Replacing the 1.4l AUA motor

ThanosPas

Member
Hi!


I'm new here and I would appreciate your help. I'm going to replace the 1.4L AUA motor of my 9/2000 A2 and in its place I'm going to mount the 2002+ 1.6L FSI BAD motor. Do you know if there is going to be any incompatibility issues except for the obvious chip and wires upgrades (they will come with the motor)? The FSI version, as you probably know, wasn't available when the 1.4L version was introduced back in 2000. Also, almost every moving part in the interior of the BAD motor is going to get replaced too (mostly with Victor Reinz parts). So, what is the previous state of the 1.6L motor is not of great importance since it will come out of the garage "brand new". My confusion lies in the mounting of the motor. Thank you for your responses...
 

spike

Well-Known Member
I don't recall any of our members doing this conversion so it's unlikely we can pass on any first hand knowledge. If you don't already use the on-line parts catalogues, that would be a good starting point to check out the differences between the two installations - http://www.partsbase.org/audi/audi-a2-a2-eu/

You could also try asking the same question on the German A2oc forum

Cheers Spike
 

ajsellors

A2OC Donor
Hi,

the 1.6 FSI BAD engine works in quite a different way to the 1.4 AUA engine so if you are planning to fit the engine as a whole there would be quite a lot of work to do to get it to run properly.

The 1.4 is a classic indirect manifold fuel injection petrol engine. The 1.6 FSI however has high pressure direct cylinder fuel injection and a stratified charge lean burn operating mode.

The fuel system, inlet manifold, head and pistons are designed quite differently to an indirect injection engine to operate with direct injection so the corresponding engine management and addition sensors and control would need to be wired to allow the engine to run.

To operate in the lean burn mode, the FSI engine also has a different exhaust system which incorporates extra sensors such as exhaust gas temperature and a NOX sensor together with a NOX emissions control unit. The FSI exhaust also has a special "NOX trap" catalytic converter which captures the additional NOX gasses generated by the engine while running in lean burn mode.

Thus, to get the FSI engine to run in a A2 with hand the 1.4 originally you are looking at additional engine wiring, FSI ECU, NOX ECU and a complete A2 FSI exhaust at least!

regards

Andrew
 

ThanosPas

Member
Thank you Andrew for your response! I'm going to buy all the necessary wiring and sensors with the 1.6 FSI as well as the FSI exhaust. I 'm going to see more into the specialized NOX trap catalytic converter though (the converter is a sure replacement anyway but I have to get things right). Thanks a lot
 

GuruX

A2OC Donor
You also have the option of fitting the AUB engine. It's something like 100 ps. Someone else here on the forum did it. It's much more of a straight swap.
 

ThanosPas

Member
I have replaced the AUA with the BCB engine 1.6L 16V (105ps) and is getting tuned as well. In fact, I believe we have done on this motor almost anything (beryllium valve seats, special LPG valves, increased compression ratio, stage 2 cams, air flow remodeling, a metallic polo gti intake manifold, hand made inox exhaust etc) that can be done except for custom made pistons, since for that "low" PS it's really not needed. Many mods have been made in the process. Now we're fixing all the electrical stuff. Our goal is to get a stable outcome at or close 140 PS out of this atmospheric motor.
 
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celsisone

Member
I have replaced the AUA with the BCB engine 1.6L 16V (105ps) and is getting tuned as well. In fact, I believe we have done on this motor almost anything (beryllium valve seats, special LPG valves, increased compression ratio, stage 2 cams, air flow remodeling, a metallic polo gti intake manifold, hand made inox exhaust etc) that can be done except for custom made pistons, since for that "low" PS it's really not needed. Many mods have been made in the process. Now we're fixing all the electrical stuff. Our goal is to get a stable outcome at or close 140 PS out of this atmospheric motor.
I Have done the AUA to AUB in my A2, I am building an 1.6 AUS bottom end with AUB 1.4 head. once set up with make 130BHP NA.
 

ThanosPas

Member
Getting 130 PS (is this right?) out of an 1.4L head (atmospheric right?) to me isn't something that I would attempt nor it's safe in my opinion. I believe it would put a lot of pressure to the head and I doubt about the longevity of the engine overall. I'd better use the head that comes with the rest of the 1.6L engine.

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celsisone

Member
Getting 130 PS (is this right?) out of an 1.4L head (atmospheric right?) to me isn't something that I would attempt nor it's safe in my opinion. I believe it would put a lot of pressure to the head and I doubt about the longevity of the engine overall. I'd better use the head that comes with the rest of the 1.6L engine.

Sent from my SM-T715 using Tapatalk
The head on AUB 100PS 1.4 are great. the AUS 1.6 engine 105PS. have done this before in a MK4 Golf. car came with AUS engine. changing the head, Cams over and all top engine parts too. ( inlet ,TB ) then get the ECU reset up. car made 128PS.

I will be fitting a 4 branch manifold and better air filter. Car with this will make 130PS easy.
 

JIGSAW

Banned
i got a little lost in all the reading , i dont understand why you use the 1.4 cylinder head as id of imagined the 1.6 head had larger valves which would give more top end horse power if thats what your after than the 1.4 head which id imagine would give more torque and low end grunt due to the smaller valves
 

celsisone

Member
The Cams from the AUB 100 bhp 1.4 are the best as the 1.6 cams are more mild.

AUB head has the biggest ports, its the same as the 1.6 polo GTI 6n2 head without the VVT.
 

ThanosPas

Member
Let's take a look at the dyno graph first. To me, instead of going cheap it's more prudent to take the 1.6 L cams to a cam specialist and perform a stage 2 enhancement that would be accurate, consistent and fit for the engine in the whole rpm spectrum.

https://www.facebook.com/boubisdval/

This one is the best in Greece. He ships worldwide, a very distinguished engineer. There are winning wrc cars with cams made by him, for example.

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celsisone

Member
A 1.4 petrol with 130 hp. Now that is very interesting. Would be the best of both worlds.
Yes I know. this is my everyday Car. I have audi B5 S4 with 600BHP for fun.

NA power at 130bhp in a car that weights 900kg.

Looked into 1.8T an A2 but driven a Lupo with 1.8t and its fast but handles crap.

Will pick up an another A2 in a year or so, 1.6FSI car then fit 1.4TFSI running gear( the engine and box weight about the same).
 

A2Steve

A2OC Donor
Yes I know. this is my everyday Car. I have audi B5 S4 with 600BHP for fun.

NA power at 130bhp in a car that weights 900kg.

Looked into 1.8T an A2 but driven a Lupo with 1.8t and its fast but handles crap.

Will pick up an another A2 in a year or so, 1.6FSI car then fit 1.4TFSI running gear( the engine and box weight about the same).
Time for a project thread I think, wouldn't want this project to be lost in just this post.
 

ThanosPas

Member
audi a2.jpg

So, here we are! The car is ready. I've used: A Polo GTI (AVY engine) manifold, stage 2 cams, I've increased the compression ratio to 11,5, special LPG valves, beryllium valve seats, a handmade exhaust, ECU reprograming, various components (clutch set (disks, pumps etc), EGR etc), there 're new Brembo brake disks, yellow staff EBC brake pads, a new rear axle with brake disks (from the 1.6L A2 version) with ATE performance disks and EBC green staff pads, as well as most parts from the steering and transmission systems is also replaced. More photos on the way!
 
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