What injectors are you guys running for stage 3?

[vailshred]

Hey guys, Im about to purchase this kit

https://www.ecstuning.com/b-cts-parts/cts-turbo-k04-x-hybrid-turbocharger-upgrade-for-b7-b8-audi-a4-a5-allroad-20t-q5-20t/cts-tr-1070x~cts/?gad_source=1

Im curious to know what injectors and other supporting mods you guys are using and that you are happy with.

I think I have seen S3 and RS4 injectors work?

My motor is 2006 a4 BPG

Tia

[james12lucy]

Everyone will tell you to use S3 injectors because they have a better spray pattern, better start up in cold, etc. RS4 injectors are superior in every way if they’re rotated 90° as the Greeks have been doing for the past decade. More flow means more power, and when rotated, the spray pattern is more similar to the 2L injectors and fixes the cold start/ black smoke issues.


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[vailshred]

Everyone will tell you to use S3 injectors because they have a better spray pattern, better start up in cold, etc. RS4 injectors are superior in every way if they’re rotated 90° as the Greeks have been doing for the past decade. More flow means more power, and when rotated, the spray pattern is more similar to the 2L injectors and fixes the cold start/ black smoke issues.


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Great info and thanks

These are both plug and play?

[james12lucy]

Great info and thanks

These are both plug and play?

They are, but you’ll need a tune; obviously.


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[Jayz691]

Everyone will tell you to use S3 injectors because they have a better spray pattern, better start up in cold, etc. RS4 injectors are superior in every way if they’re rotated 90° as the Greeks have been doing for the past decade. More flow means more power, and when rotated, the spray pattern is more similar to the 2L injectors and fixes the cold start/ black smoke issues.


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Ya know, IV seen flow test that showed RS4 don't really flow much more than stock. Always seen info saying they flow more than S3, but I believe it was R-tech(not 100%) that did actual flow test comparison with stock(k03), S3, rs4, and maybe a few others. And was surprised by the results..
Wish I could find the video/write up again.
If ya think about it, rs4 injectors are designed to supply fuel for .5l per injector on an NA car, so would kinda make sense.?
But Id always recommended s3/golf R, since they are designed for these engines..
If ya need more, theres lots of better options imo.


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[jbain2]

I ran both RS4 and S3 injectors on my GT28 setup. Which flows more than the K04 framed turbos. The RS4 injectors definitely ran “rougher”. The tuner I used directed me to the S3 injectors when I started with my last revisions. I never had fueling issues.


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[vce1232000]

S3

[b7_Andy]

@vailshred

According to the software the 8P S3 injectors flow about 10% more than the B7 RS4 injectors. I can go through my spreadsheets and find the fuel limitations I calculated for this engine if anyone is interested. The last K04 B7 A4 I tuned did perfectly fine with S3 injectors and a stock HPFP (5,500 ft above sea level). I think it was at around 22psi. S3 injectors were really quick to tune too, I can get them almost 100% on the first revision. Message me or text me if you have any questions about the tuning. I’ve tuned a few of these.

[Jayz691]

@vailshred

According to the software the 8P S3 injectors flow about 10% more than the B7 RS4 injectors. I can go through my spreadsheets and find the fuel limitations I calculated for this engine if anyone is interested. The last K04 B7 A4 I tuned did perfectly fine with S3 injectors and a stock HPFP (5,500 ft above sea level). I think it was at around 22psi. S3 injectors were really quick to tune too, I can get them almost 100% on the first revision. Message me or text me if you have any questions about the tuning. I’ve tuned a few of these.

And s3 are supposed to be like 17% more than stock, so that would make RS4 not much more than stock.
But how do you get enough fuel with a stock hpfp? Curious what your target lambda is at dif load/boost/rpm.

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[b7_Andy]

And s3 are supposed to be like 17% more than stock, so that would make RS4 not much more than stock.
But how do you get enough fuel with a stock hpfp? Curious what your target lambda is at dif load/boost/rpm.

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K04s don’t make as much power at the high altitude so they don’t require as much fuel. At sea level you’ll most likely need to upgrade the HPFP… let me check

[b7_Andy]

Here's the charts from my spreadsheets that I use to calculate the limit from each part of the fuel system (Injectors, HPFP and LPFP). This is with 8P S3 injectors using stock S3 injector calibration, a stock HPFP (running stock rail pressure - 110 bar), and a stock LPFP using a B8 S4 LPFP controller (does the exact same thing as the B7 RS4 LPFP controller but you can find them for $50 used... I use B8 S4 LPFP controllers on all my B7 2.0T and 3.2 FSI builds).

This is the stock S3 injection window:


The rail pressure and lambda target I'm using:


Here is the power limit from the S3 injectors using stock S3 calibration (the injection window can be increased if more HP is needed... not necessary for a K04 though):


This is the power limit from the stock HPFP. The stock HPFP volume is 251 mm^3 and efficiency is 80%:


This is the limit of the stock LPFP with B8 LPFP controller:


And this is the combined limit of all the fuel system components:



Here's a comparison to the last K04 B7 A4 I did. The results were taken 6,000 ft above sea level so these numbers are going to look quite a bit lower than most. It peaked at about 21.5 psi of gauge pressure:

[b7_Andy]

If you upgrade the HPFP with JHM, Autotech, 034 or any of the common piston upgrade kits it increases the volume by 50%. So the new HPFP volume is 376.5 mm^3 and at 80% efficiency this is what the HPFP limit looks like:


This is still with my fairly rich lambda target. Depending on your downpipe setup and if you actually have decent 91 octane, a leaner lambda target will give you more room here.

[b7_Andy]

Now if you do S3 injectors with the injection window maxed out and rail pressure maxed out at 135 bar, an upgraded HPFP, a TTRS LPFP with check valve drilled (same LPFP I'm running in my 3.2 FSI), and a more aggressive lambda target... this is the absolute max you'll see out of this engine without adding port injection or reinventing the fuel system:

[xRenesis]

Just throwing in some more, back when I was still 2.0t.

Ran S3 injectors, drilled rail, upgrade relief, upgraded HPFP, RS4 LPFP controller, 340lph pump on E85 stg 2. My biggest hurdle, and seeing as you're 2006, is the high pressure sensor. I tried to tell Motoza I was hitting limp mode because the sensor was maxing (early 2.0t is lower), but they wanted to try and fix this and that instead. Definitely make sure you work with whoever on the correct high pressure sensor.

[AudiB720TS]

I would do RS3 injectors. Requires a modified harness.

[Jayz691]

K04s don’t make as much power at the high altitude so they don’t require as much fuel. At sea level you’ll most likely need to upgrade the HPFP… let me check

Ahh, I missed the 5500' above sea level part. That makes sense now..did you mean the r8/q7 lpfp controller? Thats what i used, but never heard of using a b8 S4 controller..

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[b7_Andy]

Just throwing in some more, back when I was still 2.0t.

Ran S3 injectors, drilled rail, upgrade relief, upgraded HPFP, RS4 LPFP controller, 340lph pump on E85 stg 2. My biggest hurdle, and seeing as you're 2006, is the high pressure sensor. I tried to tell Motoza I was hitting limp mode because the sensor was maxing (early 2.0t is lower), but they wanted to try and fix this and that instead. Definitely make sure you work with whoever on the correct high pressure sensor.

Damn I made a reply this morning with a bunch of data and the server crashed and never posted it… need to start saving what I type before I post. I’ll write it again this evening, but you are 100% correct here.

[Jayz691]

Just throwing in some more, back when I was still 2.0t.

Ran S3 injectors, drilled rail, upgrade relief, upgraded HPFP, RS4 LPFP controller, 340lph pump on E85 stg 2. My biggest hurdle, and seeing as you're 2006, is the high pressure sensor. I tried to tell Motoza I was hitting limp mode because the sensor was maxing (early 2.0t is lower), but they wanted to try and fix this and that instead. Definitely make sure you work with whoever on the correct high pressure sensor.

So they wanted to try and keep the stock rail sensor, instead of upgrading to the 200bar?
Im tuned by them on my k04, and did the 200bar rail sensor and 3 bar map, both to just have "headroom".
Also went with APR 155bar prv for same reason, over the rs4. Max rail pressure runs 135.9 iirc.

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[b7_Andy]

@Jayz691 - The B8 S4 fuel pump controller works great. Any of the newer B8 or C7 pump controllers that are 5 pin will work I believe, but I always use the B8 S4 3.0T controller (8K0906093E). I've installed and tuned it on both the Bosch 2.0T and Continental Simos 3.2 FSI. It's allowing full voltage (12-14V) to the LPFP as opposed to the B7 A4 controller which only runs the pump with 7V I believe. Not sure when you'll max out the controller due to electrical current... I don't know if you can make a B7 that fast, but I haven't found a need to source a B7 RS4 controller for any of the builds I've done. The B8 S4 controller serves the same purpose.

@AudiB720TS - The 8V RS3 GDI injectors?

[xRenesis]

Ya, I can't remember everything that I was being told (like 4.5 yrs ago), but the stock sensor was the limit in my logs. I can't remember if I ran out of revisions when I told them "hey, everytime that sensor sees max, I get cuts" but it was whatever and I kind of just lived with it (boring).

edit
Their comment "We didn't see a spot in the log, were the rail pressure was well beyond the target rail pressure but we did notice some spots where the injector on time was exceeded and the car ran out of fuel, we made some fueling changes in this revision"
Looking at an old log, early 2.0ts HPFP sensor should be 140bar.

[b7_Andy]

Ya, I can't remember everything that I was being told (like 4.5 yrs ago), but the stock sensor was the limit in my logs. I can't remember if I ran out of revisions when I told them "hey, everytime that sensor sees max, I get cuts" but it was whatever and I kind of just lived with it (boring).

The stock sensor range is 140 bar and it will cut fuel / go into limp mode when the sensor maxes out.

[Jayz691]

@Jayz691 - The B8 S4 fuel pump controller works great. Any of the newer B8 or C7 pump controllers that are 5 pin will work I believe, but I always use the B8 S4 3.0T controller (8K0906093E). I've installed and tuned it on both the Bosch 2.0T and Continental Simos 3.2 FSI. It's allowing full voltage (12-14V) to the LPFP as opposed to the B7 A4 controller which only runs the pump with 7V I believe. Not sure when you'll max out the controller due to electrical current... I don't know if you can make a B7 that fast, but I haven't found a need to source a B7 RS4 controller for any of the builds I've done. The B8 S4 controller serves the same purpose.

@AudiB720TS - The 8V RS3 GDI injectors?

Same idea as the r8/q7 is guess, but didn't know there were others. The b7 RS4 controller was popular years ago, before people tested others, and they were $300-$400..
The r8 controller is $120/new for VNE(OE).

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[AudiB720TS]

@AudiB720TS - The 8V RS3 GDI injectors?

My understanding is 8P - 8V will work.

The latter will support more power. In both cases the harness needs modification (many tuning shops will sell you connectors with wire). In the earlier case supply seems very challenging now. So the 8V will support more power and due to supply Â…sell for less.


Full disclosure: I am still on S3 injectors, 200 bar sensor, 155 bar PRV, R8 controller. I have the RS3 harness but havenÂ’t brought myself to complete that project.

[Jayz691]

@AudiB720TS - The 8V RS3 GDI injectors?[/QUOTE]

Pretty sure its 8v when referring to rs3 injectors. 8p may work, but not really familiar with the 8p Rs3..
But does reauire head mod and harness.


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[b7_Andy]

@Jayz691 - Good to know you've had success with those controllers. It seems most, if not all of the newer 5 pin controllers will work, which is a huge plus for this platform.

@AudiB720TS - The injector scalar for Audi GDI injectors using Bosch ECUs is in ms/%. So the numbers below represent the amount of ms the injector needs to be open to inject 1% of relative fuel mass at 10 bar of rail pressure. The lower the number means the less time the injector needs to be open to deliver the same amount of fuel mass, meaning the injector has a higher flow volume.

*EDIT - I updated these with new RS3 injector info. The RS3 DNWA engine does have injectors that flow more than the 8P S3*

B7 A4 2.0T: 0.034719
B7 RS4: 0.033219
8V RS3 DAZA: 0.031969
8P S3: 0.030000
8V RS3 DNWA: 0.025646

So in relation to the B7 A4 2.0T injector:

B7 RS4: 4.3% more flow
8V RS3 DAZA: 7.9% more flow
8P S3: 13.6% more flow
8V RS3 DNWA: 26.1% more flow

The 8V RS3 injector also has a different style body so I don't think it would fit on this platform, though I've never tried. My understanding is none of the injectors from the newer style engines will work (2nd gen 2.0T and pretty much anything B8, C7, 8V, and newer). The 8V RS3 also balances fuel delivery between the GDI injectors and the MPI port injectors, which is why the GDI injectors don't need an insanely high flow volume. As far as I know, the 8P S3 injector is the highest flowing factory Audi fuel injector. I'd be curious to see what injectors the 8P RS3 uses, but that engine makes 90 Nm per cylinder from the factory and the 8P S3 makes 87.5 Nm per cylinder so I'd be surprised if the RS3 uses bigger injectors.

[AudiB720TS]

To be more specific, the RS3 injector my tuner suggests is for the DNWA engine code. Plastic tabs are cut so no "head mod" is necessary (you could still opt for it, sure).
Price I've seen is around 600-700 USD for a set of four, with gaskets. From different sources this injector should support higher horsepower.


Here's a pic (login to view):


RS3.jpg

[b7_Andy]

@Audi20TS - You are totally right! I was looking at a DAZA 2.5T engine that uses injectors with an injector scalar of 0.031969. The DNWA 2.5T injectors you're talking about have a scalar of 0.025646. That's 26.1% more flow than B7 A4 injectors and it's even 14.5% more flow than 8P S3 injectors. That's a really big difference, thanks for mentioning these!

[Jayz691]

To be more specific, the RS3 injector my tuner suggests is for the DNWA engine code. Plastic tabs are cut so no "head mod" is necessary (you could still opt for it, sure).
Price I've seen is around 600-700 USD for a set of four, with gaskets. From different sources this injector should support higher horsepower.


Here's a pic (login to view):


RS3.jpg

The rs3 get the head mod(hile drilled) so you can rotate them, cuz of spray pattern.
Here's a pic from a video comparing Porsche/RS3/S3.Screenshot_20240125-035116.jpg
And finished comparison.
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Attachment 323031

[AudiB720TS]

The rs3 get the head mod(hile drilled) so you can rotate them, cuz of spray pattern.
Here's a pic from a video comparing Porsche/RS3/S3.Screenshot_20240125-035116.jpg
And finished comparison.
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Attachment 323031

Yes, but remove the plastic tab and you can rotate them all you want without drilling. ItÂ’s a bit ghetto, but itÂ’s said to work with good results.

[Jayz691]

Yes, but remove the plastic tab and you can rotate them all you want without drilling. ItÂ’s a bit ghetto, but itÂ’s said to work with good results.

Ahh, I gotcha.

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