Hybrid turbocharger k04 build

[beachbuggy]

So this isn't your usual hybrid S3 build

This is " how to build a hybrid turbo"

Before anyone says, leave it to the pro's would would like to point out I am fully aware the all the pitfalls and consequences of what can happen if you used a bad turbo, and building a custom turbo is probably a good example. However I have a good knowledge of turbos have built my own and regularly rebuild turbos, with assistance from a good company and have access to a good machine shop.

Believe it or not it's not that difficult and if you can rebuild an engine you can rebuild a turbo.

So today I have just ordered the relevant parts in order to build this hybrid turbo. My aim is to provide those that require or are interested the knowledge to have ago yourself.

Believe it or not Turbo rebuild company's aren't that forth coming in providing part numbers or supplying parts for hybrids! However they seem fine on doing it bog standard k03 etc! And to be honest I'm not surprised.

A little research on google and you can find all the information you need. I struck lucky and found a company in Latvia that listed all the part numbers for all kkk turbos and cross references to other turbos and associated parts. With this knowledge it was very easy to work out what you could build, costings and whether what you planned on doing was possible.

So the k04-020 (k04-023) as used in our s3/TT's in stock it's 225bhp, remapped 265bhp and hybrid 300(+/-)bhp

What does it take to build a hydrid k04?

The whole ideal of a hybrid over say a GT30 is to use the existing components rather than replace manifolds,lines,pipe work etc etc
The hydrid k04 is a k04 turbo with enhanced components, allowing increased performance while retaining stock looks and parts

To do this the internals of the turbo must be upgraded, allowing more airflow and he ce more bhp/torque

KKK make all there K03/k04/RS6 turbos with the same internal components, meaning a compressor from a rs6 will fit a k03 exhaust shaft.

So we need to find the largest components we can that will fit inside the k04 housings from our S3's and in order to this machining will need to be done to get the correct tolerances and gaps between and blades and housings. Fortunately again for us the k04 has sufficient metal on the compressor housing and exhaust housing to allow the largest parts KKK sell to fit! Bonus.....

So what can we actually fit inside?

Well anyone who has followed Wellys hybrid build will have seen the pictures of his hybrid. The compressor is listed and classed by most manufactures of hybrids as a k06 compressor wheel. There is no such thing as K06 turbo from which this came from but rather a part number 5306 to which KKK relate it to. The compressor actually is from the new Audi s3 8p. Now many are listed as billet wheels, which means they are machined rather than castes as original KKK ones are made. Here is a good article of billet v Cast compressor wheels
BILLET COMPRESSOR WHEELS

The fact is that these compressor wheels in 2.0tfsi s3 can make 330bhp so any problem with metal creep is a little irrelevant when the aim is to go to 300bhp.

The largest exhaust wheel available is from the RS6 turbos, they in stock form have this larger exhaust turbine mated to the same compressor of our s3. They are also the same exhaust wheel that is used in the VXR turbos so actually commonly available.

Anyone who has seen Bills post showing the compressor comparisons between stock and hybrid K04 will have noticed the difference and to put this in to figures here are the measurements

K04 stock turbo exducer 56.06 inducer 41.86 4/4 blades
K06 turbo exducer 56.06 inducer 46.3 ( although some say it's 60/46) 6/6 blades

Exhaust turbine

Stock exducer 50 inducer 41.92
Rs6 exducer 50 inducer 45

Although these aren't massively bigger they are more efficient and will produce the extra bhp.

I have bought a good used k04 and the new compressor, turbine and parts are arriving early next week so I will update with pictures and a break down of the turbo and what is planned.

I hope this will be of interest to some

I know it's no use without pictures so I will post some soon

 

[Lee172]

Sounds very interesting

 

[MUSH]

Sounds like an Interesting thread starting here...!!

Best of luck Dan!

 

[jay1601]

was a good read. very interested in this thread

 

[Dani_B19]

Very nice little read up.

Think you might have some business coming your way haha.

So whats the max bhp that can be extracted from a ko4 hybrid?

 

[beachbuggy]

Thanks for the posts, hopefully you'll find the rest as interesting!

From what I gather And have read some builders claim 340-360bhp which I think is very optimistic! Reality is somewhere around the 300-310bhp with suitable mods is a sensible figure. You have to remember you can thrash the boxxxxks off a hybrid or calmly get the same power from a BT.

My plan if all goes well is to get a sensible/workable figure , basically 1 step up from the stage 2 so around 300 mark.

The thing is I'm not re-inventing the wheel here as its all been done before but I will hopefully doing it differently and it will with out doubt be considerbably cheaper than buying an off the shelf version.

My next post is going to show the internals of the k04, described the main components , why they fail and talk about balancing , the most critical part of a turbo.

 

[Jimgrim77]

I'm very interested in hearing more about this too. You could be onto something great here!

 

[AARON77]

Mustard

 

[Dani_B19]

But welly achieved nearly 350 but ended up with a constant 340bhp, so dont you think what your creating could achieve that?

 

[beachbuggy]

From the specs of the parts and previous hybrids , yes it could potentially make that, I hope it does but I'm just being realistic .

 

[slowcoach3]

And any cross referencing of ko3 parts would be greatly appreciated..... Great thread, I'll be following closely!

 

[Hammy999]

Great thread and well timed as am toying with the idea of going down the hybrid route, just weighing up the pros and cons!

 

[s3gazz]

Sounds great pal good look

 

[s3dave]

Great mate, i would want more than 300 bhp from a hybrid though, im expecting 340-350bhp with large port and WMI

 

[superkarl]

Great mate, i would want more than 300 bhp from a hybrid though, im expecting 340-350bhp with large port and WMI

and tubular mani, what i think bill and welly said was important in getting the figures they got

also worth saying that welly runs a higher compression ratio than stock s3's. at 9.5:1 which could also be a contributing factor in his power figures.
so your average ko4 hybrid build wont quite reach welly'esque numbers.

 

[IrishDave]

As above the higher compression ratio will make an extra 5-10% more power.

 

[Dane]

and tubular mani, what i think bill and welly said was important in getting the figures they got

also worth saying that welly runs a higher compression ratio than stock s3's. at 9.5:1 which could also be a contributing factor in his power figures.
so your average ko4 hybrid build wont quite reach welly'esque numbers.

I can attest to this lol

 

[beachbuggy]

Well I have a spare engine sitting in my workshop with eurospec h beam rods and agu piston newly built waiting for a home.

Only problem is I have no car to fit this turbo too at the moment, I waiting for an s3/a3 Quattro or TT to come available which needs an engine or cheap so I can fit and test it on. Hopefully I will in the next week or so.

I've also just bought the parts for a k03s hybrid as well so for all the A3 guys who are feeling left out I will be hopefully doing the same for that as well.

 

[Welly]

 

[Reesy]

I've also just bought the parts for a k03s hybrid as well so for all the A3 guys who are feeling left out I will be hopefully doing the same for that as well.

This bit has made me subscribe.

 

[beachbuggy]

So having ordered the new compressor and turbine wheel I am patiently waiting for thebits to arrive. I spoke to the supplier yesterday to see how it was comingalong, he said he had the parts and was going to balance it all up andhopefully get it the post to me today.

In the mean time I thought I would do a post about the turbo's, specificallythe K04, how they compare to the K03. What I plan on doing in order to hybridthis turbo and any potential issues.

So to start with I have a few pictures of the K04, taken apart, with the majorcomponents

Firstly we have the compressor and turbine shaft
This was taken from the donor Turbo, the turbo its self wasn't in too bad acondition but was leaking oil out of the exhaust, as you can see from thepicture the rear oil seal is knackered hence the oil leak. It had basicallyjust worn.

This picture shows the same as the one above but as a graphic explaining theparts of the compressor and turbine

This picture is probably the best to explain how a hybrid works over a stockturbo. In my previous post I listed the sizes of the wheels I am planning onfitting.
The main bits I am concerned with are the inducer and exducer of both thecompressor and turbine. Fortunately on the K03/K04 series all the bearingjournals and shaft lengths are all identical, hence why they are good forhybrids as there are many common parts available.

Starting with the inducer/exducer, we have, when we come to building a biggerturbo, 3 options.
1) Same size Exducer, larger inducer
2) larger Exducer, same size Inducer
3) larger Exducer, Larger Inducer

The exducer and inducer, although integral and combined in thecompressors/turbine play very different roles in the turbo and hence havevarying effects on the efficiency of the turbo.

In very basic terms the Inducer bites the air, much like a propeller on a planeand the Exducer spits the air outwards. Therefore if we have a bigger inducerwe grab more and a bigger Exducer spits the air faster. More air = More Bhp,Faster air = more torque.

Here is a picture of a K03/K03s/K04 compressor wheels. You will notice the K04(right) is both bigger in Exducer and inducer than the other 2. However the K03(left) K03s (middle) have the same size exducers but the K03s has a largerInducer (it may not look it in the photo! but why the k03s makes 220bhp+ whilethe K03 only 190bhp+)

What happens when you upgrade to a larger inducer while retaining the same Exducer?The most notable change is more airflow capability; since the turbo is taking abigger "bite" of air in every revolution, it can obviously "spitout" more air as well. More airflow sounds great... so why not go to thebiggest inducer you can find? Because that creates two main problems, one muchmore
important than the other. The smaller problem--really it's just a nuisance--isthe turbo will now have a little more lag during spool up (because the biggerwheel weighs more, plus it has to do more work with each revolution, etc). The real trouble with a large inducer increase but no Exducerincrease, though, is it makes the turbo much more likely to surge!!

I will coversurge a bit later as it's quite an important topic.

When you upsize the Exducer without modifying the inducer, the exact oppositeeffect happens: your spool up time is reduced. Why does this happen? Remember that acompressor "spits out" the air in a radial fashion. The larger Exducergives a higher wheel edge speed for a given shaft speed, and that higher edge speedmeans the compressed air exits at a higher speed than before... and
thus it builds boost faster. Another effect of this upgrade is an increase ofthe compressor's pressure ratio capability without a significant increase inits maximum flow rate.
Turbines areactually a more simple science. The turbine powers the compressor because it isa physical restriction in the exhaust flow. The more it restricts (i.e.: thesmaller the turbine) the faster it spins the shaft... but the more it chokesthe engine and robs you of top-end horsepower. The less it restricts (i.e.: thelarger the turbine) the slower it spins the shaft... but the less it chokes theengine and the more top-end horsepower you can make.

Here's a picture of a K04 turbine (left) versus the K03s (right)

Some of my research has found that many of the Hybrid K03s that are availableare basically a K03s but with a larger K04 turbine wheel, allowing for morepower.

So back to my Hybrid. Going on the above information I have settled on the K06compressor wheel which has a compressor with the same Exducer size as the K04but a larger Inducer and a larger to turbine so providing more grunt to powerthe bigger compressor.

The other main parts of the turbo are the bearing housing, compressor housing,exhaust housing, bearing, thrust bearing and collar and the seals

These can be all seen in the following pictures.

The compressor and exhaust housing are both going to be machine to accommodatethe larger wheels. This will be done by a local machine shop that I have usedbefore, I am holding off getting this done yet until I have the parts so I canmeasure them accurately and get the machining done to the exact measurementsrather than the listed ones.

The bearing housing will remain as it is as all the parts are compatible so nomachine will need to be done.

The Bearings, and seals are all being replaced and I will be fitting anupgraded T exhaust seal which overlaps rather than being a butt joint seal. Nowwhether this greatly improves the quality of the seal I am not convinced butwould rather fit one as a matter of precaution.

I think I have covered enough for now. Next as stated I'm do a bit on surge, apotential turbo killer.
Also when the parts have arrived I will post some pictures of the parts side byside for a comparison.

 

[aragorn]

Good info!

Your photo of turbines isnt working?

You should also explain how the housing size relates to the whole thing. An RS6 turbine in a K03 housing wont flow anything like a RS6 turbine in the RS6 housing for instance.

 

[beachbuggy]

Thank you , its fixed! I forgot to put the link in!! Doh

Yes I plan on doing that when I go into surge/stall. Cut back turbines and AR ratios. I don't want to bore everyone to quickly

 

[beachbuggy]

So a little update.

The new Compressor and turbine turned up in the post today. The compressor looks massive! In actual fact it is only 4mm larger on the inducer but it looks BIG!! Unforatunately I don't have the stock K04 parts with me to show side by side but I will tomorrow.

I also had a complete result last night as I bought a brand new genuine K04 which the shaft end bolt had snapped for £125 delivered. Now I don't need the compressor wheel or turbine as I'll be replacing these anyway but now I have a brand new, exhaust housing, compressor housing, bearing housing, back plate and actuator to work with, which I fanatastic result...

So plan now is to hydrid up both up along with the K03s and have a couple of test items.

Here's some pictures of the compressor and turbine and the new K04

 

[badger5]

are you using the 2283 wheel on std k04 turbine?
effective overall blade length is increased more than just the inducer/exducer, as the centre hub is smaller diameter on billet wheel

 

[beachbuggy]

Hi Bill.

Using a billet 2283 wheel with an RS6 turbine wheel/shaft. Rather than getting the blades cut back, I'm going to oversize the exhaust housing to help with (potential/possible) surge.. I think this may the best way as it's what the other hybrids do or at least I think that's what they do as there's no actual evidence. I seems the better option, the RS4 guys seem to do it if they can't get hold of RS6 turbine housings..



I think the fact the blades are increased is the reason the compressor looks so much bigger! It looks an impressive piece of engineering...

 

[Dani_B19]

Get that turbo off ed38 by any chance? Haha

 

[beachbuggy]

Get that turbo off ed38 by any chance? Haha

I certainly did :thumbsup:

 

[beachbuggy]

Turbo Surging

As promised a write up on turbo surging.

Basically Surge is where the turbo goes FAST/SLOW/FAST/SLOW...... caused by the turbo SURGING/STALLING/SURGING/STALLING and potentially BANG
Heres a clip of a boost gauge showing a surging engine



So how does this happen?

Well the compressor, as we all know, is driven by the turbinewhich is driven by the exhaust gases, stored energy, latent heat.
The turbine provides torque to the compressor by the shaft.

When our engine is running the turbocharger compresses the air supplied to it from the tip, the engine utilizes this compressed air and expels it as exhaust gas. SUCK,SQUEEZE,BANG...BLOW. Pressure builds in the turbine housing, torque applied to the turbine wheel increases and the turbine wheel spins faster, so does the compressor and the end result boost increases.

Surge is an extreme! So we now are creating more compressed air than we can use. The engine can’t consume enough air, the exhaust housing can’t flow enough air and exhaust simply is too small and restrictive. The Turbine now can’t provide enough torque to keep the compressor spinning. The compressor slows, being braked in part by the back log of compressed air.
For those who did physics remember air likes to travel from High to low pressure.

You now have a situation where there is huge high pressure in the Inlet and low relative pressure in the TIP and if the compressor can’t overcome this then the air will try to blow back or slow the compressor in an attempt to reverse/escape. Ever seen flames shooting out of the front jet engine? That’s surge.


The compressor is now stalling.. The engine now has a chance to catch up and consume the excess air, as remember it’s running at 3500+rpm still.. A balance is returned as the resistance on the compressor drops and the turbine starts effectively working again creating the required torque to make the compressor work as it should.

But then in an instance the torque on the exhaust turbine far exceeds the resistance on the compressor and we get, in a flash, the compressor spinning ,at speed , creating huge boost. Now back at the beginning and eventually the turbo will stall like it did before and the cycle continues until you reach such an RPM that the engine can consume all the air the compressor can produce.

If you’re lucky you just get a surge as the turbo goes through this cycle at worst you get rapid bearing wear as the surge can produce over 2g laterally on the compressor wheel and fatally you’ll get the turbine wanting to spin while the compressor can’t due to high/low pressure situation and the shaft snaps!

So how can we over come Surge?

The main ways are to:

Cutback the blades on the Turbine
As shown here you can clearly see the blades have beentrimmed to allow extra flow of exhaust gasses over them to help with backpressure. Downside, it increases spool time as at low turbo spin speeds theblades are less effective but at high speeds required for boost it doesn’tdiminish performance.

Over porting of the exhaust housing.
It’s not clear in this photo but the housing has been portedlarger than required to allow extra flow around the blades to again reduce backpressure and increase exhaust gas flow speeds.

Larger Exhaust housings
Not something we can do as the K04 only has one exhausthousing side, so not really relevant to us but just to show you thepossibilities here is a picture of a stock RS4 turbo and one which has beenhybrid using the exhaust housing from the RS6, you can clearly see the largerhousing allowing better flow, reduce back pressures and a potential 20bhp perturbo increase in power.

Aragorn, mentioned in one of the posts about RS6 wheels inK03 housings V Rs6 wheels in RS6 housings. Well hopefully this answers thequestion. We are basically limited by the flow of the K04 housing and have tofind other ways of improving flow and reducing surge.

Other things that can be done to reduce surge are to have ahigh flow exhaust manifold and upgrade exhaust system, both these items willhelp with flow reducing back pressure and lowering EGT’s.

As welly found these where essential to get the most out of the turbo without it surging.

I hope this covers most things.

 

[Reesy]

Turbo Surging

As promised a write up on turbo surging.

Basically Surge is where the turbo goes FAST/SLOW/FAST/SLOW...... caused by the turbo SURGING/STALLING/SURGING/STALLING and potentially BANG
Heres a clip of a boost gauge showing a surging engine



So how does this happen?

Well the compressor, as we all know, is driven by the turbinewhich is driven by the exhaust gases, stored energy, latent heat.
The turbine provides torque to the compressor by the shaft.

When our engine is running the turbocharger compresses the air supplied to it from the tip, the engine utilizes this compressed air and expels it as exhaust gas. SUCK,SQUEEZE,BANG...BLOW. Pressure builds in the turbine housing, torque applied to the turbine wheel increases and the turbine wheel spins faster, so does the compressor and the end result boost increases.

Surge is an extreme! So we now are creating more compressed air than we can use. The engine can’t consume enough air, the exhaust housing can’t flow enough air and exhaust simply is too small and restrictive. The Turbine now can’t provide enough torque to keep the compressor spinning. The compressor slows, being braked in part by the back log of compressed air.
For those who did physics remember air likes to travel from High to low pressure.

You now have a situation where there is huge high pressure in the Inlet and low relative pressure in the TIP and if the compressor can’t overcome this then the air will try to blow back or slow the compressor in an attempt to reverse/escape. Ever seen flames shooting out of the front jet engine? That’s surge.


The compressor is now stalling.. The engine now has a chance to catch up and consume the excess air, as remember it’s running at 3500+rpm still.. A balance is returned as the resistance on the compressor drops and the turbine starts effectively working again creating the required torque to make the compressor work as it should.

But then in an instance the torque on the exhaust turbine far exceeds the resistance on the compressor and we get, in a flash, the compressor spinning ,at speed , creating huge boost. Now back at the beginning and eventually the turbo will stall like it did before and the cycle continues until you reach such an RPM that the engine can consume all the air the compressor can produce.

If you’re lucky you just get a surge as the turbo goes through this cycle at worst you get rapid bearing wear as the surge can produce over 2g laterally on the compressor wheel and fatally you’ll get the turbine wanting to spin while the compressor can’t due to high/low pressure situation and the shaft snaps!

So how can we over come Surge?

The main ways are to:

Cutback the blades on the Turbine
As shown here you can clearly see the blades have beentrimmed to allow extra flow of exhaust gasses over them to help with backpressure. Downside, it increases spool time as at low turbo spin speeds theblades are less effective but at high speeds required for boost it doesn’tdiminish performance.


Over porting of the exhaust housing.
It’s not clear in this photo but the housing has been portedlarger than required to allow extra flow around the blades to again reduce backpressure and increase exhaust gas flow speeds.


Larger Exhaust housings
Not something we can do as the K04 only has one exhausthousing side, so not really relevant to us but just to show you thepossibilities here is a picture of a stock RS4 turbo and one which has beenhybrid using the exhaust housing from the RS6, you can clearly see the largerhousing allowing better flow, reduce back pressures and a potential 20bhp perturbo increase in power.


Aragorn, mentioned in one of the posts about RS6 wheels inK03 housings V Rs6 wheels in RS6 housings. Well hopefully this answers thequestion. We are basically limited by the flow of the K04 housing and have tofind other ways of improving flow and reducing surge.

Other things that can be done to reduce surge are to have ahigh flow exhaust manifold and upgrade exhaust system, both these items willhelp with flow reducing back pressure and lowering EGT’s.

As welly found these where essential to get the most out of the turbo without it surging.

I hope this covers most things.

A lot of useful info in this thread so far, but why the sudden change of font?

But seriously, keep up the good work, and do the k03 hybrid before the k04, the s3 boys have enough options as it is!

 

[beachbuggy]

I wrote it word and copied and pasted it into the thread as my computer likes to crash! For some reason it didn't like it and I had to edit all again and again.. Pain....

 

[badger5]

also cylinder "fill" and by cylinder I would include system total volume from turbo comrpessor outlet to inlet of cyl head......
more volume to fill (compress) also effects the surge line and onset from what I have seen. consider total flow, not just compressor flows...

This is why the turbo suppliers ALL claim rediculous power figures from these based purely on the theoretical compressor flow only. It do4es'nt work like that.

we shared a bunch of info in my thread here previously if of interest to read.
hybrid K04 + 3inch TIP + hi-flow Discussion Thread. - SEAT Cupra.net - SEAT Forum

Good info.. nice work dude

 

[beachbuggy]

By cylinder fill I guess you mean a reverse Venturi effect?

In so much that we are going from a small outlet on the compressor into a larger intercooler and eventually larger cylinder relative to the outlet of the compressor.. In essence when the air leaves the compressor and goes into the cylinder the Velocity must decrease and pressure increase,because we are going from a small area in the compressor housing to large area in the cylinder.

This decrease in velocity must add to the surge I would imagine as the air at the valve must be going slower than that leaving the compressor housing and be at a higher pressure so cause a back log.

I guess then that the suppliers give their compressor flow with out taking into account, factors such as FMIC, inlet manifolds, pipework sizing which all affect the flow.

 

[beachbuggy]

Bill I just read some of your post you put up and noticed this quote by RSMITH

Bill one thing i cannot understand as i continue looking over logs is that it would appear Welly can run higher boost for less airflow than me, hence he has more torque low down

This pretty much gives you an idea of what I mean, as Welly has a huge FMIC and large port head compared to Rsmith the air in system has a higher pressure and lower velocity for the same amount of airflow. To get 26psi on wellys car needs less air than 26psi on Rsmith car and hence less airflow. We can thank Bernoulli for this . it's why planes stay in the sky and keeps me alive at work...

Another thing I thought about today is that alot of the turbo companies not only clip but lighten the turbine wheels for faster spool, now looking at this picture and the one I posted earlier of my new wheel there is considerable amount of metal removed in order to lighten it and make it spool faster. While I can see the benefits of making it spool faster, surely reducing the mass of the wheel is going to reduce the amount of interia the turbine wheel will carry and whilst wont prevent surge surely must make the surge happen earlier. In much the same way a lighten flywheel works, it may spool quicker but it will also stall quicker.. This can't be good? If having the extra metal gives the turbine the required interia to over come the stall till the engine can consume all the air being produced this has to be better than a fast spool?! I may be way off the mark as it seems to simple and appreciate other factors contribute to surge but is it really a selling point to have fast spool if you're going to kill the turbo in the process...

 

[badger5]

By cylinder fill I guess you mean a reverse Venturi effect?

In so much that we are going from a small outlet on the compressor into a larger intercooler and eventually larger cylinder relative to the outlet of the compressor.. In essence when the air leaves the compressor and goes into the cylinder the Velocity must decrease and pressure increase,because we are going from a small area in the compressor housing to large area in the cylinder.

This decrease in velocity must add to the surge I would imagine as the air at the valve must be going slower than that leaving the compressor housing and be at a higher pressure so cause a back log.

I guess then that the suppliers give their compressor flow with out taking into account, factors such as FMIC, inlet manifolds, pipework sizing which all affect the flow.

not exactly what I meant no.
air being compressable, and the volume into which you are compressing it before that pressure "comes back" when flow cannot be flowed, is what I was referring to.. The charge pipework volume is acting like a plenum also (thinking of it in air compressor terms, its another "tank" to fill... question is where is the flow restriction... Fix that and surge line moves away.

robs LCR had a small fmic, which when tested had a high p-drop across it... flow restriction... not helping his surge vs wellys for example. Wellys had minimal surge in comparison.. but runs largeport head, supersize toyo cooler and pipework... when rsmith changed his fmic his surge levels also reduced..

The lupos 2283 hybrid has a 7 degree clipped turbine, to slow its spool, and ride the edge of the surge line in a more favourable way.
no surge on it, and when overlayed on other hybrid k04's no less a spool either. smallport, no mods aside from fmic (small AH thing)
Wellys also has 9.5:1 CR on AGU engine which also accounted for its better than avg joe power.

 

[beachbuggy]

Ok I understand you now,

So in Robs case it was quite clear to say that the surge was caused by the small fmic ( huge frictional forces and restriction in the fmic that caused the air pressure to drop and back up) and the surge was emminating in the pipe work between the turbo outlet and fmic. Remove that and you remove problem until the next pressure drop/backup. So basically what you need is to match all the parts to flow the required amount of air produced by the tubo and also to have a turbo suitable for the job..

 

[badger5]

Ok I understand you now,

So in Robs case it was quite clear to say that the surge was caused by the small fmic ( huge frictional forces and restriction in the fmic that caused the air pressure to drop and back up) and the surge was emminating in the pipe work between the turbo outlet and fmic. Remove that and you remove problem until the next pressure drop/backup. So basically what you need is to match all the parts to flow the required amount of air produced by the tubo and also to have a turbo suitable for the job..

It did'nt cure it but reduced its onset considerably..
total flow is what is my mantra when building BT setups... served me well so far

2283 unclipped RS6 turbine on unported hotside is very "edgy" with its onset of surge on initial spool..
engine needs to be able to consume the abundance of air before 4krpm to not suffer some surge, and you cannot let loose on boost requests until engine is good and ready to consume it. Done a few of these now to have a reasonable understanding of their "foibles"

 

[slappy_dunbar]

So in Robs case it was quite clear to say that the surge was caused by the small fmic ( huge frictional forces and restriction in the fmic that caused the air pressure to drop and back up) and the surge was emminating in the pipe work between the turbo outlet and fmic. Remove that and you remove problem until the next pressure drop/backup.

YES

So basically what you need is to match all the parts to flow the required amount of air produced by the tubo and also to have a turbo suitable for the job..

YES YES YES.

The charged-air system needs to strike a balance between flow and heat exchange.

 

[*Rich*]

Thanks for this, very interesting, and i am learning from it.

 

[beachbuggy]

Thanks, seems a lot of people finding this good which is good news

Not really much of an update. The new original k04 turned up today. The shaft had snapped at the bolt on the compressor so was going cheap. Although I had another donor k04 to use I'm going to go with this one as I know it's all good and with in tolerance. I'll be stripping it down tomorrow and whilst I'm doing take pictures for a "how to rebuild " post as well as I've had a good few requests on that as well.

Although it doesn't show much here's a picture of a stock k04 compressor v the billet k06 2283 compressor just to give an idea

I'm off to the machine shop tomorrow as well to drop the housings off. I'm going to get both k04 turbos housing done at the same time so I have spare set just in case. Then once they're back I'll need to open out the waste gate hole and assemble.

My biggest problem at the moment is a car to install it on! Having sold my recent s3 and tt I've spent ages looking for a suitable project but no joy.. The hunt continues