Converting a 1.4 petrol A2 to a 1.6 non FSI

A2Steve

A2OC Donor
Wales
Fist of all, a little disclaimer, @celsisone did the donkey work with this setup with trial and error in working out which parts do and don’t work. Having chatted with Brett about this conversion and having met him (great guy) and now done the conversion on my own car, I thought it would be worth writing up what’s involved.

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Setup 1, the more basic setup

There are a couple of options available for engine codes to be able to do this conversion.

If you have an earlier 1.4 you will have the AUA engine which has a single coil pack. The best solution for this setup is to buy a AUS engine code (they are found in Mk4 Golfs, Bora’s and some Seat Leons, that sort of era VAG). This engine has a single coil pack to so can be used as is with some modification, albeit they are harder to find than the BCB engine I have.

You also have the option to use the BCB engine, but you would need to change the rocker/cam cover as it uses individual coil packs like the BBY engine.

If you have the later BBY engine, you can use the BCB engine with it’s existing cam cover as they both use individual coil packs.



You would need to use the following from your 1.4 AUA/BBY engine to go onto the AUS/BCB block you’ve bought.

  • Inlet manifold
  • Throttle body
  • Exhaust manifold (with pre-cat internal drilled out to release more power),
  • Sump and oil pickup,
  • Cam cover plastics,
  • Engine mount and gearbox mount,
  • Gearbox, clutch and flywheel.
  • AUS/BCB oil cooler needs to be undone and swapped for the 1.4 equivalent.
  • Alternator, air con pump and bracket.
What you would be left with here is a car that had around 110bhp and a lot more torque over the standard 1.4. It’s also an engine that’s pretty bombproof and simple compared with the FSI. The engine is physically the same size and design so given that you have to use the AUA/BBY cambelt cover too, the fitment will look completely factory.

The car will also run on its factory AUA/BBY ecu and no modifications to the wiring loom will be needed.

The engines are cheap enough to buy (they were in every 1.6 mk4 golf for 5 years, so are readily available). I think this conversion is a happy medium for A2's as it gives the reliability and ULEZ compliance of the 1.4 with the power of a remapped 75. The best of both worlds maybe.

To get yourself a relatively easy conversion and an extra 30 bhp over standard, you could stop there.

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Setup 2 BCB/AUB/AVY Frankenstein

The engine that I’ve been fitting this weekend has gone a little bit further with the following specs



  • BCB engine block
  • AUB rocker cover with cams
  • Polo GTI inlet manifold with larger throttle body
  • Larger diameter ignition leads
  • Polo GTI 4 branch cat free downpipe that will need to be welded onto the existing downpipe under the car.
  • Custom cold air feed direct to cone filter
This additional work should see the car around 130 bhp (having now driven the car and having experiences of varying different outputs of modified A2's i'd put this closer to 140).

Please note if you are going to do this, the Polo GTI inlet manifold holds larger cc injectors which require you to change the connectors over on the loom (solder and heatshrink wrap job).

The AUB ECU will plug into the standard loom too, but you will need the pin code for both the original ECU and the AUB unit, you can then program the AUB pin code to match the existing pin code with VCDS to overcome the immobiliser.

The AUB ecu also allows the car to rev from the standard 1.4's hard limit of 5800 to 6500.

Ideally it would be great if someone could delete the immobiliser on the Magnetti Marelli AUB ecu and then the whole job really would be plug and play.
 
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It2s great to see others working on such projects. I'd like to do this mode, but it's just too complicated to my level of engine knowledge.
Perhaps if all goes well, I definitely like the bullet-proof with ~100hp idea, could this have a service potential? What the cost would be for such mod including parts+work time?
 
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This is very cool!!!! Great write up. Ive got most of the parts for this so will see if a spare pair of knowledgeable hands want to embark on this kind of work with me.


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This is very cool!!!! Great write up. Ive got most of the parts for this so will see if a spare pair of knowledgeable hands want to embark on this kind of work with me.


Sent from my iPhone using Tapatalk
Go for it. Any competent DIYer could do this conversion.
 
It2s great to see others working on such projects. I'd like to do this mode, but it's just too complicated to my level of engine knowledge.
Perhaps if all goes well, I definitely like the bullet-proof with ~100hp idea, could this have a service potential? What the cost would be for such mod including parts+work time?
Time and space would be against me. I only have space for one car in my garage which is always a breaker. If something was to go wrong with the car afterwards i'd have no space available to put it right either.
 
I have the BBY with the "usual" piston slap, so this is very tempting. No issues going from a cast alloy to cast iron block weight-wise?
 
I have the BBY with the "usual" piston slap, so this is very tempting. No issues going from a cast alloy to cast iron block weight-wise?
25kg extra but having now driven the car you can’t notice it in any way. It’s sprung weight so an insignificant amount.
 
Sounds good. Guess the iron blocks are not that suspectible to the piston slap issue either. :)
 
Sounds good. Guess the iron blocks are not that suspectible to the piston slap issue either. :)
I would have thought that it would have been wear to the piston rings causing the slap rather than variance in the block but i'm just guessing.

Guess we will be going down the same route then, only difference is my car being single-coil 🙂

Would be great to see others following the same path. If you can find an AUS then you won't need to worry about changing the rocker cover and disturbing the timing kit if its got a known good one.
 
Just some more questions:

1. ECU. Will it be of any benefit using the BCB ECU, or is the BBY similar enough for it not to matter? If it is a point in using it, only immo reprogramming is needed to make it work?

2. Is using a Lupo GTI intake and bigger throttle body of any significant benefit?

3. Oil cooler. The BCB uses an oil cooler/heat exchanger, the BBY does not. Of course it can just be removed, although I guess it does have a mission when the factory installed it. Does it interfere with the oil fill tube, or will it be too close to the radiator/fan shroud?
 
Just some more questions:

1. ECU. Will it be of any benefit using the BCB ECU, or is the BBY similar enough for it not to matter? If it is a point in using it, only immo reprogramming is needed to make it work?

2. Is using a Lupo GTI intake and bigger throttle body of any significant benefit?

3. Oil cooler. The BCB uses an oil cooler/heat exchanger, the BBY does not. Of course it can just be removed, although I guess it does have a mission when the factory installed it. Does it interfere with the oil fill tube, or will it be too close to the radiator/fan shroud?

1. I don’t think running it on the BCB ecu has been tried. If you are just doing the basic BCB block only swap then the BBY ecu will be fine. If you are going for the hybrid engine like I have in mine then you will need an AUB ecu with the pin code matched to your clocks.

2. Yes as you go higher up the Rev range. One of the contributing factors to going from 105 bhp to 135bhp+

3. Has been run for 20k miles without one with no issues. Yes you lose the oil filler tube and dipstick so you will have to fill from the top of the engine. There is an dipstick at the back end of the engine anyway.
 
Thank you! Seems like a BCB ECU (can ne had for cheap too) will be a good thing to try. Same with the Lupo GTI intake and throttle body. The exhaust side might be a bit restrictive though.

The question about the oil cooler is due to German Autobahn stretches where you sometimes run 5000+ rpm at wide open throttle for a while. So the stock BCB cooler will not physically fit? I suppose an aftermarket air to oil cooler can be installed using a sandwich plate, then. :)
 
If you use the GTi inlet manifold it has bigger injectors that will need the AUB ecu to run it.

If you can get the BCB ecu to match the clocks then hopefully it will work for the bigger injectors. It’s a bit of an unknown.

All I do know is that the Polo GTI inlet, TB, injectors, exhaust manifold, AUB head, BCB block and AUB ECU makes a cracking setup.
 
Gathering some more informaion and parts to tackle this next year. Looking on ebay at the BCB Ecu’s most of them dont say if they have a pin for it. What can be done to source this?

Buying the mechanicals is one thing but car electronics no matter how simple worry me.


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Gathering some more informaion and parts to tackle this next year. Looking on ebay at the BCB Ecu’s most of them dont say if they have a pin for it. What can be done to source this?

Buying the mechanicals is one thing but car electronics no matter how simple worry me.


Sent from my iPhone using Tapatalk
If you are just going down the basic BCB engine swap (option1), then you don't need a different ECU, it will run just fine on the AUA or BBY one.
 
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I sourced a Lupo GTI intake with injectors and throttle body for a decent price. Still haven't been able to find any info on the flow rates of the injectors, though.

Will try to figure out if the BCB ECU can be made to work with Lupo GTI injectors and throttle body. Don't know if the BCB uses the "small" or "large" throttle body. The BCB is anyway compatible with the 4-coil setup I have on my car.

Still not entirely sure what to do on the exhaust side, if the BBY with pre-cat is very restrictive or not. A cat in good working order is not a problem..
 
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