Welcome to the first installment for our Project Silverstone. Although it's equipped with GIAC X+ software, Techtonics exhaust with downpipe, BMC Carbon Dynamic Airbox and Forge diverter valve (see p38) there was more we could do to the 1.8T. In fact, one of the major downfalls of the factory 1.8T is its side-mount air-to-air intercooler. Let's look at why it performs poorly.
Intercooler basicsThinking back to our turbocharger system (see p80), exhaust gases are re-circulated into the turbo, which compress the air and pushes it into the intake manifold, resulting in more power. Unfortunately, one of the byproducts of this technology is heat. Hot air expands, losing its density, meaning less air molecules enter the intake, which creates less of an explosion in the combustion chamber.
As a result, the turbo has to work harder to build boost, and in most instances the ECU will reduce boost and retard ignition to prevent detonation caused by high temperatures. As ambient temperatures rise, such as on warm track days or summertime driving, cooling the air going into our turbo engines is vital to maximize engine power, or to simply maintain it.
When Fred Su removed the factory...
When Fred Su removed the factory intercooler, we noticed oil residue accumulated in the piping and core.
An intercooler is fitted to control these rising temperatures, decrease detonation and recover the air density we want to nourish the engine. In essence, intercoolers work like a radiator. After the hot, pressurized air leaves the turbo, an intercooler cools this air before it enters the intake manifold. As the air enters the intercooler, it passes through several small tubes that have fins attached to them. Once the cooler outside air flows across the fins, the heat from the pressurized air is pulled out into the atmosphere. The heat transfer works continuously while the turbo is working and the car is moving, without losing boost pressure into the atmosphere.
Upgrading the FMICNow we've reviewed how it works, it's inevitable that a factory side-mount intercooler is inadequate. It's a large restriction to the 1.8T's potential, mainly because of its small core size. The size doesn't have sufficient volume to dissipate all the heat into the atmosphere, so the hot air eventually overwhelms the intercooler and it remains "heat-soaked." In this instance a driver would have to coast without applying load to the turbo until intercooler temperatures drop.
The location of the factory intercooler presents another problem. It resides behind the front wheel well on the passenger's side, with little access to the incoming breeze from the front bumper. It receives air via a small tube in the lower grille. These conditions prevent the intercooler from working effectively.
The Evolution Racewerks core...
The Evolution Racewerks core is superior to the factory unit in size and efficiency
The front-mount intercooler solves many of these problems by utilizing a larger core and mounting behind the front bumper. This simple act makes the system more efficient in releasing the unwanted heat into the atmosphere.
We located Evolution Racewerks in the City of Industry, CA. The company manufactures high-performance race and street products, including intercoolers and rollcages. We asked Fred Su from ER to fabricate an intercooler for us and he used Project Silverstone as one of the test vehicles for a pre-production kit.
Evolution Racewerks FMIC solutionThe intercooler kit from Evolution Racewerks included: 20x11x3" core, 2" piping, silicone hoses, T-bolts and clamps. The core uses a high-density bar and plate design for efficient cooling. The design allows less outside air to pass through the core and into the water radiator but doesn't pose a critical problem for the Mk4 because there are other air openings to cool the radiator.
Fitting and mounting the core...
Fitting and mounting the core to the car looks simple but takes time
The dimensions of the core are considered oversized for the 1.8T, especially with a factory turbo; we chose it because we plan to upgrade Project Silverstone with a big turbo in the future. Fortunately, the large core works efficiently with the factory turbo without any repercussions.
The piping is 2" into the intercooler and 2.25" out of the intercooler to the intake manifold. The 2" piping is optimal for the factory turbo setup because the air can flow at a higher velocity. There's no loss of boost pressure, even with the larger core to fill. Using enlarged tubing risks the chance of encountering turbo lag. The 2.25" piping out of the core provides greater flow for top-end power.
The Evolution Racewerks' intercooler kit should take an able mechanic approximately five hours to install. However, it took slightly longer on Project Silverstone because we have a European bumper and rebar.
With the final production kit, a new rebar will be included. Fortunately, cutting and shaving will be minimized if you have a factory bumper.
Evolution Racewerks plans to offer the Mk4 GTI FMIC kit in fall/winter '06. It will be available in polished and type-three hard black anodize. They currently have the Audi A4 1.8T B6 kit available. Other kits in development include the B5 S4 2.7T, B5 A4 1.8T, B5 Passat 1.8T and Mk5 GTI 2.0T.
Fred meticulously feeds in...
Fred meticulously feeds in the new piping; one of the install's harder tasks
TestingOn identical 64 nights in Los Angeles, we tested Project Silverstone's factory versus the Evolution Racewerks intercoolers for intake temperature and ignition timing. With the help of Jeff Moss from Torque Factory, we coordinated several continuous third gear pulls on the same strip of pavement for both tests. The reason for using third gear was to obtain the highest variation in temperature.
At a stop, the car's intercooler is absorbing heat because cooler air is not blowing through it. As we slowly move to third gear, the intercooler is rushed with cooler air without spooling the turbo, and we can determine our lowest intake temperature. Once we hammer the throttle, the hot air from the turbocharger begins to flow through the intercooler, and we finish our session at 6000rpm to record our peak temperature.
Average ignition timing was also tested from 3000-5000rpm. Ignition is important because it can determine how much time the fuel and air has to fill each cylinder.
The results were astonishing. With the factory intercooler, we realized an 18C increase in temperature during this test, compared to a measly 3C increase with the Evolution Racewerks FMIC.
With the cooler air, engine power remained strong across the rev range, even after continuous test runs. The average timing increased from 4.73 to 6.23 with the FMIC. This 1.5 increase in ignition timing enabled more time for the fuel to burn completely, and for pressure to build in each explosion, resulting in more torque.
You can read Jeff's comments below but as a bolt-on conversion we were very happy with the results. It shows that the ER FMIC maintains charge temperatures very efficiently. This constant temperature means your engine will perform more consistently and with greater safety margins.
Jeff Moss' ImpressionsProject Silverstone felt pretty strong to begin with. What can I say; it's a great running car. I can't say it definitely gained power with the FMIC because we didn't measure it, but it did feel stronger and definitely more consistent.
If we did 3-4 runs on the dyno within five minutes of each other I can tell you we'd have pretty similar dyno numbers with the Evolution Racewerks FMIC. Whereas, with the factory intercooler the power would be all over the place on the fourth or fifth run.
The 3C temperature change we detected in the FMIC during our road testing is phenomenal. There isn't much more we can ask from a FMIC. It maintained inlet temperatures with great efficiency, which is what it's supposed to do, while the factory side-mount is far less able to do this.
Sam's ImpressionsI have to admit, I was worried about issues we might encounter fitting the FMIC on my car. I didn't want to shred the front bumper or lose my engine cover. I also entertained ideas of anodizing the piping and core black for a more stealth look. I didn't want to draw attention to the FMIC. However, Fred at Evolution Racewerks reassured me I was worrying over nothing and that the bumper wouldn't be chopped into pieces.
In the end, the installation lasted most of the day because of the European front bumper. It's several inches shorter than the US bumper, so offers less space for the FMIC. Watching Fred work, I'm glad I didn't tackle this job myself because of the precision required to fit it behind the bumper. It was at this moment I wished I hadn't switched to a European bumper.
After the FMIC was installed I felt butterflies in my stomach and wondered if the kit would perform. In the back of my mind I was worried about losing boost due to the large core and longer piping. After all, the car pulled strongly with its current setup and I didn't want to sacrifice any of that.
As it turns out, I needn't have worried. The car pulled smoother and quicker than before. I noticed the improved throttle response immediately. I also felt the car was faster and more consistent.
If you turn to the Project Silverstone feature on p38, I had the opportunity to take the car into the canyons for some spirited driving. For a solid 30 minutes I was pushing the car to its limits in 90F ambient temperatures on the mountain roads. However, I felt no turbo lag or loss of power and thoroughly enjoyed the experience.
Now I can't wait for the big turbo upgrade.