Compression dropping headgasket

[crazyass713]

Well some of you may have scene my thread on vortex (400awhp or bust)

basic specs are:

3071r
apr mani
garrett 500hp IC core
chris tapp tune (93 and 104oct for w/m)
direct port w/m
scat rods
bob q built head (hey bob did my friend come get that piston?)
cams of some sort, bob mentioned a 51 and 53 combo 

the details can be found here http://forums.vwvortex.com/zerothread?id=3468669



so run 034's .7 CR drop headgasket or not?

let me know why if you wouldnt mind, thanks -jake

[bobqzzi]

While dropping the compression is a good idea, using a thicker head gasket to do it is a bad idea.  One of the reasons these engines are so detonation resistant is because of the squish.  Using a thicker head gasket may actually result in lower compression and more detonation.

[crazyass713]

really... bob what squish are you refering to and how does it help suppress detonation?

[Bastard]

The RS4 version of the 2.7T does exactly this to drop compression .3 to a 9:1 ratio

[bobqzzi]

The RS4 version of the 2.7T does exactly this to drop compression .3 to a 9:1 ratio

The 2.7T doesn't have squish pads to begin with so it doesn't really matter. i believe this is one of the reasons the 2.7T usually has a lower specific output than the 1.8T

[crazyass713]

could you please explain the squish pad theroy to me? im guessing there are areas on the gasket that are softer and thicker (the squish pads) but what do they acomplish?

[Don®]

Example of said squish area:

[crazyass713]

thanks for the pics don, i know what squish area is... now my next question is why would the .7 cr gasket cause detonation? thanks for being so patient and informative guys...


happy holidays btw

[BoostdEuro]

While dropping the compression is a good idea, using a thicker head gasket to do it is a bad idea.  One of the reasons these engines are so detonation resistant is because of the squish.  Using a thicker head gasket may actually result in lower compression and more detonation.

[crazyass713]

let me rephrase that then...

why does the squish help supress detonation?

[bobqzzi]

Because it takes the end gases that are most likely to detonate and "squishs" it towards the center of the chamber which results in more turbulence which improves mixture homogenity.

[crazyass713]

thanks bob... thats the reply i needed... you have an email btw, some bad news for my build happened today