upgrades for 1.8T engines

[Steve Q]

Saw this on another page and thought I'd share as I thought it might be useful for our members 🙂

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.
 

your 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

 go to his store- http://shop.dthaus.com/main.sc

Manifold

You have quite a few options here. The cheapest is going to be the ATP knockoff. You can find it on eBay or HERE It is the exact same thing as the ATP manifold, which retails at 400. And if anyone is wondering about the ATP rumor, that they are crap, it is NOT true. The first batch they made sucked. They have since revised the design and are not having any more problems. The clones are based off of the upgraded design. You can get the ATP in either T25 or T3 flanges, but i've only seen the T25 in the knock-off version.

If you want a better manifold you have a few options. Each of these manifolds (unless otherwise noted) have a T25 or T3 flange and fit your standard 35-38mm WG. You only want the WG flange if your running an external wg. If your running internal wg you need to get a manifold without the flange.

SPA- They make some of the best manifolds in the world, and use a totally different design than anyone else. They only use T3 flanges They used to only offer a funky WG flange but now they have the regular 35mm or 38mm flange, and they even sell their own. Just make sure you don't get the funky WG'd one or you'll have to fab up an adapter. You can find their manifolds on ebay  from their store the one you want is going to be the top mount manifold. Just search "longitudinal" in their store and it should come up

Pag Parts- They always have quality parts and Arnold is a great guy to do business with. It is slightly more expensive than SPA and should be comparable in performance. They are also about to release their v-band manifold. This new manifold with work with the newer lighter Tial exhaust housing. You can get the manifolds from their website

Treadstone- This manifold is really well made, and cheaper than both Pagparts and SPA but not as easy to work with. No one seems to know (not even the guy who made it) what application this manifold was made for. It'll require a bit of modification to get it to work, but if you got the skills I would definitely go for it. You can find them from their website

Tubular Manifold- The two most popular are Full-Race and 034. 034's is cheaper but they have messed some up in the past. They always corrected it tho.
 

Intake

Again you have a few options. For the Elims there is a silicon/hard pipe TIP pre-made for you guys. You can buy it from 034, ATP, Forge, Samco, Neuspeed, APR, and there are even some on ebay. The hard pipe is only on ATP and 034 and doesn't collapse under high boost, but is more expensive. For the full turbo guys your gona have to go custom. There is an angle block from ATP, but most people say it sucks. And it will be metal so there's no risk of collapse under high boost. You just need to find a way to mount a MAF and filter onto the end of the compressor inlet. Most people just do a u-bend to the MAF and then stick a filter on the end. For the guys running a full turbo with a 3" inlet, you just need a custom 3" u-bend (will require welding), which will connect to the 3" vr6 MAF, and then stick a BPI Flow Stack on the other end of the MAF and you should be all set. For the guys who have to use the 4" ford lightning MAF it will be somewhat trickier. The pipe will have to go from the 4" MAF to whatever size your compressor inlet is (most likely 3") and you will need a 4"-3" silicon reducer if you want to run the BPI filter.

Injectors/AFPR/MAF

This part is simple, you just get whatever your tuning calls for. USRT has pretty much any injector you'll need. I recommend the AFPR instead of a FPR because you can slightly alter it and if you ever had to change your setup, you wouldn't need a new FPR. But lets say your getting a 3071r setup and you know your keeping that setup, the tuning calls for a 3 bar FPR which you can find much cheaper than a AFPR. So you can get either. Just make SURE you get an FPR designed for a TURBO car. NA FPR's aren't designed to increase flow as boost is added, so even tho your running the correct BAR, it will not run right. And you can get a VR6 MAF from the Vortex classifieds for really cheap. If the tune calls for a vr6 MAF and you are DBC you need the MAF out of a mk3. DBW guys use the MAF out of a mk4 or tt225. while they both will technically work the bolts are 90* rotated betwen the two models. So if you get the wrong one, you will have to ghetto rig it in there with zipties or permanently seal it with something like jb weld. neither of which is really a good idea. Just get the right one

FMIC

You have 2 main options. Ebay or Quality. A regular sized ebay core will be fine for anything under 300hp. If your going above that, or live in a really hot area, you should at least consider the larger ebay core, if not a higher quality core. Cores are rated based on how "dense" they are, essentially how close together the fins are. Larger surface area means more cooling. The ebay cores have a relatively low density so a larger core is required. When looking for ebay cores, i would stick with Godspeed or CXRacing. If you want a quality core Evolution Raceworks, Garrett, and Forge all make very nice large cores

Clutch

Southbend is what you should be looking at. All the other kits are either inferior or overpriced. AWE kits are just southbend kits resold at a higher price, and they alter the stages a bit. With southbend you just need to match the torque capacity to the setup you're getting. A stage 3 is usually fine for most setups. Starting with the 2871r and up you should look into the stage 4 and 5.

New Mounts

This is the optional choice for the smaller BT guys, but honestly everyone should do it. Its not that expensive and makes a big difference. You should be getting all 3 motor mounts and both tranny mounts. A new rear diff mount is a good idea too. 034 motorsports is where you should get them from, tho not everyone seems to like their snub mount. But they do offer a nice discount if you buy all the B5 mounts.

Walbro 255lph

This will be good enough for over 400whp. Going above 500 and you'll need get an in-line fuel pump. You can get them from a LOT of places. You should just go ahead and pick one up from a place your ordering some of your other parts from and save some shipping.

MBC/EBC

An ebc will be more efficient but a mbc will be cheaper. If your getting an MBC go with the TurboXS, if you going with an EBC go with either Greddy, Apexi, or Blitz. Like the Walbro pump I would pick it up from a place your buying other parts from.

WG

Only needed if your going to be running an external WG. The most common is the Tial 38mm and you should buy one from the same place your buying your manifold from.

Exhaust

3"+ is what you want for BT. Cheapest way would be to get a custom 3" exhaust from turbo back and just choose whatever muffler you want. You will definitely need a new DP if your getting a full turbo. They sell pre-made DP's for side mount manifolds at ATP, or each company who sells a manifold usually also carries a DP to fit as well, or you can custom make your own. For you economy BT guys who can just barely afford one of the smaller elim setup's, you can get away with just a TP/HFC and either removing both or just 1 muffler. But you are going to be hurting performace until you get a full 3" exhaust

Building the Engine

I was going to go real in-depth into this, but decided not to. If you have any questions on building the engine give Bob Q over at QEDpower a call. He will be able to hook you up with practically anything you need.

The most basic build is stroking the 1.8 out to 2.0L. The displacement is factored by the width of the cylinder wall times the stroke of the piston. For 2.0L you want a 83mm bore with a 92.8mm stroke. To achieve this you must bore the cylinders over 2mm and use an ABA crank. You will also need either a piston with a lower deck height or the pins moved. Either way its a custom job that will take a few months, so ordering these should be first on your list.

When it comes to rods, they should be upgraded if your doing a 2871r or higher. Pre-01 guys have 20mm wrist pins (Scat). 01+ guys will use a 19mm wrist pin (Integrated Engineering). Around 330 tq is the breaking point of rods, but it all depends on the tune. Just running a pump gas setup, you shouldn't need rods, but if your planning on pushing the turbo, they sohuld be changed.

article courtesy of Chao 92287 on the audi forums: 

https://www.audiforums.com/forum/members/chaos92287-22062/

 

 

Another really good read https://www.audiforums.com/m_823224/tm.htm