RS2/S2 pistons wanted

[Pisobiker]

Ok lets see:

CR = compression ratio;
CV = cylinder volume;
Vcc = combustion chamber volume.

With 81 mm bore and 86,5 mm stroke we have:

CV = 445.5 cc

CR = ( CV + Vcc) / Vcc

which for a theoretical 9.2:1 CR gives a total Vcc (included head gasket thickness, piston dish, valve dishes and whatever) of 54,33 cc.

@ 1.3mm depth dish volume is ~3,55 cc so if we say I have missed 0.2mm on the ADU pistons difference would have been ~3.55 cc for ADU vs. ~4.1 cc for ADU.

New values give a CR of 9.12:1

To go at 9.0:1 difference should have been ~0.5 mm, like saying 3B dish depth of 1.3mm vs ADU dish depth of 1.8mm. I don't think I did a mistake that big!


Marco

[Audi Parts Guru]

Looks like i'm right then :nana:

[Doug_RS2]

Does the thicker RS2 metal head gasket not account for the slight difference in compression ratio?

[Greg_S]

all the S2/RS2's use the same head gasket now anyway dont they?

[Audi Parts Guru]

Doug, 3B/ABY/AAN/ADU engines all use the same metal head gasket now

[s2avant]

It looks like it could all be a case of Audi superceding part numbers. It's entirely possible that the pistons used to have different part numbers, in just the same way as the head gaskets used to be different.

I would imagine Audi probably decided to make just one piston so they would have to use the ADU version as fitting these to 3B or ABY engines would not be a problem.

The headgasket is the same situation. The RS2 used a metal gasket so instead of using different versions for 3B or ABY Audi superceded to one gasket for all three engines.

I may be wrong about the pistons (in light of the photographic evidence provided by Marco) but it would explain any differences.

Ben

[SteveH]

Guys, this is obviously another urban myth then You'd be suprised how many people I've spoken to, have advised they are different

[Jeffer]

This can also be one of audi's creative price solutions.

"Audi" Hmmmmmm, we are making a Rs2, lets see?????
Porsche powered.........?
People can not be told that the rs2 has the same pistons as S2, we lose our face on that.
Lets make up a new part number so we can charge even more rediculous prices on those pistons!
:wacked:

Just a thought, wondering through my mind. :wacked: