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The fact that I could not run the REVO Stage 2+ software was a bit of a disappointment. I started looking for new injectors for the Golf. Soon found out that the injectors are very expensive because they were direct injection injectors. I started thinking where am I going with this car. My friend had a Golf Mk6 35 Edition. This Golf was equipped with a KO4-64 turbo. This is the same turbo as the Audi S3 and the Golf 6R. The people were getting really good and reliable power out of the cars without straining the gearbox. This was a very appealing option.
So what did I need to go KO4
I started doing some research on the net to see if I could find what I needed to do the conversion. I came across this pic:
As I already had done the recycle valve relocation, the only parts I had to buy were the KO4 turbo, Audi S3/Golf R injectors, and some seals for the oil and water lines that connect to the core of the turbo. The layout of the KO4 turbo was identical to the KO3. This meant all the pipes that connect to the KO3 connected to exactly the same positions on the KO4. This was great news, as I wanted to upgrade but didn’t want to end up fabricating stuff. Everything must just fit perfectly then you know you will not have issues with components breaking.
Here are some links to KO4 Turbos:
K04 Turbocharger BorgWarner # 53049880064Getting some extra upgraded components.
As I was planning to get as much out of this turbo as I could, I decided to do some more shopping. Forge Motorsport makes a piece of art wastegate actuator for the KO4 turbo. What is nice about this actuator vs the standard one is the spring inside the actuator could be changed out. Depending on what boost levels you are running you could fit a stiffer spring in the actuator. This meant that if you had issues with the wastegate being pushed open when boosting higher levels, you could fit a stiffer spring to counter that. This just meant that your maximum boost level without the control of the ECU will be higher.
Here is a link for this unit:
Forge Turbo Wastegate Actuator – K04 TurbochargerThere was another part I had to get. I read that most people that did the KO4 conversion on the Golf 5 GTI’s also fitted an upgraded fuel pressure relief valve that sits on the high-pressure fuel rail. This valve limits the pressure in the rail to a maximum of 130 bar. The Golf 5 GTI in a standard form never reached the 130 bar mark. When you go KO4 and run like REVO stage 3 software, which utilizes the aftermarket High-Pressure fuel pump you run a pressure of 130 to 132 bar. For this setup upgrading the valve is a must. The valve to use is the Audi RS4 valve. This valve opens on 140bar.
Fitting this valve does not mean you will be running a fuel pressure of 140 bar. The ECU controls the fuel pressure, this valve just helps that when you need the 130 bar pressure the safety valve won’t open and you don’t reach the 130 bar.
Here is a link for this unit:
RS4/R8 Fuel Pressure Regulating ValveGetting the turbo ready
The first thing I had to do was to remove the Neuspeed silencer delete adapter on the KO3 turbo. The adapter between the KO4 and KO3 is different.
The next thing I had to do was to fit the ForgeWastegate Actuator to the turbo. I was really glad that I bought the actuator at this stage so I could fit it with the turbo off the car. Fitting it with the turbo on the car would have been a nightmare as there is just no space to get in there.
This was like car porn. Everything was shiny and new. I could not wait to get this fitted to my car.
Running into an issue
The next Friday after work I started to strip the intake manifold of the Golf 5 GTI. When the intake as off I realized this was not going to be an easy job. I had to do a carbon clean on the car as well. The intake ports on the car were filthy, full of gunk. It took me the rest of that day cleaning the port. I didn’t have all the proper equipment to do it quick so I had to suffer doing it.
This was a really messy process to go through. I had to turn the engine so that cylinder no 1’s valves were closed. Then I had to blank off the other port so nothing could fall into it. I sprayed brake cleaner in the port until the port was closed completely in liquid. Let it stand for half an hour and then just use a homemade scraping wire to scratch the carbon lose from the surface. Then I used a rag to dry out the brake cleaner and used an old vacuum cleaner to suck the loose carbon out of the port. Then repeat until the port was completely clean.
This was a good 5 to 6-hour job to get all the ports cleaned. I told myself next time I want this done I will pay someone to do it.
Putting everything back together
Now that the intake port was nice and clean I could continue fitting the Audi S3/Golf R injectors and the KO3 turbo.
Getting the old injectors out of the head was a mission by itself. I didn’t have an injector extraction took so I had to use a vice grip to clamp on the injectors to be able to wiggle them out. Taking the injectors out I ended up damaging the injectors but wasn’t too worried about it. I used a gun barrel brush I bought to clean the injector holes. You must make certain that bores are clean as you don’t want to damage the injector or the Teflon seals on it.
Everything went together like a puzzle. I would say out of the whole build the hardest part was to remove the throttle body. The space is limited and the throttle is upside down with the torques screws showing downwards. You can’t see them especially the back 2 screws. You have to take the throttle off to be able to remove the intake support mount underneath the manifold.
Here is a link to Golf R\ S3 Injectors:
Golf R OEM Fuel Injectors – Set Of FourStarting the car
Everything was back together and the car started with no issues. You can start the car on the bigger injectors and turbo, you can drive the car as well but don’t go do hard pulls with the car. Just drive to the tuner so he could load the new software.
The next step was to get to a tuner.
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2 thoughts on “Should I go to KO4 turbo on my MK5 GTI?”
Hello.This post was really interesting, particularly since I was browsing for thoughts on this issue last Tuesday.
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