To K04 or not to K04??
 

i have a 2001 awm 1.8t with a ko3s that has just made itself a large paper weight. I cant seem to find a direct ''K03s'' replacement for a reasonable price where as i can get a K04 fairly easily. Would it be advised to replace my k03s with a k04 on a stock tune or what would you recommend?

i was planning on a chip in the future and some other small stuff but nothing real crazy as a BT setup.

Thoughts???

Where are you looking to source the K04?

Personally I see nothing wrong with a K04 on a K03 tune. I ran my FrankenTurbo (K04 hybrid) that way for a while.

That's more or less what I was concerned about the k03s tune on a k04. I was looking to source a turbo from turbo pros or something like that. A new Borg Warner turbo is $1k and Im not spending that kind of money on a stock size turbo. Where else could I source a decent turbo from? I would like to put a k03s back on it but if it's cheaper to just put a k04 on it I will

not to threadjack - but.

If you had an APR stage 1 tune and dumped a k04 into the car. Would the software be somewhat compatible?

or limp mode?

Have you considered getting your current turbo rebuilt? It is my understanding this can be done for $400 or less, depending on what's needed and which shop you choose.

There are lots of places to find K04 turbos. ECSTuning.com is one of them, and they have a decent kit for $700ish.

It would very much compatible. Plenty of people have done this. I ran my FrankenTurbo on a GIAC K03 tune for quite a couple months.

hmm, but would it be using the turbo efficiently ?

Ok well i have a theoretical question, Lets say you did the diode mod for an awm engine with the k03s and boosted up to 15psi to stay on the conservative side. Would the computer be able to adapt the fuel trim enough to keep the A/F ratio halfway hunky dory if you swapped to a k04? From what i understand the k03s and k04 are similar in their airflow characteristics vs that of a standard ko3. I wouldnt imagine doing this with a standard k03 would be any good as far as using stock fuel and timing maps. Im sure chipped is a different story. Just trying to be cautious about the engine going lean while building boost and causing detonation or burning a hole in my nice pistons.

BTW i havent done the diode mod to my engine yet but i had just gotten everything to do it when all this happened.

Again thank you for you guys' input!

Can't be too far off. Compared to a K03 the K04 will have a tiny bit more lag, but it will flow more at higher RPMs whereas a K03 would drop boost pressure sooner.

As you mentioned the K04 has similar flow characteristics to a K03... so to answer your question your car should be able to maintain proper A/F ratio with a K04 in that application.

the reason people put bigger turbos into cars is to gain more power. if your not going to update the tune a k04 is pointless. yes you can run a k04 just fine of stock software but you wont net much of anything. a k04 is $1000. a k03 is like $600 new. ill sell you one used for $75. unless you plan on upgrading everything if you put a k04 in it, stick with a k03. and if you are going to upgrade other things, you might as well get a frankenturbo as its more power for same price.

side note: although 2001's came with a different k03 (supposedly. ive seen an email on here from borgwarner claiming its the same) any longituinal k03 will work just fine and wont change power torque or spooling