Hybrid turbocharger k04 build

Regarding wastegate actuator, spring rate, force:

Cut up a bad K03 actuator to get some idea of the spring and dimensions:

Canister (actuator) OD: 59mm
Spring diameter: 37mm
Wire diameter: 2.5mm
Windings: 3 (plus top and bottom)

Spring uncompressed: 66 mm
Spring compressed with 11 lbs load: 46mm
Spring rate: 11 lbs / 20 mm = 0.55 lbs/mm = 14 lbs/inch = 0.25 kg/mm = 2.5 N/mm

Dimensions: see photos

https://www.dropbox.com/sh/2ifx7vdb9qr95gu/vc4IhBLaXY

Also, used a K03 (from 2.7T) for the following 'spring rate' calc:

Travel: ca. 15mm
Start pressure: 7 psi
End pressure: 14 psi

Based on above: around 2mm per psi.
With the 'active' diameter the air/vacuum is working on of about 2" or around 3 square inches
14 psi = 42 lbs
7 psi = 21 lbs
spring travel: for 21 lbs = 14mm. Spring rate based on that: 1.5 lbs/mm or 0.675 kg/mm or 6.75 N/mm or 38 lb/in.
Obviously, a big discrepancy to the above spring rate of 14 lb/inch (not sure what the US unit for spring rate is).

Flapper active diameter: ca. 25mm or 1 inch. Area: 0.75 square inch

Backpressure in exhaust manifold to equal spring pressure: Example with 5 psi crack pressure of wastegate:

5 psi x 3 square inches = 15 lbs preload on the actuator spring.

15 lbs / 0.75 square inches = 20 psi back pressure required to lift the flapper.
 
all nice calcs but not that relevant to your boost duty cycle control...
It would not be unusual to see an exhaust manifold pressure far higher than you imagine, depending on setup... Upwards of 2:1 pressure ratio minimum on k03/4 framed turbos...
 
audi upgrades
badger5 said:
all nice calcs but not that relevant to your boost duty cycle control...
It would not be unusual to see an exhaust manifold pressure far higher than you imagine, depending on setup... Upwards of 2:1 pressure ratio minimum on k03/4 framed turbos...
Click to expand...

I thought I need stiffer wastegate spring?

"2:1 pressure ratio": what is 2 and what is 1? Cylinder pressure 2, exhaust pressure 1?
In absolute numbers (examples) available?
 
beachbuggy said:
3) is the boost map. I have a slight over shoot but it's capped with a MBC at 23 psi ( this logger only goes to 22.5psi hence the flat line) and I found if I go over 21 psi below 4250 rpm the thing will surge if I keep it below that until around 4500 then I can ramp it up to what ever I want with out surge.

As I now have an uprated actuator if I try and aim for 21psi, the KFLDRL map will always cause it to over shoot and surge because the N75 isn't quick enough. So I've set load map for around 18psi which means that when it tries to react to hold 18psi it will overshoot but stay within the surge limit 21psi and thus by the time is controls it,it'll be at 21psi anyway, if that makes sense?. No need for a clipped turbine. After 4750rpm I'm free to ride the PSI rodeo all the way to the redline..yeeehaaaa :)

BOOST.png
Click to expand...

"if I go over 21 psi below 4250 rpm the thing will surge": How does 'surge' materialize (in data, and real world)? I don't seem to have the limit, running happily at 25 psi (RS6/2283) (needed to get the desired 21 psi at redline due to "overshoot", but NOT liked since I am on stock rods (and 25 psi at mid range might put too much stress on the stock rods).

Setup: AMB engine, high flow log manifold, 3" DP, custom TIP, S4 MAF, 550cc. RS6/2283 combo, stock WG spring.
 
beachbuggy said:
As you can see I have either a boost leak or the N75 maps can be tweaked to make actual meet requested.

BOOSTV6b.png
Click to expand...

Any suspicion yet for the boost dropping from 5500 on? N75 with MBC in parallel, stiffer actuator spring, correct?
Since I have similar issue (overboost mid range or falling boost, depending on perspective), a strong springed actuator was suggested here. IIRC, you put a stronger (borrowed from T3, right) spring already in, but still seeing the 'hump' shaped boost curve.

There got to be a way to get a flat 22 psi, or?

What type of MBC are you using? My current trials have been with 'fancy' ball-and-spring MBC (from integrated engineering). On other cars (AEB), I am running the simple 'faucet type' (nothing but an adjustable valve) type MBC. Maybe I need to give the cheapo MBC a chance (only one trial, deemed too touchy and abandoned after a few failed trials to dial it in).

Note: I also experimented with 'flow modified' N75 (varying the restrictor diameter in the leg to the compressor), hoping reducing the restriction (larger hole = more air flow) would 'speed up' the reaction time of the N75 to 'catch' the boost swing (see earlier N75 only logs), but both trial holes 'overdid' it (the first (2.1mm) resulted in max boost of 15 psi due to too much air getting to the actuator).

Wish I knew how to manipulate the N75 control...(or tuning the Me7.x for that matter). Certainly on my bucket list for the future...
 
vtraudt said:
I thought I need stiffer wastegate spring?

"2:1 pressure ratio": what is 2 and what is 1? Cylinder pressure 2, exhaust pressure 1?
In absolute numbers (examples) available?
Click to expand...

inlet manifold to exhaust manifold... lots more in exhaust manifold than inlet with minimum that sort of pressure ratio on k0x framed turbos
 
vtraudt said:
Any suspicion yet for the boost dropping from 5500 on? N75 with MBC in parallel, stiffer actuator spring, correct?
Since I have similar issue (overboost mid range or falling boost, depending on perspective), a strong springed actuator was suggested here. IIRC, you put a stronger (borrowed from T3, right) spring already in, but still seeing the 'hump' shaped boost curve.

There got to be a way to get a flat 22 psi, or?

What type of MBC are you using? My current trials have been with 'fancy' ball-and-spring MBC (from integrated engineering). On other cars (AEB), I am running the simple 'faucet type' (nothing but an adjustable valve) type MBC. Maybe I need to give the cheapo MBC a chance (only one trial, deemed too touchy and abandoned after a few failed trials to dial it in).

Note: I also experimented with 'flow modified' N75 (varying the restrictor diameter in the leg to the compressor), hoping reducing the restriction (larger hole = more air flow) would 'speed up' the reaction time of the N75 to 'catch' the boost swing (see earlier N75 only logs), but both trial holes 'overdid' it (the first (2.1mm) resulted in max boost of 15 psi due to too much air getting to the actuator).

Wish I knew how to manipulate the N75 control...(or tuning the Me7.x for that matter). Certainly on my bucket list for the future...
Click to expand...



Proper N75 control will achieve this. me7 capable of doing it

if you dont have access to getting this mapped properly, find yourself an EBC which will...
 
badger5 said:
Proper N75 control will achieve this. me7 capable of doing it

if you dont have access to getting this mapped properly, find yourself an EBC which will...
Click to expand...

Will check with tuner. But what EBC 'comes to mind' for this purpose?
 
badger5 said:
inlet manifold to exhaust manifold... lots more in exhaust manifold than inlet with minimum that sort of pressure ratio on k0x framed turbos
Click to expand...

What pressure are we talking about?
Say 3" DP, not cats, cat back exhaust after the turbo,
Say high flow log manifold from cyl to turbo.
 
Bit of a Resurrection here but wowww what a great write up !
I have a spare k04 and thinking of having a bash at hybridizing it :)
I'm quite clear on all of the build other than where abouts was the exhaust/turbine housing machined ? With the proposed Chanel's to help prevent surge ? Thanks great thread
 
beachbuggy said:
So a little Friday night update for anyone coming in from the pub!

I took the turbo's to the machine shop today to get the housings done. I use a small machine shop in Woking that I've used in the past for head skimming. Couple of old boys with what looks like a workshop from the bowels of the Titanic but they are very good. I had already got a quote from another shop and they wanted £120 a turbo for the work as they said it would be tricky! Needless to say the shop I went today are going to charge £20 a housing or £40 a turbo! I think this is a really good result as it means the price is being kept well within check.

As with all turbo's there is a required clearance between the housing and blades. This has to allow for heat expansion and centrifugal forces that might cause the blades to touch the housing. Also the clearance has to be tight enough to maximise the airflow and enough to minimise the contact possibility.

Having read Bills post he kindly put up on page 1 from seatcupra.net and measuring the original turbo I had (0.48mm) the clearance of 0.50mm has been decided on and the housing are going to be machined to this.

I hope Bill doesn't mind me quoting him but this is a bit he wrote on the other forum.
I make a call to CR to confirm whats deemed the correct/acceptable clearance.. 0.020", give or take 0.05" - which is 0.508mm clearance, plus or minus 0.127mm (min 0.381mm max 0.635mm) These are Barn Door Tolerances... and exceeded anyhow.
rolleyes.gif







Now the thing to bear in mind this clearance factor doesn't allow for the surge proctection afforded by some hybrid makers, and as I'm not using a cutback blade I have decided to take another approach. This is going to be a little bit of a trial but as this turbo is a project believe it's a good place to try this, who knows it may be good option. I have borrowed a design used in jet engines which smoothes air flow through a jet engine in order to prevent surge. The only thing I can't do is use Vanes and stators, which smooth the air flow making it more efficient but I can use a design which will allow increase airflow around the turbine blades at high pressure but wont reduce the clearance around the housing and turbine blades.
Click to expand...
Is the 0.5mm clearance the total diameter increase in the housing or the distance from each blade to the wall ie diameter increased by 1mm oversized overall.
 
vtraudt said:
What pressure are we talking about?
Say 3" DP, not cats, cat back exhaust after the turbo,
Say high flow log manifold from cyl to turbo.
Click to expand...

Numbers for backpressure floating around out there are up to 60 psi on K04. Realistic? What is stock backpressure (K03, stock manifold, cat)?

Can high back pressure cause valve lift?

With respect to valves: is the stock valvetrain of the 1.8T good for 350-400 cHP (7200 or less rpm)?
 
vtraudt said:
Numbers for backpressure floating around out there are up to 60 psi on K04. Realistic?
Click to expand...

60 psi of backpressure in front of the turbine is about the most stock valve springs can tolerate.


vtraudt said:
Can high back pressure cause valve lift?
Click to expand...

Yes, and the symptoms of it are mis-firing and spiking boost pressures.


vtraudt said:
With respect to valves: is the stock valvetrain of the 1.8T good for 350-400 cHP (7200 or less rpm)?
Click to expand...

Yes. A small-frame turbo such as a hybrid K04 puts added loads on the cylinder head, but we've seen intake airflows exceeding 280g/s without back-pressure issues.
 
vtraudt said:
Numbers for backpressure floating around out there are up to 60 psi on K04. Realistic? What is stock backpressure (K03, stock manifold, cat)?

Can high back pressure cause valve lift?

With respect to valves: is the stock valvetrain of the 1.8T good for 350-400 cHP (7200 or less rpm)?
Click to expand...

yes. high backpressure can keep "weaker" exhaust valve springs to hold them open... eg high milers for example, agu heads with 100k miles + on them.. It is also an "unknown" in terms of you cannot predict which are weaker or not until they show some evidence of it.. (eg: accepting high levels of ign timing without any torque increase benefit or reduction in egts, and also higher than normal egts where the combustion process is leaking directly into the manifold, causing potentially excessive egts.)
 
slappy_dunbar said:
60 psi of backpressure in front of the turbine is about the most stock valve springs can tolerate.
Click to expand...



==> what is a high mileage stock K03 with cat running (for comparison). I have plug in the manifold: what gauge is used to measure the pressure?


slappy_dunbar said:
Yes, and the symptoms of it are mis-firing and spiking boost pressures.
Click to expand...


==> boost spikes: i try to wrap my head around why valve lift would cause spikes: extra exhaust gas from valve lift spool turbine, pumping more air, higher boost, wastegate (N75 or MBC) not quick enough to catch. Should be a high frequency spike (unlike a boost swing (with quite low frequency).
slappy_dunbar said:
Yes. A small-frame turbo such as a hybrid K04 puts added loads on the cylinder head, but we've seen intake airflows exceeding 280g/s without back-pressure issues.
Click to expand...

==> not entirely clear why a low restriction (K04 with manifold, DP, cat back) system is causing MORE back pressure than a highly restrictive (tiny manifold, tiny turbine, plugged up cat, low flow exhaust). Can someone explain?
 
badger5 said:
yes. high backpressure can keep "weaker" exhaust valve springs to hold them open... eg high milers for example, agu heads with 100k miles + on them.. It is also an "unknown" in terms of you cannot predict which are weaker or not until they show some evidence of it.. (eg: accepting high levels of ign timing without any torque increase benefit or reduction in egts, and also higher than normal egts where the combustion process is leaking directly into the manifold, causing potentially excessive egts.)
Click to expand...

badger: thanks for the insight. Very interesting. Is boost a factor? RPM (since even healthy new stock springs will float at some RPM (even without combustion, just mechanics from a 'swinger system')? Valve float occurring at higher RPM?

When measuring (who has logs?) back pressure, what are the driving variables? Should be correlation with g/s (more air in, more exhaust out), AFR (leaner, more exhaust volume), timing pull, EGT (hotter, more volume), turbo turbine (larger, more flow, less back pressure), clipping of turbine, partially open wastegate flapper.

Has someone run 320 g/sec (with water/meth, high flow intake/heads, high flow manifold, K04 frame turbo, DP not cat, cat back) on stock valves/springs?

For 280 g/sec: fresh stock springs? (not sure cost vs. upgraded springs)? Or just (cheap enough) get upgraded (how to select? who are the usual suspects and sources) springs when building 280 g/sec or above system (i.e. 2283 project).

Of the 2283 users out here: who floats? who does not? who is on stock springs? who is on upgraded springs?
 
vtraudt said:
When measuring (who has logs?) back pressure, what are the driving variables? Should be correlation with g/s (more air in, more exhaust out), AFR (leaner, more exhaust volume), timing pull, EGT (hotter, more volume), turbo turbine (larger, more flow, less back pressure), clipping of turbine, partially open wastegate flapper.
Click to expand...

All are contributing factors.

vtraudt said:
For 280 g/sec: fresh stock springs? (not sure cost vs. upgraded springs)? Or just (cheap enough) get upgraded (how to select? who are the usual suspects and sources) springs when building 280 g/sec or above system (i.e. 2283 project).

Of the 2283 users out here: who floats? who does not? who is on stock springs? who is on upgraded springs?
Click to expand...

I don't think I've heard of any 2283-based hybrid turbos which cause valve float in their setups. It's really not that common of a concern on K04-framed turbos. Especially in light of the fact that such turbos are flowing more in the 260s. I don't think I've seen one push into the 280s, actually. For reference, here's its efficiency map:

2283Map.jpg
 
vtraudt said:
badger: thanks for the insight. Very interesting. Is boost a factor? RPM (since even healthy new stock springs will float at some RPM (even without combustion, just mechanics from a 'swinger system')? Valve float occurring at higher RPM?

When measuring (who has logs?) back pressure, what are the driving variables? Should be correlation with g/s (more air in, more exhaust out), AFR (leaner, more exhaust volume), timing pull, EGT (hotter, more volume), turbo turbine (larger, more flow, less back pressure), clipping of turbine, partially open wastegate flapper.

Has someone run 320 g/sec (with water/meth, high flow intake/heads, high flow manifold, K04 frame turbo, DP not cat, cat back) on stock valves/springs?

For 280 g/sec: fresh stock springs? (not sure cost vs. upgraded springs)? Or just (cheap enough) get upgraded (how to select? who are the usual suspects and sources) springs when building 280 g/sec or above system (i.e. 2283 project).

Of the 2283 users out here: who floats? who does not? who is on stock springs? who is on upgraded springs?
Click to expand...

Not everyone knows or realises vag also did something different on their k04 valvetrain cars..
There would have been a reason for this.. and backpressures isthe key part here.
Shimmed their stock springs +1mm

You can buy cat gold or supertech springs as uprated parts if pushing the small k04 framed hybrids to their full potential. It can only be a good thing.

I would'nt call it float but being held open from closing.
 
badger5 said:
292g/s here doug on 2283 wheel'd bbt
Click to expand...
270 g/s here, on N75 at about 22 psi (stock MAP sensor limit) steady.
Try to get a bit more (280) but not sure if it can be done using N75 and stock MAP. Would like to keep the N75 control.
BTW: has anybody written maps yet for the available higher pressure MAP sensors for the 1.8T?
 
vtraudt said:
270 g/s here, on N75 at about 22 psi (stock MAP sensor limit) steady.
Try to get a bit more (280) but not sure if it can be done using N75 and stock MAP. Would like to keep the N75 control.
BTW: has anybody written maps yet for the available higher pressure MAP sensors for the 1.8T?
Click to expand...

The MAP sensor limit is hard coded in the logic of the map and would require decompiling then replacing in numerous places to allow the use of larger sensors...

For the most part its irrelevant these days as mapping knowledge has advanced enough that the 1.5bar MAP sensor limit is not an issue in context of using it to manage boost... open loop control will sort that out

<tuffty/>
 
I know this is an old thread, but I actually signed up to this forum to follow it. Any updates?

Thanks for having such great information available.


E
 
Plenty of people running bbt dans turbo inc myself.
He actually makes them to order now. Great little unit for ease of fit and iff the shelf supporting parts
 
daz-20vt said:
Plenty of people running bbt dans turbo inc myself.
He actually makes them to order now. Great little unit for ease of fit and iff the shelf supporting parts
Click to expand...
Glad to know. I definitely want to build a hybrid in the near future.

E
 
beachbuggy said:
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.
Click to expand...
I know it's a long shot but do you still have the engine?
 
Hello,

Sory for the digging but this topic has a lots of good info.

Strait to my point. I have a k03 in a 1.4 tsi engine currently i have upgraded to a 43/56 11 blade compressor wheel and a k04-064 shaft no clipping forge internal wastegate with red spring and 2mm internal porting. I have reach 330ps at 30psi with methanol injection.

I have talk with my turbo engineer and i want to upgraded one more time and my goal is 350ps. This is my plan and i want your opinion.

  1. 46.4/60 11 blade copressor wheel
  2. K04-049 shaft (a litle bit lighter that 064 because of open type back)
  3. 360 racing thrust (big ports front small ports back) can handle 30psi
  4. Single feed jurnal bearing
  5. Single feed main housing
  6. K04-023 compressor housing or k03s ported
  7. 38mm External wastegate in manifold to reduce back pressure and better pressure control
So what do you think? I will reach my goal? Should i change anything?

Thanks in advance
 
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