The Porsche 930 (also known as the 911 Turbo and Turbo Carrera) was produced from 1975-'89, first with a three-litre engine until 1977 and then with a 3.3 litre.
The owner of this 1982 example wanted a full restoration and performance upgrade, but with improved driveability and reliability because it was his 'daily drive'.
It had a factory-fitted Kremer 'whale rear wing and an engine upgrade that increased the power by 80bhp, but the low and mid-range performance and driveability suffered. Its four-speed gearbox didn't help matters.
The 930 had a reputation as a fast car that was difficult to drive, more so on the road than the racetrack, and this one was typical!
When we inspected the engine it was quite 'tired', so we replaced any worn parts while we were upgrading the performance. This included lightening the crankshaft, increasing the compression ratio, tidying up the cylinder head ports, changing the camshaft, and fitting a late-model roller bearing turbo with a twin-scroll exhaust housing. We fabricated a new exhaust system, incorporating a new and more efficient remote wastegate.
The replacement turbo was designed for the later model water-cooled Porsche engines, and since this engine was air-cooled we modified the oil system to improve the cooling and lubrication.
We fitted a Motec engine management system to control the ignition and boost, which were the most critical areas to achieve the owner's goals. To keep the engine bay looking standard from above (although it certainly didn't look standard from underneath!), we mounted the Motec unit out of sight and retained the original Bosch K-Jetronic fuel system.
The new set-up transformed the car's performance and driveability. The engine made an extra 30bhp at the top end, but more importantly it had double the power and torque between 2500-3500rpm. The new exhaust system was a major contributor, yet it was remarkably quiet and resonance-free.
With a replacement five-speed gearbox the car accelerated hard from 2000rpm almost without turbo lag. It had much better road manners than before, but it was an absolute rocket when you put your foot down!
Tidying up the electrics and ancillaries made everything work and feel like when the car came off the Porsche production line.
Any Porsche 930 owner who doesn't like the model's on-road behaviour would be much happier after it's had the Corse treatment!
- MICK MITCHELL
Corse Automotive & Motorsport specialises in upgrading and restoring Porsches and other high-performance cars for road or track. For a chat about your requirements, call us on (02) 9757 2966 or send us an email.