# K03s/K04 hybrid try this out!



## Laswell2001JETTA (Oct 17, 2012)

Ordered a k04 turbo to upgrade my current k03s turbo. I noticed that the k03s has a bigger compressor wheel, but the k04 has a bigger turbine wheel.... so i made a hybrid. Just got dont with the test drive and i'm very pleased. I need to update my tune now but so far so good.


----------



## CorrieG60 (Jan 18, 2004)

Pics, and maybe a how-to on how you did the swap?


----------



## Laswell2001JETTA (Oct 17, 2012)

*Write up!!!!*

As I stated before I made a hybrid turbo from a K04 and a K03s. Here is what I discovered:

1: K03s has a bigger intake side fan compared to the regular k03. The exhaust fans are the same size as far as I can see. 

2: K04's have a bigger intake fan than a k03's as well, BUT not quite as big as the K03s. The exhaust fan is bigger than the k03 and k03s by quite allot. 

Here is a pic of the intake housings of a K03s and a K04 turbo:









The k03s is on the left and the K04 is on the right. As you can see, the TIP hole of a K03s is bigger than the TIP hole of the K04. The K04 does have the appearance of being more ported and "open" but when you hold both of them side by side, the K03's has bigger ports depth wise. The K04 has shallower porting. I've been reading that K03 TIP's won't fit onto a K04 turbo, this is true only for the K03 turbos. The k03's turbo tip is in fact BIGGER than the K04. 

Next is a picture of the exhaust fans:









The K03s is on the left and the K04 is on the right. The k03s has a smaller fan in this case with 11 fan blades and the K04 has 12. I'm not sure if fan blade count makes a difference either way the Ko4 is bigger, so bigger is better. Also the Shaft nut on the K03s is a 10mm nut, and the k04 is a 13mm nut.

With this in mind I decided to make a hybrid of the two turbos and hopefully get the best of both worlds. Now it's time to take them apart. 

Here is a link I used to take apart the two turbos. Read this link. He goes into detail on how to take it completely apart. For this build, just remove the fan and the plate behind the fan. 

http://nomads.eurodiscussion.net/t3730-rebuilding-a-k03-or-k04-turbo-picture-heavy

REMEMBER THE NUT YOU REMOVE ON THE INTAKE FAN IS LEFT HAND THREAD!!!!! I almost broke mine trying to get it apart. 

Once you have both fans removed take the core of the K04 (with the bigger exhaust fan) and place the fan back plate and fan off of the K03s onto the K04. Be sure to keep the back plates with the fan that they came with because the fans sit inside the plates ans if you put a bigger fan in the smaller recess, you'll have problems. 

Once you install the fan onto the shaft screw the nut back on, the torque spec of the fan nut you removed in step one is 18-20 INCH pounds. 

re assemble the turbo following the link above^^^... be sure to use the K03s intake housing and the k04 exhaust housing when you assemble the turbo. 

AND YOU'RE done!!!

My Jetta 1.8t (AWP) is running on a 20psi tune from reflected tuning. When the turbo was installed I noticed a much faster spool time (2k rpm in 5th gear was the best I got).. it'll spike boost past 20psi. My fueling is not setup for the new turbo quite yet so it's not running quite as good as it can BUT it is much better already.


----------



## Laswell2001JETTA (Oct 17, 2012)

Been driving the car for a few days so par. All is well. I have a few oil leaks that I need a address but nothing bad. 

Here is a picture of my boost gauge. This was taken in 4th gear @ about 2500 rpm.









I plan on getting my ECU re-flashed for this turbo because it'll spike to 20+ then come back down to 15, then back up and back down... kinda surges almost. IDK if I need bigger injectors or 4 bar yet, I'm investigating.


----------



## Stetr24vw (Dec 20, 2006)

Bumping this back from the dead... how were your results?


----------



## toolu (Feb 25, 2012)

Stetr24vw said:


> Bumping this back from the dead... how were your results?


Considering he didn’t balance it, it probably didn’t last very long.


----------

