Im currently driving a 180 FWD Audi TT, and the turbo is starting to leak some oil when building bigger boost, its not smoking constantly or on idle, just when doing a small pull, there is a puff of stinking white/blue-ish smoke.

Only thing I know is the fact that it has a K03(non s), not sure what model exactly. Our marketplace is very limited when it comes to turbos for these cars, there is a K04 and a K03s. Everyone will say go for K04, and I'd love too, but does someone have a flow comparison, or some graphs with proof how much better the k04 is over the k03s. 

I couldnt find a good K03s compressor map, but I did found a K03 vs K04. And it hold boost so much better over the rev range. I'd love to have a stable 1.5 bar (21 psi).



I did read that the compressors on the two are very simular, but the K04 as a bigger intake port. And the k03s could only get you ~10bhp more.

Just wondering the opnions and experiences on the forum.

Hmm I do have a upgraded ic and exhaust, for ghe fuel system, are BAM injectors not enough? I did see allot going drom k03 to k04 with succes. But your advise would be a k03s i assume?

I honestly dont want to upgrade the fuel pump and/or injectors if I dont have too. Its still my daily and I am not looking forward to burning a hole in my pocket for gas(its €2,60 per liter for us).

If I can have 1.3-1.5 bar stable on my current setup, with the possibility for more in the future that would be awesome.

Im reading more and more, and I was considering the K04-023 at first, but I am leaning more and more to a k03s.. Pure on the fact that its a daily, I barely punch the gas on the road anyways, and I am not looking forward to buy 10 different mods just to run a K04.. I rather buy a TT with BAM engine

replacing a k03 with yet another k03 makes zero sense to me. compression limits notwithstanding, there are almost no drawbacks to going to k04s imo


you don't need those to run a k04, and you can always do those incrementally.

Dude, if you don't want to do anything, just buy a CHRA only for your current turbo, swap the CHRA, and job done. They cost peanuts for original BW CHRA.
You don't need to change anything.

There is near to zero benefit going K04 or K03S without upgrading injectors and fuel pump.

So either go with what you have now, or upgrade the fuel system and go for bigger turbo.

A little off topic but I was confused for why JE sells 9.5:1 stroker pistons off the shelf and currently readily available, but I realized they are probably made exclusively for race fuel(100octane+) or e85.

This forum is a lot more informative about actual tuning experience when it comes to choosing a CR for a BT 1.8t, which seems to always be 8.5:1 for 93 octane or 9:1+ or higher with race fuel, E85 or W/M. I was under the impression that you can use 9.5:1 on pump gas(93), no water methanol at that boost level but I guess I was wrong. 8.5:1 seems to be the best choice for high boost/knock Safety without sacrificing a noticeable difference in low end torque.

Edit: Not sure if below is true. Id like someone to verify

Then there's bad turbo sizing to match expected airflow which will create bottle necks from excessive flow from cam and throttle body upgrades. This then causes a back up and create high EGT's and back pressure in smaller turbine housings if not choosen correctly. It seems like, in most cases, high EGT's can be bypassed using E85 or methanol so you can use whatever set up you want.

People are saying it's harder to tune(9.5:1) but some say it's possible to make high(400+)HP  on "pump" fuel but I think octane is rated differently in Europe than the US for some of the guys that make those claims.

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