Conversion of a gasoline engine to diesel

Hello everyone,

I've been toying with the crazy idea of converting my somewhat older Passat, which has a gasoline engine, to run on diesel.

The vehicle is a Passat Variant Type 32b Syncro (Audi Quadro all-wheel drive system), and the body is in very good condition. It was manufactured in 1986, has 313,000 km on the odometer, and is powered by a 2.2-liter 5-cylinder engine producing 120 horsepower.

'For the conversion, I would ideally like to install an Audi 2.5L TDI 5- or 6-cylinder engine, preferably with a PD (Pumpe-Düse) injection system. (If necessary, I would also be willing to settle for a 1.9L TDI-PD engine).'

I am already aware that a significant number of modifications will be necessary (fuel lines, transmission, braking system, engine control unit, catalytic converter, possibly with a particulate filter).

What mainly interests me is whether something like that is generally allowed.
Furthermore, the engine control unit (ECU) must (should) operate independently, without any immobilizer, ABS, or any speed sensor signals; is that even possible?

Has anyone ever done something like this before? Could someone give me a rough checklist of what's needed? I suspect that the 'small details' will probably take up most of the time and effort.

Regards,
Irish beer.

P.S.: If anyone was going to advise me to just buy a new car, I can only say that the only thing that still excites me about new cars is the engine and the temperament of modern diesel engines; everything else can go. I will be selling my Octavia 4x4 74KW TDI PD. Right now, I'm not convinced by any new car, regardless of the manufacturer.

It's simple: You won't find the 2.5L 5-cylinder PD TDI engine yet, and if you do, it won't be at reasonable prices. The 2.5 V6 TDI engines are not PD engines.

Next problem: It's not enough to just have the engine with its wiring harness; there's so much other junk attached to it that it can be sickening. We should mention the immobilizer system, which is usually located in the combination instrument panel of the engines mentioned above.

Drivetrain: Your engine probably won't be putting 250 Nm or more of torque onto the transmission. In that case, you would need to replace the entire drivetrain.

It's likely the inspection will end up being a single-vehicle inspection, since your car didn't originally come with that type of engine. However, I'm not entirely familiar with the specifics of this process.

It's nice that you're still driving something classic.

Best regards, WarLord.

Basically, only the engines from the Passat 3B and 3BG are suitable, as they have all been installed before. I wouldn't worry too much about the drivetrain itself, but the transmission and the quattro's transfer case probably won't handle the torque very well, and after 313,000 km, the clutch and other components with TDI technology will likely fail quickly.
If you manage to do that, then the braking system might need to be upgraded with potentially larger brakes, but it largely depends on the new gear ratio. With your current transmission, your TDI won't be faster than your 5-cylinder engine.
Do some research on the dimensions; a PD 4-cylinder engine is quite large compared to a gasoline engine!

Matthias.

Good luck!

Hi,
I've read about converting to a 2.5 TDI 5-cylinder engine somewhere before, maybe you could check the Passat registry.
The A6 transmission should also fit within the transmission tunnel, but I'm not sure about the rear axle and other components.
I also suspect that there will be very little space in the engine compartment of the 32B, as there is already very little room in the A6 with its 5-cylinder engine, especially at the front and near the firewall. (And that thing has two timing belts!!).
The 6-cylinder engine might be a better fit in that case, especially because you should be able to find suitable front subframes from the Audi 80 B4 for the 32B.

Since you would need all the technical components from either the C4 or 4B models anyway, I suspect that, considering the time and effort involved, you would be better off with a well-maintained Audi C4. Especially with higher mileage, the A6 as a C4, produced from around 1996 onwards, is no longer really expensive. And as for the lifespan of these vehicles, especially those that have had their oil and timing belt changed according to the maintenance intervals, you can read about it here in the forum.

Regards,

Olli.

Hello everyone, and thank you very much for the initial responses.

Okay, I'm already aware that I need to do something with the transmission. The Passat in question is a 5-cylinder model, so I'm familiar with the space constraints in the engine compartment.

Vor einigen Monaten hatte ich bei meinem 'Haus und Hof'-VW Händler (bei dem mein Vater schon Stammkunde war) so ein Betrachtungsgerät für diese Microfime samt einem ganzen Satz Microfime für ein paar Euronen ergattert. Hier habe ich schon mal bei den Getrieben von Audi und VW gestöbert, was zusammenpassen könnte. Es ging mir dabei eigentlich um Zahnradsätze, damit ich überhaupt auf eine vernünftige Übersetzung kommen kann, denn sonst würde mein Passat mit dem Diesel ohne Getriebeänderung mal höchstens schlappe 160 laufen. Das sind ca 30kmh weniger als er jetzt mit dem Benziner läuft. Laut Tacho komme ich auf ca 195; im Windschatten eines BMW hatte ich es auch mal auf 205-210 gebracht, aber das nur nebenbei. EiA top speed of approximately 210 would be perfect.'Welcome! After all, I don't want to race with this classic car.'
I have fewer concerns about the torque with the main gearbox, but I'm more worried about the rear differential, which seems undersized even for the gasoline version. It's not much 'bigger' than a shoebox.

Speaking of torque, the torque on my current machine is specified as 170 Nm at 3000 rpm.

By the way, I bought a used replacement gearbox about a month ago. According to the seller (a Passat Syncro mechanic), it should have around 80,000 kilometers on it. Based on the appearance of the gearbox, the transfer case set seems to have been replaced, at least the housing piece in that area is new.

Regards,

Irish beer.

Enjoy your meal!

My dream car!
32B Syncro with turbodiesel engine!

I was planning to modify a second-generation Golf Syncro last year, but then I didn't because...
Due to space and time constraints, and because the TÜV (German technical inspection authority) required a minimum gear ratio.
that corresponds to the original (i.e., the diesel engine), and I didn't ask anything further.

"Why don't you ask the testing facilities in your area what they think and what they..."
want to have.

If it can't be a TDI:
The AAZ engine (1.9L indirect injection) can also be tuned to produce 130 horsepower and 240 Nm of torque.
The AAB (2.4L swirl chamber) is only available as a naturally aspirated engine, although some companies offer...
You can get a turbo conversion kit for that car; it will definitely make a difference.

Advantage: No electronics.

Hi, Jockel.

And, what happened to it?