Our AANs, 3Bs, ABYs and ADUs came equipped with water-cooled, pressure-lubricated, turbos made by KKK (Kühnle, Kopp & Kausch, part of BorgWarner Turbo Systems since 1997
. We often call them a "K24s" to distinquish it from the K26s used on the earlier Audi 10V turbos. More specifically, for the 3B, AAN and ABY turbo is designated as "K24-7000". Its Audi PN is 034145702 as shown in this diagram:
(Note: This does not jive with the SN plate with its 034145703B (which isn't in the parts catalogue). The key thing on the SN plate is K24-7000.
Here are schematics as to how the cooling and lubrication occur:
Here are the PNs for the water and oil feed and return lines:
Here are 3 of the 4 lines (coolant feed line is hidden in this photo) on Tom S's (RS2 America's) AAN:
Scott Mockry (SJM Autotechnik) says that the K24-7000 has a 2470 GGA Compressor, and 6.13 exhaust Turbine, Audi part number 035 145 701B, or 703B, KKK # 5324 970 7000. (Note: His Audi PNs don't work). Reference with turbo map: HERE
The K24-7000 is a good turbo without much lag. However, by 23 or 24 psi of boost (typical of MTM Stage 1+ (3 Bar MAP sensor and stock injectors)), it is starting to fall off its efficiency curve, making a lot of heat. This limits its capacity to around 280 reliable horsepower (hp). Some tuners have pushed the K24-7000 harder, into the 300 hp range but I am skeptical about turbo reliability under those conditions. At that point, it is better to go to a larger turbo. There are a number of choices for this.
The OE plug and play KKK turbo choice in this situation is the K24-7200 that was used on the ADU engine of the RS2 in 1994-1996. In RS2 ADU application the K24-7200 made a reliable 315 hp. Subsequently, tuners have been able to push the K24-7200 to produce up to 380 hp with RS2 360 cc injectors and more agressive boost and timing curves. The K24-7200 has more lag than the K24-7000 but where the K24-7000 starts to run out of steam as the engine RPMs go above 5500, the K24-7200 continues to produce boost.
Scott Mockry at SJM Autotechnik says that the RS2 K24-7200 turbo has a 2672 GGC Compressor and that the Audi part number is 034145703D, KKK # 5324 970 7200. (These work). Reference with RS2 turbo map HERE
Here is the PN for the K24-7200 (note the two numbers based on the VIN of the RS2). The 034145702B was dropped from the parts system on 01/05/2003 in favour of the 034145703D. The KKK PN for this turbo was 5324-970-7200 (where 7200 designates the RS2 application)
There are a variety of Serial Number (SN) tags that have been put on these K24-7200s. The common number is "7200" Here are some examples:
Photo courtesy of Sebastian.
This one is tough to see but what I think I see on the bottom line is 5324-988-7200:
Here are a couple of photos that show the differences between the K24-7000 that was stock on the 3B, AAN and ABY and the K24-7200 from the RS2 ADU.
In this first photo, the 3B, AAN and ABY K24-7000 turbo is on the top of the photo and the ADU RS2 K24-7200 turbo is on the bottom of the photo:
Photo reference: UrS4.com Turbo FAQ
Here they are again, this time the RS2 K24-7200 turbo is on the left and the K24-7000 is on the right. In both cases the hot-sides of the turbos are on their respective right sides and the cold side (the compressor side) is on their respective lefts. You can see the coolant and oil line connections on the center sections. If you look at the two cold sides, you can see that the RS2 turbo on the left has a thicker overall scroll than the K24-7000 on the right side. You can also see that thicker, raised portion of the scroll, where the bolts connect the scroll to the backing plate is wider on the K24-7000 on the right and narrower on the RS2 K24-7200 on the left. In fact, that is a good way to tell, at a glance, whether the KKK K24 turbo is an RS2 7200 turbo or the OE 3B, AAN or ABY K24-7000.
This is what Scott Justusson (qshipq) said about the RS2 turbo:
"The RS2 (turbo)
is all K26 turbo. I've had a couple dozen of RS2 and RS2 Competition turbos apart in the past 6 years. The hot side is based on the smallest of the K26 series housings, with a Porsche specified hot side wheel, and the appropriate milling of the housing (which results in a slightly larger downpipe opening). The center section is stock Audi K26 WC, and the cold side is a K24 cold side housing with a K26 cold side wheel."
REF: Turbo FAQ at UrS4.com
There was also something called the "7200 Competition" (7200 Comp) turbo that was based on the normal 7200 but with some tweeks. This is what Scott Justusson said about that:
"Take a RS2 turbo apart, then a "7200 comp" apart, there is a difference. Cold side housing and turbo wheel are different, BTDT. Basically, if you use whatever KKK's numbering system is at the time (I did this back in 94 - at least 2 numbering systems ago), you will find that the cold side wheel is larger on the 7200 Competition. The RS2 'Competition' is actually and ascribed misnomer, as the "RS2 Comp" really doesn't exist. What does exist is the "7200 Competition". Which is EXACTLY how KKK delivered the RS2 hot side housing, RS2 hot side wheel, and RS2 "+1" cold side wheel and housing. KKK also labeled the box it came in "7200 Competition". I know this, cuz I sold about a dozen of them when they were available.
The easiest way to tell the RS2 plain Jane from the 7200 Competition is that the plain Jane comes with the Audi tag on the cold side, the 7200 Comp doesn't come with any tag on the cold side. The hot side housing and wheel will carry the same part number, so will the center bearing section (it should they are both K26 derivatives).
There is also another cold side (wheel and housing) that is larger than the 7200 Competition. I currently run 1 of these in my fleet.
Everyone has "opinions" on these turbos, and it would appear it's shrouded in grand mystery. I laugh, KKK knew what that hot side was (awesome), and (my guess) KKK was likely restricted in using a Porsche/Audi proprietary "RS2 Turbo". The rules have changed since, because the only way to build a 7200 Comp these days, is to order the RS2 turbo complete, and add larger cold side wheel/housing. Bringing full circle what I did to my first RS2 turbo in 1994."
On the topic of K24-7200 shaft sizes and design, the following information has come to light:
Twoqu (Robin) previously posted photos and said:
"Here is a photo of a damaged RS2 turbo shaft and impeller on the left and a near perfect K26 turbo shaft and impeller on the right.
The diameters are probably the same, but there are some important differences:
Here is a shot that shows these differences. The RS2 turbo impeller shaft is on the left, and a typical(??) K26 on the right. The threads go opposite directions for each of them (one's LH, the other RH). The RS2 shaft is also necked or under cut (someone has suggested so it twists slightly when it stalls, rather than loosening the nut
"took a genuine K24 shaft. applied calipers to main section. 8.5mm
took a genuine K26 shaft. applied calipers to main section. 10mm.
I dont' have an RS2 shaft handy but the only difference is the little necked section below the threads as shown in that pic. other than that they (because I did have all 3 side by side not long ago) are identical shaft-wise: length, OD at the cold wheel, and OD for the larger main section.
The RS2 and K26 cold wheels I have both fit the K26 shaft identically and interchangeably, proving what seems well documented - the RS2 is really a K26 family turbo, just with its own specific turbine/shaft and cold wheel specs."
As boxflares (Steve M) says "the RS2 shaft is significantly different and stronger than the K24/7000"
Kryptonite on the S2Forum measured a K24 shaft at 8.0 mm and a K26 shaft at 10.0 mm
***********RECENT K24-7200 History ********
Somewhere around 2004, there was a group buy of "RS2" turbos. These were built by Borg-Warner (who had purchased KKK in 1997) but were done outside of the Audi parts system so their designations are different than shown above. Here are the details:
The 2004 RS2 turbo group buy GB) turbos were arranged through Jeff Labombard who did the GB with Tim at TJM Motorsports (also Northern European) in NH. At the time Tim was just starting with Dalback racing and had the ability to get the Turbos through his connection in Sweden. Dahlback had a special turbo run done by KKK and Jeff and Tim tapped into that for 20 turbos. Jeff recalled that it took an extra couple months. All parties involved had impeccable credentials and the turbos came from the same production line as the Audi part. They are genuine factory parts, just not labeled for the VW/Audi parts system. The upper line on the 2004 GB turbo serial number plate reads K24 1335. The lower line on plate has the actual serial number like: 24 4089063. Or as shown in this photo from Mike S.:
I am not sure the relationship between the 2004 group buy and subsequent purchase of a pallet of K24-7200 turbos by Force 5, as shown here:
Here is a "close up" of the tag on the box, i.e. 5324-988-7200, just like the blurry tag shown above:
For experts, here are some comments made by Frank (the Don) Amoroso back in the day (early 2000's) about the capabilities and limitations of the K24-7000 and K24-7200 turbos:
"Boostus Maximus (How much boost is too much?)
Hello fellow S heads,
In my quest to decide on the appropriate boost levels I should be running at altitude, I have put together a spreadsheet (I apologize for the attachment but I wanted to convey the data in tabular fashion) that shows max boost level guidelines for running the K24 and RS2 turbos, without exceeding their respective Pressure Ratios at different altitudes. As well as the effective Pressure Ratios at different boost levels at altitude (mine to be exact, 5,350 feet).
I will not get into the definition of a turbo's Pressure Ratio (PR
), but the equation is...
Pressure Ratio = (Atmospheric Pressure + Boost Pressure) / Atmospheric Pressure
Given this, one can determine if a given Boost Pressure will cause the turbo to operate outside its efficiency range.
The RS2 compressor map shows a PR
of 2.8 to be the top of the scale. The K24 compressor map shows a PR
of 2.4 to be the top of the scale.
This issue is extremely long and involved and there has been volumes written off-list (especially for the RS2).
Here comes my big disclaimer for the people who will get bent out of shape for some reason or another... My purpose in sending this out is not to start a huge email campaign to discuss all of the intricacies involved here, but rather to present MY guidelines based on my research and the data that I have acquired from the likes of Ned Ritchie and Scott Justusson, etc.. Once again these are MY guidelines and they are not to be taken as postulates, they are simple math and I only offer it to you so you can determine how much, if any, your particular setup is running out of its efficiency range.
If you truly want to dig into the details including not only definitions but also how to read a compressor map, I must, once again, strongly encourage you to read Corky Bell's book Maximum Boost. Along those lines if you want to see some Garrett compressor maps (KKK does not release theirs to the general public) check out http://www.turbonetics.com/
Note Well: Many tuners run their setups at boost levels that result in PRs that are greater than MY limits (especially at higher altitudes). Since max torque creates the best need for boost, tuners seem to like to overkill it in that range. They have their reasons for doing this and I don't claim to know what those reasons are. I, OTOH, am offering up the objective math.
For my Atmospheric (Barometric) Pressure figures I used the table found at HERE
These may be conservative figures but tough luck. The pressure for a given altitude is given in PSIA, Pounds Per Square Inch Absolute. The boost pressures are given in PSIG, Pounds Per Square Inch Gauge. For further clarification on both PSI Absolute as well as PSI Gauge see Ned Ritchie's tech tips at HERE
Here is the data...
Frank Amoroso, Technical Editor UrS4.com.
It is often possible to rebuild a KKK turbo. "Habe Ich gesagt" posted this list of re-build parts for an RS2 K24-7200:
RS2 Turbo rebuild PNs:
KKK New Part #
KKK Rebuild Turbo #
Compressor wheel 2672GGC/26/2202
Turbine housing K24-6.12
Bearing Housing K26 D75/51/41 (CHRA)
Shaft & Turbine Wheel K24/G
Here is a exploded view of a typical KKK journal-bearing, water cooled, pressure-oiled turbo, in this case a K24-7200:
A partial list of the part numbers for the above is available HERE
Twoqu on the S2Forum did a great thread on disassembly of a K24-7200. I captured this and added a couple of diagrams to create this KKK turbo disassembly pdf
(Full credit to Twoqu (Robin)).
There are also places on the internet that will supply parts or do the work. There is probably a turbo shop in the nearest large city to you. Here is an example of rebuild parts:
Photo courtesy of This KKK turbo rebuild company
REFERENCE: UrS4.com Turbo FAQ
Thanks to those whose photos and diagrams are used here.