C5 Allroad 2005 BHW-> 1.2TDI PD or CR

I have an Allroad 2005 6spd manual with the BHW engine(2.7t 6spd originally) and I wan't to downgrade it to a 3cyl TDI. From my research it looks like the 1.2TDI(PD) ANY and AYZ codes don't share the same bolt pattern as the other 4cyl vag engines. What about the 1.2TDI (CR) CFWA code? How complicate would it be to make the ECU talk to all the elecronics(air suspension, ABS, climatronic, transmission low range control module, etc.) in the car?

https://www.facebook.com/pg/ekotuning/photos/?tab=album&album_id=726508297363058

This guy didn't use an adapter plate to mate the 1.2tdi engine to a 2.5tdi gearbox

Agreed, BHW swap would definitely be your best option.

I find the BHW has way more power than I need. It's nice to drive but I want to build a camper on the back of the allroad(Romahome style). I travel a lot with it( I've already done Canada, USA and part of central America. I would like to have something that gets me 1500km(~930miles) from a full tank which means not more than 5L/100km or not less than 47 US mpg. Right now I get around 6.5-7L/100km(33-36mpg). The 1.2tdi PD can push out 120hp just with bigger injectors and a VNT17 or 90hp with just a remap. It should be enough with a low range gearbox for some light off roading otherwise the clutch takes a big hit. I'm just gathering information for now.

So a CR engine in the C5 is a big NO? If I decide to pull the trigger on a 1.2tdi engine I better stick to the same production year(01-05)? A guy here put a 2.0tdi CR in an 01 A6 and it looks like he had to keep both ECUs to make the electronics happy.

Nothing is a big NO, the question is how much effort and time do you want to spend on the install. I am not familiar with the 1.2 PD motor, but if it has the modular plugs which plug into the car body like the BHW, then it will be as close to plug and play as you can get. The other thing to consider are the mounting brackets. I would assume the 1.2 PD was only fitted in transverse mounted cars. Not sure what options you have for mounts when you turn it for the AllRoad.

I still think you will be disappointed with FE making a smaller motor push around a heavy car.

It would seem like the expense and time would make for a long return on investment

But you do you. I have done some things that in hindsight, probably could have spent my time in a more useful way.

That engine will be running so hard moving that beast that your fuel economy likely will not improve like you think it would.

I'm getting motivated by the guy who built an A8 D2 (FWD) 1.2tdi. It has about the same curb weight as the C5 Allroad. At 120hp (210ft-lb) the 1.2tdi would be a bit less powerful than the stock BHW 136hp (247ft-lb). Not sure about how reliable it will be at 2x the stock hp. I'll try to contact the A8 guy to see If he still has the car.

I don't think that will work out the way you intend it to.



Your power-band will wind up changing to levels where the car becomes anemic at any speed and your fuel economy will wind up suffering.



Rather than put the money for injectors, a tune and a larger turbo why not look into doing the same thing with your current setup? More power doesn't always mean less efficiency.

build a 2.0 ALH it will be better for that car than using a 3 cylinger engine in a 2 ton hunk of metal.

Agreed. 1.2L is a false economy for propelling such a heavy car, especially if and when you'll be using more of the low-range gearbox, and you want to pull a camper with it to boot?! A thorough understanding of BSFC maps should make it abundantly clear. After reaching a best point, going higher up the torque curve toward full-load causes BSFCs to get worse and EGT, smoke and NOx to go through the roof, plus engine lifetime to go down.
http://forums.tdiclub.com/showthread.php?p=4169223&highlight=BSFC+map#post4169223

The previously referenced D2 A8 with a 1.2 swap is a FWD model and, don't be misled, a C5 Allroad is significantly heavier than a FWD D2 A8. That project car in question underwent a further serious weight reduction programme that doesn't really make it practical as a daily driver, not to mention a car that will pull a trailer. Look up Vekke's posts for details.

Since your Allroad already has been swapped out for a 6-speed gearbox and BHW, aside from the usual weight reduction, rolling resistance, friction and aerodynamic improvements, there are many things you can do to improve the fuel consumption with that setup, including an Eco tune; getting rid of the low-range box that adds weight and friction and revising the gear ratios (what transmission code and final drive ratio are using?); using low-viscosity engine and driveline fluids); etc.

The C5 Allroad with a 6-speed manual / TDI swap is my personal favourite if I were to embark on a project. Here I thought to engineer my own stop-start system and mild-hybrid system by connecting a bank of batteries under the rear seat or trunk (finding a used DC Tesla Powerwall would be perfect!), and re-wind the alternator to the maximum amperage the casing will support - this is routinely done for competition car audio systems and can go up to 300 amps giving about 4.5 kW of retarding power that I can command with a steering-wheel switch to go to full-charge mode when I'm going down hills. At other times the alternator basically freewheels saving the parasitic losses.

PS: I used to live in QC (Sherbrooke) and Mike (yatzee) is a good friend.

Trade your Allroad for my German-imported A4 Avant TDI quattro (details in sig). 5.6 L/100km commuting to work and driving around town in summer and can go to low-5s on the highway. It still has QC plates and insurance for a week or so...

The idea is to convert the allroad into a pick up and build a small camper on it. It won't be pulling it. The low range gearbox is something I'll be installing once the camper is done. It's more for steep hills in the mountains. I'll be taking it to south america for the next trip. I did central america, usa and canada with a roof tent on it. It's time for a change. I want to test it first as a camper and then start messing with the engine. A DMF is the second thing that needs to be done. I have a 240mm SMF clutch kit right now and I can't drive it below 1800RPM. It vibrates a lot. The BHW engine I have already has the Colt cam stage 2 and it was remapped by neurotuning in Drummondville. I'm just gathering ideas for the engine at the moment to see if it's really worth it to replace it or just leave it as it is. I have the EHT gearbox (2.5tdi allroad without low range) 100km/h at 2000rpm. The a4 is a nice car but I want the air suspension The electric setup would be awesome If you decide to put a BHW into an allroad shoot me a message. I think I still have my wiring papers somewhere.