Robert Bowen
Robert Bowen
11/24/08 8:51 a.m.

While lots of hotrod VW Rabbits and Golfs are powered by naturally aspirated engines, many of Volkswagen’s current offerings rely on turbocharging.

These force-fed, 1.8T-spec engines can now be found in many cars carrying the VW and Audi badges, including the popular Golf, GTI and TT models. Like the German manufacturer’s earlier engines, it isn’t hard to make more power from the 1.8T, provided the proper recipe is followed.

Earning Its Cred

When Volkswagen released the five-valve, inline four-cylinder 1.8T engine in 1997, enthusiasts gave it a lukewarm reception. The engine just didn’t get much respect outside of diehard VW geeks.

There were two reasons for this. The first was the engine’s initial application, the heavy and unloved-by-enthusiasts Audi A4. The second was its unimpressive 150 horsepower rating.

VW and Audi deemed the engine fit enough to drop into the Golf, Jetta and TT for the 2000 model year. The VW products initially got the 150-horsepower version, while the Audi TT made 180. Increases in output were around the corner, as the TT could also be had with an optional 225-horsepower version of the 1.8T starting in 2001. Likewise, the Golfs and Jettas started to get the 180-horsepower engine in 2002.

VW actually produced two different versions of the 150-horsepower engine, one for the New Beetle and another for the Golf and Jetta. The New Beetle version is choked by a smaller turbocharger, smaller intercooler, smaller injectors and a smaller exhaust system.

The 150-horsepower engine found in the standard-issue Golf and Jetta, in contrast, shares the turbocharger, injectors and exhaust systems with the 180-horsepower setups. So if you’re thinking this means that the only difference between these two powerplants is the engine management system, you’d be right.

The ECUs found in the 150-horsepower Golf engines limit boost to 0.6 bar, while the 180-horsepower mills are allowed to produce 0.8 bar. There are some minor differences in compression ratio, exhaust and turbocharger specs between the years, but for the most part the 150-horsepower Golf/Jetta engines can all be made to run like the 180-horsepower versions with nothing more involved than a modified ECU.

The 225-horsepower engine found in the Audi TT is a different beast altogether. While the block and head are pretty much standard 1.8T parts, they received two big intercoolers, larger injectors, stronger pistons and beefier rods in addition to different engine management software.

No matter what their origin, however, all 1.8T engines have similar five-valve heads. The first versions used a separate idler shaft to drive the oil pump; after 2000, the 1.8T moved to a crankshaft-mounted oil pump and dropped the idler shaft. Note that although these engines resemble VW’s earlier four-cylinder versions, the shape of the oil drain ports rules out bolting the 1.8T’s head on the older engines.

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