Porsche 911 Modified

Porsche 911 Modified

Coupé, 1978

Highlights

  • Approximately 980 KG!
  • 3.5-Litre Tuthill Engine
  • For anyone looking for a serious, analogue Porsche!

1978 Porsche 911 RSR Homage – 3.5-Litre Tuthill Engine

An uncompromising, twin-plug 911, painstakingly re-engineered over a 12-year period with no expense spared, featuring extensive Tuthill components, 320bhp at the wheels and weighing approximately 980kg.

LIVE AUCTION: This lot will be auctioned on Saturday 14th November, 2026 at 11.00am local time at NEC, Birmingham, B40 1NT

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The vehicle in detail

By the late 1970s, the Porsche 911 had evolved into a genuinely formidable sports car, combining its distinctive rear-engined layout with increasing performance, usability and competition successes. The 911 SC was launched in 1978 with a 3.0-litre flat-six producing 180bhp and 195lb ft of torque, enough for 0 to 62mph in around 6.5 seconds and a top speed of c.140mph, a very popular car on its own accord, yet also providing the basis for countless subsequent developments, both on road and track. For enthusiasts, the appeal of the earlier competition cars has never waned, with the lightweight, wide-bodied RSRs representing the ultimate iteration of Porsche’s air-cooled 911.

The car we are offering is a remarkable example. Originally delivered new to Germany in 1978, this matching numbers 911 was first registered in the UK in December 1982 and is now correctly registered as a Historic Vehicle. Originally built as a 1978 911 SC, it has been comprehensively re-imagined and re-engineered in far more ways than the fairly commonly seen cosmetic backdates.

The project was conceived in 2012 by its previous owner, a lifelong Porsche enthusiast, with the intention of creating an uncompromising, lightweight, naturally-aspirated 911 using many of the finest components available with the end goal of having a truly road-legal car that is equally legal and eligible to race. Twelve years later, at the end of 2024, the completed car emerged, having been built without shortcuts and with a substantial investment, but unfortunately never racing in anger post-build due to the owner’s age.

At its heart remains the original matching 3.0-litre engine, professionally enlarged to 3.5 litres and assembled by the highly respected Porsche and Ford engine builder, Iain Ross. Built to a 10.6:1 compression ratio and featuring twin-plug ignition, extensive Tuthill supplied and machined components and PMO 50 carburettors supplied by Patrick Motorsports, it’s further equipped with an M-Saver fuel cell, RSR oil tank, RSR race headers and RSR silencers. The engine has been dyno tested at approximately 320bhp, providing an extraordinary level of performance in a car weighing approximately 980kg. This equates to a power to weight ratio of 327bhp/tonne, more than any of its rivals of the period, more than the 3.3-Litre 930 Turbo and almost as much as the Lamborghini Countach LP400.

The original 915 five-speed gearbox received similarly meticulous attention, having been totally rebuilt by Tuthill Porsche and fitted with a limited-slip differential. This work was carried out in 2014 at a cost of over £8,000, while the history file records Tuthill invoices exceeding £32,000 from that year alone.

The chassis has been developed to complement the engine specification, with emphasis on balance, precision and weight reduction. The suspension is Tuthill-supplied EXE-TC Classic Porsche Circuit dampers, while RSR hollow front and rear anti-roll bars, adjustable rear spring plates, refurbished front wishbones and new lower ball joints further sharpen the handling. Braking is handled by monstrous AP Racing six-pot front and four-pot rear brake callipers with new and uprated brake discs throughout.

Weight reduction was a fundamental part of the build. The car features lightweight resin front wings, front bumper and rear bumper, a lightweight resin bonnet, lightweight rear engine-lid with rear wing and polycarbonate side windows, rear quarters and rear screen. Inside are new ST-style front seats and competition harnesses and a fully welded roll-cage.

The scale of the undertaking is reflected in the comprehensive 1-inch thick ring-binder history file, including over 100 documents detailing all the major expenditure and specialist work carried out over the course of the build totalling over £80,000 in parts and labour alone. Unfortunately, the individual who conceived and commissioned the build never had the opportunity to enjoy the finished car for any meaningful length of time, with only a few hundred miles covered since completion. Our vendor purchased the car directly from him in December 2024 and now offers it following a change of focus towards an early Lotus Elite project as this 911 is understandably hardcore as a road car, and rapid as a race car.

For anyone looking for a serious, analogue Porsche that drives as well, as fast and as impressively as it looks, and that can be enjoyed equally on the road or track, this RSR Homage offers an unparalleled combination of specification, engineering and documented investment. Finding another 911 built to this level, with this degree of expenditure and so few miles since completion, would be extremely difficult and would cost well into six figures to replicate. We invite and encourage your inspection to appreciate the sheer quality on offer.

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Specifications

Year of construction: 1978
Model: 911 Modified
VIN: 9118300954
VIN copied
Body: Coupé
Series: 911 Backdate/Modified
Power: 320 HP
Cylinder capacity: 3.5 Liter
Steering: left
Transmission: Manual
Drive: Rear drive
Fuel: Gasoline
Interior material: Fabric/Leather combination
Interior color: Black
Exterior color: Black
New / used: Used car
Ready to drive: yes
Car location: GBUnited Kingdom
Elferspot ID: 6338310

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