I wrote this on a FB group (no not the Club GTI one) and slapped myself when I realised it was too long to read and some folk night take a dim view to be "educated". So I deleted it and put it here. The youngsters today come with all sort of hype often generated by the influential but sadly misinformed. We have seen comments, inevitably to identify VR6 12v hardware changes, as "OBD2" VR6s, even if the comments that are being made are in Europe and not North American. We have seen the misconception that KR 16v cams are the best for a 16v or the twin exhaust cam mod. Truth is, a KR intake cam would have been better for performance on early 9A 16v motors before there were ABF engines. Of recent, "BAM 20vT engines are the best as they are forged..." . Oh dear. The latter I will like to take time to delve into. It is best to come from Club GTI as we are known for debunking many myths. VW/Audi produced thousands of EA827 and EA113 20v turbo engines over the years between 1995 and 2005. Engines output varied depending on applications. During that time tailpipe exhaust standards, overall emission regulation/monitoring and CO2, became more stringent in various markets and engine control complexity grew while power demand from the customer went up. VW/Audi are not a charity and as you will imagine do have to make profit from each production powertrain fitted to a customer vehicle. I will attempt to show at high level, what hardware and controls match the various types of EA113 1.8T engines, in the hope of enlightening folk about them. If you build these engines and know them intricately and are well versed in what I am presenting, then this post does not apply to you. If you think a "BAM" coded motor is better than all the rest, then read on as this post is for you. High output, premium brand low compression EA113 20vT engines. There are 'low' comp (9:1) 'high power' 20vT engines that fall into EU2 or EU3 category. The 210ps EU2 engine was an APY/AUL fitted to the 8L S3 The 225ps EU2 engine was an APX fitted to the 8N TT The 210ps EU3 engine was an AMK fitted to the 8L S3 and 1L Leon Cupra R The 225ps EU3 engine was a BAM and was fitted to the later 8L S3. 8N TT and 1M LCR To separate the TT flagship model a 240ps EU3 engine - the BFV, was fitted to the first version of the Audi TTS as seen above. For the above engines, EU2 power differences were based on a calibration setpoint as the hardware was the same. Similarly EU3 power differences were based on a calibration setpoint as the hardware was the same. Engine codes were based on power rating and territory. For example Europe's EU3 225ps BAM code had a sister the BEA code destined for the North American EPA market. EU3 engines had increased emissions monitoring and were EOBD compliant, so the Bosch ME7.X ECU gained computing size from 512k to 1024k and the hardware gained some features, such as 2 stage VVT, planer/UEGO sensor, and an actual upstream EGT measurement. The head, crank, pistons, rods and block, are the same between EU2 and EU3 low comp engines. All engines ran similar air charge piping and twin side mount intercoolers, to suit various types of 5304 KKK turbos. The cylinder head has a cast hole to incorporate charge pipe brackets as seen circled below. Low power, high compression EU2 (excluding large port AGU/AJH) and EU3 engines. For more mass produced VW group vehicles, the firm used a cheaper engines in the powertrain line up. These engines run higher compression, biasing towards fuel efficiency and have the power and torque reduced compared to what was termed "high power low compression" engines. Low power high compression EU2 Era Initially EU2 high compression engines, shared many components with their low compression, high powered EU2 and EU3 counterparts, except higher compression Mahle pistons with 9.5:1 CR, a less capable turbocharger 5303 turbos or later a combination of 5304 compressor wheels and 5303 turbines, different charge systems, a single side mount intercooler and the lack exhaust valve spring shims. Picture taken from my own engine work shows the differences in piston dish between an AJQ piston @ 9.5:1 CR on the left and an AMK @ 9.0:1 on the right. Low power, high compression EU2 engines examples were: ARZ, AJQ, AYP, APP, APU, AJL. Picture below shows a 6K Ibiza which ran an EU2 AYP engine. Low power high compression EU3. Engine cost cutting strikes In order the maximize profitability, in preparation for EU3/EOBD in 2001, low power 20v engines had a few changes to the controls and reciprocating mass. Pistons were changed for new 19mm small end tapered conrods, dropping the old '027' rod design that was used since the days of the EA827 8v. Rod big ends were also cracked. Picture below shows the new EU3 06A cracked rods. The EU3 era also brought EOBD emission monitoring with it. This mandatory emission monitoring standard was required for European vehicle homologation and bares similar complexity to OBD2, introduced in North America 5 years earlier in 1996. As a result ECU memory was increased as per the EU3 high power low compression 20vT engines. To help reduce cold start emissions, a fast heating UEGO sensor (Bosch LSU 4.2) was utilized. 2 stage VVT, allowing 22 degs of movement on the inlet cam was a feature shared with the high power 20vT. To save cost, exhaust gas was modelled throughout the system which saved fitting expensive EGT sensors. Familiar low power high compression engines codes that were EU3 were: BFB from the A4, AUM and the AUQ from the Golf 4 BJX/BBU from the Polo GTI. The Golf GTI Anniversary 25 below ran a 180ps EU3 AUQ engine. Differences high power EU2/EU3 20vT to low power EU2 20vT As mentioned above, the higher power from 210 to 240ps base motors differ from other lesser 150 to 190ps engines via the piston dish (9:1 vs 9.5:1), the addition of exhaust valve shims, hole for charge pipe on the cylinder head and of course turbo hardware. Blocks and cranks are the same. Examples of EU2 'lesser' engines, that are similar to the low compression high power engines, are the ARZ, AJQ, AYP, APP, Pre 1999, the 150ps high compression AGU/AJH has a similar short engine to the EU2 low compression engines above but has the large port head. The large port head was later dropped dropped due to poor port velocity. These early engines were controlled by an ECU derivative of 12v VR6 or 10v VR5 - the M3.8.X ECU. AJH engine below plucked out of a VW Sharan MPV. I hope this post helps to enlighten the actual differences found in the 20vT engines and it is my hope the hype seen for buying up cars with so called BAM engines becomes a reductant fad of the past.
If I remember right from when I looked into it years ago, all engines, from 3.2 downwards (I think it was 2003-2005 years?), were all built using 4130 material on the bottom end, or at least the crank - making a 4340 a good base upgrade given the strength variances; https://www.capitalsteel.net/news/blog/4130-vs-4340-steel-comparison
While this is not a EA390 thread, EU4 VR6 engines did have cost cutting measures for components like the crankshaft. But I will have to leave that for another thread as I wish to keep this one strictly EA113 20v based.
"All" engines, 20v included (I forget the years, around 2000-2005 ish models, only the 1 to 3.2 litres if I remember right as it was an Audi report). I just found it interesting that a 20v or R32 crank is essentially a re-designed 1 litre one! You'd think given the additional stresses and thermal loads on the performance vehicles they would have somewhat upgraded, but if so, then it's only at the manufacturing stages (forging v casting I guess), I just though you'd be interested as you were talking about the bottom end. EDIT FOR BELOW - Apologies. didn't mean to detract, I've been looking for the pdf of those facts for people interested, was a decade ago though but I'll see what I can dig up, bulk buying tons of steel is nothing new though and stands to reason, I always find the limitations of oem interesting given their budgetary constraints and thought such things may be a part of the oem production information that you may want to include.
OEMs tend to carefully choose when to make changes like that and have very good data sets to support such changes. It is off topic for this post but you are free to PM any links that make the original quote.
I think some ebayers must have been reading this thread - it seems people are asking the same money regardless of whether its AGU, AUM, AUQ or BAM
Very interesting Eddie, I like these kind of articles full of fact and not myth or hearsay. In my case when I was looking for a TT to run as a track car I looked for a BAM engine car purely because they come with the EGT , VVT and wideband Lambda . Makes tuning them a lot easier and I believe there is more protection for the engine especially if you are pushing the limits. The ECU will recognise if the fueeling is lean and try to add extra fuel and also the EGT protection is handy.
EGT is modeled on the Exhaust Gas temp feature for most vehicles without an actual sensor. OEMs do a very good job in ensuring various temps points at the, valves, exhaust flange, turbo, and cat are validated within a band of tolerance before the vehicle can be signed off. Having an actual measured exhaust gas reference pre turbine, just helps with a more accurate model for the rest of points I listed. I have experimented with VVT and several other ME7 features on a 20vT, using my own 8L S3. I have confirmed VVT is stepped between part load over lap and some internal EGR for FE and NOX reduction with the inlet opening at ~-4 deg BTDC. At full load post 4400rpm, the inlet cam actuator is de-energized and the inlet cam stops in its end stops at 18 deg ATDC. Effectively for performance mode, a VVT engine is the same as a non VVT EU2 APX, APY and so on. Planner sensors (UEGO) are used to have more accurate control of fuel mixture set point from cold and at high load. Pre EU3 it was modeled, adapted and learned via the front binary sensor. Pre EU2 vehicle's can still be mapped without UEGO feedback, if you would cast your mind back to AGU/AEB, APY 20vT engines as well as various 12v vr6 turbo and supercharged cars. Later post EU3 ME7, is just far easier for folk to re-calibrate, both commercially and now by the home user.
