Have you read the VW Self Study Programme releases on each engine?

They are quite easy to get hold of, and they do talk about the technology employed, though I think it's fair to say that you won't find anything particularly revealing, as I doubt they want to give away any manufacturing secrets to their competitors...

 

Main difference between two is DPF filter in newer BPC engine vs conventional catalyst converter in AXE. And it looks like VW made changes only necessary to facilitate for that:

• Different (smaller) turbo,
• exhaust manifold, added various probes: oxygen, egt, pressure
• camshaft has slightly different profile, but it is still weak point- had to change mine @280K
• I read somewhere about early bpc with smaller injectors, but I'm not 100 sure of this
• electronic EGR
• Intake manifold
• Ecu
• plastic rocker cover

I dont know about any major differences internally, but I'll be very happy to learn about them, if exist

 

Thanks both,

triffic - thanks, yes I think I have all the relevant SSP Info, I'll check again though,
...the R5 engine doc I have is dated 03.

karolwrobel - thanks, some things there I've now learned, camshaft profile is interesting, that might contribute to smoother running engine, smaller turbo too yet I think both are 128_Kw. same with smaller injectors, I'll check part numbers.

I'll keep seaching, if there were enough improvements it might be a better replacement for the AXE if ever needed.

 

I've read more about this in the past from a tuning point of view but can't find the threads now. The injectors and the camshaft are different, I'm pretty sure the injectors have a smaller stroke in the later engines, with a camshaft profile that is smoother. Whether this has anything to do with camshaft wear or injectors wearing their seats in the head I don't know, but it almost certainly has something to do with allowing a later injection of fuel to help with DPF regeneration. I'm pretty sure the downside of this is that you can't inject as much fuel so you will reach the ceiling when tuning sooner.

 

axd and bnz blocks are both the same in bore and stroke and the oil ways are the same. It does come with a smaller turbo on the bnz but this is a gen2 turbo so can still produce the same power as the axd. The turbo mounting is different and the injectors are smaller in the bnz 7.5mm chamber rather than an 8mm chamber of the axd. Mains, big end, little end bearings are the same along with piston design and rings. Both still have plasma coated bores and both are an 18:1 compression ratio . Camshaft profiles are lower on the bnz camshaft and has a double bump on the injector profile but this is for dpf regeneration. Head is the same on both and still have a 36mm inlet with a 31.5mm exhaust and share the same design followers. Exhaust manifolds are different as the turbos are different fixings and the later is cast where as the early is a pressed stainless steel laminate design.. Timing gears are the same a long with the firing order. Oil pump and windage tray are the same. The alternator shaft is different between the two with the bnz has a different profile for the drive so a different shaft.. Some bnz engines didn't have piston skirt cooling but most did, the ones that don't have a different piston profile to aid splash cooling from crankshaft lubrication. Rear engine mounts are not interchangable between the two. You won't be able to swap the later engine onto the old axd ecu as it won't meet the requested so mapping will need to be done. I've done the swap from axe to bnz but I have done other modifications just for a power point of view.

 

misterdave - thanks for reply, I have since seen a post by Pendle Performance, where an owner had
exchanged a BPC for an AXE and had performance limits because of the fuel injection mapping of
the AXE ECU not having enough duration, they copied and pasted the BPC parts into the AXE
ECU & it was ok then, (it may not have been as simple as that, probably had other tweaks also).

festa - thanks for reply, You've certainly got some experience with the 5 cyl engine I have noticed,
things like "The alternator shaft is different between the two with the bnz has a different profile for the drive..."
would not be noticed by many. The BNZ with it's different mountings etc, would not so much be a
possible swap as the BPC, although with particulate filter it would have the cast exh manifold I
suppose.

 

The problems your going to have is the later bpc/bnz has a different software in the ecu to run the egt and o2 sensors in the exhaust. The axd/axe ecu can be upgraded for this but not many can do it. I think you should be able to use your current exhaust with the v band to mate up to the later turbo without the use of the dpf. You should also should still be able to use your current egr if it's still connected and work it off you current vacuum. Most stuff will move over but I kept mine simple. For ease you would be better to keep your current engine or find another for a rebuild, they are out there.

 

Hi festa, thanks again, where I am there is even less known about these, you are right I'll be better off going for a straight swap if the time comes, it gets pretty deep researching the manufacturing processes, metallurgy, computer programming, racing engine tricks, etc. Just on that alternator drive, while checking around I found that some people had trouble with that drive shaft and gear in the gear train, also some other broken gear teeth.

 

Gears can go wrong on either code engine and broken teeth can be as simple as something has gone through or the gear has been moving and increased back lash. What tends to happen is the bushings on the gears get hot and wear but by then the harding will be knocked off the teeth which then increases oil supply to this area and reduces flow to others which then produces another problem. The bushings can be made up by a machine shop and also the top hats they sit on as these look like a tool steel ...Alternator shaft gets pitting from the front dust seal with water ingress on the shaft

 

Hi festa, thanks very much for the info, do you know of any people doing any commercial development of these 5 cyl engines and parts (British or cont. European) ?, seeing they only had a relatively short application life it would be difficult to imagine that there are.

 

There's not much available..uprated valve springs, forge rods, ground camshafts and thats about it..outside the engine air filters, turbos and exhaust manifolds are also available. Head bolts no as these are a 1.5mm fine pitch so these are a custom and not off the shelf.

 

Ok, thanks everyone, if I come across anything significant about these I'll be back here.