model was the E, which stood for Einspritzung, (German for injected). And then there was the top performing S, for the Super model. The S nomenclature was first hung on the 911 in 1967 but earned its pedigree from a series of high-output 356 engines. All three could be had as standard coupes, with or without an electric sunroof, or in the form of a not-quite convertible called the Targa.
Figure 7: The ingenious semi-convertible Targa.
Figure 8: Placement of the torsion bar cover gives away the difference between the long wheelbase (upper) and the short wheelbase (lower).
The last year of the '60s also introduced the first significant change in the 911. With the B-series, the wheelbase was stretched just over two inches by lengthening the rear suspension's trailing arms. This essentially shifted the car's weight forward, dramatically improving the 911's handling.
An outward clue for this change is the small torsion bar cap along the bottom edge of the body just ahead of the rear fenders. On the earlier cars, this cap is about half an inch in front of the arch and on the lengthened cars, it's nearly three inches forward. Another hint are the small fender lips, delicate appendages that would on later 911s billow to Draconian proportions.
Figure 9: The pre-1969 cars had the narrowest of fender lips.
The rear suspension for the 911 continued to use the proven trailing arm/torsion bar system used on the 356. Suspension movement was damped by telescoping shock absorbers. The front suspension incorporated longitudinal torsion bars running through the A-arms. Depending on the year and model, different shock absorbers were used in the strut assemblies to inhibit vertical travel and increase responsiveness.
The 2.0-liter flat-six engine that was introduced with the Type 911 remained with the car for 1969, but the engine case was now made of magnesium instead of aluminum. This change in material alleviated 22 lbs. from the aft end, yet the early1965-1968 aluminum engine cases are stronger and are much sought after by Porsche engine builders.
Figure 10: A 1969 2.0-liter with mechanical fuel injection.
While the 911T motor used lower compression pistons and milder cams than either the E or the S, it still managed to produce 110 horsepower and a 6,500 rpm redline. The fuel/air mixture was blended by a pair of tri-throated Weber 40 IDT carburetors.
The mid-level E was intended as Porsche's luxury car. Its interior and exterior trim mirrored that of the higher priced S but as the engine was somewhat detuned, it was less demanding to drive. The E received the new Bosch mechanical fuel injection system developed during Porsche's Carrera 6 racing program. The MFI helped the engine produce a respectable 140 bhp at 6,600 rpm.
The E was also furnished with a softer ride by replacing its front torsion bar suspension with Boge hydro-pneumatic gas and oil filled struts. To further damper road input, this self-leveling system was combined with tall sidewall 14-inch Fuchs wheels. In 1972, the Boge system was relegated to the option list and the E came equipped with the standard torsion bar front suspension.
After three decades, chances are slim of finding an E with its hydro-pneumatic system intact. Thankfully, most have been updated to the better performing suspension of the T and S. With a front suspension change and the fact that the E was originally equipped with ventilated disc brakes like its more powerful sibling, it makes a good candidate for a track car.
Figure 11: Ventilated discs of the 911S.
Figure 12: The brake calipers of the 1970 911S.
The S also received the new mechanical injection system. Fitted with high compression pistons and cams with a more aggressive profile, the top of the line Porsche screamed to 7,200 rpm and produced 170 bhp. The S had a sharp torque curve that restricted its power output until the tachometer needle reached the five grand mark.
Not the sort of performance that flattened you into the seat like a '69 Chevelle packing a 454 cu. in. V-8, but with a comparative displacement of only 122 cubic inches, the Porsche could reach 135 mph and maintain it as long as traffic allowed.
Unlike the later motors, the 1969 911S cylinder heads used unique valve sizes similar to Porsche's racing engines. Because of this distinction, along with the difficulty of finding correct pistons and cylinders, the unit is even pricier to rebuild than the other 911 motors of the period. In ensuing years, the intake and exhaust valves were standardized to 46 mm and 40 mm, respectively. The heads for the three models were then differentiated by port size.
To bring this lightning bolt to a stop, the S received race-inspired aluminum Ate calipers clenching ventilated front discs. Although these S-type vise-grips were state of the art at the time, they have a tendency to flex under hard braking and can deform the rotors. Many club racers now swap the highly-prized calipers for the cast iron A-type found on the later 911SC. While there is a palatable difference in stopping power, the car pays a price in additional unsprung weight.
Figure 13: The front fender-mounted oil cooler of the 911S.
Along with its more powerful brakes and engine, the S makes an optimal track car because of its forward oil cooler located in the right front fender. Keeping the oil temperature low is a good idea for any engine, but is critical for an air-cooled motor. Most 911s modified for the track have an auxiliary oil cooler mounted in the front spoiler. The advantage of the S is that it is already plumbed for this enhancement.
Figure 14: The original chromed steel wheels and hub caps.
Transferring the engine power to the wheels, the S and the E both carried the 5-speed, 901 gearbox. A few carried Porsche's unique Sportomatic transmission, a semi-automatic 4-speed. The T received the less costly Type 902 4-speed transmission. If you are thinking of purchasing a car with a 4-speed, rest assured, they are easily replaced by a 901 gearbox.
The standard wheels for 1969 through 1971 were 5 2 inch slotted steel and came either painted silver or with optional chrome plating. These were topped with polished hubcaps retained from the earlier cars. Standard on the 1969-1973 S models were the famed Fuchs alloys sized at 6x15 inches. Fuchs could also be ordered on the E but as mentioned, came in 52 x14 size to add to its cushy ride. An optional wheel for the T was an extremely light 5 2 x15 inch magnesium wheel which is a rarity nowadays.
Figure 15: The classic five-spoke Fuchs wheel.
For better performance and safety in their stock classes, a majority of the clubs allow the wider Fuchs that came on later 911 models. As these lightweight 7x15 inch alloys slip right under the stock fenders, they have become favorites amongst racers and street runners.
Figure 16: The optional ZF limited slip differential.
1970-1971: The C and D-Series
For 1970, the C-Series was launched with a new 2.2 liter flat-six. The enlarged motor had a broader torque curve and better lower end power. The valves were standardized but the intake and exhaust ports for the S were nearly 10% larger than either the T or E. The higher displacement bumped the power output across the 911 lineup. The 911T now developed 125 bhp, the E, a significant 155 bhp, and the sacred S put 180 horses under the driver's right foot.
While the E and S continued to sip their petrol with the mechanical injection, Zenith 40 TIN carburetors now topped the T motor. Ventilated disc brakes, already used on the other models, were added to the entry level car. The 5-speed transmission was now an option for the T, but buyers of the S lost their chance to order a Sportomatic. Not a major concession, as most enthusiasts will agree.
An important addition to the 911's option list in 1970 was the ZF multi-disc limited slip differential. Under adverse conditions, whether it is a slippery road or hairpin turn, the unit transfers power away from the slipping tire to the wheel with the greatest adhesion, thus propelling the vehicle forward. A limited slip is a near necessity for running tightly twisted road courses.
To further reduce weight at the back end, the rear deck and center bumper panel on the S were made from aluminum. These are notable pieces for the concourse specialist but for a racer campaigning on high-speed courses, a lightweight, aftermarket wing is a preferable and often a necessity.
The D-series cars of 1971 received little change, save one important improvement inside the engine. Fabricated into the case cross-members were small squirters that delivered a spray of oil onto the bottom of the pistons. This dramatically cooled the crown thus extending the motor's longevity and reliability. Once again, this was an example of Porsche drawing on experience gained at the race track.
Figure 17: A custom made oil feeder delivers cooled transmission fluid to each gear cluster.
1972-1973: The E and F-Series
In 1972, with the E-Series, Porsche employed two of the most significant changes to the 911 to date. First and foremost, the fabulous flat-six was now pushed out to nearly 2.4 liters (actually 2341cc) by increasing the stroke of the 2.2 liter motor. Although compression ratios diminished because of air pollution and low-octane fuel requirements, the E and S put 165 and 190 horses to the flywheel, respectively. The T finally received the Bosch MFI and generated 140 bhp.
More than just an increase in displacement, the longer stroke of the 2.4 widened the torque band. Power was now on tap at lower rpm making all the models, and especially the S, one of the fastest production cars of the time.
Attached to the new engine was a new transmission, the 915. Created to accept the higher horsepower and torque of the larger motors, the 915 lost the racing-inspired shift pattern of the 901 gearbox.
Unfortunately, Porsche concluded that a majority of their clients in 1972 were sitting in traffic jams more often than on starting grids and the new 915 transmission was given the typical H-I pattern. In this layout, fifth gear is acquired through a gate on the right and then forward to the top of the I in the paradigm. Reverse gear is also to the right lying below fifth.
Shift patterns aside, and although the 915 is somewhat heavier than the earlier transmission, it has become the weapon of choice for club racers with normally aspirated engines producing less than 300 hp. When horsepower begins to reach the stratosphere, many race mechanics suggest additional modifications to the transmission, including exterior oil coolers and spray bars that insure every gear cluster is getting its required douse of lubricant.
Figure 18: The unique oil filler hatch of a 1972 911.
Another prominent change in 1972 was the relocation of the oil tank. An E-series car can be quickly recognized by the oblong hatch behind the passenger door which affords access to the oil tank's filler neck. This was another effort to transfer weight away from the rear and improve the 911's haunting oversteer.
Figure 19: The factory designed S front spoiler.
Still, it wasn't a revolutionary idea. The race-bred 911R of 1967 had its tank in this position. Porsche must have found some value to this placement as, in 1989, with the introduction of the Carrera 4, the tank was again set ahead of the right rear tire. For 1973, however, the oil tank returned to its original position in the engine bay as unwary gas station attendants (remember them?) proceeded to mistake it for the fuel tank.
To reduce front end lift, a notable problem when cruising in triple-digit speeds, a small air dam was added to the bottom of the front bumper. Not only did this subtle lip look sporty, it actually worked and became standard on the S model. Where club rules allow, however, aggressive spoilers with leading edge "splitters" work even better at keeping the 911's nose to the ground.
Figure 20: An aftermarket version of the RS front spoiler incorporates a splitter into the design.
Figure 21: Inexpensive favorites for the race track ATS cookie cutter wheels.
The F-series was launched in 1973. Changes for this year were minor and mostly cosmetic. The T did receive the new Bosch K-Jetronic fuel injection system midway through the model year. The chin spoiler became standard on the E.
The forged Fuchs remained the wheel of choice for most customers but a new cookie cutter wheel from ATS was offered on the 911E. These wheels were supplied to subsequent 911s and are now coveted by autocross racers as an affordable, lightweight substitute to the pricey seven inch five-spoke Fuchs.
Weighing the attributes from all fifteen 911s, each of the three models from each of the five years, some say the 1972 911S stands out as the best of the best when it comes to body, suspension, motor and gearbox. But it only stands out if you are planning to campaign a stock 911. With enough work and the right equipment, even a destitute 1969 911T can be turned into a high-speed performance champion with the potential of knocking the doors off most would-be competitors.
What to look for:
Buying a car, any car, is a test of patience and determination. It takes time to find the right vehicle for your purpose and an iron will to wrangle the price down to what you want to spend. Sometimes you need the wisdom to walk away from a car that is overpriced no matter what its condition. If you intend to compete in Porsche events, it is worth your time to join a Porsche club. Even if you don't have a car to run, take the opportunity to watch your potential competition, note their modifications and try to spy a few pointers.
Clubs are also a great place to find a car. Just be sure the performance enhancements fit the rules you plan to race under. More likely than not, a club 911 will be in good condition as there is hardly a stronger automotive love affair than that between a driver and his race car. But keep in mind, while these chariots may only be driven on weekends, they are driven to the extreme.
There are many prominent racing clubs across the country that welcome 911 competitors with open arms. Of those exclusive to the marque, the Porsche Club of America is perhaps the best known. This clan of Stuttgart followers run an array of competitive events with dozens of classifications. Hardly a weekend passes that the PCA does not have some sort of gathering.
Another parish, and one that is focused entirely on track events, is the Southern California based Porsche Owners Club. If you want to mingle with serious racers whose experiences span the gambit from amateur to semi-professional, than the POC is tailored to you.
Although this book is not about building a concourse automobile, if you can afford to by a well maintained 911 it will make your life and your project a lot easier. Buying a non-running hulk will give you more headaches than you can imagine.
Remember, a 911 from this era is a piece of machinery that has been in constant use for over thirty years. And if it has been sitting still, then the forces of nature have been having their way with it.
The first step in reviewing a candidate is to give it a good visual going over. If you are serious about club racing, stay away from the Targa and the sunroof coupes. The Targas are roughly a hundred pounds heavier as their frames were reinforced to reduce body twist. Electric sun-roofs add about sixty pounds to the top of the car, so unless you are looking to get a suntan at 140 mph, they are best disregarded.
Scan for wrinkles in the sheet metal, a sure sign of a poorly repaired accident. Body panels should line up straight and true. Doors should open and close easily, as must the trunk and rear deck.
For a 911, rust is the most lethal of enemies. Corrosion is difficult to contain and can quickly destroy a uni-body chassis. Porsche tried to address this problem in 1971 by submitting a number of underbody sections to a hot dip zinc coating process. Starting with the E-series, the floor pans were galvanized.
Inspect the underside of the doors for damage. Remove the headlamps and look at the light buckets. This is a favorite spot for the rust goblins. Look deeply into the trunk area, especially around the fuel tank and batteries. A little surface corrosion can be fixed but extensive damage to the suspension pickup points or around the motor and transmission mounts can be fatal for a chassis.
Check the vehicle identification number to verify what you are buying. The tags are in four locations; inside the trunk above the fuel tank, on the hood latch panel, for late 1969, it showed up on the driver's side A-pillar and on the driver's doorjamb after 1970. A good restoration book can decipher the chassis numbers and tell the car's exact model year, engine type, date of manufacturing and a variety of other details.
Odometer mileage is often the first thing considered when buying a used automobile, but if you are intending to build a racer, this indicator is overrated. One racer I know has campaigned his 1967 911S for over thirty-seven years. The odometer reads a true 54,000 miles. As each mile has been accumulated on the track it is obvious this S is a bit more worn than its 1,500 miles per year average would indicate.
Figure 22: An old soldier-this 1967 911S has been raced since 1969.
A general rule of thumb for these 911 motors is that a complete rebuild should be done just beyond the 100,000 mile mark. The problem is that the VDO speedometer/odometer gauge only registers five digits. Taking the car's condition into account can help determine how many times the indicator has rolled over. If the current owner has no record of an engine overhaul, be aware you may soon inherit a costly addition to the car's purchase price.
Cosmetics such as faded paint and worn carpets are usually secondary considerations when shopping for a project car. Then again, if you are not planning to drive your new purchase directly into the garage to begin stripping it down, buy something that won't be mistakenly towed away as an eyesore.
Another important point is drivability. Buying an automobile that can't be road tested is to be handed a Pandora's Box - untold horrors await you. If the engine runs well enough, doesn't leave an Exxon Valdez oil spill on the ground, the transmission moves through all the gears, including reverse, then you are ready for the next step. Visiting a Porsche mechanic.
You could possibly perform a leak-down test yourself and crawl further under the car's dirty belly in search of more rust. You might even use a few lengths of string to check the squareness of the body, but unless you know your way around that complicated flat six, it's best to turn to an expert for an opinion on what you are about to adopt.
Clearly, I have ignored interior and exterior details. The reason is that, beyond the question of weight, they bear little on performance. Such items as seats and door panels will be exchanged for aftermarket pieces.
Lightweight racing buckets are surprisingly comfortable compared to the factory supplied sofas. In the case of carpeting, you will most likely want it replaced with thinner material or removed altogether.
A car stereo is another item that will receive the delete button. There is hardly anything that adds more wasteful tonnage to a track car than an array of speakers, amplifiers and a multiple CD-player.
That said, be sure to scrutinize the club rules before you begin modifying your car. Certain classes allow you a minimum of changes from the original configuration. If you have never driven in competition, stay in the stock class for as long as you can stand it. This is an excellent place to learn how to drive a car to its limits before you begin to transform it into your ultimate racer.
I have purposely avoided addressing the topic of purchase prices for these cars. It is like discussing Internet stocks, every expert you talk with on the subject has their opinion. I have seen cost guides value a 1969 911S in poor quality for $6,000 while a perfect '73 is said to command only $15,000. At the same time, a 1970 S, in merely decent condition, might change addresses for over $40K. Go figure.
While the T and E will be less costly than the much sought after S, the only true indicator of a car's value is the number of greenbacks that are put into the seller's hand. There are deals to be had and great cars to be found. It takes time, patience and a bit of luck.
Figure 23: The smaller and lighter four cylinder 912 motor.
The 1969 912
The 912 was virtually identical to the 911, save for the four-cylinder engine and 4-speed transmission. Introduced alongside the 911 in 1965, the car was equipped with the 90-hp unit found in Porsche's discontinued 356. Because the smaller motor was lighter than the powerful six, the 912 didn't suffer the extreme oversteer associated with the 911. The added wheel-base in 1969 only increased this benefit.
While a lot of first time club racers opt for a 914 as an economic way into Porsche racing, the 912 is a viable alternative for those who can not stomach the idea of driving anything other than an offspring of Butzi Porsche's design. Some might snub their noses at the race classes filled with stock 914s, 924s and 912s, but they are as competitive as those dominated by the cars harboring 3.6-liter turbos.
With a few minor modifications, the 912 can be morphed into a 911. The chassis easily accepts whatever engine your pocketbook can sustain. For those on a tighter budget, a stock 912 is a perfect induction into Porsche racing.
Figure 24: This owner defies the norm of racing a coupe by having just as much fun competing in his 1973 Targa.
The Porsche Targa revolutionized the automotive world with the concept of a removable center roof section. The name was lifted from the Targa Florio, the classic Sicilian road race that was conquered by Porsche's spirited little 550A in 1956.
The Targa body style bestowed 911 drivers with the open-air feel of a convertible while the wide, brushed steel roll-over hoop delivered the safety of an enclosed automobile. By 1969, a solid, curved piece of glass could be ordered to replace the flexible rear window.
The top section was cleverly engineered to collapse and fit in either the trunk or on the rear shelf created by the folded back seats. All three models of the 911 could be had in Targa form and like the coupe, they continue to enjoy a passionate following. In today's 911 market, the Targas command premium prices.
The rigidity of the open-topped car, however, never matched that of the coupe and efforts to reinforce the chassis only managed to condemn it with a hefty weight penalty. This ultimately detracts from their making a proper track car.
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A well-traveled 1967 911.
A 1973 2.7-liter Carrera RS.
A 1979 930 Turbo.
A pair of highly modified 911 racers.
The "Softer" 911E.
A 1969 Long Wheelbase 911.
The ingenious semi-convertible Targa.
Placement of the torsion bar cover gives away the difference between the long wheelbase (upper) and the short wheelbase (lower).
The pre-1969 cars had the narrowest of fender lips.
A 1969 2.0-liter with mechanical fuel injection.
Ventilated discs of the 911S.
The brake calipers of the 1970 911S.
The front fender-mounted oil cooler of the 911S.
The original chromed steel wheels and hub caps.
The classic five-spoke Fuchs wheel.
The optional ZF limited slip differential.
A custom made oil feeder delivers cooled transmission fluid to each gear cluster.
The unique oil filler hatch of a 1972 911.
The factory designed S front spoiler.
An aftermarket version of the RS front spoiler incorporates a splitter into the design.
Inexpensive favorites for the race track ATS cookie cutter wheels.
An old soldier-this 1967 911S has been raced since 1969.
The smaller and lighter four cylinder 912 motor.
This owner defies the norm of racing a coupe by having just as much fun competing in his 1973 Targa.