We test GReddy's 2001 Volkswagen GTI Mk4 1.8T turbo upgrade on Project Envy. This month we look at the installation.
If you've seen the audio/visual setup in Project Envy, it's no secret the '01 Golf is excessively heavy. Its power-to-weight ratio is miserable, resulting in a loss of available horsepower. To compensate for this, and to build a more complete car, we turned to leading aftermarket tuner, GReddy Performance Products, to squeeze more power from our 1.8T motor. And the most effective way to do that is with a bigger turbo
GReddyBased in Irvine, CA, GReddy Performance Products is well known in the import market for exhausts, turbo kits, cooling systems and electronics. Established in '94, GReddy has expanded into the European market with the G2 exhaust for Mk4 VWs, B5 Audi and BMW E46. The company even branched out into front-mount intercoolers for the Mk4s.
Today, the company maintains a steady pace toward breaking into the European market, and we were interested to see an Audi A4 1.8T B6 turbo kit displayed at the 2005 SEMA show. GReddy will soon be releasing a new stainless steel exhaust lineup for several Audi and VW applications, utilizing an oval muffler and dual 76mm tips.
Turbo essentialsA turbocharger is a highly efficient pump that compresses air into a small space. It sucks in wasted energy from the engine's exhaust gases, compressing the gas and forcing the energy up the intake path. Mixed with fresh air, this pushes more air into the combustion chamber than atmospheric pressure alone is capable of. Additional fuel is matched to the air volume to create a larger explosion in the cylinders, resulting in more power to the wheels.
The 54-piece turbo kit includes everything you need, besides a qualified mechanic
The size and design of the turbocharger is very important in fostering power. Often tuners will design their turbocharger with custom specifications to create different configurations for their uses. Using an extremely large turbo can create enormous power but produce noticeable lag. The car might not hit full boost until 4000-5000rpm, for example. On the other hand, a tuner could utilize a smaller turbo to harness decent power with minimal lag.
The factory-equipped '99-01 Golf 1.8T (AWW engine code) utilizes a Borg-Warner KKK03. The size of this K03 turbo is relatively small, enabling it to spool extremely quickly, but it only produces 150hp at approximately 7psi of boost. Yet the surge from the turbo can be felt from 1800rpm, with consistent power through the rev range.
GReddy's solutionThink back far enough and you may remember our cover story from et 4/02 - a GTI with Rieger aerodynamics and 19" OZ wheels - it was the test mule for GReddy's fledgling VW turbo program. After a successful install and dyno, the car produced 269whp.
For the past four years, GReddy has continued fine-tuning its 1.8T turbo kit to create the most power and reliability without turbo lag, surging or long-term damage.
A close-up of the TD04H-19T turbocharger, accompanied by the aluminum suction and compression pipes.
The first prototype featured in et used a larger TD05-18G turbo which benefited from a high peak horsepower but at the expense of lag. So GReddy returned to its workshop and came up with a new design.
We sat down with GReddy's Planning Division Manager Mike Chung, to discuss the developments. "The original design was inspired by our Acura Integra turbo kits that use a TD05-18G turbocharger - larger than the TD04H-19T we use now for the 1.8T," he explained. "It was too laggy for European cars and the turbo had a hard time spooling. We quickly learned that European cars excel in low- to mid-range torque. So the TD04H-19T was selected because it had a bigger turbine (19T) and compressor wheel with a smaller housing (TD04H). This allowed the turbo to force air through faster and provide substantial power across the range. The 1.8T motor is also very strong, so we raised the boost to 18 or 19psi without worrying about blowing it up. The GReddy turbo upgrade is intended for the average street enthusiast."
The latest kit retails for $3395 and includes a Mitsubishi TD04H-19T turbocharger with integral wastegate. An adapter is also included, allowing it to use the stock manifold. An improved downpipe mates to new turbo and existing exhaust system. For better airflow, an Airinx intake, filter and upgraded airflow meter are included.
More air requires more fuel, so GReddy provides 370cc injectors. To tune the software, a freight box with a next-day shipping label is currently included in order to send your ECU to GReddy's headquarters for reprogramming. Finally, all the necessary oil lines, silicone hoses and hardware are included in the kit.
We're slightly skeptical about the appearance of the Airinx filter, but here it is along with the upgraded airflow meter
Baseline dyno Project Envy was a great fit for this kit because it needed the additional power and also demanded daily drivability. We took the Golf to Dynamic Autosport in Irvine, CA to acquire a baseline dyno figure.
The car was already equipped with basic engine modifications, including a GReddy front-mount intercooler, Airinx intake kit, Oettinger exhaust, Forge Motorsport 007 diverter valve and Upsolute software. On the Mustang dyno, the car put down 143whp with 163 lb/ft of torque.
Because the Mustang dyno is geared toward AWD cars, we expect the actual power to be 10-15% higher. Nevertheless, after recording the baseline figure we proceeded to install the turbo kit and tune the ECU at GReddy's headquarters.
InstallationThe upgrade took approximately 8-9 hours to install, utilizing a full workshop and lift. The kit is bolt-on except for the ECU, which needs to be shipped out for tuning. You can see the major installation steps in the photo captions.
Like most projects, we encountered problems. When GReddy attempted to tune the ECU, the Upsolute chip was glued and the mechanics had a difficult time removing it - unfortunately resulting in damage. However, this is an unusual occurrence and we have since acquired a new ECU, which GReddy is in the process of tuning.
We will bring you the final installation details and power figures once the tuning process is complete. At present the company has no software for the car since the kit is designed for '02-05 1.8Ts. Ours is an '01 so it'll take them a little longer to program the car. Once done, GReddy should be able to offer the kit to VW 1.8T engines from '99-05 - so we're performing a public service, really.
GReddy claims the turbo kit will make 245whp, so stay tuned for next month's issue and see how our project car fares once the software is tuned and whether we reach the target output.
Work begins by removing the catalytic converter in order to replace the downpipe and reach the exhaust manifold. The 02 sensors were also disconnected | 
Removing all the heat wrap, oil pressure hoses, air induction hose and coolant lines to the turbo is a time-consuming process | 
Next we removed the exhaust manifold. There are 13 nuts securing it to the motor. |
After the manifold is free, remove the factory turbo by loosening three tight bolts | 
A side-by-side turbo comparison of the factory K03 and GReddy TD04H-19T | 
You can clearly see the compressor blades inside the turbocharger housing |
This oil feed line was one of the more difficult pieces to remove from the system. | 
Before installing the new turbocharger, we fitted a braided oil pressure feed hose to the turbo | 
To fit the new turbo with the factory exhaust manifold, a turbine adapter is required to mate them properly |
The new suction pipe was also fitted to the turbocharger inlet | 
Time to reinstall the big turbo on the exhaust manifold | 
Meticulously cutting the factory downpipe from the exhaust system |
The new downpipe is positioned into the exhaust housing outlet flange and inside the catalytic converter | 
GReddy welded the downpipe to the catalytic converter for a good seal, then removed the pair completely for a better weld | 
Preparing the air induction hose with a silicone coupler |
Reinstalling the Airinx intake is one of the final steps | | |