TDI 1.9L to 2.0L: Bore Up Guide

Hello,

I currently have a defective AFN engine block at home, and I'm wondering if I should bore it out to 81mm and use pistons from a 5-cylinder inline engine (2.5L). Is this possible, or will the pistons even fit? (Of course, the oil jet system would need to be modified).
Has anyone ever done a conversion like this before?

Regards

There was a similar case in the Deppentuning.at forum. It experienced a piston seizure after a short time.

I don't think something like that is durable or practical for everyday use. I'd rather have more torque than more displacement.

Hi,

IMHO, there shouldn't be any piston seizure. It's probably not drilled and honed optimally (incorrect piston clearance, uneven surface).
One reason why I personally wouldn't modify the 1.9 engine is the deck width between the cylinders.
Let's see how long the timing chain tensioner lasts on the new 2.0 TDI engines with 170 horsepower.

Best regards, Rainer.

Hello,

Thank you for your opinions.

I was afraid of that too, but I can't believe I missed it. The amount of work involved is also disproportionate, especially since I also have to take on the connecting rods (with 30mm piston pins).
Then, let's go with a longer shelf life, and next time, we'll add more.

Regards

It's not true that you can damage a piston by boring a cylinder.

I built one myself, a 2.0 model.

The pistons require a small recess for the oil spray cooling of the piston crown.
If you install 81mm pistons, you also need to use the corresponding injectors with the appropriate spray pattern to ensure long-term reliability.

There are even pistons with a diameter of 83.5mm (2.1L).
'Are there only problems related to the cylinder head gasket?'

But with an 81mm bore, everything is still within the acceptable range.


VAG also builds the 2.0 TDI engine with the 81mm bore as well.
Engine displacement is still irreplaceable by anything.

and it only benefits the charging behavior of the device.
I would definitely recommend drilling it.

Why bore it out? Install pistons that reduce the compression ratio from 19.5:1 to 18.5:1! No drilling required, no risk of piston failure, and ready for more power.
See:http://shop.dieselschrauber.de/

Sincerely,
Fabu

...nonsense.

To reiterate: you will not experience piston failure from using higher octane fuel!
That's absolute nonsense.

So, if someone already needs new pistons anyway, I would even recommend boring out the cylinders, because it improves the engine's responsiveness.
Engine displacement is known to be irreplaceable, even if it's only 100cc.

to reiterate,
to add to that,
just to reiterate,
to go back to that,
to circle back to that,
to bring that up again,
to mention that again,
to emphasize that again.

With my 2.0-liter engine, I haven't experienced any problems with the head gasket.

Regarding the topic of step size.
The absolute, meaningful upper limit for the bore diameter is 83.5 mm for the 827 models.
88mm is the cylinder bore diameter. Therefore, there are 4.5mm remaining if you fully utilize the 83.5mm.
At a diameter of 81mm, the head gasket seals onto a surface of 6mm. The head gasket bore is 1mm larger than the cylinder bore.

Best regards, G.

FaBu wrote:

Why bore it out? Install pistons that reduce the compression ratio from 19.5:1 to 18.5:1! No drilling, no piston seizures, and ready for more power. See:http://shop.dieselschrauber.de/ Mfg Fabu

Are these still available?

Hello,

what is?

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

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.

Fabu wrote that there are other pistons available on the "dieselschrauber" website (although I don't quite understand what he means by that).

There used to be pistons with a larger cavity, but it wasn't cost-effective, so they haven't been part of the product range for a long time.

Best regards, Rainer.

Rainer, can you tell me why it wasn't worth it?

Best regards,
Mario

"Oh, even though I'm not Rainer, I think it didn't make economic sense (ha, a pun), and it certainly wasn't about reducing the density."

matthiasTDI96 wrote:

ohh, even though I'm not Rainer, I think that, commercially (ha, a pun), it wasn't worth it. It certainly wasn't about reducing the density.

You would have deserved a +point just for that.