The Volkswagen Mk4 Obsession Tuning Guide

The Mk4 Volkswagen

Mk4 stands for Mark 4 edition which means their 4th generation production models. Volkswagen released some of its mk4 Golf’s and Jetta’s including the GTI and GLI in 1999. These early models came with a choice of engines, the atmospheric 2.0L, the 1.9L Diesel, the 1.8 Turbo and the Vr6 who was a favorite amongst youngsters in their previous mk3 production. The Mk4 Golf and Mk4 Jetta became rapidly a favorite for many because of the massive amount of available tuning options. For a larger upfront fee you could get the Golf GTI or the Jetta GLI version which came fully loaded with the 1.8T or the VR6 engines. It’s until 2002 that Volkswagen released the 20th anniversary edition of the GTI 1.8T.


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The Mk4 Golf and Jetta 2.0L Engine

There is not too much to talk about her as this engine is not very exciting for modifications unless you are willing to spend a large chunk of change on the project and rebuild the engine, drop a supercharger or a turbo to get a descend amount of power out of the car. Otherwise your simple software upgrade will yield you nominal gains. Maybe if you add a Cold air intake, header and a full length exhaust, you might start feeling some extra ponies, but nothing to make you go: WOWW! None the less, I would focus my energy and my hard earned money on engines that get a lot of gains with much less investment. Event thought there is a lot of tuning option available for these engines, I personally don’t find it’s worth the bang for the buck! Let’s get on with some more interesting stuff cause we have lots to talk about here!

The Mk4 Jetta and Golf 1.8T Engine

The 1.8T was and still is a very interesting and powerful platform to turn your car into a raging street monster. If you are only looking to gain a little extra power you can get yourself a tuning software upgrade and you will be able to get an extra 40-50hp out of your car with a much faster throttle response. You must know for starters that the 1.8T had different options throughout the years. At first it was introduced with a smaller ko3 Turbo offering 150hp with 155lbs of torque. In 2001 Volkswagen upgraded their OEM equipped 1.8T’s with a Ko3-Sport Turbo which was suppose to offer 180hp and 174lbs of torque, but dynamometer testing showed consistent results of 163hp and 170lbs of torque. It’s only in 2002 that Volkswagen made a few adjustments and delivered on their true promise of 180hp and 174lbs of Torque. So if you are look for a 1.8T Mk4 jetta, an 1.8T Mk4 Golf or an 1.8T mk4 GTI then you want to get the AWP engine which was made available as of 2002. This will be your best bet if you want to tuned it up with the least amount of investment or complications.

Volkswagen Mk4 1.8T tuning Options

For starters, once you have your Mk4 Golf or Mk4 Jetta with the AWP engine (2002 and above) you want to get yourself a performance software installed. Be careful what you choose and what you put in your car, low quality software can reduce the life of your engine and cause unexpected failures. Select only reputable companies with a proven track record. The ECU or Engine Control Unit, is the brain of your engine and you don’t want inexperienced tuners playing in there. In some cases it could be fatal to your engine. A good tuning company will charge you in the range of $500 for an entry level tuning software and it will be your best investment ever.
Now that you have your new software installed you will experience a completely new car. It will be stronger, faster, react on a dime and give you a total trill of driving. This major increase in power (from 180hp to 225hp) will not only hook you into tuning but will give you some amazing driving experiences. Unfortunately, or fortunately to the tuning companies, after a few months you will get use to your new thrill machine and you will want more power. You are now officially an adrenaline junky.

Options for more power on your Mk4 1.8T

To help your car breath better, you may install a cold air intake, it will allow for a better flow of air without being restricted to the designed 180hp limit. Now that your car can breath in properly, you also want it to release combustion gases without the limited restrictions. To optimize the whole flow of combustion a full line exhaust including the downpipe would be the optimal solution. If you are on a limited budget, then only the downpipe unit will be sufficient since most of the restriction is located within the OEM Twisted downpipe. A quality full length 3″ exhaust with downpipe can run you between $1200 to $2500, and only the downpipe between $500 to $800. Now having both the Cold air intake and the downpipe (or full exhaust) you can go back to see your tuner and ask for a software upgrade. Not all companies offer this service. If your tuner does, then you will be able to gain an extra 10hp and 15lbs of torque for all this extra investment. Personally I would either not invest this money for only 10hp/15lbs or would go to the next tuning level where it gets interesting and where your cold air intake and your exhaust will be fully taken advantage of.

The Mk4 Ko4 Turbo Option

The Ko4 Turbo which is also used on the Audi TT225, can be fitted on your Mk4 Jetta, Mk4 Golf or Mk4 Gti. These are OEM Turbo’s and can be bought new or used either from your dealership, a tuner shop or from a scrap yard. Make sure that if you buy them used you verify the propeller and the impeller for any damage and also check if there is any play on the turbo shaft. Make sure you ask for a low mileage turbo. You can also get the used turbo refurbished by professional to ensure long term reliability. A new Ko4 turbo will run you in the ranges of $1500 while you can get a used one for $300-$400. Please make me a favor and don’t buy the cheap China turbo sold on eBay, they will either fall apart or cause damage to your engine.

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In order to complete this build you will also need the Audi TT225 Original Injectors (386cc) and the Original MAF (Mass Air Flow) housing. You will use your car’s MAF Sensor and put it into the Audi TT225 Housing. With your Cold air intake installed, your exhaust system in place, your Audi TT225 Injectors and MAF housing, you are ready for a software upgrade to give you a stunning 265hp and 300lbs of torque. Now we are talking! But there are better options for more or less the same money.

Going Big Turbo on your Mk4 1.8T

The Ko4 upgrade is nice and will make your car amazing to drive, but if you invest just a little more you will end up with a beast. I am talking about a bolt on Big turbo upgrade. The cheapest option is to use the GT28RS Turbo kit also called the disk potato turbo with 440CC injectors (415cc Green Giants) and a big turbo software upgrade. You will still need a cold air intake, a downpipe, ideally a full 3″ exhaust kit and a small front mount intercooler. Keeping the boost below 20psi will yield you a 350hp beast! Don’t go over the 20psi mark otherwise you will need an engine job. Even though changing the engine Rods is not mandatory, I do recommend it for those that have a hard time to control their heavy foot or their boost controller.

The Ultimate Mk4 GTI 1.8T Setup

Keeping in mind that your car is front wheel drive, too much power will keep you spinning all over the place and is not fun to drive. So you don’t want to overdo it! A recipe that has been tested and worked for many is the one that follows. This information comes from many years of testing, experimenting and tons of money invested so you can save time and money on your next project! Here it goes! You either keep it simple with a basic software upgrade or you go all the way to a big turbo setup which I am about to reveal.
This is what you will need:

1- Garrett GT3071R (ideally internally wastegated)
2- Siemens 630cc injectors
3- Audi TT225 or OBD2 VR6 MAF Housing
4- Aftermarket Rods good for 350WHP+
5- Cold air intake
6- Full 3″ Exhaust line
7- 3Bar Fuel Pressure Regulator
8- Performance software supporting the above
9- EBC ( Electronic Boost Controller)
10- Front mount intercooler ( Don’t get the side mount, they don’t do the job)
11- 1.8T After market Iron cast Exhaust Manifold

Please consider that your clutch will need to be upgraded to be able to handle this amount of power and this starting with your Ko4 upgrade. Since you will be doing a transmission job anyways, you might as well change out the 2nd gear to a TDI Mk4 2nd gear, this will make your gear much longer and you will be able to fully enjoy the full potential of your setup.
You can expect more or less 400hp and 350lb of torque, which makes the car absolutely amazing to drive. Aggressive, responsive, it’s a Ferrari killer! Anything beyond this point is a waste of money, unless you are planning to install a Quattro 4 wheel drive system.

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Volkswagen Mk4 R32

The ultimate Mk4 Tuning car is no other that the Volkswagen Golf Mk4 R32. This little beauty was introduced in 2004 and came fully equipped with a gorgeous body kit, Aristos 18″ wheels, sport suspension, big brakes, 4 motion (4 wheel drive), Konïg bucket seat only to name a few options. Roaring the streets this bad boy is equipped with a 3.2L engine that is begging to be driven! This platform offers an amazing tuning potential for those not afraid to spend some coins. With an investment of more or less $25 000 in Tuning you will end up having a true street monster pushing 530hp and 500lbs of torque. Otherwise, the basic tuning option will only yield a few extra ponies, going from the base line of 240hp to a potential of 255hp. None the less, if you have the money and are looking for a crazy fast car project then this is your best mk4 option!

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