Alan Lancaster from Preston is a dyedin-the-wool Audi enthusiast, with two of these solid Teutons in his garage – a TT roadster and now a new A4 2.0 TDI Cabriolet – the subject of our test
But he goes back a long way with Audis and it was in the mid-nineties that he had his first tuning experience, with one of the original A4 TDI 90s, which responded very well to the efforts of the tuners. Alan first came to Tunit at Chorley with his last car, an A6 Avant 3.0 TDI Tiptronic, whose only real sin was to have an exhaust emissions figure of 226gm/km – just the wrong side of the 225gm/km excise duty break point that now almost doubles the annual cost and hikes the depreciation on such cars. He loved the A6, with its space, performance, and cargo capacity, and was thrilled to bits with the car’s performance after the Tunit conversion, and he was equally chuffed with the 40mpg plus economy, which was a good 4 to 5mpg gain over the car when it was standard.
Alan might say that he blames Gordon Brown for having to sell the A6 Avant! I think it was all just an excuse to buy the handsome A4 Cabriolet in Akoya Silver that has taken its place – so let’s hope that his wife doesn’t read this! It’s a gorgeous looking car that’s very striking in that colour and set off even better with some cracking 18-inch RS4 alloys which took his existing tyres, reducing the cost of the wheel switch. It’s still only a few weeks since he took delivery of the cabrio, and even less since he had the Tunit conversion fitted, so when he was offered the opportunity to bring the car back to Tunit for this feature, and see some “before and after” engine dynamometer figures taken, he jumped at the chance.
Anxious to see what the tuned 2.0 TDI engine was producing, the boys at Tunit soon had the A4 on the dynamometer rollers and tied down securely to the floor-mounted anchor points. Alan, earmuffs securely in place, was fascinated to watch the test procedure, which first involves setting up a huge cooling fan to keep the engine and its intake air cool, and taking a few preliminary runs to establish gearing figures. Then, for a power and torque run, the test driver gets the car rolling, usually in second gear, and then drops it into the gear that is nearest to a direct 1:1 ratio, usually fifth. After that, its no-holds-barred full throttle, up to and just beyond peak power, and the driver can tell from the response if it’s a “good” run and the engine is pulling well. On the dyno’s graphic display you see just how steeply engine speed climbs and the shape of the power curve – a nice smooth one being the objective. A frequent result of a Tunit conversion is that a somewhat ragged “before” curve, indicating flat spots and hesitation, is transformed into a smooth “after” curve that indicates better engine response, and higher engine efficiency, meaning better economy, as well as more performance!
“…the final Tunit figures came out at a pleasing 169.7bhp, at 3,500rpm, compared with the standard engine’s 151.8bhp at 3,860rpm…”
After a few small tweaks, the final Tunit figures came out at a pleasing 169.7bhp, at 3,500rpm, compared with the standard engine’s 151.8bhp at 3,860rpm, and peak torque was 278lb ft at 2,900rpm compared with 236lb ft at 2,900rpm for the standard motor.
The shape of the power curve is impressive – in terms of the wide plateau either side of peak power – and you can see that the Tunit engine delivers more power than the standard engine’s maximum all the way from 2,900rpm to 4,350rpm, whilst the rate of increase in power from 2,000rpm to 3,000rpm is some 70 per cent greater!
Alan was really impressed with how the car felt out on the road, particularly the flexibility and mighty torque, and was dying to lose the bulk of us two heavy passengers for his trip home; I’m sure that he enjoyed that drive. I heard from him a few days later and he reported fuel economy of just over 40mpg in mostly short local journeys, as against the previous 36mpg and, needless to say, he was thrilled with the Tunit conversion. If you’re at all suspicious of economy gains frequently reported by Tunit customers, you have to bear in mind that the torque gain represents a true engine efficiency gain. Whilst you have plenty of scope to enjoy the extra performance on the open road, in normal motoring you mostly travel at the pace of the traffic flow, when you’re using less fuel as a result of that higher engine efficiency, and frequently using a higher gear than you would have done before. With today’s fuel prices, getting more miles from your tank is a huge bonus to be added to the the fun that you’ll get from a Tunit conversion.