KO3S VS K04 Why upgrade?

[Petrina Polo]

I have been doing a little reading...

My understanding is as follows...

Borg Warner produce a K03 Turbo that is fitted to our cars. (Polo GTi) There are a few different types of K03 Turbo. Apparently an older version, known as the K03 with 12 blades and a revised version with 8 blades and different actuator known in tuning circles as the K03S (but not its official name).

Apparently the K03S can hold a little more boost and flow a little more air.

My reading leads me to beleive the Polo Gti has the more efficient K03S.. but the Mk4 Golf Gti also with a 1.8T the older K03.

My further reading suggests this K03S turbo is good for around 215hp (160kw) without overspeeding the turbo.. The previous version K03 good for 195hp (146kw). APR on its site has different outputs for Polo Gti and Golf Mk4 chipped. (does this confirm the K03 vs K03S)

My reading also suggest that the K04 Turbo which is considered an upgrade for our cars is only good for 220hp without overspeeding the turbo. The K04 has 8 blades of slightly different design which can flow a bit more air.

If what I read is true, what is the point of spending $3000+ to change our K03S Turbo for the K04?

[jesum]

from what i understand after reading Guy's postings, the k04 is good for top end power. it keeps pulling till redline.

[AGO41T]

from what i understand after reading Guy's postings, the k04 is good for top end power. it keeps pulling till redline.

i wish my K04 did that

[decat]

get a K04-001

try to get a K04-001

[Gti Dave]

Not planning on doing this upgrade anytime soon and I see it as being pointless for my applications since I don't take mine to the track and since traction is already an issue.

[Plautos]

The turbine shaft is responsible for give power and when it will be released.
You need to understand the exhaust manifold is pressurized, so the cylinder chamber is pressurized and if you have pressure inside the chamber there is some difficulty to make a cleaner air fuel mixture, because there are some remains of the previously burn inside the chamber contaminating the new cycle.

The K03S is saddled with a tiny turbine:
Inducer: 45mm => Area 1589,625 mm^2
Exducer: 38mm
Tip height: 6.8mm
Blades: 11

Compared to the K04 turbine:
Inducer: 50mm => Area 1962,5 mm^2
Exducer: 42mm
Tip height: 6.4mm
Blades: 12

We can see the k04 is 23% bigger, so roughly speaking it is capable to give 23% more power them a k03, because it is capable to do a better exhaust and therefore cleaner air fuel mixture will arrive.

But….

The compressor wheel is tiny, designed to work with a boost of 0,6kgf so it will give pressure soon and fast for the entire rpm range, but when we tune our engines and require more boost, the compressor wheel it is not capable of sustaining it for much long.
So we need a bigger compressor, found in the k04-22-25-29

The K04-001 compressor looks like this:
Inducer: 35mm
Exducer: 50mm
Tip height: 3.7mm

The K03-052 (K03S) compressor is a bit larger still:
Inducer: 38mm
Exducer: 51mm
Tip height: 4.4mm


compressor wheel RS4: k04-25
40mm inducer,
51mm exducer

compressor wheel RS6: k04-29
42mm inducer,
56mm exducer

Now is a question of flow. The right thing to do is research turbo maps and chose which compressor will sustain the pressure desired for the entire rpm range.

There is a lot of variables when you are going to tune an engine and choose the correct turbo, but this is a good start to understand if it worth or not.

In my case, I went for the k04-25, I had to machine the compressor housing to fit the new compressor wheel, in the end it looks just like a k03s and it is totally plug and play. Worth the cost paid.

[Petrina Polo]

Thanks. Always a quality response from Plautos.

[Bboy_Sparx]

Holy crap! Talk about a response!! Hahaha

[pogo_55]

As street cred seems to be high on your list of priorities, you definitely need to get a K04 regardless of how much more/less power it makes than stock.
The problem with the K03s is it has a silencer built into it which all but removes the turbo whistle. The K04 hasn't and has lots of whistle audible at low revs.
Fully sik man...... If you like that sort of thing.

[JK8]

The turbine shaft is responsible for give power and when it will be released.
You need to understand the exhaust manifold is pressurized, so the cylinder chamber is pressurized and if you have pressure inside the chamber there is some difficulty to make a cleaner air fuel mixture, because there are some remains of the previously burn inside the chamber contaminating the new cycle.

The K03S is saddled with a tiny turbine:
Inducer: 45mm => Area 1589,625 mm^2
Exducer: 38mm
Tip height: 6.8mm
Blades: 11

Compared to the K04 turbine:
Inducer: 50mm => Area 1962,5 mm^2
Exducer: 42mm
Tip height: 6.4mm
Blades: 12

We can see the k04 is 23% bigger, so roughly speaking it is capable to give 23% more power them a k03, because it is capable to do a better exhaust and therefore cleaner air fuel mixture will arrive.

But….

The compressor wheel is tiny, designed to work with a boost of 0,6kgf so it will give pressure soon and fast for the entire rpm range, but when we tune our engines and require more boost, the compressor wheel it is not capable of sustaining it for much long.
So we need a bigger compressor, found in the k04-22-25-29

The K04-001 compressor looks like this:
Inducer: 35mm
Exducer: 50mm
Tip height: 3.7mm

The K03-052 (K03S) compressor is a bit larger still:
Inducer: 38mm
Exducer: 51mm
Tip height: 4.4mm


compressor wheel RS4: k04-25
40mm inducer,
51mm exducer

compressor wheel RS6: k04-29
42mm inducer,
56mm exducer

Now is a question of flow. The right thing to do is research turbo maps and chose which compressor will sustain the pressure desired for the entire rpm range.

There is a lot of variables when you are going to tune an engine and choose the correct turbo, but this is a good start to understand if it worth or not.

In my case, I went for the k04-25, I had to machine the compressor housing to fit the new compressor wheel, in the end it looks just like a k03s and it is totally plug and play. Worth the cost paid.

Yip correct!!

The PGTis KO3s is almost the same as a K04 001. The KO4 0032 is the best in the range, the same that comes in the S3 and Seat Cupra...

Pgtis use the K03s
MK4 K03 - 110kw K03s in the 132kw
MK5 - K03s, some BWAs rumoured to have K04.

I had the complete list... ill try to find it.

[JK8]

[mikepologti]

has anyone else managed to fit a k04 25? or anything else for that matter ?

[Petrina Polo]

Which K04 does APR fit in its turbo upgrade package?

[jasn78]

petrina i think you will find its the 001

[mikepologti]

yeah it is the k04 001 im pretty sure. i hear some of the brits atach garrets to theres, cant see the point personally wayyyy to much wheel spin.