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Volkswagen Engine Tuning - 1.8T Tuning Guide

The VW/Audi 1.8T Is The Little Engine That Could (Make Lots of Horsepower). Paul Piola Discovers What Tuning Options Are Available From 28 of The Top Specialists.

By Paul Piola

If there was ever an engine that got the tuning world's attention, it was the 1.8T found in a plethora of vehicles including the Volkswagen Golf, Jetta, New Beetle and Passat plus the Audi A4 and TT. From '96-05 these models sported the K03 turbocharged and intercooled 20v inline-four. It didn't get off to a potent start, however, since early versions developed only 150hp (about 130hp at the wheels on FWD cars). But the engineers knew the motor's potential and released the 225hp Audi TT in '01 using a K04 turbo. The following year, all 1.8T outputs were increased, thanks to a modified K03 turbo. The Passat saw 170hp, while the A4, Golf, Jetta and Beetle enjoyed 180hp, which commonly relates to about 145 and 155whp, respectively.

Since the quantity of 1.8T tuners is more than double any of our previous tuning guides (E36 M3, VR6 12v, E36 325i/328i), we've approached this guide differently - looking at each company's options, rather than price categories. If you're in the market for a 1.8T or already drive an unmolested example, this list should keep you busy for hours.

While numbers will vary from tuner to tuner, and from dyno to dyno, power output for cars with the stock turbo, upgraded software and a cold-air intake (CAI) will usually be between 175-185whp (more with a cat-back or turbo-back exhaust). Once you start getting into K04 turbo territory, don't be surprised to see over 200whp with a good exhaust system. If your pockets are deep, some companies have more radical setups exceeding 300whp...

034 Motorsport
One of the major restrictions in the factory exhaust is the downpipe off the turbo housing the cat. So 034 fabricate its own mandrel-bent piece with a bung for the 02 sensor. The $155 piece is reportedly good for an extra 10whp on stock cars, and up to 30whp on modified ones. 034 also fabricate a $850 transverse header for anybody wanting to regulate boost with an external wastegate.

The company is also known for its programmable stand-alone engine management. The 034 EFI will work on any 1.8T engine, and is supplied with a plug-in harness. The EFI features closed-loop boost control, anti-lag, wideband integration, and is designed for DIY tuning. The entry level 1C system starts at under $2000. 034 Motorsport also distributes ATP turbo kits.

Advanced Engine Management
AEM has a CAI for '00-06 Golf/Jetta for $300, and a $507 turbo exhaust manifold.

Advanced Tuning Products
Known for its turbo kits, ATP sells a CAI for $119, and a $395 cast-iron exhaust manifold with an external wastegate flange for T25, T3 or T3/T4 turbos. Its front-mount intercooler (FMIC) for Golf/Jetta retails for $975.

Its quick-spooling K03/K04 Eliminator kit for FWD 1.8Ts uses a GT25R for $1750 and gets around 215whp. Next is the G2X kit for the '07 A4 and Passat costing $1275 with installation. By using its software and injectors ($795) and optional 2.75" inlet pipe ($150), it's good for 218whp with 248 lb/ft through the stock exhaust, and 235whp, 264 lb/ft with a 3" test pipe replacing the cat on 93-octane. Torque peaks at 3500rpm in both cases.

The GTRS turbo upgrade uses a GT28RS ball-bearing turbo, which starts at $1595 with installation hardware. If used with ATP's larger inlet pipe, you get 235whp with 244 lb/ft at 4800rpm through the stock exhaust on 93-octane. Add the $780 software and injector upgrade and power surpasses 250whp. Add a 3" test pipe and the number improves to 260whp with 280 lb/ft at 4300rpm. Around 300whp is possible with a full exhaust.

For $100 extra you can upgrade to the GT2871R. With a 3" exhaust and inlet pipe, power can exceed 350whp through the stock intercooler.

Lastly, a stage 4 turbo for '00-02 GTI and Jetta uses a Garrett GT30R dual ball-bearing turbo and includes hardware, external wastegate, GReddy boost controller, injectors, downpipe and exhaust manifold for $4000, giving a safe 300whp.

APR has a plethora of 1.8T parts. The firm's software retails for $400-500 for one program, depending on the model. What's neat is any additional software, with programs for 91-, 93-, 100- and 104-octanes, is toggled through with your cruise control stalk.APR's TIG-welded 2.5" and 3" cat-back stainless exhausts are offered for the A4, Golf, Jetta and Beetle, ranging from $970-1250. A turbo-back system for the TT costs $2600.

APR also sells the much-needed FMIC for A4, Golf, Jetta, Passat and TT from $1050-1200. This makes it safe for APR's K04 upgrade, which retails for $1700-1800, plus software and optional injectors. With the injectors and APR exhaust, this setup has reportedly shown 215whp.

Next, the stage 3 turbo for A4, Golf, Jetta, Passat and 180bhp TT uses a Garrett/Allied Signal ball-bearing turbo. The $4500 kit ($4700 for TT quattro) includes an inconel exhaust manifold, high-flow cat, hoses, injectors, larger MAF housing and hardware. Not included but required are APR's exhaust system and downpipe. Putting out 250whp, you're now approaching S4 territory.

APR's final package is the stage 3+ kit, good for 310whp with APR's exhaust. The $5000 kit is for A4, TT, Golf, Jetta or Passat ($5200 for 180bhp TT quattro, $6900 for 225hp TT including intercooler) and uses a Garrett Ballistic Series turbo; this stage needs an intercooler. On 93-octane, it's good for 320whp on '00-03 non-VVT models, and 330whp on '04-05 VVTs.

The APR cast aluminum intake manifold for big turbo cars goes for $900, or $1300 with a larger throttle body. APR has seen up to 40whp gains with the latter, but stronger connecting rods are recommended.

Autobahn Designs
ABD sells a variety of parts, starting with $495 GIAC software, and a $230 CAI for Golf/Jetta.In addition, the tuner offers a FMIC for the A4, Golf, Jetta, Beetle and Passat for $1100-1200.

After all that, you're ready for ABD's K04 upgrade, which costs $1295 over the basic upgrades. If this 65whp gain isn't enough, you can try ABD's K05 system, which costs $2985 and includes software, 3" MAF, injectors and the turbo (a modified K04). This package gives 5-10whp over the K04.

To capitalize on the increased flow from the big turbos, you can add ABD's $500 intake manifold with larger plenum, which reportedly gives 15whp on a stock 1.8T, and over 20whp on modified engines. ABD also sells exhaust systems from Brospeed, Supersprint and Techtonics.

Some of Autotech's entry-level products for the 1.8T include a $120 6061 aluminum cam gear for Golf, Jetta and Passat to advance or retard the cam timing up to 10, as well as its $50 intermediate shaft pulley for the Passat, with a 60% weight reduction.

Its exhaust system features 2.5" piping and a free-flow Magnaflow muffler. It's shown up to 14whp in Autotech tests. They also sell a $200 T304 stainless downpipe with flex joint made by a VW OE supplier.

AWE Tuning
AWE offers a K04 upgrade for '97-01 B5 A4 and Passat for $1700-1800 that's good for 50whp gains over stock with its exhaust system, which costs an extra $730-765. For manual transmission cars, AWE's $200 PC16 injectors and GIAC software will add another 10whp and 23 lb/ft.A K04 is also available for the Beetle and retails around $1875 with an exhaust.

For '02-05 B6 A4, AWE has a GT28R turbo capable of 235whp and in testing they found gains of 30whp over the K04, with more torque.

AWE recently introduced its Golf and Jetta K04 with GIAC software, Audi TT MAF and 380cc injectors for $2000. AWE reports you'll need an exhaust and intercooler to make full use of this kit.

Boost Engineering
Boost Engineering has a turbo kit for '96-06 Golf and Jetta, including six-speed cars. It uses a Garrett GT28 ceramic ball-bearing turbo, and includes downpipe, 2.5" high-flow cat, software and gaskets for a bolt-on package. A FMIC is also included, with powdercoated piping that allows you to revert to the stock intercooler during harsh winters to prevent damage to the new unit. The package retails for $3750 and is good for 260whp.

Known for its carbon fiber intakes, these are the chosen intake systems for the likes of APR. Carbonio's CAI helps reduce turbo lag while improving power and throttle response. The kits start at $279 for VW, Golf and Beetle and reach $379 for the A4.

Dahlback Racing
The Swedish-based company is known for building the 580hp Golf RSI - check out the videos on the site. Dahlback has a variety of performance programs for the 1.8T, ranging from 170whp to well over 450whp if you've got the coin.

ECS Tuning
www.ecstuning.comECS sells crank and accessory pulleys to free lost power for around $225 a set. For those going after 300whp, ECS offers stronger internals for your 1.8T short block, including rods, pistons and rings. JE pistons range from 9-9.5:1 compression. The rod and piston set costs $1550-1600, but you can order separately if needed. The firm also distributes APR parts.

EIP Tuning
EIP has four different stages for the 1.8T.Stage 1 starts with a high-boost ECU, CAI and cat-back. It retails for $1200 and is good for 20-30whp with 50-60 lb/ft gains at peak. For an extra $1000, stage 2 nets you another 15whp with more consistency, thanks to the FMIC.

For $2496, stage 3 gives you a choice of two T3/T4 turbos - the bigger one is slightly laggier but good for over 300whp. The downpipe is included in the turbo kit but you'll need EIP software, as well as a 2.5" or 3.0" exhaust, which EIP sells for $650-700.

Stage 4 involves an Electromotive management system and forged pistons for an additional $3500 over stages 2 and 3. Most swap in the optional forged rods for another $1200 as well. EIP also offers 2.0 and 2.1 liter stroker cranks.

EuroCode Tuning
EuroCode offers turbo-back exhausts from APR, DeCorsa, GHL, Neuspeed and Thermal R&D, ranging from $800-1000. They also sell a cat-delete downpipe for A4s and Passats, reportedly good for 15whp. The firm also distributes APR and Evolution Racewerks products.

Evolution Motorsports
Evolution Motorsports has a program for the 1.8T in conjunction with GIAC. It starts with an ECU upgrade for gains of 30-50hp and continues with a CAI for $295. The CAD-designed FMIC will set you back $1000, but will increase longevity and consistency.

Evolution Racewerks
Evolution Racewerks offers Sport and Competition front-mount intercoolers for A4, Golf and Passat, selling them through distributors. Prices range from $1095 for the Sport, to $1395-1595 for the Competition. Both are complete kits including a power steering cooler, and come polished or in a stealthy black anodized finish. The Competition was designed for turbos bigger than the K04 and include a bumper reinforcement bar. ER reports that a 245whp car showed an average 70 reduction of intake temps over stock with the Competition FMIC (see et 9/06).

ER also makes a unique $195 test pipe. Since the K03/K04 turbo inlet is almost 3", the pipe tapers down to 2.5" in order to fit either the factory or most aftermarket cat-back exhausts.

Euro Sport Accessories
Euro Sport sells its Cool Flo intake ($200) and Cool Flo Race intake ($220) for Mk4 Golf and Jetta. Its crank pulley underdrives the accessories 23% to liberate horsepower. Euro Sport also works with GIAC software, which sells for $400-500.

Forge Motorsport
The $190 Forge silicone intake hose found 13whp during our testing (et 3/06) with improved flow. It also sells a $150 billet aluminum diverter valve, which replaces the factory plastic unit to increase response and durability.

For Mk4 owners who aren't ready for a FMIC, Forge has a $600 side-mount intercooler that apparently gives a 40 temp reduction over stock. Forge does carry FMICs for both Audi TT versions for $1200-1550, which have reportedly shown a good temp reduction.

GHL Motorsports
GHL sells a 2.5" turbo-back exhaust for the A4, Golf and Jetta from $810-1050. These systems feature hand TIG-welded 304 stainless steel with mandrel construction, a high-flow cat and lifetime warranty. For high power applications, they also have a $1100 3" turbo-back for Golf and Jetta.

For TT, GHL sells a cat-back exhaust for $900. Downpipes can be purchased separately.

GIAC's wide selection of software includes models such as the '99-06 Audi A4, '01-05 TT, '99-05 Golf and Jetta, '99-05 Beetle and '99-05 Passat. The firm also has software for big turbos, including K04-20 and K04-23 turbos on '01-05 Golfs and Jettas, plus K04-15 software for the Passat, and K04-1 or E05 turbos on Golfs or Jettas.

GReddy sells a turbo upgrade for the Mk4 GTI. It uses a TD04H-19T with an 85mm exhaust housing for good spooling. The $3395 kit includes injectors, adapters, downpipe and AFM (see et 10/06).

Kinetic Motorsport
Kinetic has a K04 upgrade, featuring its own turbo manifold and FMIC for $1850, plus software. The intercooler and exhaust manifold, which work on both longitudinal and transverse engines, go for $725 and $295, respectively (see et 1/07).

Neuspeed has two intake kits. The $200 P-Flow is CARB-approved, even when used with its $400 software, which raises boost to 15-16psi (17.5psi on A4). At $240, the Race Series CAI draws air from the inner fender and includes a billet smog pump fitting but isn't recommended for rainy areas.

Next is Neuspeed's turbo intake pipe, which reportedly flows 63% more than the crimped factory unit. For $260 it's available for variable and non-variable cam Golf, Jetta and Beetle. Owners of the A4 and Passat can use Neuspeed's Xtreme intake hose from Samco that's 70mm at the MAF and tapers to 58mm at the turbo. It sells from $300.

The T6061 aluminum crank, power-steering and alternator pulleys ($200-300) reportedly net 5whp.

For real power, Neuspeed's BorgWarner K04 upgrade kit ($1800-2000) for GTI, Jetta, A4 and Passat includes Iridium plugs, P-Chip, fuel pressure regulator, gaskets and hardware. For '97-01 A4 and '98-05 Passat, the kit also has a 180 fan switch.

For this kit, Neuspeed sells the needed exhaust for Golf, Jetta and Beetle with a 60mm (2.36") or 70mm (2.75") mandrel bent, TIG-welded, 304 stainless pipe ($600-800). A 60mm downpipe is also available ($290), but requires cutting and welding. Exhausts are also available.

NGP Racing
NGP distributes APR, Forge and Euro Sport products. Complimenting these are other parts such as its $700 Ross Racing T6061 aluminum intake manifold for Golf/Jetta which improves air flow. The unit can be used with either a factory or 70mm throttle body, which can mount on either side. It comes with a -6 fuel rail for Bosch injectors, and has provision for the intake air temp sensor along with three holes for 0.25" NPT fittings.

If your 1.8T is due for a rebuild, stroke it from 1984-2090cc. The different compression JE piston-equipped kits start at $1940 with factory forged rods and cast crank, and go to $2690 with 4340 forged rods and forged crank. Also available are fully-built 1.8-2.2 liter stroker short blocks with forged internals from $3650 to special order.

NGP also sells Simple Digital Systems programmable engine management to control boost, rpm, ignition, fuel, etc. Starting at $1311, it includes the ECU, harness, IAT, H20 temp and crank sensors, fuel trim control, LCD programmer, timing magnets and coil/amp unit. MAP, knock and 02 sensors are additional.

The German-based company carries a full line of software upgrades for the 1.8T, good for 15-25hp, depending on the model. Coupled with its intake, downpipe, turbo and intercooler upgrades, the company reports 50-80hp increases for the A4, Golf, Passat and TT.

Revo Technik
A British-based company, Revo Technik has its own software for the A4 ('01-05), GTI and Jetta. The $499 stage 1 software produces 20-30whp and 30-35 lb/ft. It's designed for cars that are near stock.

For an extra $50, stage 2 is for cars with a K04 turbo, bigger injectors, turbo-back exhaust and FMIC. Stage 3 retails for $699 and is designed around ATP's GT28RS or similar-sized turbos. It works with 550cc injectors and a larger MAF from the R32 or 225 TT.

Techtonics Tuning
Techtonics carries its own line of cat-back exhausts for A4, Golf, Jetta, Beetle, Passat and TT. Prices start around $400 for aluminized mild steel and go up to $800 for its stainless steel systems built for quattros.

Formerly Chiptronics, The Austrian-based company carries a full range of software, reportedly ranging between 20-30whp gains.

Unorthodox Racing
Known for its CAD-designed and CNC-machined 6061 billet aluminum lightweight pulleys, Unorthodox pulley sets retail for about $310. Apparently, these provide power gains through weight loss, and about 15% of gains come from underdriving the accessories. Their philosophy is to not underdrive too much since people need their air conditioning, power steering and batteries to work!

GReddy Boost Engineering
APR Advanced Tuning Products
Advanced Engine Management
2205 126th St., Unit A
CA  90250
Eurocode Tuning
Autobahn Designs
Unorthodox Racing
034 Motorsport
Revo Technik NGP Racing
Oettinger GHL Motorsport
AWE Tuning Evolution Motorsports
Kinetic Motorsport GIAC
Techtonicss Tuning
Evolution Racewerks
Dahlback Racing
Euro Sport Accessories
ECS Tuning
Forge Motorsports
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By Paul Piola
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