I have read elsewhere that downpipes can help to extend the life of K03s and turbos in general, because it allow for more efficient exhaust movement away from the turbo, which i guess helps keep the temps down...

 

Meh, not significantly or measureably by any means. Theres certainly not anything bad about doing it, but its not going to stop them from blowing.

Just maybe make it happen 50 feet farther down the road? LOL

The problem with the K03's has been poorly designed oil lines that are prone to clogging. They have been pretty relyable running at stock boost and under normal conditions (picture your mom driving the car). Most of us complain about how unrelyable they are because were running 16lbs of boost instead of 8lbs, and like to drive it like you stole it....

Seriously though, the easiest way to get at the downpipes is just to pull the motor. So if you pull your motor to replace the K03's at the very least gut your precats and relocate your O2's to make "piggie pipes"

 

hrm.. how does more turbo pressure cause the turbos to go bad? i mean.. the exhaust is causing the turbos to spin, thus causing the pressure. there is no manual lever that controls the rpms of a turbo. boost is controlled by a boost control valve, whether it be manual or electronic. so say your cars ecu is tuned for 10.5 psi. once it reaches that level, the ecu commands the boost controller to do its thing, and release pressure. it doesnt tell your turbos to stop spinning. now if your ecu is tuned for 18 psi, then your ecu allows that much boost before commanding the controller to release pressure to the wastegates. again, it doesnt have the turbos spin faster to achieve 18 psi as it did when it was spooling up 10.5. the turbo spins by the same exhaust making the same pressure. ecu or boost controller decides what pressures to allow. im assuming that people are just demanding more when they do have the ecu tuned and want to go fast. and ive had a tuned turbo car, and it is super addictive not to go fast all the time..but as of now i have a stock S4 b5 and im not tempted to gun it everytime. once its chipped itll be a different story..

 

I dont really know what your saying, your boost controller dosnt directly change the speed of the turbo through a "switch" but yes it does indirectly change the turbine speed by opening the wastegates and diverting the exhaustgas.

Let’s begin by describing what a turbo wastegate is. A wastegate is essentially a device that bypasses some exhaust flow around the turbine section of a turbocharger to control maximum boost.

Yes your turbo spins faster to make more boost. The more exhaust that is passing through the turbine side the faster the compressor side will spin. Hundreds of thousands of RPM btw. Your boost controller, be it electric or manual, decideds what pressure the wastegates open. That allows exhaust gas to BYPASS the turbocharger so it dosnt make it spin fast. At 8lbs of boost the n75 is telling the wastegates to open and not let the turbos spin faster. If you remap for 16psi than the n75 is going to tell the wastegate to stay closed for longer turbos will spin faster and make more boost.

If a turbo made the same ammount of boost at any RPM than you could be at 21lbs idiling.....

 

so is the k03 to a k04 bigger turbos or just stronger bearings or support all together?

 

K04's are just bigger than k03's. Bigger Housing, bigger wheels. People blow their k04's all the time too though, if you push a turbo past where it wants to be working it will do damage.

The k04's are nice because they bolt up to our stock exhaust manifolds and downpipes in the stock location. All you need are the k04 inlet pipes which go on the compressor side. Then you have a stock car, with better k04 turbos. Even if its not fueled, stock intercoolers, etc the turbos will make 8lbs of boost but because they dont have to work as hard the air is cooler and you get a little more power. Stage 3-.

 

ok.. so if i get an apr chip then youre almost guaranteeing that my original turbos are going to give at some point, and pretty soon at that.. right? even if i give proper warm up and cool down time before and after runs? and how much and where can i find some good k04 turbos and compressor inlets? and if i get the turbo work done before the tune do i need to let apr know that i have bigger turbos on my car?

another question.. where can i get some quality divertor valves? i noticed at idle the rpms fluctuate slightly. i started looking under the hood and heard a vacuum leak, and at first i suspected the vacuum line to the driverside divertor valve. after it was changed, the vacuum leak was still apparent. touched both divertor valves at idle and the driverside one was humming, almost vibrating while the passenger side one was doing nothing. i then pinched the vacuum line going to the divertor valve and the ruckus stopped... so i have a bad diaphragm in it i suspect. so i need to find some quality ones and also will this have an adverse effect on the performance of my car? besides running slightly lean with a vacuum leak....

 

Then explain what a wastegate is ?

Yes, and in the b5 S4 this is called the N75 which contols the wastegate actuators (see above).


Half right and half wrong. Opening the wastegates slows the turbine speed thus lowering air volume and pressure on the compressor wheel side.

Aren't you contradicting your statements above? You bypass exhaust gas through wastegates not excessive boost, that's what diverter and blow-off valves are for.


Chew on this. Are trying to say that an engine demands the same volume (cfm) of air at any given speed (rpm) for any given pressure (psi)?
If this were possible then why wouldn't turbos just spin at 100 rpm and call it good?
I'll tell you why, turbo rpms are directly affected by engine rpms. The higher the engine revs the more air volume it demands thus causing the turbos to spin faster.
It's simple physics. Think about it...

I think the point you were trying to make was that on a 10 psi tune, at 10 psi the wastegates are opened slightly to prevent the turbos from increasing in speed to create higher than demanded boost.

And on an 18 psi tune the wastegates are held closed longer to allow the turbos to increase in speed thus creating the desired pressure.

 

The car will last 200k + miles, the turbos will not. Doubling the boost will make it happen sooner. Could be next week, could be 100k miles down the road. Thats the point of this thread, some people blow them at 35k some havent blown em yet at 150k its a crapshoot. There is no magical number, if they blow they blow, chipping is going to make it happen sooner.

K04's are kinda hard to come by lately. www.achtuning.com usually offers good prices and might have them in stock. Its about $2700 for the turbos and inlets. While you install them you should gut your precats in your downpipes for more power and faster spool (piggie pipes)

Some places sell stage 3- tunes, but i think giac might be a better choice than APR.

Diverter valves are common problems. That audi "710n" valves from the TT are a common replacement for cheap. If you want a quality rebuildable valve try the forge 007's or APR r1

 

ya.. hp cleared it up.. im a tech but dont know much about turbos. i got a t6 and an s4 a little while ago and trying to understand mods and things that im doing to them.. someone had explained things to me improperly. theres not much demand for working on forced induction vehicles where i am.. so.. gotta make money.. ya know??