VW 1.9 TDI: 66kW vs. 81kW - What's the Difference?

Hello forum members,

I'm not particularly skilled at working on engines, but I'm very eager to learn. Since there are many knowledgeable people here (or so it seems to me ), I hope someone can explain to me what the difference is between the 1.9L TDI engine from VW with 66kW and the one with 81kW.
What exactly did VW change to extract those extra 15 kW? It's obviously not just a change to the engine control unit (ECU) software, because the existing 81 kW can also be further increased (through software).
Perhaps someone can explain this to me?

Thank you & best regards,

Ole.

It depends on which 66 kW and 81 kW models you are referring to.

In the Golf 3, the difference was essentially a different turbocharger. The 66 model (1Z, AHU, ALE) had a turbocharger with a wastegate, while the 81 model (AFN) had a VTG (Variable Turbine Geometry) turbocharger.

The VTG LAder is explained very well here http://www.technologie-entwicklung.de/Gasturbines/VNT15-Turbo/vnt15-turbo.html. (I assume you know what a wastegate turbo looks like.)

The Golf 4 initially had a 66mm wastegate (AGR) turbocharger, and later a 66mm variable geometry turbocharger (ALH).

Currently, VW only offers VTG TDI engines (except for the 1.4 three-cylinder 75 hp engine in the Lupo and Polo).
(I don't know about the 3L Lupo.)

m;

There are many posts about this topic in this forum.

Here's a tip: Try searching for the two most common engine codes, '1Z' and 'AFN'; you'll likely find a lot of information.

Regards,
Private.

Aside from the turbochargers (which only play a very minor role), the two performance variants differ only in the fuel injectors.

-> Technical article on turbo tuning or an excursion into the AKTE database.

CU Gremlin.

...but the control units, ESPs, and much more are different.

The question is, what is truly IMPORTANT in the difference?

I definitely forgot about the nozzles.

The hole diameter of part 1Z is 184 micrometers.
AFN 205

m;

Find out what types of pumps are installed in those engines.

Warning: 1Z is a special case because it still had some signal boxes with potentiometers.

Otherwise, you will find the same pump for engines AGR, ALH, AHF, and ASV .

The engine control units differ only minimally in terms of their characteristic maps (e.g., the EGR map). This can be easily logged (RWG voltage) by driving the vehicle before and after replacing the injectors.

Only the nozzles are really important.

CU Gremlin.

However, the 1Z pumps with HDK and AFN codes are different, at least according to VW part numbers.

or am I just completely losing it?

m

The 1Z pumps with HDK and AFN are also different - at least according to VW part numbers.

or am I just completely losing it?

m

No, that's why I'm saying that the 1Z is a special case because it's very old. The pump there is also mechanically different. That's why the other pumps simply don't fit there mechanically...

but otherwise, all have the same pump. Except for the ALH with automatic transmission, of course, which has 11mm pistons...harharhar .

CU Gremlin.

Ah, I've learned something new again.

saving info ...... done.

m;

Thank you very much, everyone.
I missed that: AHU engine, 11/98, Passat Variant 1.9l TDI, type 3B (automatic).

But if I understand you correctly, the main issue is likely with the nozzle, possibly also the turbocharger, and the software. Does the AHU engine even exist with 81 kW, or was it given a different name?

As you can probably tell, I'm still quite new to this. Thank you very much for the helpful and informative assistance!

Best regards,

Ole.

Hi Ole,

Thank you very much, everyone.
I missed that: AHU engine 11/98 Passat Variant 1.9l TDI type 3B (automatic). The AHU is exactly the same as the 1Z (I own one myself). With the 1Z, only the serial numbers were exhausted, so VAG used a new engine code. (It sounds silly, but that's how it is). There are no more technical differences than there are between other model year changes of the 1Z (minimal).

But if I understand you correctly, then it's mainly about the nozzle and possibly the turbocharger and the software? Correct! Please read the article about the 827 engine block. Then you will notice that (almost) all 4-cylinder TDIs are based on the same block and only the attachments have been changed. (Link: here)

Does the AHU even exist as an 81kW engine, or was it renamed? Each engine code fundamentally represents only one power output! As soon as even a minor change is made, a new engine code is assigned. The AFN, as I mentioned in my previous post, is the closest to the 1Z (and therefore the AHU) with an output of 81 kW.

Regards,
Private.

Why do you want to know the difference?

When it comes to making a purchase decision, I wouldn't necessarily choose the 1Z.
You can easily find reasons using the search function.
P.S. Before I knew about this forum, I wouldn't have known the correct information, and I would have likely chosen the wrong engine and then been frustrated.
There was nothing bad intended against 1Z drivers .

I think the question would be easier if you asked what the difference is between a 66kW and an 81kW engine.
Namely, the engine block and cylinder head.

When it comes to making a purchase decision, I wouldn't necessarily choose the 1Z.


If you have the choice, which is often not the case. For example, with the Passat 35i, you usually don't have a choice, because the AFN engine costs significantly more (around €1,000 - €1,500 difference, which is a lot considering a purchase price of €3,500), despite having the same equipment.

The 1Z engine isn't as bad as some people make it out to be. Yes, it has a wastegate turbocharger, and there are some reported issues with the pumps (as you can read here). However, we never regretted the decision to put a 1Z engine in our Passat 35i B4. The engine was incredibly robust and rarely gave any trouble (except for the boost pressure regulation, which I was investigating, but then an accident happened that resulted in a total loss *cry*), and it didn't have any misfire problems. The base engine was also very reliable; the only issue we had was a leak in the air conditioning system.

Well, now we're driving a 3-series with an automatic transmission, but it's just not the same.

Best regards, WarLord.