It looks like an early 2.5 986 Boxster. It handles like one too. But… whoa… so this is what 400-turbocharged-bhp feels like in a 1,250kg Porsche! The innocent little Boxster starts making all sorts of evocative whistling sounds and the rev counter needle simply takes off. In what feels like an instant, I have to frantically grab the gear lever and shift to third, whereupon the rate of acceleration feels even fiercer. When I inevitably lift, there is all manner of wheezes and sneezes from the engine bay and brutal cracks and bangs from the exhaust. If it was dark, I’d put money on there being sheets of flame too.
This is a 986 Boxster 2.5 with a four-cylinder engine transplant. Now, if you’re tempted to turn the page in disgust, please don’t. I know some of you will be fascinated by what is going on here, but there will surely also be others who have just uttered the word ‘sacrilege’ under your breath in a very British way and who find the whole thing a bit abhorrent. At face value, I can see your perspective – really, I can – but I urge you not to do so, because there’s much more to this story than just swapping one engine for another.
For starters, this is as much about compassion for the original Boxster as anything else. The brains behind the Booster project is Matt Faulks, a name you might recognise from Porsche Post September 2024 in The Enthusiast at the back. He owns a highly modified 996.1 Carrera 4, which he’s taken past 340,000 miles, and also runs his own engineering consultancy christened MFAC. As he says: “I have a lot of time for the M96 engine and I say that as someone who’s driven over a quarter of a million miles with one. However, what kicked this project off was when I saw a mint-condition Speed Yellow 2.5 986 being shredded for parts on eBay. A main bearing had gone in the engine and the car was literally just being ripped to pieces. I thought: ‘That car had 20 years still in it...’”
It’s a sad thing that many an early Boxster is now being destroyed to make a few quid from an otherwise untenable financial position. Without turning this feature into a deeply technical one on the M96 engine, it’s a rather unpalatable fact that to rebuild one of these engines isn’t cheap. That can be a major headache if you own a 996, but there’s some reassurance that it’s a 911 and that values not only support such investment but are also on the rise (or so they say). With a five-grand Boxster needing a 10-grand-plus engine rebuild, the picture is a lot bleaker.
Faulks’ interest in Porsche’s original Boxster stemmed from the fact that he was in the
market to buy one himself, which he duly did during lockdown. It was a bargain purchase, advertised as a non-runner. Unsurprisingly, he had it working perfectly on the same weekend he picked it up. With the world in suspended animation and a little time on his hands, he set about what appeared to him to be an interesting technical challenge: making a pathway possible for 986 owners who had suffered the ignominy of an engine failure or would at some point. It had to preserve everything that made the 986 great to drive, which meant mass and mass distribution within one per cent of the original (Matt achieved just half a per cent in the end), and it needed to be cost-effective. It also had to be reversible, if desired, and with no drilling or modification to the chassis to keep the DVLA happy.
The more Matt shared what he was doing with the enthusiast community, the more interest grew. Suddenly, what had started as a bit of fun looked like being a business and ‘Booster’ was born – the name an obvious contraction of words in the style of Porsche’s original naming convention. That’s when the idea of marketing a kit with everything required to carry out the conversion with an instruction manual to guide buyers along each step of the way started to come to fruition.
Matt’s chosen engine for this ‘repower’ is the classic VAG 1.8T 20V ‘06A’ engine, as used in countless Audis, VWs, Škodas and Seats. In its high-power form, it is best known as the engine in the original Audi S3 and the Audi TT 225, but it has also seen countless uses in motorsport, from the Seat Córdoba and Škoda Octavia WRC cars of the early noughties to the Formula Palmer Audi and, latterly, the FIA Formula 2 Championship. It’s an engine with a reputation for strength and the ability to make lots of power with very little modification. It also happens to be available in plentiful quantities and, compared to the Porsche M96 flat-six, is astoundingly cheap.
The usage of the 06A is no happy accident. I think it’s fair to say that this inline four is one of those well-loved engines that have been used in countless conversions and modified to the hilt for decades. As Matt says, it comes from a time before manufacturers were able to use computer analysis and predictions to engineer engines and other components to be almost completely reliable at what they needed to do, but with not a penny’s worth of excess material or components for the task. Therefore, many of these earlier engines (up to the turn of the millennium) had an excess of strength built into the fundamental design. Elements needed to be upgraded to make more power, perhaps, but the standard engine could take it up to a remarkable extent. You might say the same of the turbocharged Mezger flat-six, the Nissan Skyline GT-R ‘RB’ engine or the Toyota Supra MK3 ‘2JZ’ engine, all of which are known for enabling huge power increases and all with a link to motorsport. The 06A very much fits into that category.
“The first thing I did was try to understand what the impact would be on the centre of gravity and the mass balance of the 986,” Matt explains. “What I didn’t want was to end up with something where the centre of gravity was very high. I didn’t want to invoke that tippy toes, unstable pendulum, light rear end thing.”
However, after Matt had 3D scanned the entire car and the donor 06A engine and put it into 3D computer design software, he was pleasantly surprised.
“The M96 is a flat engine and quite short, but you’ve got the exhaust manifolds under it so it’s got to be a little bit higher to clear them and then there’s the intake manifold on the top, “he explains. “Yes, that’s plastic, but there’s a lot going on there and the height difference (versus the 06A) is really the height of the (06A’s) rocker cover and 30 per cent of the head, which is alloy anyway. The iron block of the 06A has a lower crank centre line so, as we lowered the engine to fit in, that reduced the centre of gravity impact again. Overall, the effects are minimal. We can’t avoid moving the engine backwards because the Porsche gearbox (ironically, it’s actually an Audi gearbox!) stays in the OEM position, so the front face of the bell housing is the same as it was with the M96 in place. However, rather bizarrely, the 06A is actually shorter than the M96, because the M96 is designed with the timing gear on each end. Obviously, that meant the mass would move slightly rearwards, so the solution was to add some additional material to the tombstone mount at the front of the engine to move the balance of the car back forwards again. The really good news is that – again, rather unexpectedly – the 06A engine is around 50kg lighter than the M96, depending on the manifold and turbo installation.”
The Booster conversion is available in two kits. The Fundamental kit (£1,250+VAT) is designed for those with plenty of technical capability and who are going bespoke on various elements of the engine. It provides just the basic elements to mount an 06A in the car, consisting of a three-piece front engine mount CNC-machined from billet alloy and a 3D-printed cut template with laser-cut steel weld-ins to allow for easy modification of the gearbox mounts along with a weld-in laser-cut and pre-folded cross member element that also forms the required cut template.
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The Enhanced kit (£2,500+VAT) is far more extensive and includes everything you need to build the car, bar the engine. That means the mount is exactly as mentioned above, but there is also a new single-mass flywheel with a 240mm clutch taken from the Audi RS 4 that’s good for 325lb/ft with no gearbox modifications required. A coolant temperature sensor kit, throttle body and IAT extensions, high-flow fuel pump kit (good for up to 500bhp) and a kit of fasteners are also included. Perhaps most helpfully of all, there’s also a hard-bound, colour, 20,000-word build manual guiding you through every process from removing the M96 engine onwards. To be honest, there’s so much information on offer it’s probably best to grab the ignition key now and get driving. If you want to learn more, visit www.986booster.com where there’s even a 40-minute YouTube presentation video on the conversion.
Anyway, all of that will count for little if the driving experience doesn’t perform and, perhaps most crucially, feel right. This probably isn’t the moment to delve into the merits or otherwise of the regular 718-series cars, but I do think it’s fair to say they have split opinion. How will a regular inline ‘four’ in a 986 fare, particularly if you’re not a fan of the flat four Porsche’s thrum and thrash?
The first thing to notice is indeed the noise it makes. Matt has been testing different back pressures on the rolling road and, on the day of our test, he admits the exhaust is particularly ‘free flowing’ for the sake of emissions investigations the previous week (the conversion is slightly ‘cleaner’ than the original). What it does make is an amusingly serious rally car-like roar, even at idle – the sort you might hear in the service park at a round of the WRC. It is loud but, as someone who endured an aftermarket ‘sports’ exhaust on his 996 and the associated motorway drone, it’s not as bad as Matt makes out. Either that or I’m losing my hearing as I get older…
At this point, I should say a little about this particular 986. Outside of the engine kit, there is nothing on it that’s away from standard apart from some upgraded brake discs, pads and Michelin Cup 2 tyres. All the dampers and bushes are standard (and, perhaps, original in some cases) and Matt politely reminds me not to judge its dynamics too much on its merits as a 2.5 986 versus other 2.5 986 examples, if you catch my drift. What it does have is lots of power – more than 400bhp, in fact. The spec of the engine is one of the fun parts to this conversion; it’s really down to what you’re looking to create and, of course, your wallet. The options range from a straight engine swap, in which case you have 225bhp if you put the engine in untouched (a functioning engine should be £1,000 upwards) to one rebuilt by a specialist such as Matt’s chosen one, Badger5, in which spec here it’s good for 500bhp. The standard engine is safe for tuning up to around 290bhp but one of these, fully built up from a bare, cleaned block, is around eight grand with race bearings, steel rods and stronger, lighter valve gear (see right).
Matt has teamed it here with a big, older tech turbocharger (a Garrett GT3076R) for those traditional thrills and advocates the use of a McLaren 570 GT4 charge-cooler (a water-air intercooler, of the type used by Porsche’s 718) to keep inlet air temps down. He’s using the Igntron aftermarket ECU, which uses a mathematical model for its calibration. This sophisticated replacement ECU slots straight in and has allowed Matt incredible control over the engine’s boost characteristics. That’s vital, because the Booster uses reduced boost in first and second gears, only making the full 1.7 bar once in third. It’s also calibrated to manage the torque in a linear fashion through the gears. Without getting too technical here, the crucial part to understand is that peak torque is restricted to 340lb/ft and is only developed at a relatively high 5,700rpm. Instead, power is developed with revs, producing a searing top end but one that avoids the huge dump of low-down torque characterised by modern turbocharged engines that would a) break the gearbox and b) risk spitting the little Boxster off into the nearest hedge at every opportunity.
That’s the theory. In practice, it’s absolutely mighty. I’m not sure I’ve ever driven a modified car, let alone one with an engine conversion, that feels so OEM as the Booster. Its manners – all the boring bits like low-speed running in traffic, idling, behaviour on clutch take-up, etc – are meticulous and that’s courtesy of the Igntron ECU and the extensive time spent calibrating the software. It’s really quite surreal because, before long, to drive it feels entirely Porsche-like. I find myself thinking out loud. “Did I miss something? Did Porsche make one of these originally?”
With its deliberately old-school turbo installation, it’s entirely possible to drive around in the Booster permanently off boost but, with less than two litres of displacement, it’s a leisurely experience. It’s only as you approach 4,000rpm that the already aggressive engine note hardens and the sound of rushing air becomes apparent. From there, once on boost, there’s an exhilarating band of acceleration all the way to 7,000rpm (this engine revs slightly higher than standard thanks to the modifications). Yes, it’s every bit as fast as you might suspect. Frankly, if you were driving any number of modern Porsches, including those with rather large price tags, you would be left gasping and incredulous. That sense of shock on people’s faces would be one of the most amusing aspects of owning a Booster. It’s just not fathomable how quickly this little 986 can accelerate.
What the boost curve does mean is you have to really chase the power. On a country road, you have to be totally engaged in the act of driving, making sure the gear selection is correct to put you in the power zone exactly when you need to be. It’s a very involving driving experience, something often missing from modern turbo-powered performance cars with their anytime, anywhere ‘go’. There’s no room for laziness here.
Perhaps surprisingly, the rest of the Boxster experience more than keeps up. The Cup 2s find amazing grip and it feels as though it would need very deliberate provocation to unstick the rears under power, particularly with the carefully massaged torque curve. I have to concentrate hard to find any gaps in the Booster’s armoury and the only negative feedback for Matt I can detect is a little softness to the throttle response when blipping during downshifts. It takes quite a flex of the foot to bring the revs up enough during heel and toe changes, but Matt’s aware of this and explains the technical reason why. He’s working on a mod to overcome it too. Push the Booster really hard and those standard, aged suspension components start to betray a lack of control and precision given the forces at work. It will be interesting to try the car when it’s had some suspension development too, which is on the cards.
The Booster really is spectacularly good. It’s an indecently good value way to own a Porsche sports car with major league performance and one that’s always only a single accelerative lunge from putting a massive grin on your face. Given the history between Porsche and Audi, and the fact the 06A’s time coincided with the leadership of the ultimate VW Group godfather, Ferdinand Piëch, there’s a definite sense of keeping it in the family. With that link, the fact that Porsche’s early history was based around four-cylinder cars and its sporting, tuning scene often featuring roadsters, the Booster feels entirely appropriate as a new-wave Porsche outlaw. What a way to reinvigorate a poorly 986 2.5 that’s down on its luck.