Porsche 911 Carrera (996)

An enterprising engine swap brings Project Arena Red back to life

HERE’S THE HEADLINE. AND IT’S A GOOD one. After many twists, (U-)turns and broken dreams, Project Arena Red is alive. And in place of the sadly departed M96 engine is a 3.8-litre direct-injection 9A1 lifted from a 991 Carrera S that a reversing lorry hadn’t noticed. The resulting carnage along the entirety of its nearside flank unwittingly provided the perfect donor for my reborn 996 Carrera. So, what I now have is a 996 with somewhere around 400bhp, a complete chassis overhaul and so much trick fabrication and invention by Litchfield that, I suspect, it will remain forever unique. To say I’m happy with how things have turned out is something of an understatement.

Of course, it also means I’m an idiot. I knew the old engine would need a teardown and just assumed I’d do a 3.7-litre rebuild, so spending money on shiny things like a deep pan oil sump and essentials such as new oil scavenge pumps and then splurging on a full exhaust system just seemed like a part of the process. Even the Zircotec exhaust coating, although a little extravagant on my humble Carrera, was an exciting piece of the puzzle: not exactly essential, but embracing the current restomod trend for spending way too much money on making older cars better than they were when new.

Then I got the call. Litchfield’s Scott Chesshire had already done so much on the car and to impeccable standards – fitment of the KW Clubsport coilovers, RSS suspension arms, Eibach hollow anti-roll bars, rebuild of brake calipers and fitting of new OEM discs and Pagid pads, and tidying up a few interior pieces such as the new Rennline adjustable throttle pedal – but, as feared, the big job would need doing. So, we started discussing 3.7-litre conversions and the usual talk around M96 rebuilds. A plan emerged.

Then it all changed direction completely. Idly typing ‘991 complete engine’ into ebay revealed maybe half a dozen results, all complete engines from salvage cars, ranging from around £5500 for a 3.4-litre (345bhp and a real little screamer) to anywhere from £8500 to £12,000 for 3.8-litre engines of various mileages, ages and provenance. The bigger flat-six is good for 394bhp at 7400rpm and 324lb ft at 5600rpm and propelled the near-1500kg 991 Carrera S to 188mph and 0-60mph in the low fours along the way. Can you see how my mind started racing? My 996 was on the road to an extreme engine swap.

Iain Litchfield doesn’t like to do things by halves and decided that an engine of unknown origins from ebay was a very bad idea. Plus, he suggested having the 991’s wiring loom and various other bits could be an important part of the conversion. A couple of weeks later I got a picture of that remodelled silver 2014 Carrera S, which had covered just 15,000 miles. Then another of it on the ramp beside my car, both engines dropped out on pallets below. Surely this was going to be the easiest engine swap ever?

Oh dear god, no. Iain and his boys won’t use the word but I suspect ‘nightmare’ has been uttered around my car many, many times. Scott and his colleague Stuart Macpherson have performed

miracles to make this thing work. Here’s a rundown in note form by Stuart, which provides some insight to the task but hardly describes the effort and ingenuity required to marry the whole thing up:

‘Removed engine and gearbox on both cars. Offered 991 engine up to 996. Found rear mounts needed to be moved back and up.

‘Decided to keep 996 gearbox due to driveshaft and gear cable positions. (The 991 was a PDK and the gearbox is HUGE, anyway.)

‘Tried fitting 996 gearbox to 991 engine. Everything lined-up pretty well, but required fabrication of three further mounting points. Also cut out clearance for starter motor and refabricated.

‘Fitted lightweight flywheel matched to 997 clutch plate and cover that picks up 996 splines. Clutch actuation rod then had to be carefully measured to achieve full engagement and disengagement.

‘At this point the engine was ready to refit and we could pick up on the gearbox mount. The rear engine mounts were carefully removed and the cross-member cut out. With the engine finally sitting in the engine bay a new cross-member was made and the original mounts could be refitted to this new structure.

‘The next job was refitting all of the hoses and pipes. The two coolant hardlines were removed from the 991 and the shape was similar to the 996 but would not fit, so they were cut and welded to follow the profile of the car and the new heater hoses and air-conditioning pipes.

‘The 996 runs a mechanical power-steering pump whereas the 991 runs an electrical pump. Neither of these would swap over so it was decided to run an electric pump as used in the 996 Cup cars. We fitted the pump in a fabricated bracket, then had to remove the rack and make some custom unions to accept the new hoses.

‘The most difficult part of the build was the wiring loom. In both cars we stripped back and carefully removed all of the DME [Digital Motor Electronics] wiring. The wiring diagrams were cross-referenced and the 991 loom was spliced into the 996 loom.

‘The 991 utilises a full CAN bus for running the instrument cluster and other functions whereas the 996 uses the older analogue signals. So each gauge had to be hardwired to the new Syvecs ECU and then be calibrated to work.

‘The 991 exhaust system was refabricated to fit inside the 996 bumper. A bespoke air intake also had to be fabricated. The engine cooling fans have been fabricated to work with the new 991 engine, too.

‘The original accelerator pedal was cable operated whereas the 991 uses a fly-by-wire set-up, so we made a new bracket to mount the 991 pedal and created new wiring.’

The detail is incredible and, as usual, the guys at Litchfield have gone above and beyond. The new Syvecs ECU opens up a whole world of possibilities, too. Variable-slip traction control? No problem. These are things we’ll investigate down the road… For now, the car is running beautifully. It’s been on the dyno for various calibration cycles and essentially Project Arena Red is finished.

Except they’re never finished, are they? The car is going to be so good mechanically that I felt the rest of it needed to be up to scratch, too. Therefore, it’ll soon be apart again, stripped for a new respray (yes, I’m keeping the colour!), the engine bay and mechanicals all detailed and better than new. Plus I’ve ordered some new custom seats from Corbeau and I’m investigating a full retrim for the inside, too.

This is all illogical and absurd and with a similar spend I could maybe have bought something way more exotic than a 996 Carrera. But I suppose this affliction isn’t necessarily logical and the 996 is going to be bloody amazing. Similar power to a 996 Turbo (we’re hoping up to 430bhp might be achievable), narrow-bodied, lighter than a GT3 RS and with a fantastic suspension set-up, I think my 911 has the potential to be truly a magical thing. If I call it a restomod it’s gotta be worth £150,000 too, right?

Jethro Bovingdon (@Jethrobovingdon)

Date acquired May 2013 Total mileage 150,432 Mileage this year 0 Costs this month TBC, but probably the equivalent of a clean 997 Carrera S mpg this month n/a