Rules of thumb when tuning an ABY?!

[Lindahl]

I got a couple of noob questions considering tuning of the ABY engine:

As I understand the upper limit of the factory pistons are around 550 bhp, can anybody confirm/disconfirm this statement.
Who produced the factory pistons, and who is the preferred supplier of aftermarket pistons, JE, Wössner or another?
When do you typically change the rods - tq, boost pressure, and what supplier is recommended.
When do you need to add another fuel pump, or do you simply switch the factory pump?
How sensitive is the ABY to fitting semi large injectors, 630-820 ml, and does anybody know BSFC of the ABY engine in different tunes?
When do you need to switch cams and/or revise the head? Is the ADU head different from the ABY head?
When is equal runner exhaust manifold design neccesary?
For what level of bhp is a 3" downpipe adequate?
When is boost creep a problem with the factory 30 mm wastegate?
When is improved intake manifold incl. bigger bore throttle body (VR6 OBD-II or larger) neccesary.
How "good" is the ABY at utilising potential turbocharger flow, I know that volumetric efficency changes with less restrictive set-ups, but do you typically need to dimension the chargers a little bigger than on paper, to reach a certain level of bhp?
How vulnerable is the 20VT to surge?
When is the factory ecu no longer suitable, and is VEMS the way to go then?
How much tq can the later 6 speed transmission handle?
When do you upgrade drive shafts?
Is the S2 factory differential setup, with open front/rear differential adequate in the 600 bhp range? I have searched the net for possible upgrades, but it seems that there are only a limited set of options including fitting the V8 rear differential. But do the factory set-up handle okay in combination with softer compound tires like the Toyo R888, and can the factory differential/drive shafts handle hard launch with tires like the R888?
Finally does anybody have head to head experience with a turbo like the Precision 5857, is the boost threeshold increased significantly with the Precision billet on a 2226 cc ABY?

A lot of questions, I know, but I will welcome any help in regards to the questions above.

Thanks!

[Jamo]

As I understand the upper limit of the factory pistons are around 550 bhp, can anybody confirm/disconfirm this statement.

They can take more but at stock compression ratio you couldn't get to that bhp limit you would have to skim them or put a CR reducing headgasket into the engine

Who produced the factory pistons, and who is the preferred supplier of aftermarket pistons, JE, Wössner or another?

Mahl, karl schmidt some debate over it, aftermarket whoever you want CP, JE are commonly used

When do you typically change the rods - tq, boost pressure, and what supplier is recommended.

Torque, anyone again your own choice and budget. cheap ones like Scat or higher end like Pauter, Carrillo

When do you need to add another fuel pump, or do you simply switch the factory pump?

Change it for a bosch 044 5 bar or 10 bar pump

How sensitive is the ABY to fitting semi large injectors, 630-820 ml, and does anybody know BSFC of the ABY engine in different tunes?

Increasing to a larger Injectors size is handled only by a remap, ecu can compensate with closed loop but only within it's adaptation limit which is much when you are as above doubling or going bigger in injector size

When do you need to switch cams and/or revise the head? Is the ADU head different from the ABY head?

No, No however you can get gains from porting and different cam combo's speak to RWD19T. Porting would be the best option

When is equal runner exhaust manifold design neccesary?

No, good for peak hp but a Wagner cast manifold is not equal length and tested over 500 bhp

For what level of bhp is a 3" downpipe adequate?

No cat probably 600, with 100 cell cat around 550 depends more on how much back pressure your exhaust boxes generate

When is boost creep a problem with the factory 30 mm wastegate?

ABY wastegate is 34mm, old audis use the 30mm wastegate. To stop creep use a stiffer wastegate spring 1.9 bar which gives 0.9 bar mechanical boost

When is improved intake manifold incl. bigger bore throttle body (VR6 OBD-II or larger) neccesary.

It's not, you can use stock for over 500 bhp, buy a reverse mounted manifold for less lag and lower inlet temp is the improvement method

How "good" is the ABY at utilising potential turbocharger flow, I know that volumetric efficency changes with less restrictive set-ups, but do you typically need to dimension the chargers a little bigger than on paper, to reach a certain level of bhp?

at the power levels your talking over complicating the tuning, a good tuner such as Pro-Mo can spec a turbo direct to the I5 or plenty of off the shelves turbos work perfectly with the car, better looking a PR of compressor maps

How vulnerable is the 20VT to surge?

Any turbo car is depends on the turbo, will surge with too small or too big a turbo

When is the factory ecu no longer suitable, and is VEMS the way to go then?

Never, can be tuned by MRC to 600 or above. VEMS is if you want more flexibility like Wideband lambda feedback and removing the pesky MAF

How much tq can the later 6 speed transmission handle?
A lot more than you'll generate with a 2.2 and 500 bhp, the dual mass clutch is point of failure before the gearbox

When do you upgrade drive shafts?

Whenever you want

Is the S2 factory differential setup, with open front/rear differential adequate in the 600 bhp range? I have searched the net for possible upgrades, but it seems that there are only a limited set of options including fitting the V8 rear differential. But do the factory set-up handle okay in combination with softer compound tires like the Toyo R888, and can the factory differential/drive shafts handle hard launch with tires like the R888?

V8 diff is weaker than the open difs, uprated diffs come from Quaiffe

Finally does anybody have head to head experience with a turbo like the Precision 5857, is the boost threeshold increased significantly with the Precision billet on a 2226 cc ABY?

boost isn't everything, a bigger turbo can shift more air at less boost when in peak zone. A billet wheel will change turbo responsiveness independent of the engine type so it's not really a valid question IMO

A lot of questions, I know, but I will welcome any help in regards to the questions above.

[Lindahl]

Hi, great reply

I do have a couple of questions for your answer:

Do you have a link to the reverse mounted manifold?

I think I didn´t express myself very clear about the Presicion 5857. What I meant was if anybody had made a back to back comparison of this turbo and the Garrett GT3582, which are comparable in terms of flow. Precision states that this turbo will be less laggy than the GT3582, and providing equal power. But what about the ability of making boost earlier on. At present time I got a GT3582 1.06 mountet on a VR6 12v (which by the way doesn´t seem to be a very popular engine in here ), and this combination makes ~1.8 bar of boost around 5000 rpm, so I guess this turbo would make similar boost around or above this rpm range on the aby. If the addition of the Precision design and billet wheel would improve this I would prefer the Precision over the Garrett, if you get my point.

In regards to the question about the aby being sensitive to injector selection, I know that you wouldn´t be able to run >630 cc injectors on the factory map, but some engines are more sensitive to large injectors than others, resulting in lousy idle and part throttle. But is this a problem with the aby?

Even though you upgrade the wastegate spring, won´t you see boost creep when you are in the 5-600 bhp range?
Can the 34 mm wastegate flow sufficient to keep boost down?

I´m not sure if you answered my question about when you upgrade the factory connecting rods, but when is it advisable to do so?

Thanks for the very helpful information sharing

[Rusty]

The whole purpose of this forum is the 2.2 I5 20v Turbo so VR6s don't play much of a part in our discussions. They're a funny engine, sound awesome but there are a lot of design compromises that are worked into them to make them as small a package as possible. While the I5 is a smaller capacity unit, it is very strong and can be reliable with even silly BHP. Stock rod limit is agreed at around 400ftlbs, replacement rods are usually lighter so it's a bit of a no-brainer to replace them when going over RS2 spec.

Check out Wagner Tuning for the reverse IC lup911 , amongst others. He does the complete B4 chassis kit including XM and IC.

The VR6 is 2.8, the I5 is 2.2 so it'll make boost later on for the same pressure ratio, there are a few on here running the GT35, check out gnutz2 and his Golf. As for the choice of another turbo, many claims are made and the differences in the final result are varied. If you speak to the manufacturer about your application then they might be the best place to start...

A larger WG would be a good plan for that power band, spring choice depends on control method and mapping so is best decided between you and your tuner. The low spring rate on the stock WG works well as a safety feature but it doesn't give razor sharp boost control and requires correct mapping to ensure that boost buildup isn't slovenly.

[Lindahl]

Okay, so the Wagner intake manifold is the reverse mounted manifold!?

What about intercooling in that bhp range, will the Wagner RS2 evolution intercooler be sufficient?

Thanks!

[Bram]

Okay, so the Wagner intake manifold is the reverse mounted manifold!?

What about intercooling in that bhp range, will the Wagner RS2 evolution intercooler be sufficient?

Thanks!

http://www.s2forum.com/forum/showthread.php?t=46444

I am open to offers

[Jamo]

Hi, great reply

I do have a couple of questions for your answer:

Do you have a link to the reverse mounted manifold?

I think I didn´t express myself very clear about the Presicion 5857. What I meant was if anybody had made a back to back comparison of this turbo and the Garrett GT3582, which are comparable in terms of flow. Precision states that this turbo will be less laggy than the GT3582, and providing equal power. But what about the ability of making boost earlier on. At present time I got a GT3582 1.06 mountet on a VR6 12v (which by the way doesn´t seem to be a very popular engine in here ), and this combination makes ~1.8 bar of boost around 5000 rpm, so I guess this turbo would make similar boost around or above this rpm range on the aby. If the addition of the Precision design and billet wheel would improve this I would prefer the Precision over the Garrett, if you get my point.

In regards to the question about the aby being sensitive to injector selection, I know that you wouldn´t be able to run >630 cc injectors on the factory map, but some engines are more sensitive to large injectors than others, resulting in lousy idle and part throttle. But is this a problem with the aby?

Even though you upgrade the wastegate spring, won´t you see boost creep when you are in the 5-600 bhp range?
Can the 34 mm wastegate flow sufficient to keep boost down?

I´m not sure if you answered my question about when you upgrade the factory connecting rods, but when is it advisable to do so?

Thanks for the very helpful information sharing

The precision is faster responding than the GT35r I've seen maps on none S2 cars although GT35r generated more torque. I haven't seen it with Billet wheel sorry

The idle issue is down to the choice of injectors rather than engine type as it's down to the injector reaction time for the small spray.

For instance a siemens deka 630cc has a slower reaction time than an EV14 1000c injector.

Even though the EV14 is larger it gives a better idle.

I use them, between it and the siemens which gives a good idle anyway at 630cc I wouldn't choose another one.

Wastegate is fine with an uprate spring, make sure though that you either have the output pipe made in 2" or run it as a separate pipe not connected to the downpipe and reconnect it lower down or have it's own silencer and run it as a separate output.

Rods are a must for the turbo's your talking about.

[Jamo]

http://www.s2forum.com/forum/showthread.php?t=46444

I am open to offers

I have the same IC brilliant bit of kit

[URQguy]

http://motorgeek.com/viewtopic.php?f=14&t=34852&hilit=turbo

There is a bit of information that should help you in your turbo quest.

Here is a dyno sheet from the same vehicle on the same dyno with a Percision 5857, although a few weeks seperated the tests.



Read through that thread first though. Remember that the test was done to see the spoolup characteristics on a 20vt i5, and not max power.

[driftin jo]

boost creep

Jamo ,
Boost creep is caused by the waste gate not being able to to divert enough gas, your answer of using a stiffer spring would make no difference to how much gas can be bypassed.
what you have done Jamo is you have confused boost creep for waste gate creep which is when the wast gate starts to open when you don't want it to, this is were you would use a stiffer spring to stop it happening.

Boost creep happens with really big turbos such as those used by javad at 034 , I think he found he could not map the boost properly at about 650 hp or so but was if I remember rightly only a problem when making that power with a turbo capable of making 850 hp . What this means is that it is not just hp dependent on when you cannot control boost but more turbo specific i.e. you could probably control boost with a standard waste gate if the turbo was only capable of 650 HP Max.

[Jamo]

Jamo ,
Boost creep is caused by the waste gate not being able to to divert enough gas, your answer of using a stiffer spring would make no difference to how much gas can be bypassed.
what you have done Jamo is you have confused boost creep for waste gate creep which is when the wast gate starts to open when you don't want it to, this is were you would use a stiffer spring to stop it happening.

Boost creep happens with really big turbos such as those used by javad at 034 , I think he found he could not map the boost properly at about 650 hp or so but was if I remember rightly only a problem when making that power with a turbo capable of making 850 hp . What this means is that it is not just hp dependent on when you cannot control boost but more turbo specific i.e. you could probably control boost with a standard waste gate if the turbo was only capable of 650 HP Max.

Think you'll find I already covered it with using a 2" pipe of the wastegate and having it vent off to a seperate silencer.

Only ever seen it on Newsh car where he had the 30mm wastegate instead of the ABY 34mm

Javad also states you don't need a bigger wastegate on motorgeek as it makes it harder to control boost as it more sensitive per opening step

http://www.034motorsport.com/dispelling-wastegate-myths-a-128.html

[newsh]

Yeah I had boost creep when I fitted the GT30 and full turbo back 3" single box exhaust, adding a second box helped but I was still getting 2 Bar in the midrange and 2.5 Bar at the redline, exciting though Turned out I had the earlier 30mm WG for some reason With the 34mm unit on there Mihnea was able to map it. It depends so much on how restrictive the exhaust is of course.

[driftin jo]

Think you'll find I already covered it with using a 2" pipe of the wastegate and having it vent off to a seperate silencer.

Only ever seen it on Newsh car where he had the 30mm wastegate instead of the ABY 34mm

Javad also states you don't need a bigger wastegate on motorgeek as it makes it harder to control boost as it more sensitive per opening step

http://www.034motorsport.com/dispell...ths-a-128.html

http://www.motorgeek.com/viewtopic.php?f=6&t=132&start=1275

half way down page.

"Also, the Tial 44mm was a drop in, we're making these now for people who are interested, direct fit for the stock Audi Wastegate With the GT40R I could only run a minimum boost of 25psi, I estimate with the GTRS that would be over 30psi, not where I want to start on a baseline, the 44mm should keep it below 20psi for the first few baseline pulls"