2.5 V6 Quattro B5 - Engine Swap and Stage 2

quattrosun

Member
Joined
Oct 20, 2024
Location
Scotland
TDI
1.9 AFN; 2.5V6 AKN
I have an early (2001; AKN) audi A4 B5. The Fuel pump blew on the M6 at 200k miles. I am looking at options for replecement and figured it would be worthwhile putting in a lower mileage engine. I have sourced a 170k AKN engne from a car of the same year and model (150hp). But I also have an option to buy a lower mileage (117k) engine from a 2001 B6 quattro (180 sport).

Does anyone have info on whether this will plug in? I know it will bolt up but I am concered about coding of fuel pump/immo/clocks etc.

Advice greatly appreciated. I have already pulled the engine. I plan to upgrade injectors and turbo on whichever engine goes in :cool:.

edit* the B6 engine is complete but in a water damaged car. ECU and relays have been pulled so this is obviouly a gamble. Also interested to hear opinions on that.
 

d24tdi

Veteran Member
Joined
Jan 6, 2019
Location
MT
TDI
BHW x3, BEW x2, ALH x2, AHU, 1Z, AFB, AKN, BCZ, BDH
We never had any of these engines here in North America (officially at least) so expertise here on this forum is pretty thin, given that most members are in the US and Canada. There may be UK and European groups that would have more to add.

That said, some of us have seen them and dealt with them. My impression is that the base engine components are the same or at least interchangeable all the way from the earliest engines to the late series with rollerized valvetrain and upgraded heads. There *may* be some differences in internal components between the "low horsepower" (150hp) and "high horsepower" (163-180hp) versions for each series such as pistons and compression ratio. I believe most components are the same and the main differences throughout the entire range of the 2.5L V6 have to do with fuel pumps, injectors, turbos (hi/low HP), and then the change to roller heads for the "Bxx" code engines. Emission system components also changed along the way -- some have EGR coolers and electronic throttle flaps whereas others done, for example. Finally, there were various different engine control system iterations (early MSA, later EDC) and different ECUs and wiring harnesses to go along with them. But probably all of these things can mix and match if you know what you are doing. I do know for sure that folks have done the conversion from sliding finger to roller heads on the early engines and that is doable with no struggle.

Bottom line, if I had to guess, I would think if you wanted to change engines you could accomplish that by taking the low mile engine (which, if out of a B6 platform car, would probably be a late roller cam Bxx motor) and then transferring over all of the external components from your existing engine: wiring harness, turbo, exhaust, inlet system, etc. Not certain about fuel pump and injectors compatibility -- you would need more research there.

HOWEVER: I would also think about another point. If all that went wrong with your engine is the injection pump and the engine ran well otherwise, why not replace the failed VP pump with much less work and just continue on with your current engine? Did you have any concerns with compression, oil use, operation, etc? If not, keep in mind that the engine you have now is a known quantity that you can speak to the maintenance and functionality of. Any used engine is a gamble. It might have lower miles but you have no knowledge of its past upkeep or any issues it could have. If it's been exposed to flood damage then you have that huge variable in addition.

TDI engines, including the V6, can last many hundreds of thousands of miles with good care. The only inherent question mark on the early AKN-era V6 engines is condition of the cams and followers, depending on how well they got regular oil changes. You can look at that easily enough, and replace if needed, or even change to roller heads from the later donor motor if you really want to dig into it. By keeping your existing engine you also avoid any questions about compatibility with a different year motor and its components. The AKN is already a high-output 180hp version so a nice place to start. If it's in good condition at 200k, which it easily could be, then you could upgrade the IP and injectors on it and tune for them, and have a very nice running setup.

Just some thoughts. Mainly, envious of your B5 with a factory TDI V6! Keep it going one way or another.
 

d24tdi

Veteran Member
Joined
Jan 6, 2019
Location
MT
TDI
BHW x3, BEW x2, ALH x2, AHU, 1Z, AFB, AKN, BCZ, BDH
One more thought -- of the few members on here who do have some 2.5L V6 knowledge, @adamss24 is one of them. I am paging him here for you as he may be able to add more comments or correct any mistakes/gaps in my novice post above. :cool:
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
AKN is 150bhp, AKE is 180 Bhp. I have a b5 with an AKN Engine to which i fitted a AKE Block with cam Roller bearing cylinder heads. Everything is plug and play but you have to use suitable engine head bolts as they’re different !
Everything can be mix and matched however there is difference between vacuum pumps so you have to use the one suitable and the vacuum hose needs A bit of a fettle.
As above, if the rocker finger engine is in good shape why change ? Engines go long time with decent maintenance !
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
If you go to the trouble of changing engines then replace the exhaust manifolds, they are breaking internally and will destroy your turbocharger turbine wheel. The v6 tdi respond well to tuning, bosio race 683 nozzles and gtb2260vk/ gtb2056vl is as plug and play as possible.
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
When I rebuilt my “new” engine I was a little stubborn, plan was to buy a nice 1.9 tdi quattro sport and swap a highly tuned engine which I have on a mk2 golf. Unfortunately I didn’t find the right car at the right price and setled for a b5 v6 tdi quattro as it had better kit and was tastefully tuned as well: rnse media system with Bluetooth streaming, recaro fully electric seats, rs4 b6 steering wheel (fully working), Bose, genuine towbar, front s4 bumper and was a straight car with original paint !
I had the AKE engine in a car in my yard and many, many parts leftover from yesteryear ! Mainly I had a pair of cam roller heads (brand new) which I bought in 2004 from Jeremy Lear in uk. Trouble was they were both Left hand side cyl heads but they were complete with genuine billet camshafts (not the problematic hollow cyl heads). I also had brand new injectors with Bosio race nozzles balanced at United diesel in uk. Tuning wise I fitted a hybrid gtb2260vk and a chipped ecu which I mapped with the help of Razvan Albulescu- also member on this forum- which helped me on several projects long the years !
Soon I found out the side Intercoolers on the b5 don’t flow great and I used seat exeo cores with alloy end caps and made larger Intercoolers which they barely fit behind the s4 bumpers. I didn’t want to use a FMIC as I didn’t want to chop the genuine bumper too much and wanted to keep the stealth look as authorities are notorious with modified, old cars !
Car is a hoot to drive, plenty power and a few weeks ago i sheared bolts on a rear driveshaft...
I have upgraded brakes to rs4 genuine brakes on the rear and a mix and match 350mm front brake system with Mercedes ml v8 discs and some brembo 4 pot calipers of unknown origin (Mitsubishi evo 8 o believe) which still gives me a bit of a headache as car has upgraded alloy uprights (c5/b6) and nothing fitted properly !
While I had it I sourced a rear s4 bumper and a replica rs4 tailgate spoiler. I also fitted a 3D dash dysplay - this made the biggest impact to modernising the interior !
Wheels are Audi A8 d3 18”x 9” wide commonly known as fat 5 ! They are very heavy but look right with a 30mm drop on eibach springs and kyb SR shock absorbers. So far the car needs thicker rear antirol bar and strengthening brackets and better suspension- a kw variant is on the cards next year. I also have a gte2260vz to fit when i can find time for it, the kit is mainly built but time is scarce ! As the weather turns bad I will put it in storage for the winter as I hate cleaning salt from it’s underside- I have a Tiguan r line 4 motion to drive in bad weather !
So there you have it: my 1 year project which is becoming one too many !
 

quattrosun

Member
Joined
Oct 20, 2024
Location
Scotland
TDI
1.9 AFN; 2.5V6 AKN
Thank you both @d24tdi and @adamss24 (who has already given me some excellent advice outside the forum.

I am impressed by the knowledge on this platform and will admit I had no idea it was mainly made up of members on the other side of the pond!

I have decided to keep this as simple as i can. I plan to replace the engine like for like (the AKN at 170k is off a friend and known to be good, the original engine was leaking oil and long overdue timing belt etc).

I have discovered that tuning of these early TDIs is not straightforward and I need to find someone capable of socketing the ecu (with programmable PLCC32 chips) before I move forward with bolt on upgrades.

Since starting this thread I have found some people in the UK still tuning these cars so parts are not as scarce as I feared.

I will endeavour to update this thread as things progress but it's mid winter here in the Scottish Highlands...far too cold to be spinning spanners 🔧


Thanks again for the advice here. It's much appreciated.
 

quattrosun

Member
Joined
Oct 20, 2024
Location
Scotland
TDI
1.9 AFN; 2.5V6 AKN
Its back to below zero and snowing here so things have slowed down. I have the replacement engine on a stand ready to go back in as soon as waterpump and thermostat arrive. TB kit and all pulleys siting on the shelf.

I have pulled the clutch and it's v. worn so think I will replace this while I'm at it. I have part numbers for sachs SRE clutch and pressure plate which i will go for if I can find someone to chip my ECU. These are:

Sachs Performance Clutch Pressure Plate 883082 999754 £255 + VAT
Sachs Performance Clutch Disc 881864 999526 £210 + VAT

I have been unable to find anyone who can carry out soldering work on my ECU so it's looking like tuning is going to be more challenging than I expected. I do have someone local I can ask but I expect too complex. After this i will still need someone who has the programmer to read and write files, plus someone to actually write the custom tune...

Once the engine is timed up and back in the car i think I will throw some Allroad injectors in, do the cam cover gaskets and see how she runs.

At this stage I will be in a better position to look for a turbo and injectors and find someone to write a tune.

Unfortunately ribble valley diesels no longer stock the P970 nozzles (firad) as they were unhappy with performance. It would be good if there was something available which delivered less fuel than bosio race for these cars.

I will see if I can work out how to post pics to update some of the progress made. I have pulled and inspected exhaust manifolds (look very clean) and begun swapping over of my known good ancillaries.

Now just waiting for the sun to come back out!
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
I could probably get you a chipped ecu with stage 1 chips written on a pair of chips, however if you want a custom tune then you need a custom setup meaning loads of logs with vcds. Unless you go for exactly the same setup as I have and maybe make a “one size fits all” tune...
Good you found Sachs SRE parts numbers, it’s a good idea to replace while you’re at it however the stock clutch can take some abuse- later 2.5 tdi LUK clutch takes easy 550Nm.
I still have original Sachspressure plate on my car but with a stronger 2.0 tfsi disc on v6 hub I had. It holds well so far with no signs of slippage as yet !
 

quattrosun

Member
Joined
Oct 20, 2024
Location
Scotland
TDI
1.9 AFN; 2.5V6 AKN
That could be a good option. Nobody in the UK wanted to touch the ecu so I had been thinking about keeping it simple and just running BAU (auto) injectors with the Van Aken tuning box. But unsure if this will actually result in any extra power.

If I took you up on the offer of a chipped ECU would this take better advantage of the upgraded nozzles compared to say Steinbauer/Van Aken box?

Could I reasonably expect to get 225ish bhp from stock turbo? I now have 2 VNT20 turbos in good nick. Good news about stock clutch, I may be able to save a few quid sticking with OE.

I also have a spare AKN ecu i could trade/exchange if you did have a socketed one for sale.

No rush my end, snow and holidays have put a total hold on any deliveries and I have some work to do on the Octavia & 4runner when the weather clears up!

Cheers
 

quattrosun

Member
Joined
Oct 20, 2024
Location
Scotland
TDI
1.9 AFN; 2.5V6 AKN
Luk clutch fitted engine now ready to go back in. I have split and cleaned the original turbo and have found someone with a set of BAU injectors from an auto allroad in Scotland.

Just a Sunday update :cool:

 

d24tdi

Veteran Member
Joined
Jan 6, 2019
Location
MT
TDI
BHW x3, BEW x2, ALH x2, AHU, 1Z, AFB, AKN, BCZ, BDH
All looking very nice and good to keep up with what you are planning and assembling. Cool to see someone doing good work with the 2.5 V6! These engines are unfamiliar beasts here in North America where they were never originally sold... But I happen to now have three of them sitting on the floor here :p and am getting ready to proceed with a swap of one of them, a BCZ, into my 2001 6-speed Allroad in place of a gas engine hopefully this year. The other two, AKN and AFB, can hopefully serve as parts sources if needed but I do not have a clear feel of what combinations from which engines can work successfully together. So trying to learn as much as I can about them, and reading of projects by those across the pond like you who know them firsthand is helpful and fun to watch.

So, what is the final recipe of parts you are settling on here? BAU injectors, stock ECU and VP44 pump, your original AKN ECU and harness, stock VNT20 turbo and new stock style clutch?

Will be very interested to see how the setup comes together and how you like it. :cool:
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
I would not use old exhaust manifolds if possible, They are known to fail internally and damage the turbine wheel and geometry in the process ! Gat a fab shop to fabricate a pair of exhaust manifolds from thick 3mm stainless steel bends and pipe.
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
D24tdi: the best would be to use a bau/BDG/Bdh engine or ake with cam roller heads. They are plug and play, only need to use later cylinder head bolts as heads are shallower.
 

d24tdi

Veteran Member
Joined
Jan 6, 2019
Location
MT
TDI
BHW x3, BEW x2, ALH x2, AHU, 1Z, AFB, AKN, BCZ, BDH
Good to know. The BCZ is similar with roller heads but a few less HP, correct? Do you know what all the differences are between the BCZ spec and the BAU/BDG/BDH? Would a set of BAU injectors bring a BCZ up to the 180hp level of the others?

Thanks for your info! Like the OP in this thread I expect to have plenty of questions for you as I dig into the V6 engines over time.
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
Good to know. The BCZ is similar with roller heads but a few less HP, correct? Do you know what all the differences are between the BCZ spec and the BAU/BDG/BDH? Would a set of BAU injectors bring a BCZ up to the 180hp level of the others?

Thanks for your info! Like the OP in this thread I expect to have plenty of questions for you as I dig into the V6 engines over time.
Yes. As far as I know bcz is also a cam roller head design. I believe it’s a de-tuned engine from factory...I had one at some point in a c5 allroad 2004 and it didn’t make as much power as the 2001 allroad or the 2004 BAU engine ! So probably pumps and injectors might be smaller as well !
 
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