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1.8T K04-064 Turbo Upgrade – What’s It Like?

Photo of 1.8T engine bay with K04-06 inset picture. Is the 1.8t K04-064 turbo a good combination?

This video is for people who are either thinking of doing the 1.8T K04-064 turbo swap or people who have already done it and are wondering how other people (eg me) find it.

Before I get into the details, I think it’s worth giving you a run-down of the spec of this car so you can put into perspective the things I am saying.

The Car

This 1.8T K04-064 turbo swap is fitted to a MK1 Octavia RS. It’s got a 70mm turbo back exhaust system with a single silencer at the rear and a large cat of unknown heritage. I’m going to assume it’s a 200-cell jobbie, but the truth is I have no idea what it is.

Other parts include a Greddy blow off valve which I’m not sure is working properly and a MAF sensor whose position makes me think it is causing the rich idle issue.

The engine is completely stock internally.

In the service history it says it was mapped a couple of years ago to 313bhp. No dyno graph though.

The program on it could be better, for example it runs very rich at idle. The program the engine is running also has a massive effect on how the car drives, if you have a K04-064 already, let me know in the comments how your setup compares to mine.

So that’s the spec, what’s it like to drive a K04-064 on the 1.8T motor. Let’s go for a drive and find out.

1.8T K04-064 – Fuel Consumption

Let’s get the boring thing out of the way first. For 20 Euro of fuel, I get around 240km out of a 1.6 MK1 Ford Focus. If I drive this Octavia in the same way I get around 200km. At 240km the Focus is doing around 7.5litres/100km, I let you do the math for the Octavia. Generally speaking, the fuel consumption is a little better than I expected. If I drive normally. If I drive like a complete tit, I can get it down to around 130km from 20 Euro.


I’ll start with the exhaust. I said the car is wearing a 70mm system with a single small silencer at the rear. When I’m on it, I love it. When I’m somewhere where there is no one else, I love it. Plenty of drama and it sounds like I expect a big turbo 1.8T to sound like.

However, when I’m driving around town, it’s too loud, it draws far too much attention. And on the motorway, it’s a disaster. Cruising speed is limited to 120kmh because of the epic drone at any speed above 120kmh and even at 120kmh it’s not what I would call quiet.

The car needs an extra exhaust silencer. I want it whisper quiet when I’m not using the power, but I also don’t want to restrict the engine or lose the drama when I’m on it. I think I am going to fit a valved system, but I haven’t decided what I am going to do yet.


Amazing. It makes all the choo choo noises I could wish for. Maybe too much. It sounds like it could be suffering from compressor stall on lift off, which is why I said I think the Greddy BOV might not be working properly. But I might be worrying about nothing. Volume wise I have zero issues with the intake side, my only concern is the mechanical longevity of the turbo. If I have to lose some of the noises for longer turbo life, I’ll do it. I will look into the BOV in more detail in the near future (subscribe for that article and video)

Around Town

It takes a bit of getting used to. If I drive around out of boost, it’s docile enough. But if you get into the rpm where is starts to make boost, I need to be quite accurate with my throttle inputs to keep things steady. It’s not bad around town, it just takes more effort than stock car. Any stock car.

Country Road

It’s really enjoyable. I need to bear in mind that there will be a delay in pushing the throttle and getting extra power (at lower revs) but I expect this can be said for any turbocharged engine. When the power comes in, I can meter it out with the precision I want. Sure, the experience is not as precise as a normally aspirated car, for sure I have much more confidence dealing with lift off oversteer with a naturally aspirated engine, but that’s not to say the turbo is less enjoyable. It’s a different experience and it’s not something I have conquered yet. Personally, I like challenges. If I feel I know everything about a car inside 5000km I’d be disappointed. The 1.8T K04-064 turbo is not perfect but it has a ton of character.


At higher engine speeds eg 130/140kmh plus I find it a bit hard to modulate the power. It really wants to go with even the slightest increase in throttle, this could be down to the map (let me know what you think). But the biggest issue is the exhaust noise.

Boost Threshold

It makes boost around 2500rpm. Honestly, I wouldn’t mind getting boost around 3-3500rpm. If I’m low in the rev range, I don’t want a lot of power anyway and a higher boost threshold would make it easier to drive at slow speeds e.g. town driving. In a way, maybe the K04-064 is too good in this respect but I expect the mapping has got something to do with this.

Turbo Lag

Above 2500-3000rpm boost is almost instant, say a half a second delay. The delay gets less the more RPM I have. And I could say it’s a bit too responsive at higher RPMs. Again, this could be a mapping issue.


Something I am noticing more as I get used to the car is a situation where it seems to be over boosting. The boost pressure is going above 1.5 bar at least according to the boost gauge. Perhaps the boost gauge is the issue. I see different amounts of vacuum at idle, perhaps it varies by as much as 0.3 bar so it would be the gauge or perhaps the gauge is right and there is some other issue. Idle RPM seems to be solid though which makes me think I’m not looking at boost/vacuum leaks, touch wood.

On The Whole

On the whole I like the 1.8T K04-064 turbo a lot. The car has a ton of character and plenty of speed. I could always use more but I don’t want to touch the internals if I don’t have to. For 99.99% of the time, I think the power is about perfect.

Other Options

There is conversation here about the merits of the K04-064 versus GT28 frame turbos

More Information

This site has an excellent guide on the K04-064 upgrade. The parts needed and what needs to be changed

Find performance parts on ebay

This page was last modified Sep 9, 2023 @ 11:14 am

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