recommendations for vems or something else

[JariP]

How about considering that 20vt CR is only claimed to be 9.3 for marketing purposes and the actual CR is around 8.8 from factory. If it was real 9.3 my last two engines have been running over 10 to 1 after shaving almost 1mm off the deck and cylinder head face combined.

Anyway the 20vt combustion chamber and cylinder head are not bad at all. The intake port approach angle gives the air flow good tumble action in the cylinder and the critical burning phase happens right under the hot exhaust valves making it a somewhat fastburn chamber maybe even when comparing to genuine pent roof four valve chamber.

[A80Avant]

Also the headgasket makes the compression close to 9:1. I don't know how the 8.8:1 came up, unless you know someone from Audi who can confirm it or someone has actually measured it.

My ported head has also been extremely skimmed for higher compression but the chamber has been also modified to allow for less knock possibility. I'm running the same timing as I did previously on my non ported head and that setup.had pistons which were meant to.give 8.8:1 with the original headgasket. They were s3 pistons modified from pkm

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[gnutz2]

Also the headgasket makes the compression close to 9:1. I don't know how the 8.8:1 came up, unless you know someone from Audi who can confirm it or someone has actually measured it.

My ported head has also been extremely skimmed for higher compression but the chamber has been also modified to allow for less knock possibility. I'm running the same timing as I did previously on my non ported head and that setup.had pistons which were meant to.give 8.8:1 with the original headgasket. They were s3 pistons modified from pkm

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Ive measured it

http://www.s2forum.com/forum/showthread.php?t=25254

[A80Avant]

most interesting! good stuff

[GintsK]

gnutz2, could you please answer to my question in your CR thread? Seems to me there is one imprecision.
http://www.s2forum.com/forum/showthr...310#post608310

Gints

[gnutz2]

gnutz2, could you please answer to my question in your CR thread? Seems to me there is one imprecision.
http://www.s2forum.com/forum/showthr...310#post608310

Gints

I see whhat you did.

(3.14 x 81 x 81 x 0.5) divide by 4000 = 2.58cc

But if you look at a piston very very carefully only the squish in front of the inlet valves comes above the deck height by .5mm, it is actually tapered, the rest of the squish is level with deck.

I'll get a picture of a piston to show.

I went over and over the calcs but got the same anwser.