AAN into Ur quattro, 400-450 Bhp Target

[Ross]

The dyno graph looks pretty similar to my GT3071R coupe, in that torque is quite consistent but the peak isn't that high. Hence the power is quite progressive... my K26/7 is making similar peak power but a huge wedge of midrange torque puts the power lower down, and it then starts to let off >6500rpm. Where-as the Garrett just kept pulling hard to 7,000+.

Peak torque in 3rd at 3500rpm seems right to me, that's exactly what I was seeing, although due to surge it often wouldn't make peak until about 3800rpm. If you want power sooner on the 2.2 you need something newer... that GTX2876 does look rather promising to give you that extra 500rpm of spool and similar power.

I changed turbo because I was frustrated at the on/off switch at about 3,800rpm; I wanted better pick-up lower down. Getting the head port + polished makes a big difference, it is more responsive and alot better off-boost. The turbo still came in too agressively but the improvement driving round town is substantial. On-boost is more efficient, so 0.5bar at say 3,500rpm was producing more torque than before, hence on the road it's quicker even if spool is no earlier. As a one-off cost it's not cheap but IMO worth every penny.

I ended up moving to a newer K26/7 hybrid (wanted a direct replacement for stock so that was my only option for 400hp+), I still have the same 3800rpm in 3rd gear for max torque, however it's making low boost alot earlier and combined with headwork it pulls well from alot lower down than before. I guess the point I'm making is peak boost isn't everything - it's how it makes that boost and how efficient it is with boost too.

[URquattroGus]

Darren, I'm Essex based, so not too far. Thanks for the offer, might have to take you up on that depending on how things go.

Ross, you've described pretty much exactly my problem, much better than I ever did too!

My only concern is that fitting the GTX2867R may give surge problems low down the rev range and not be easy to map.

I'm tempted to change the turbo as its quite bolt on, and I can sell the barely used GT3071R.

I reckon I can do this and then get head porting done if I'm still not happy or when funds allow.

The K26/K27 sounds good but that would mean changeing ex manifold and also oil and water lines so has some complications.

Funny really as with the 3071 I thought I'd got the spec just right looking at others experiences. Its not undrivable by any means, maybe just a bit too on off as ross says.

I could quite happily live with it as it is but I can't help but think I can do better.

[URquattroGus]

I've ordered a GTX2867R with 0.63 AR Turbine Housing. Comes with anti-surge compressor housing as standard.

A very expensive christmas presnt to myself! It will be interesting to see how this compares to current turbo. I don't plan to change anything else at the moment so this should be a straight swap give or take a few mm here and there.

Excited but worried at the same time! Feel better now I have some kind of hare brained plan.

Once it arrives and I fit it the GT3071R with 0.63 housing will be for sale. It's only been run for about 2,500 miles from new.

[DJones]

Be interesting to see how you get on...

So what do the numbers mean:

GT 30 71 R

GTX 28 67 R

If it was a GT5576r it would make sense i.e. 55 being inducer 76 being exducer..

I understand the .63 and .82 hot sides etc but not got my head around the cold side?

Thanks in advance..

Darren.

[macspring]

Also dying to see how you get on with the new turbo.




Just to record it on this thread while it is fresh in your mind. What rpm does the GT3071 start to make say 0.5 bar of boost ?

And what is the maximium boost pressure in bar and at what revs ?

Sorry for the questions, but had thought a GT3071 would have been suitable for me ?

My impression was that the Garretts were early enough boosting and just went on boosting, and that a a KKK 26/27, boosted a bit later, but with such a step that it felt powerful, but didn't boost quite as high as the Garret, which is more linear ?

Does this concur with what your found with your GT3071 ?

Thanks.

[macspring]

Duplicate post.

[URquattroGus]

Be interesting to see how you get on...

So what do the numbers mean:

GT 30 71 R

GTX 28 67 R

If it was a GT5576r it would make sense i.e. 55 being inducer 76 being exducer..

I understand the .63 and .82 hot sides etc but not got my head around the cold side?

Thanks in advance..

Darren.

GT or GTX is the series

25, 28, 30 is the farme size or series (probably share the same centre housing rotating asembly?)

71 and 67 are the largest daimeter part of the compressor wheel, the exducer side.

The GTX2867R has ;

Compressor side a 49.7 mm Inducer and 67.4mm Exducer with a "trim" of 55. 0.6 A/R Housing.

Turbine Hotside 53.8 Exducer and 76 Trim.

GT3071R has:

Compressor side a 53.1 mm Inducer and 71mm Exducer with a "trim" of 56. 0.5 A/R Hosuing

Turbine Hotside 60mm Exducer and 84 Trim.

I believe trim is the ratio between the inducer and Exducer. Roughly speaking the higher the trim the mmore airflow it can generate, but also usually larger trims are heavier and have more rotating mass so can mean slower spool, although this is more critical for the exhaust side.

So with it looks to have flow comparable with the GT3071R and with a wider map in some places, but has samller rotating parts.

Hopefully this means similar power and better spool.

Garrett desbribe the GT3071R as a ma of 460bhp turbo and the new GTX2867R as 480bhp.

I think the GT claims are conservative and maybe the GTX is a bit less conservative though.

To try and understand things better and for my general interest I bought these two books;

http://www.amazon.co.uk/Turbocharging-Performance-Handbook-Motorbooks-Workshop/dp/0760328056/ref=sr_1_2?s=books&ie=UTF8&qid=1325243349&sr=1-2

http://www.amazon.co.uk/Turbo-High-Performance-Turbocharger-Performance-How-/dp/1932494294/ref=sr_1_1?s=books&ie=UTF8&qid=1325243349&sr=1-1

[DJones]

GT or GTX is the series

25, 28, 30 is the farme size or series (probably share the same centre housing rotating asembly?)

71 and 67 are the largest daimeter part of the compressor wheel, the exducer side.

The GTX2867R has

w
aa
saa
ds

Thanks, what does the last bit mean "w aa saa ds"?

[URquattroGus]

oops, sweet Fanny Adams, nothing! was trying to see if I could cut and paste a basic table and whether the format would work/how it would look.

In between this the phone range several times. Full post is above.

[URquattroGus]

Also dying to see how you get on with the new turbo.




Just to record it on this thread while it is fresh in your mind. What rpm does the GT3071 start to make say 0.5 bar of boost ?

And what is the maximium boost pressure in bar and at what revs ?

Sorry for the questions, but had thought a GT3071 would have been suitable for me ?

My impression was that the Garretts were early enough boosting and just went on boosting, and that a a KKK 26/27, boosted a bit later, but with such a step that it felt powerful, but didn't boost quite as high as the Garret, which is more linear ?

Does this concur with what your found with your GT3071 ?

Thanks.

Ross may be able to answer this better.

Sorry, I cant really tell you when it makes 0.5 bar, difficult to drive and look at my current boost gauage, which is my only basic way of telling at the moment.

However, I think my car was mapped with 1.7 Bar and peak power is a 5600 currently. There is a dyno plot earlier on in the thread.

The GT3071R is still very suitable, it's a great turbo that lots of people have been happy with.

I just want to try and have my cake and eat it. This could go well or could be a waste of time.

[URquattroGus]

Angus

Not sure where you live but your more than welcome to drive mine to see what you think. I know how frustrating it can be...

As for the inter-cooler efficiency you can log the inlet temperature via VagCom to see what it peeks at and the difference from cruising to full boost.

Darren.

How can I connect Vag com? I looked into this once and it involved bodgeing a few wires into certain pins??

My only experience of VAG com when a friend connected to his S3 via ODB.

[DJones]

How can I connect Vag com? I looked into this once and it involved bodgeing a few wires into certain pins??

My only experience of VAG com when a friend connected to his S3 via ODB.

Crikey its been a long time since i wired mine.... from memory i went down to a local scrap yard and got the three diagnostic sockets. There are three, blue, black & brown but only the black and brown are used.

I would need to dig out my wiring diagrams but i think the AAN uses an (L) wire from pin 13 and a (K) wire from pin 55 (both wires will already be in the loom). From memory both of these go to the brown plug and the black plug is an earth an live.

You then need the 2+2 connector to convert it to an OBD connector and plug a cheap VagCom lead into it, you can down load the software from Rosstech.

Mine now has a fixed OBD connector in the glove box just like a modern Audi no bodging....

Job done...

Darren.

[prj]

IMO you will gain very little, because you will have lots of surge problems.
This 0.63 A/R on this will just surge all the time. It will build too much boost early on, and all that air will go nowhere, because the engine can't process it.

3071/0.63 on a carefully reworked head and an exhaust manifold optimized for velocity has more torque everywhere than a RS2 turbo on a stock engine.

Or I could be wrong, and it could be good, but from my experience on a 2871/0.63 it's going to be a nightmare to map and all the possible gains will be lost due limiting boost because of surge...

[djh]

When do you reckon it will be mapped by?

[URquattroGus]

You many be right. It does have a anti surge housing for what it's worth.

If the engine can't ingest enough then I may have to consider head porting.

A 0.83 hotside could also be fitted but this may defeat the object slightly.

As for mapping, well it arrives on 3rd of Jan hopefully, so a couple of weeks to fit it inbetween work maybe, depending on whether anything has to be altered.

Then realistically mapping could take place late Jan maybe.