BUYING: 928 GTS
It didn’t succeed in replacing the 911 as Porsche intended, but the 928 refused to bow out quietly, leaving its final mark on the sports car scene with the awesome 5.4-litre GTS…
What to watch out for when on the hunt.
After being introduced to the world at the 1991 Frankfurt Motor Show, the GTS was the only 928 in production, enjoying exclusivity until the model was discontinued (alongside the 968) in 1995. On the surface, the GTS wasn’t a huge departure from the GT that came before it (factory bosses described the GTS as “polishing the diamond”), but as is always the case with the evolution of Porsche products, significant changes had been applied to the engine – now a 5.4-litre V8 chucking out close to 350bhp – and chassis equipment, though that’s not to say the exterior was neglected. Among other changes, Style Porsche boss, Harm Lagaay, introduced more muscular rear wheel arches, wider alloys, a 911-aping rear reflector fill panel and Cup-style door mirrors, as well as a lick of body colour for the ‘ironing board’ rear spoiler. While the changes didn’t deliver
a Porsche offering unrivalled value for money, they did make the 928 a more desirable model in readiness for its last few years of assembly.
2,904 Gts-badged 928s were built before production ended. Only 192 were right-hand drive and, typical of previous 928s, the vast majority were equipped with automatic transmission. This was, after all, a car Porsche originally designed for cross-continent touring, rather than an attack of the track. Today, save for the limited edition 928 Club Sport (mainland Europe and North America only), the GTS is considered the most desirable model in the 928 family, but top-of-the-line performance and exclusivity commands a premium price tag when compared to the cost of buying an earlier model.
Fortunately, most owners have recognised the value in keeping their GTS in tip-top condition over the years, meaning it's not unusual to find an available example with very low mileage, though you’ll have to sit tight if you’re holding out for a specific colour and/ or one of few kitted-out with a manual gearbox. Whatever GTS you end up with, you'll rest assured knowing you’re in possession of a practical, powerful, class-leading grand tourer representing the last hurrah of the legendary 'land shark'. Here’s what you need to know when searching for a 928 GTS in the classifieds.
BODY
The GTS was regarded as a special Porsche from the moment it was launched. Most owners treated it accordingly. There are, of course, a few examples that have suffered neglect (accident damage or poorly observed maintenance), but on the whole, you should be able to spot a poorly kept GTS just by looking at it. They’re either really good or really bad!
The 928’s monocoque shell is constructed from galvanised, zinc-coated steel, while its body panels are aluminium. This was an impressive exercise in reducing weight and fending off corrosion at a time most car manufacturers were unfamiliar with the word ‘underseal’. Even so, almost twenty-six years have passed since the last GTS rolled off the production line, and unless the car you’re looking at has been sitting in a temperaturecontrolled storage facility, there’s every chance factory introduced perforations in bodywork — the weakest points of the galvanising — will be showing their age. Make sure you have a good poke around.
It’s common for paint to bubble on the doors, wings and bonnet, especially if the car has been kept under a poor quality cover trapping moisture. Don't be alarmed — aluminium doesn't rust (though it can corrode under certain circumstances), but bubbling is unsightly. A body shop will need to fix the problem.
An independent inspection from a marque specialist is always advisable when buying a used Porsche. Among other things, those in the know will be able to tell you if you’re looking at rear quarters full of filler. With this in mind, don’t be afraid to spend time checking out every last part of the car until you’re satisfied you’re paying a fair price. The seller shouldn’t rush you. If they do, then what are they trying to hide?
Have a look at the condition of the car’s sills. Early 928s feature exposed lower panels covered in protective stoneguard and paint, whereas the GTS features plastic side skirts that do a great job of hiding corrosion. Worse still, they can trap moisture if they’ve been removed and incorrectly refitted. On the plus side, they repel road dirt.
The GTS inherited the S4’s large rear spoiler. It should be colour-coded. The part is positioned above the rear reflector fill panel. It's expensive to replace. If cracked, factor the cost of renewal into what you're willing to pay.
SERVICING
When buying a GTS, good service history is vital. Check to make sure there’s a complete stash of paperwork and no unexplained periods of being off the road. These cars hate not being used.
Ensure all fluids, filters and timing equipment have been changed in accordance with the manufacturer’s instructions. Ask what grade and content of oil has been used. If you’re about to buy a car that’s been left standing for a while, invest in new timing equipment. This can be bought from Heritage Parts Centre or Design 911 at a reasonable cost and is a DIY job, although you will need specialist tools. If you don’t want to take on the work yourself, speak to a Porsche servicing and restoration specialist.
It’s also a good idea to have the car’s fuel injectors ultrasonically cleaned. They’re unlikely to have been serviced at any point in the past, but are prone to trapped dirt particles, resulting in inconsistent fuel spray patterns that can inhibit performance. Expect to pay between £10 and £20 per injector. Contact the guys at Injectortune ( injectortune.co.uk) for assistance.
Service intervals are recommended at 12k miles, with timing belt intervals every 48k miles. If, as we suspect, your GTS is left standing for long periods (winter storage) and doesn't cover much ground, ensure you change the oil at least once a year, regardless of mileage.
ENGINE
By the time of the GTS’S arrival, strict emissions laws required the use of milder camshafts than had been used on the 928 S4 and GT. To compensate for an expected loss of power, engine displacement was increased to 5.4-litres through increased crankshaft stroke (up to 85.9mm from 78.9mm). A revised compression ratio, lightweight pistons, new connecting rods, updated Bosch engine management, improved airflow equipment and electronic knock control contributed to almost 350bhp and 369lb-ft torque, with a surprising amount of power delivered down in the lower rev range.
In 1993, GTS engine block lower studs were replaced with bolts for improved strength and reliability, while a new design of piston ring strengthened skirts and reduced oil consumption.
Fortunately, Porsche's largely aluminium 5.4-litre V8 engine is over-engineered and under-stressed, meaning most problems only occur through user error or neglect. Fluid leaks are rare, but check the condition of the oil and coolant anyway — a 928 run on an incorrect mixture of water/coolant will encourage head gasket failure. Check for white smoke from the rear, but don’t be alarmed to see this on start-up. It’s likely to be evaporating moisture in the exhaust system from where the car has been sitting motionless (full marks to any owner intending to use a GTS as a daily drive!).
The 928 is Porsche's only coupe powered by a front-mounted V8. The GTS 5.4-litre 32-valve unit is an exceptionally smooth engine, with linear delivery of power from the 3,000rpm mark after an exciting release of torque and horsepower. A malfunctioning unit should be easy enough to detect. That said, if this is the first time you’ve driven a 928, then it might be worth inviting someone familiar with the model to help evaluate your prospective purchase. For comparison purposes, try to get seat time in more than one GTS. Members of an owners club may be of assistance, inviting you to try before you buy.
INTERIOR
From the S4 onwards, 928 dash clocks featured a digital display providing important driver information, such as service interval alerts and error messages. In fact, the dash clock cluster is littered with more than twenty warning bulbs letting you know if anything is amiss.
It may have become increasingly more refined as the years rolled by, but the 928’s interior design remained largely unchanged from the earliest cars of the late 1970s through to the GTS. The same Hasbro-esque control knobs sit each side of the steering wheel, while the dashboard cleverly splits at each end and continues its shape into the door cards.
928 interior design is one of the model’s most celebrated features, which is one of the reasons Porsche left well alone. GTS seats tend to be full leather, with pale grey the most common variant. Modern car care products make it possible for visibly damaged leather to be brought back to life without the need for a retrim, but look out for wear on seat bolsters, side cushions (where occupants have dragged their butts) and steering wheel discolouration, which might command a fair chunk of labour to put right.
The GTS is a heavy car when compared to the earlier GT. The additional bulk is partly due to extra soundproofing, where Porsche wanted to achieve ‘the best of both worlds’ by producing a fast sports car doubling up as a comfortable cruiser. Even so, you're looking at a car built almost three decades ago, so expect the occasional rattle or creak from loose interior fixtures and fittings. Get your screwdriver at the ready and you'll soon right those wrongs!
BRAKES
The GTS came with ‘big black Brembos’, far bigger than the stoppers bolted to the S4, which were already a substantial improvement over the 928’s earlier anchors. New discs and pads in a variety of styles and compounds are readily available from the likes of EBC Brakes, Heritage Parts Centre, Frazerpart and Design 911. ABS is a standard feature of the GTS — it may be heavy, but this Porsche stops as well as it presses on.
TUNING
Before you’re tempted to tinker, make sure the car is properly serviced and is running without fault in a standard state of tune. You’ll be surprised at the positive impact fresh fluids, filters and other consumables will have on the driving behaviour of an older car.
Importantly, consider whether you want to modify a GTS. Standard examples hold their financial value well — irreversible modifications may impact the sale price you’re able to achieve when it comes to passing your pride and joy on to its next owner.
Porsche threw everything it had at revitalising the 928, breathing new life into an influential product line that had been around for almost two decades. The GTS has, consequently, become the most sought-after model in the 928 range. It’s an excellent car, but that doesn’t mean there isn’t room for improvement.
ECU chips from 9Tuning ( 9tuning.com) are claimed to deliver an extra 15bhp and 18lb-ft torque without any additional hardware changes. Derestricted exhausts will improve throttle response and release trapped ponies, while those keen on using a GTS at the track might want to consider the benefits of increased displacement through the appointment of a stroker kit designed specifically for the 32-valve V8. Currently on offer for $10,612 at the 928 Motorsports website ( 928motorsports.com), the kit will produce a six-litre engine if the standard diameter piston is retained, whereas upgrading to an enlarged sleeve bore and piston will yield a massive 6.57-litres. Machined from single billet 4340 steel and shot-peened for stress relief and surface hardness, the package is rated at a whopping 600bhp. Just remember to tell your insurance company of the changes!