Audi TT 225 Quattro - Tuning - Tech

In the 8/06 issue we introduced you to our '02 TT 225 quattro. It's one of the ALMS edition cars and we spent our first visit slamming it on H&R coilovers, before fitting the company's sway bars.

This month we've decided to up the power stakes with software and an exhaust, as well as a few overlooked items like plugs and a diverter valve.

GIAC softwareFirst on our list was a trip to Euro Sport Accessories - a renowned VW performance shop that installs GIAC software. GIAC is known for creating "factory smooth" programs with good power and reliability. In fact, we also have it on Project Dub - our '06 GLI - and it runs faultlessly.

During the upgrade, the TT's ECU was programmed to adjust ignition timing, fuel delivery, fuel metering, boost settings, rev limiter and the speed limiter to optimize performance and, in some case, economy.

We chose GIAC's Flashloader - a handheld device that enables the user to enter up to five enhancement programs (depending on the year/model of the vehicle). The first program is performance pump gas (91 or 93 octane), the second is your stock file, third is for race gas, fourth is a valet mode and fifth is a kill function so it can't be started without the Flashloader.

The minimum amount of programs you can choose is two, so you could just choose the performance pump gas program and stock. For those of you still under warranty, we recommend this option as it allows the car to return to stock for servicing.

With our decisions made, Euro Sport Accessories handled the task with ease. They started by reading the TT's ECU and VIN numbers. This was then emailed to GIAC and the appropriate X-plus key program was sent back. Once the information had been uploaded into the Flashloader, the data could then be transferred to the car. It took about 90 minutes to upload everything but then the car was ready for a test drive.

On the road, we immediately noticed the increase in torque throughout the rev range. The car seemed to pull noticeably harder from around 2000rpm all the way to 5800. The Audi now seemed to pounce when throttle was applied, yet the extra power was delivered smoothly and progressively.

Visit www.giacusa.com for your program options and contact details for your local GIAC dealer, or simply call Euro Sport Accessories to schedule your GIAC software upgrade at 800/252-0415.

Brisk spark plugsAlthough magazine tech features rarely speak about spark plugs, they're an important aspect of a performance engine. For our TT we'd chosen to use Brisk Silver plugs (www.BriskUSA.com). This particular plug has a special silver-wire center electrode and a high dialectic-strength insulator that's designed for fuels that are hard to ignite.

Silver is one of the best electric and heat conductors, and has been found to offer greater resistance to fouling in spark plugs, as well as being suited to cold starts.

Brisk USA recommended we use the D12YS because of the high boost from the GIAC chip, and all the bolt-on products we will be installing. The D12YS racing plug is beneficial for supercharged, turbocharged and nitrous engines, so was ideal for our purposes.

After setting the gap to .30 (.28-.32 is recommended for the 1.8T) we installed the plugs and torqued them to factory spec. We then started the TT and it fired without hesitation. We used our "seat of the pants dyno," completing a few laps of the neighborhood, and everything felt promising. Throttle response was punchier and the car felt slightly more responsive when we blipped the pedal. Of course, it's difficult to tell if the car was simply responding to new plugs, but we seemed to feel a genuine improvement.

Brisk Silver D12YS plugs (each) $11.99

Bailey diverter valveFor those of you who don't know, a diverter valve is a pathway for boost when the engine isn't using it. During shifts or on deceleration - whenever the throttle is closed - the boost needs an escape route or it will send shocks back to the turbo, causing it to stall and limit boost production (turbo lag) when you get back on the throttle. These shocks can damage the turbo if the pressure is sufficiently high, and in some cases can break intercoolers, burst hoses, etc. The diverter valve's job is to open when the throttle body is closed, rerouting the boost to the low pressure, intake side of the turbo where it can do no harm.

Bailey Motorsport has developed a direct-replacement, alloy body diverter valve that eliminates these problems. The DV30 uses a high-temperature composite piston because it reacts faster and more predictably than a rubber diaphragm, which can split. These piston-type valves can handle up to 4bar (60psi) of boost and have 75% more flow capacity than the stock valve. By reacting faster, turbo stalling and the resulting turbo lag are greatly reduced, especially on chipped or modified turbo applications.

Every valve is pressure-tested prior to leaving the manufacturing process. Fitting is a 30-minute bolt-on job using the detailed instructions included with each valve.

The boys at AWE Tuning and Euro Sport Accessories both recommend the Bailey diverter valve in conjunction with GIAC software because the stock Bosch rubber diaphragm has been known to sometimes fail at high boost.

Sadly, these valves don't work with all vehicles but visit www.baileymotorsport.co.uk for an application list.

Fast Intentions exhaustTo end on an exhaust note, we approached Fast Intentions of Northridge, CA for new pipes. The shop specializes in welding fabrications such as rollcages, and is known for building custom performance exhaust systems, including intricate race headers and downpipes as well as intake manifolds.

Co-owners Danny Akre and Tony Meyerson founded the company a year ago but have five years experience building custom exhaust/header combination for drag cars (V8 and four cylinder), track racing (SCCA), Shelby Cobra track cars and exotic supercars. But after years fabricating and testing products, they decided to open Fast Intentions and make their skills available to a wider audience.

An aftermarket mandrel-bent exhaust is one of the leading horsepower gains for most turbo vehicles, although the TT 225 has a very efficient stock exhaust that is difficult to improve upon. A sports exhaust also gives you a tuned sound that's music to our ears.

Judging by the looks of the factory exhaust, we felt there were several areas that could be improved. After meeting with the pair and discussing the final exhaust plans for the TT, Danny decided to run a 2.5" stainless steel mandrel-bent exhaust out to a straight-through single stainless steel muffler, finishing with dual 3.5" Sebring tips. We selected the 2.5" diameter piping because the Audi will only receive bolt-on performance products while retaining the stock turbo. A 3" diameter would've been nice, but was considered overkill for this application.

Mike Mendrek started the process by unbolting the front portion of the factory 225 exhaust system. The stock exhaust then simply unbolts and was easily removed. He then removed all the rubber hangers.

Measurements of the pipe lengths and curves were taken and transferred to a 10ft length of 2.5" T304 pipe. After the desired lengths were cut, the mandrel bending could begin - mandrel bends are essential to a tuned exhaust. If you were to take a drinking straw and bend it, the straw would collapse at the bent area. With non-mandrel bent pipe, the tube can collapse, making the exhaust more restrictive and flow less. With a mandrel bending machine it's possible to keep the bends at the 2.5" diameter to maintain gas flow.

Once all the bends were completed, Mike started fitting the pipes using special stands to hold the exhaust system in place. Danny and Mike then marked the areas to be spot-welded. Once the welding was complete, the Fast Intentions exhaust was removed and Mike began the job of TIG welding all the joins. This was the most time-consuming part of the job but the quality was top-notch; to truly appreciate craftsmanship look closely at the welding and the mandrel bends... simply butter.

After the welding was completed, Danny and Mike centered the muffler and placed the dual Sebring tips front and center. The tips (custom designed by Fast Intentions for Sebring) were first spot-welded and ultimately TIG welded in place.

The final results were beautiful eye-candy from top to bottom.

Tony then fired up the Audi and the initial sound was breathtakingly deep. We quickly asked Tony to step out of the TT so we could take it for a spin around the block.

Throttle response and in-gear pull from mid-range to redline was noticeably improved. The deep sound heard outside was muted in the car so we'll still be able to hear the girlfriend's comments about how we spend too much money on our cars.

After the test drive, we returned grinning from ear to ear. The TT's exhaust was just what we'd hoped for.

Fast Intentions carries a line of exhausts for Audi B6 S4 and B5/B6 A4 1.8T. However, they can build pretty much anything so visit www.fastintentions.com or just telephone 818/882 2788 to schedule an appointment.

The Fast Intentions TT 225 stainless steel exhaust designed and photographed here retails at $1100. However, you could have the same system constructed from aluminized steel and it would be about $875 installed.

Dyno numbersOnce everything had been fitted, we visited the dyno to examine the results. First up, we returned the GIAC software to the stock program using the Flashloader. The car was strapped down to the dyno and it produced 158hp at 5500rpm and 170 lb/ft at 3000rpm at the wheels. This figure essentially shows us the gains from the Fast Intentions exhaust but it's very close to what a stock TT 225 would deliver. So the exhaust gains are more about the mid-range and throttle response as well as the improved exhaust note.

We then switched to the pump gas program and ran the car again. This time it developed 182hp at 5250rpm and 216 lb/ft at 3000rpm. So we gained 24hp and 46 lb/ft at the wheels from the GIAC software. This is a very useful increase and confirms what we were feeling through the seat of our pants.