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I know it's been talked about before and shot down but I've just noticed that Buehn Engineering are doing K03 hybrids.

They are said to give more power and reliability that the standard K03 but are about half the price of a K04 setup. Straight bolt on, no RS4 inlet pipes needed.

K03/K04

# Complete bolt on
# Utilize stock inlet piping
# K03 turbine wheel
# K04 compressor wheel
# CNC machined compressor housing
# Quick, stock like spool
# Increased airflow and boost capabilities over stock
# Increased reliability
# Updated bearing housing

http://buehnengineering.com/27t.htm

I often have the debate in my head "what would I do if my K03's let go?" but can never bring myself to want to go the full K04 route.

What do you guys think?

MarkB wrote: I often have the debate in my head "what would I do if my K03's let go?" but can never bring myself to want to go the full K04 route.

What do you guys think?

Likewise Mark. I often conclude I would end up with the minimum K04 setup and only around 350BHP if lucky, which to be honest suits me.

I will be eagerly waiting to see what the experts have to say about your find.

Would port/polish and ceramic coating make them any more viable?

What are the K03/16?

This looks interesting - is it the case that if you went with the hybrid 03's you wouldn't have to have all the additional work associated with 04's??? (i.e. bigger injectors, fuel pump, re-map etc...). Also; would the stock i/c's still be sufficient?

They look very appealing to me, give a little more of every thing with out the big costs.

Take a look at the forum http://buehnengineering.com/forum

I've just posted a question, see what comes back...

My guess, I repeat guess, is that you could possibly run higher boost than a safe remap with a stock K03. Boost would still be less that using a K04 and would not safely hold boost for as a high rpms as a K04 would it would be intermediate. I expect power could be ~350BHP maybe even more but would still be limited by fuelling and cooling as per K04s.

If the K03's are known to be prone to failure and a K03 hybrid is "better" the question is is it better to the extent it can run higher boost and be more relibale, or should it be used no more aggressivly boost wise than a stock K03, but would in that situation be more robust, so therfore a sensible replacement if push comes to shove.

I would be unlikely to repalce K03s with K03s due to the risk of a repeat. If I was advised a K03 hybrid would run my current remap more safely and the cost was significantly less than K04's i would consider them, making a sensible repair job on the cards instead of a fairly major (cost) upgrade.

you wouldn't have to have all the additional work associated with 04's??? (i.e. bigger injectors, fuel pump, re-map etc...). Also; would the stock i/c's still be sufficient?

It's like with all these things, the wore you put in the more you get out.

They can be run without uprated fueling but to get the most out of them fueling can be uprated.

Intercoolers are worth doing, end of story.

To get the most out of the turbos Map tweeks will be needed, as ever!

GrahamS4 wrote:Boost would still be less that using a K04 and would not safely hold boost for as a high rpms as a K04 would it would be intermediate. I expect power could maybe fo to 350 maybe even more but would still be limited by fuelling and cooling as per K04s.

K03/16's as listed on the site have a clipped turbine wheel I beleave which extends the range they hold boost but does increase lag.

Check this out... http://forums.audiworld.com/s4/msgs/1852852.phtml

This is where I am most interested Mark/S4TAN.

We like K04's as they are a good upgrade to our S4s but are stock on RS4s where they seem reliable not only on stock cars but remaped and otherwise modded cars too.

If fuelling and mapping is altered to match the K03 hybrids potential are they any more reliable than a stock K03 on a remaped car?

I think they are meant to be more reliable as they are built to a better spec and work less hard. Lets hope someone in the know comes along soon

If fuelling and mapping is altered to match the K03 hybrids are they any more reliable than a stock K03 on a remaped car?

It's a good question Graham...

The main thing that stops me from doing a turbo upgrade (of any sort) is the cost of the work itself - i.e engine out etc, not the parts cost ... i wonder if going the hybrid 03 route (and therefore not having to change associated pipework) would allow the work to be done with engine in-situ? (car on 4-point lift and all work done from underneath). Probably not but would definitely sell it for me ...

My understanding personally is that the K03's exhaust side is very limited on flow. I really think it's short sighted, rather save the little bit extra to give you a bit of headroom to keep expanding. With lowered CR & K04's with a modded hotside - I really have not lost much bottome end power at all - the car is still quick to spool. Considering I have large inlet piping, large FMIC and large tubular manifolds... I should be worse than a straight off K04 setup.

S4TAN, the engine would still need to come out, I would only do it if mine failed so no option but to change/upgrade

Zero you have said, as others will that they will be limiting, but then all mods are ultimately limiting. It all comes down to how far you wish to go and spend

I really think it's short sighted

Personally I don't think that's a fair assessment - in essence, if you weren't planning on a big power upgrade, then putting a new, more reliable (and slightly more powerful) set of 03's in would be a reasonable thing to do, as it would keep the cost factor down to a minimum due to not having to change/upgrade anything else: you get a brand new set of turbos, better than the previous ones in performance and reliability and at a minimum outlay. And that's the bottom line here for some of us: cost.

Well said that Man

There is talk on AW of being able to remove K03's without removing the engine. just a K04 can't go in the same way.

A K03 to K03 hybrid swap may be possible without engine out. As S4TAN says this would really make it for me. It's a shame the job is so labour intensive, which is why none of us would take shortcuts wth parts, but if the K03 hybrid is a viable budget route (with little or no other future power gains required) I think many will be interested, myself for sure.

I like my K03's, the whining noise my left hand one makes is much like a police siren, a constant reminder not to speed too much