Turbo kit for A4 B6

[Gele]

Hello guys

I'm looking for a turbo kit for my audi A4 B6 2003 1.8T bfb.I want it to be around 230-260bhp? Would you recommend me where and what to buy. Thanks:)

[Steve Q]

Here's useful info taken from another page:

I decided to make this thread in response to everyone taking such interest in BT'ing their A4. This will be B5 specific, but most of this will still apply to you b6 and b7 guys.

What are your goals?

This should be the first question you ask yourself before you even think about piecing together your BT kit. Everything in your setup will depend on what kind of power you want and what you plan on using your car for. Here's a list of the most popular choices and their respective power ratings at the crank.

k04- ~235hp
gt2x- ~275hp
gtrs- ~350hp
gt71r- ~400hp
gt28rs- ~400hp
gt2871r- ~450hp
gt3071r- ~500hp
gt3076r- ~550hp
gt35r- 600+hp
T3/T4- 300-500+hp

These are all estimations, the actual numbers will depend on where you live and what kind of supporting mods you have. Factor in ~10-15%. Anything past a gt2x is gona have some sort of lag. Here's a boost comparison of the turbo's

Ko3, Ko3s, and ko4-015 sizes

Ko3 - 97-2000

COMPRESSOR WHEEL
Inducer: 33.6mm
Exducer: 46mm
Tip height: 3.7mm

TURBINE WHEEL
Inducer: 45mm
Exducer: 38mm
Tip height: 6.8mm
Blades: 11

Ko3S - 01+

COMPRESSOR WHEEL
Inducer: 38mm
Exducer: 51mm
Tip height: 4.4mm

TURBINE WHEEL
Inducer: 45mm
Exducer: 38mm
Tip height: 6.8mm
Blades: 11

Ko4-015

COMPRESSOR WHEEL
Inducer: 35mm
Exducer: 50mm
Tip height: 3.7mm

TURBINE WHEEL
Inducer: 50mm
Exducer: 42mm
Tip height: 6.4mm
Blades: 11

As you can see and have been told, the ko3s has a larger compressor wheel than both the ko3 and ko4 along with a more effecient design. However, the ko4 has a slightly larger turbine wheel which makes it able to flow the higher power made by chipping better. The best thing to do if you really want to go this route is to buy a ko4 AND used cheap/dead ko3s and swap the compressor wheel and housing to the ko4. This should net you a few more whp and tq

K04

The k04's lag is pretty much non-existant but you'll max out around 250hp and you won't be able to hold that power until redline. You will not have to change anything else except for the oil lines and software. For the aggressive files, you will need bigger injectors, an adjustable FPR, FMIC, and tuning. Some form of an aftermarket exhaust is also highly recommended.

GT2X

With the gt2x you still have next to no lag but you will be push more power than a k04 and be able to hold it till redline. This turbo is only oil-cooled and doesn't have a "cookie cutter" tune readily available for it. You will need oil lines, bigger injectors, software, FMIC, MBC, AFPR, TIP, and exhaust. You can run this turbo off a tweaked aggressive k04 file. I would suggest the GTRS over this turbo.

GTRS

This is the elim version of the GT28RS. You can use pretty much any 440cc tune. I would recommend Unitronics and CTapp above all the others. You will need 440cc Injectors (I would advise Seimans, and Delphi over the greentops, Genesis 430 will work too), VR6 MAF, AFPR, MBC, Exhaust, FMIC, and TIP. A new manifold and dp are not required, but will help the turbo breath much better and produce more power.
 

GT71R

The elim version of the GT2871R. Has the 71mm compressor wheel found in the 2871r but a smaller turbine wheel and uses the stock k03 flange. You will need the turbo, oil lines, exhaust, Tuning (Uni/CTapp), 440cc Injectors, VR6 MAF, AFPR, MBC, Exhaust, FMIC, Walbro 255, Clutch (stg 3 or higher), and TIP. I wouldn't even run this turbo on the stock manifold, even tho you technically could, its gona really choke it.

GT28RS
Finally we get into the "real" turbo's. This is the turbo you want to go with if you don't want to swap internals and you want minimal lag but still want nice power. You will need Tuning (Uni/CTapp (see a pattern forming), if you have a b6- REVO), Exhaust Manifold, Custom Intake, VR6/Ford Lightning MAF, 440cc/630cc Injectors, AFPR, MBC/EBC, Exhaust, FMIC, Clutch, and New Mounts.

GT2871r
Now we're talkin serious power. You have pretty much 2 options. The .63/.64 A/R or the .82/.86 A/R. The .63 and .82 are T3 flanged, and the .64 and .86 are T25 flange. T3 flows better. With the .82 you will have more lag, but more topend power. You also will not have to swap out rods. With the .63 you will have much faster spool (20+psi before 4k), but you will have to swap out rods. You will need Tuning, Exhaust Manifold, Custom Intake, VR6/Ford Lightning MAF, 440cc/630cc Injectors, AFPR, MBC/EBC, Exhaust, FMIC, Clutch, New Mounts, and Walbro 255. (new fuel filter at the same time is a good idea).
 

GT3071r
You will definitely be replacing rods. You have the option of choosing a .63/.64 A/R, .82/.86 A/R. Same deal applies to the flanges as with the 2871r. Go with .63 A/R if you want the quickest spool, .82 A/R if you want the better topend. You will need Tuning, Exhaust Manifold, Custom Intake, Ford Lightning MAF, 630cc Injectors, AFPR, MBC/EBC, Exhaust, FMIC, Clutch, New Mounts, and Walbro 255. With this turbo you have two options for manifolds. Either a log style or a tubular stlye. Cast log styles spool quicker but can be restictive at topend. Equal length tubular manifolds don't spool as quick but are beasts on the topend. Full-Race and 034 offer the best tubular manifolds but they are pricey. You have the option of changing pistons while you swap rods. You can do this to lower compression and be able to run higher boost, but the stock pistons have seen over 700hp so you don't have to swap them out.

GT3076r
Considered the best streetable turbo by many. It'll give you the highest numbers without the lag of a BAT. If you have a 1.8T this is the largest you should be going. Setup is gona be the same as a 3071r.

GT3582r
This is where we start getting into serious power. This will not really be a streetable turbo, and you should really consider upping the displacement. Technically, if you are reading this guide, you are not going to be getting into this territory or anything higher.
 

T-Series
There are a large variety of t3t4's out there. One to fit every goal. These turbo's are journal bearing, where the GT series are dual ball bearing. The GT series spool up faster and hold up better when really pushing the turbo. So why get a t series? They are cheaper, can usually be found for half the price, and they are easier on your clutch and internals due to the more gradualness of the power. Also you can swap in a DBB chra later down the road if you want better spool. The most popular choice is the 50 trim. When pushed the .63 is capable of 400hp+, while the .48 delivers quicker spool and yet still pushes over 300 to the wheels. There is a 57 trim, but it is known to cause surging on 1.8T's. If you up the displacement a bit, it would deliver great power with quick spool. There is also a T3s60. It will spool faster than the 50 trim but not deliver as much power. Looking at around 300whp spooled just past 3k. It spools just before a .48 50 trim but makes a little less power.

With any of these setups you'll need Tuning, Exhaust Manifold, Custom Intake, VR6/Ford Lightning MAF, 440cc/630cc Injectors, AFPR, MBC/EBC, Exhaust, FMIC, Clutch, New Mounts, and Walbro 255. You can get away with a stock clutch for a little while but if you want to launch it at all, you'll need a new one. And if your pushing a 50 trim to the max, some new rods wouldn't be a bad investment.
 

Turbo

Cheapest place your probly gona find it, is Boost Factory or 20 Squared They have t3t4's for 625, and gt series for around a grand. Some other places that offer them are ATP, Pagparts, Kinetic Motorsports, Option Imports and of course "the dreaded" eBay. Honestly, you should not be buying from eBay since most turbo's on there are fake and garbage. Tho there are a few exceptions, the real ones cost just as much as from the websites listed above. The difference between the fake ones and the real ones is usually the compressor housing. Real one's have Garrett, Airresearch, KKK, or some company stamped onto the housing. The fake ones will have a blank housing and a little blue plate that lists the turbo name and serial number. You can find rebuilt t3t4's left and right, or a trashed t3t4 for dirt cheap and rebuild it yourself or send it to Garrett, but you cannot rebuild GT series turbo's in the same fashion.

If you're  going with a GT3071r, 3076r, or 3582r you have another option. Mike@DTH sells a Full-Race Package which includes the turbo, Full-Race manifold, Full-Race downpipe, TIAL WG, and WG dump tube kit for under 2900. This is about a good a deal as your going to find. And makes big power much more affordable. He also sells elim setups and other things like ER comp FMIC's, and should be cheaper than most/all other places. He can get you more than just what's on his site, so go to his store- http://shop.dthaus.com/main.sc

Hope this has all helped 🙂

Cheers

Steve

[Gele]

Does anyone know where in Dorset i can do a quality remap?

[Steve Q]

14 minutes ago, Gele said:

Does anyone know where in Dorset i can do a quality remap?

You thought against a new turbo now?