2.0 pistons: Aftermarket vs OEM

I am trying to setup a new engine configuration based on all the data I can gather.

The things that interest me on this comparison are:
1. Piston mass
2. Bowl shape
3. Material
4. Ceramic coating easiness
5. Lowering compression ratio by machining bowl or whole piston

I will start and address point 5.

By choosing OEM I can have the following:

1. 2.0 PD piston: 18.5 static compression
2. 2.0 CR piston: 16.5 static compression

My target is 16 static or lower.

To obtain this target with PD pistons the bowl will be enlarged too much. The OEM crown cannot be shaved to obtain lower ratios. Custom pistons might be.

Bowl shape and pip will affect combustion. Please view the following.

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Representation is done at maximum engine power.







Representation is done to compare maximum engine torque.



IP stands for Injector Protrusion and is measured in mm.

The only way you're going get below a 16:1 static ratio without custom machining is to use the Diamond forged aluminum pistons. However, don't expect much over 40-50K miles before the ring lands get worn out as cummins and duramax guys have found out.

http://www.mooregoodink.com/news/?p=1777

40-50k is more than acceptable for a competition/race engine.. Looks like the CR piston with some minor work would get you down about 16:1..

Yes. The CR pistons are a viable option. Low dead space volume, low compression ratio.
Hard to source. Expensive at dealership.

The diamond pistons may last longer on moderate driven TDIs.
For a competition car, 50K is more than 1 season. Much more.

Is there a weight difference between OEM and Aftermarket con-rods ?

A low weight but stronger combination of con-rods and pistons might put a smile on my face.