AFN Engine Tuning: 6-Speed Optimization

Hello everyone,

In the past year and likely in the near future, my car (Ibiza 6k, '98, AFN, CYP, 260,000 km) covers approximately 85% of its mileage on highways.
Overall, I am satisfied with the car and the associated costs.
However, there's a big BUT: I find it impossible that the tachometer already shows over 2500 RPM when the speedometer reads 120 km/h.
I believe there is sufficient traction available to lower the engine speed towards 2000 rpm at a real-world speed of 120 km/h (e.g., 130 km/h on the speedometer), which would reduce fuel consumption. I would also gladly accept a quieter driving experience as an added benefit.

Now, a lot has already been written and discussed on this topic. However, it seems there are no shared experiences available. If anyone has any, please share them here.

As for the actual renovation work, it is likely to be quite extensive.
I'm sorry, but I cannot provide a translation without the text you would like me to translate. Please provide the German text that you want translated into English.
What makes me somewhat hesitant and raises questions about the practicality of this relatively old vehicle, especially considering environmental zone restrictions.

There are likely also conversion kits available.
/viewtopic.php?t=314&highlight=afn+6gang
It would be great if someone could give me a tip on where to find something like that, preferably via private message.

Then I had the idea whether it might be possible to only replace the internal components, so putting a 6-speed gearbox into a 5-speed housing. It's probably never been done before because it wouldn't work.

My actual question concerns the benefits of such a conversion, which I would like to clarify through some preliminary considerations.

I need the engine performance curve for the AFN engine, but neither the friendly customer service nor the KdF car dealership is providing any information, or my inquiries are simply getting lost.

Does anyone have anything for me? Preferably from SAE or MTZ publications.

Sure, here is the translation of the text from German to English:

"With the help of translations:"
http://www.dieselschrauber.de/GKB.html
Based on the engine characteristic curve, I can create and examine a diagram showing the "Jante/Normal" driving conditions and see how the entire process develops in terms of fuel consumption. I'm not yet sure how to handle the rolling resistances, but I will probably make generous estimates.

It would be great if someone had data for me.

I have a testimonial/review.
However, with a 1.4 TDI engine and a 6-speed gearbox (FSM).

The engine was running at 1600 rpm in 6th gear while traveling at 100 km/h.
at 130 km/h at 2100 rpm.
140 km/h at 2250 rpm.
160 km/h at 2600 rpm.
180 km/h at 2900 rpm.
(all values are approximate and based on memory)

It worked perfectly fine, even with the 3-cylinder engine! And of course, it was much more fuel-efficient; I also drove a lot on the highway.

The transmission is from a Volkswagen Polo 1.9 TDI with engine code ASZ, identification letter: FSM.

What kind of car was it, and do you still remember the fuel consumption?

It was an Audi A2.
"Around 140 km/h, which is about 4.7 liters [of fuel]... I can't say exactly. You know yourself that it's rare to be able to drive at a constant speed on the highway."

It basically doesn't matter what I used it for... the fact is, you will consume less with the transmission .

Okay, thank you. Now I'm interested in the characteristic curve data, specifically for the AFN.

Okay, I'm ready. Please provide the German text you want me to translate into English. Just paste it here, and I will give you the translation.

Unfortunately, that doesn't help me at all.

I don't know what your problem is.
You wanted information about a long gearbox... hopefully you've received it now!
worry about it and build it in

To make sure it's clear: I want to assess the potential of my engine and whether the effort involved is worthwhile. Comparisons with PD engines are just a reference point, but not reliable indicators ("dieselschrauber" confirms this in the link).

I'm afraid that the lower RPM will increase fuel consumption to such an extent that it won't really be worth it. I won't do the work for just 2 grams. That's why I need data from the AFN.

If you factor in the labor and costs involved, it's never really worth it to fix an old Audi A4. How long can a car from 1998 even be expected to last?

Even if you drive another 100,000 km with it, the 'savings' would be just €1000, calculated at a very generous rate of 0.8 liters per 100 km. With that amount, you can barely afford the necessary parts, if at all, especially if you don't want it to be complete scrap.

To figure out if it's worth it, I want to do some calculations. Based on the car's current condition, I estimate it still has about 140,000 kilometers (or miles) left in it.

Okay, it seems like we couldn't find any suitable candidates. It was worth a try, though.

That kind of thing never pays off.

Even if it doesn't help you with determining the fuel type:

"I'm in a similar situation with my car – a 2002 model with 180,000 km on the odometer. I've decided to just keep driving it until it completely breaks down. It makes economic sense considering how much value you lose with a new car, and I can realistically assess the condition of my current vehicle."
"However, I wouldn't start any major modifications, as the cost involved isn't really predictable, and €1000 can quickly disappear these days. The fuel savings won't be significant enough to justify it. I think, overall, the cheapest option is simply to continue as things are. If you happen to find a gearbox in good condition, along with other parts that are reasonably priced, and you enjoy tinkering, then it could be a nice project. As a hobby,..."

Basically, it's not really a problem.
Just remove the old gearbox and put in a new one... The parts are compatible with both gearboxes anyway.
You can sometimes find those transmissions for around 500 euros, if you're lucky.

I have an AHF engine that has been modified with a DRW transmission, which is very similar to the AFN. The fuel savings are limited. The conversion isn't quick because you have to replace many expensive parts.

For that, the car handles much better than before and accelerates really quickly on the track.

Es sind alle Gänge länger übersetzt als mein altes EBF Getriebe. Dann kommt nochmal der 6. Gaput something on top of it.

For every 1,000 RPM, you're traveling approximately 60 km/h.

Okay, my apologies... you have a 5-speed transmission installed... yes, that's already quite an expensive undertaking... and you won't be able to do it for 1000 euros.