S2 Avant MTM -> RS2 -> GT3071R -> CT355

[gedu]

Also, your turbo can produce limited amount of pressurised air. With the power you already have you most likely are a bit outside compressor map (how much, dunno, don't know how much pressure drop your OEM inlet makes). A good porting and some fine touches to cams could make your VE approach 98% (yes, seen that). But then there is a down side if you don't change your turbo, turbo will go out of compressor map earlier in revband, as you can cram all that air more efficiently into combustion chamber. ofc, with better VE you will make more power with lower boost

in short: you are on limits of your current turbo, it can only produce so much air efficiently.

[Bram]

Hi Gedu,

Thanks for the info! So if I understand correctly it also does not make any sense for me to do a porting job with my current turbo. It will not improve a lot to it.

Another option for me would be to upgrade to a GT30 and do a porting of the head and go the short intake route. However then I will loose the quick spool-up, right? This is what I like about the GT3071R, quick spool-up, massive torque and more than anough 450HP.

What are your thoughts?

Cheers

[A80Avant]

Bram,
when i went to Greece 2 weeks ago i talked to my mechanics about the same things.Upgrading to GT3076R with .82AR,get the EVO EM and stay with the original inlet manifold.Aronmatic had a similar setup at some stage and made 471hp crank with 2.2bar overboost and 2bar to the red line.He was using a hacke racing inlet manifold,not very good quality though and 2.2bar came at 4200rpm.

I too am thinking of a ported cyl.head which is never bad for the engine.I will do that at some point,i am just thinking of turbos in that matter because although the GT30R is an easy change,there are much better turbos outthere that might give much more power,same cost and slight modifications of the rest of the parts(downpipe etc).
On the other hand,i had an RS2 measured with the GT3071R and similar parts as mine and yours and it made some good numbers,which kind of makes me think of whether there is a need to upgrade at all...And if upgrading slowly,then an aftermarket ECU is needed as you have to pay the tuner everytime you make a change...

So im wondering...if the power now is so good,i would either make the parts slowly and put them all on to have a new remap with motronic and stop there,OR get the VEMS,start learning it,and change slowly.

On your thoughts though, if you get the GT3076R with .63AR you may have similar spool and maybe 50-60hp more,while if you get it with .82AR you may get 100hp more and by using the reverse inlet manifold you may end up with more or less similar spool.

If all that is true,why not get a CT turbo that repo says and get good spool more hp ??

[Bram]

Hi Vasilis,

I think that for 2.2 bar overboost I will have to lower the compression ratio to stay on the safe side. I do not want to lower the compression though, so the 2 bar that I get now will be sufficient for me.
I also looked at the diagrams from Aron with his GT3076 0.63, but that boost comes very late (say 900 RPM later) then mine and he reaches the same 369 WHP as I have. So I guess my GT3071R is already running on max performance probably....... and I like it

Before I might be interested in a turbo from CT I would like to see some performance diagrams first. I am not convinced yet about these turbo's just because somebody tells me the CT turbo outperfoms the Garrets. And switching to CT also means I have to switch to a T3 Wagner, wich will also cost me $$$

I am more and more thinking of first upgrading my clutch to get the max of boost from the GT3071R
And also buying the new Wagner RS2 IC and leave the inlet track OEM for now, so I can run cool in summer.

Let's see in the after Feb. period how things develop once I get back to NL, because here in India I can not work on my car at all! O well, at least I save some money now

[Billman]

Maybe sometime i get an Holset diagram (problem is my engine internals-they are stock and i am holding the boost back).

[Bram]

That would be interesting as well, but I was more referring to CT turbo S2 Rolling Road result diagrams

Cheers

[A80Avant]

bram,you are already getting the most out of the turbo.Is your clutch slipping? Mine is uprated and i too am pretty much on the limit of the 3071r and have no problems.

another turbo that might be better than the gt3076 is the S256 borg warner.Im thinking about that myself...

[Billman]

everyone is welcome in the diesel turbo club :-)))

[A80Avant]

I am not sure yet.I will measure my car,modify the downpipe to be VEMS ready and less restrictive and decide later on what to do.Since im not opting for more than 500-550hp crank i may choose to make small safe modifications,or even think of still keeping the motronic and just adding a wide band

[Bram]

bram,you are already getting the most out of the turbo.Is your clutch slipping? Mine is uprated and i too am pretty much on the limit of the 3071r and have no problems.

another turbo that might be better than the gt3076 is the S256 borg warner.Im thinking about that myself...

No I am not getting the most out of the turbo as the spool-up is restricted to 1.8 bar in the lower revvs to save the OEM clutch. In 1st gear under WOT I burn the clutch easily now.

So I will upgrade the clutch en take a Alu flywheel, so my tuner can program the ECU for 2.0 bar all the way up from 3200 to 5500 RPM and then let her drop to 1.7 bar at redline.
That way I think I will hit the 600 Nm

[A80Avant]

after i change the downpipe config a little i may be able to do that with stiffening up my wastegate spring.So far im reaching 1.9 to 2bar around 3600-3800rpm depending on gear and it holds to 1.7bar with good EGTs.If they drop i may get away with a bit more

[Bram]

That sounds good Papvas. Someday I will aim for that boost level as well in the 3xxx RPM range

When I hear your 1.7 bar at redline I think you are having about the same performance regarding BHP as I have, since Erdal knows how to tune a i5 very well.

[A80Avant]

funny thing is that according to the map the car should have 1.7bar up to 6500rpm and then drop to 1.65 to the red line.But since i came here in the UK the car keeps the 1.7bar nicely,even without me touching the wastegate spring valve.SO now that i have tampered with it a bit,i am keeping an eye on the EGTs to make sure everything is still ok.

[Bram]

Turbo pressure meters are not always that accurate. And I guess the ECU itself will adjust everything according to what remains inside the limits set by your tuner

[Bram]

Currently I am planning my next upgrades

I still have doubts about the IC upgrade I am facing to have done before summer. It will either be the Wagner reverse inlet setup or the bigger Wagner RS2 IC.
When I compare the IC sizes between the 3 options I get the following list:

1) Audi RS2 OEM: 500x185x63mm <----- I currently have this one
2) Wagner RS2 IC: 500x205x85mm
3) Wagner Reverse IC: 500x220x90mm

What would be enough for my GT3071R setup?

The third option would cost me a lot of extra money, left alone the extra work, but would allow me to use the 034MS HO coil kit to be fitted, which I still have laying around......