8 Minutes
For a new generation of enthusiasts the Porsche 911 997 series represents the childhood image of the classic German sports car. That makes any tampering with the factory rear-mounted flat-six an almost personal provocation. Yet here we have a clean, unassuming 2007 Porsche 911 Carrera 4S Cabriolet listed on Bring a Trailer that hides a decidedly un-Porsche powerplant under its rear hatch. Walk all the way around this convertible and, apart from an aftermarket Pioneer head unit, you could easily mistake it for an untouched 997. But pop the rear deck and the surprise is obvious — this 911 houses a Honda K24Z engine instead of the original M97 flat-six.
This is the sort of Frankenstein tuner project that polarizes purists and excites builders. The M97 engines fitted to many 997s have known weaknesses, most notably intermediate shaft bearing failures on high-mileage or abused units. A swap like this sidesteps that particular reliability minefield and embraces a different tuning philosophy: lightweight, high-revving, and VTEC-driven performance grafted into iconic Porsche chassis dynamics.
What’s Under the Rear Hatch
Engine and Induction
The replacement heart is a Honda K24Z, the same basic architecture used in late 2000s North American Accord and CR-V models and later in Civic Si and Acura ILX variants. In stock form the K24 is modest in peak horsepower, but with a reputation for stout internals and a broad aftermarket. This build is far from stock. Key engine components and modifications include:
- Forged Wiseco pistons
- Manley forged connecting rods
- King rod bearings
- Magnesium valve cover for weight savings and looks
- 1,700 cc injectors paired with a Bosch high-flow fuel pump
- Link Extreme standalone ECU for full engine management control
- Boostlab 58X turbocharger for forced induction and substantial power gains
Taken together, these upgrades transform the K24Z from a refined OEM four-cylinder into a turbocharged, high-output power unit. The parts list on the engine alone likely exceeds the cost of an entire Civic Si with a K24 installed from the factory. Output estimates are not published on the listing, but conservatively this setup is likely to make well into the high hundreds of horsepower at the wheels, given the fuel, induction, and internal upgrades fitted.
Chassis, Brakes and Suspension
Braking and Hardware
To match the additional performance, this 997 uses Brembo brake rotors at all four corners, helping to ensure stopping power and thermal capacity appropriate for spirited driving. Brembo hardware is an OEM-level upgrade that also improves fade resistance on track or canyon runs.
Suspension and Bushings
Underneath the car, the owner refreshed key suspension bushings and control arms to retain sharp handling and reliability. Work includes new strut and subframe bushings plus SPC adjustable front and rear lower control arms, added front and rear caster arms, and strengthened rear tow arms. These parts help maintain alignment precision under load and allow cornering geometry to be tuned for more aggressive driving while preserving ride quality.
The remainder of the suspension is largely original to the 997, which means the car still benefits from Porsche’s factory chassis tuning that made the Carrera 4S such a rewarding platform in the first place.
Interior and Exterior
The exterior appearance leans into the sleeper aesthetic. From a distance it reads as a well-kept 2007 Carrera 4S Cabriolet: classic 997 lines, convertible roof, and understated details. The only outward hint of modification appears to be a Pioneer head unit in the dash, otherwise the cabin is period-correct 997 black leather with a Bose audio system intact.
That stealth presentation is deliberate. The car looks like a tasteful, gently used 911 yet has been re-engineered at a mechanical level to create a very different driving experience than the factory Carrera 4S.
Performance and Driving Character
Swapping a turbocharged, high-revving K24 into a Porsche 911 transforms the driving experience. Compared with the M97 flat-six, the inline-four K24 delivers a different torque curve and powerband — VTEC-assisted top-end rush, tight throttle response, and, with the Boostlab turbo, rapid spool and strong midrange torque. The lighter weight of a K-series engine compared to a six-cylinder might slightly alter front-to-rear balance, though chassis bracing and subframe bushings help the 997 maintain composure.
From a practical standpoint this machine is likely faster off the line and in the midrange than a stock Carrera 4S, and potentially competitive with early 997 Turbos depending on final engine tune, turbo sizing, and drivetrain losses. Whether it will consistently beat a factory 997 Turbo in real-world runs comes down to tuning, traction, gearing, and how well the conversion integrates with the Porsche transmission and differential.
Market Positioning and Appeal
This 2007 Carrera 4S with a K24 swap occupies a niche space in the collector, enthusiast, and tuner markets. It will appeal to buyers who value originality and traditional Porsche engineering less than raw, creative performance builds that prioritize reliability, tunability, and an unconventional approach.
Prospective buyers include:
- Tuners who revere the K-series platform for its aftermarket support and high-revving nature
- Drivers seeking a unique and surprising track or canyon weekend car
- Buyers who value the stealth, sleeper look with modern tuning potential
Conversely, the car will likely put off purists and traditional collectors who prize factory originality. For auctions like Bring a Trailer, that divergence between preservation and modification creates strong debate and often strong bidding from the right buyer segment.
Comparisons and Context
The K24 swap in a 997 is unusual but not without precedent in the wider automotive tuning world. The most popular swaps remain Toyota 2JZ and GM LS series engines due to their displacement and torque characteristics. However, the Honda K-series is favored for its rev-happy personality and lightweight packaging, which is ideal when weight distribution and nimble handling are priorities.
Relative to a stock 997 Turbo, this build focuses on a different ethos: instead of raw factory turbocharged straight-line performance, it offers a high-revving, turbocharged four-cylinder with immense mod potential and a playful VTEC character. Comparison points include:
- Power delivery: more peak revving and VTEC top-end versus the flat-six’s torque spread
- Weight and balance: K24 is lighter, potentially benefiting handling
- Reliability: avoids some known M97 failure modes but introduces swap-specific integration and cooling considerations
Specifications
- Model: 2007 Porsche 911 Carrera 4S Cabriolet (997 series)
- Original engine: Porsche M97 flat-six (replaced)
- Current engine: Honda K24Z with boostlab 58X turbo and Link Extreme ECU
- Induction: Turbocharged, large injectors (1,700 cc) and Bosch fuel pump
- Internals: Wiseco pistons, Manley rods, King bearings
- Brakes: Brembo rotors front and rear
- Suspension upgrades: New strut and subframe bushings, SPC adjustable control arms, caster arms, rear tow arms
- Interior: Black leather 997 cabin with Bose audio and Pioneer head unit
Final Thoughts
This Carrera 4S conversion is an example of modern tuner creativity meeting classic sports car architecture. It will attract buyers who want an unexpected performer in a familiar shell — a true sleeper that rewards close inspection. Whether you view it as sacrilege or inspired engineering depends on your priorities: originality and resale, or personal performance and build quality.
If you want to know whether this K24-powered 997 out-accelerates a standard 997 Turbo, there is only one conclusive answer — put it on a dyno and the street, then place a bid and find out.
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