Kerma 17plus Turbocharger (DOKA), ALH and BEW Mk4 TDI

What It Is
A Kerma-exclusive upgrade turbo for the ALH and BEW engines, built as the direct successor to the popular but now-obsolete 17/22. It's a drop-in replacement for the stock VNT17, so it bolts into your existing VNT17 plumbing without requiring a different turbo housing setup. Expect a 2-3 week lead time on this turbo.

What Makes the DOKA Version Different
The core upgrade is a 52mm aerodynamically engineered billet compressor wheel with 55mm tip technology, in place of the standard cast wheel. That gets you:

• Significantly more surge resistance than a standard 52mm compressor
• Compressor burst virtually eliminated during over-speed, since a billet wheel handles high shaft speeds that would fail a cast one
• Reliable operation at 24-25 psi boost, well beyond what the stock compressor wheel is built to survive

What to Expect on Boost
With stock plumbing, peak boost comes in around 2200 rpm. Upgrade the intake and intercooler plumbing and that drops to around 2000 rpm, with a usable power band that extends past 4500 rpm. Kerma's own R&D ALH Golf has recorded 210 whp uncorrected at 5000 feet elevation, running the full set of supporting modifications below.

Getting the Most Out of It
This turbo is built to be paired with a complete supporting setup, not run in isolation:

• Kerma ECU tuning
• Injectors flow-rated for 200+ hp
• High-flow turbo-back exhaust
• Colt Stage 3 camshaft
• 3-bar MAP sensor
• Upgraded intercooler, turbo inlet pipe, and intake manifold

What's Included and What to Add
The install kit ships with the turbo. You'll still need a turbo adapter to connect stock or upgraded intercooler plumbing, along with your choice of braided oil supply line, and, on 1998 through mid-2001 cars, the ALH retrofit kit. All three are configured as options at checkout.

Warranty
2 year, 24,000 mile manufacturer warranty when this turbo is run with Kerma tuning. The warranty does not extend to installations tuned by other shops, since Kerma's calibration is specifically built around how this turbo behaves.

Fitment
1998-2006 Mk4 Volkswagen Golf, Jetta, Jetta Wagon, and New Beetle with the ALH or BEW engine.

Common Questions

Will this bolt onto my stock plumbing?
Yes. It's built from a VNT17 core, so it's plug-and-play with all existing VNT17 plumbing. You will still need a turbo adapter for your specific intercooler setup, chosen at checkout.

Do I need the retrofit kit?
Only if your car is a 1998 through mid-2001 model. That kit is required for those earlier cars and is offered as a checkout option.

Will I get the warranty if I use a different tuner?
No. The 2 year, 24,000 mile warranty applies only when this turbo is paired with Kerma tuning, since other tuners aren't calibrating specifically for how the DOKA compressor wheel behaves.

Do I need other upgrades to see real gains from this turbo?
You'll get the most from it paired with matching injectors, tuning, exhaust, camshaft, and intercooler work. Running it alone will still improve on the stock turbo, but the full supporting setup is what unlocks its real range.

How does this compare to the old 17/22?
It's built as the direct replacement for the 17/22, with a more surge-resistant billet compressor wheel. Customers moving from a 17/22 to the 17plus have reported smoother power delivery, quicker response, and noticeably lower exhaust gas temperatures.