At last! After more than a year, the engine overhaul on our ’03 VW GTI is finally wrapped up. Spread across eight issues, we’ve shown you everything our little 1.8T has gone through. It started when we were stranded in downtown LA. The car was towed to Raven Motosport in Long Beach, CA where we rebuilt the bottom-end using Integrated Engineering’s two-liter stroker kit with Mahle pistons, an FSI crank and H-beam rods.
034Motorsport then continued by preparing an AEB valvetrain updated with enlarged ports, oversized valves and an Autotech intake cam.
Once Raven had the motor balanced, built, installed and running, we drove to 034 in Fremont, CA where the team prototyped a new turbocharger kit for the transverse VW 1.8T.
Now equipped with a quick-spooling Garrett GT2871R turbo and other 034 goodies, it was time to strap our Mk4 to the dynomometer and get it running without any hiccups.
“Once it was on our dyno, we started the tuning process,” said Javad Shadzi at 034. “The tuning involved about 100 pulls, making adjustments to the mapping after each pull. We optimized the timing based on feedback from the knock sensors and adjusted the boost level among other things. We also made pulls using part throttle and light load to ensure the power delivery was as smooth as possible.”
With 550cc Bosch injectors, the first dyno run showed the stock fuel pump leaning out, only making about 230whp. So 034 installed its FP34 fuel pump kit.
The kit comprised a fully enclosed Bosch 044 pump inside a one-liter reservoir. The unit comes with a return line from the fuel pressure regulator, so fuel can be dumped back into the tank if unused. “The stock pump pushes fuel into the FP34 reservoir to fill it. The new pump then draws fuel from the tank and pressurizes it into the fuel rail. Once we did that, we had plenty of fuel for the new turbo,” Javad explained.
The result was still short-handed at 250whp on the dyno, So 034 determined our original downpipe was restrictive. A stroll to the parts shelf found a 3" downpipe, which immediately made 12whp off the bat. Then 034 continued to massage the maps again.
After days of testing and some on-road driving, our big-turbo 2.0L 20v was putting out 281whp and 307.1 lb-ft on 91-octane fuel.
034 also performed testing with 100-octane fuel and saw 301.1whp and 318.3 lb-ft of torque.
With our baseline of 203.8whp and 237.4 lb-ft, we couldn’t be more pleased, especially when you factor in that the car started life with 150hp at the crank.
With the final touches to the GT2871R turbo kit, it should be available from 034’s website when this issue hits newsstands. Based on the testing with our car and others, a generic ECU file will be supplied with the kit that will offer most of the performance benefits. However, a custom tune is recommended to get the most from the components. This was essential for us because of our 2.0-liter motor and AEB valvetrain.
Compared to what you might read online, our dyno numbers are a bit low for a GT2871R upgrade. However, we’re running weak-sauce 91-octane and sacrificed a little power for drivability.
After running Silverstone for several months, we’re pleased to report the car starts without hesitation, the idle is smooth and there are no flat spots in the power delivery – not a single headache.
We don’t have to worry about a hose popping off or a component failing because the kit uses quality parts able of withstanding abuse. Plus, the manifold design keeps the turbo out of sight in the stock location, rather than some tubular headers that put it on show, giving us a stealthy appearance.
Best of all, we can’t argue with the power. It’s not like driving a 500whp drag car, but the GT2871R hits its 20psi full boost at 4000rpm with virtually no lag.
Obviously, the stroker motor plays its part by helping build low-end torque, and also giving us the reassurance our rods won’t pierce the block. Our ported AEB head and high-flow intake manifold are also the most efficient valvetrain possible.
There are more parts we can fit to gain extra power, such as a 3" exhaust, water/meth injection and more aggressive cams, so we might try these in the future. Running on 93-octane or better would also net us about 290whp. But we shouldn’t complain; for a daily-driven FWD hatch, we can happily say it’s our ultimate VW street car.