Porsche 911 Carrera (996.2)
A tuning session cures the 996’s reluctant running – and returns some impressive figures to boot
IKNEW THE 996 WASN’T ENTIRELY HAPPY because the fuel consumption had disappeared through the floor (22mpg average in normal driving). Fitting freer-flowing exhaust back-boxes shouldn’t require any additional set-up work, but I’d also added less restrictive cats and a different system design that mixes the gas paths in the centre below the rear valance.
As I mentioned last month, it was also struggling for low-down response and torque, another sign that it was running too rich, even if top-end enthusiasm seemed to have improved. I described the situation to Rob Young at DMS Automotive, who said he’d seen such a problem on 996s many times before, so it was off to Southampton to investigate further.
I’ve never been up close to a car on a rolling road before, and certainly not my own pride and joy, so when it was strapped down and a giant – and deafening – fan was placed in front of its snout, I felt a little nervous. But I’ve known Rob for years and trust completely in his abilities and experience.
Rob’s first run was merely to see where things currently stood, not just in terms of the power and torque, but also to see how accurate the lambda sensor data being sent to the ECU was. Satisfied that his own readings (via a probe) matched the car’s (a sign of a well-designed exhaust system, apparently – nice one Kline Innovation) it was time to delve deeper.
It would have been nice to know what the car was putting out before the fitment of the exhaust, but I was bursting with pride that after 18 years and 85,000 miles the 996 logged 310bhp and 280lb ft of torque on that first run – that’s just 5bhp less and actually 6lb ft more than the claimed factory figures. Admittedly, the graph betrayed the rather limp delivery between 3000 and 4000rpm, but that’s what we were there to sort out.
Rob then got busy with the laptop, increasing the ignition advance while seeking to optimise the target lambda, and then did another run on the rollers, then some more keyboard tapping, and then another run, and so on, eventually arriving at an amazing 339bhp and 300lb ft. Such figures put it on a par with the factory X51 Powerkit (341bhp and 274lb ft), which had the benefit of different cams, cylinder head work and revised induction.
I was staggered, and, I must confess, in a state of slight disbelief, but Rob seemed very happy indeed with OCL’S health and confident in what had been achieved. The actual ‘proof’ was the journey home, which is the best drive I’ve had in my 996 during the four years I’ve owned it. The mid-range muscle has returned, but the way the power now really takes off, particularly over 4000rpm, is addictive, and it really howls, too (helped slightly by deleting the Heimholtz resonator with a simple kit).
Tellingly, and in spite of not sparing a single horse for the entire slog home, we averaged a frankly baffling 29mpg. Love it.
Date acquired May 2016 Total mileage 85,447 Mileage this month 251 Costs this month £594 tuning mpg this month 29.0