Head Gasket Thickness

[chrisjunkie]

Hi all,

After talking to boostin today before he came to help re-build my shortblock, He asked what head gaskets I have. Genuine Subaru are too thin apparently.. and this is a very valid point.

I am going to go and get someone to work out my compression whatnots so that I know what thickness of gasket I need.

It is EJ208 heads going on a ver7 STi shortblock. Has anyone done this before and what thickness head gaskets did you use?

Thanks to boostin for his help so far.. had it not been for this piece of advice my engine might have been on track to blow up in the next few months! 8)

[PhatRS]

http://www.dragsource.com/index.php?navselect=calculators&calctoview=6

heres a good sight to work out what you need.

[chrisjunkie]

Shyte nice site! Will definately be using it, might save me some money!

How do I find out about the depth of the piston etc?

[Guest boostin]

You'll need to have the pistons and heads CC'd (both blocks, EJ207 and 208) and whatever CC you lose between the 208 and 207 you'll have to make up for in head gasket thickness.

[chrisjunkie]

Sweet and thats easy enough to calculate I suppose

[Guest boostin]

Yeah but the measuring needs to be done properly by an engine builder. Getting the compression wrong can make a good car a pain to drive.

[chrisjunkie]

So I get the difference in cubic centermeters? I'm getting confused. Does CC mean compression check? or Cubic centermeters haha

[Guest boostin]

Cubic centimetres.

A 0.7mm head gasket has a volume of 4.66cc.

A 1.2mm is 7.98cc.

A 1.5mm is 9.98cc.

A 2.0mm is 13.30cc.

http://www.online-calculators.co.uk/volumetric/cylindervolume.php

Its surprising the volume that's in such an apparently small area.

Genuine gaskets are anywhere between 0.7mm and 1.2mm depending on the engine.

[chrisjunkie]

I have measured the old HG's and they are 0.5mm thick. So my new 1.2mm HG's are a 0.7mm increase. This should be OK i'm presuming... thats a 4.66cc increase. It wont be perfect but I'm not going to be rap*ng it or anything so if its not quite right it should be sweet?

I know I'm being a royal pain in the arse but I'm trying to save as much money as possible without the danger of blowing the thing up again :-\

[Guest boostin]

Do your new ones say they are 1.2mm? Or is that what you're measuring?

[chrisjunkie]

i'm fairly sure thats what my packaging says. Will check later on today

[Wiretap]

the steel gaskets purchased from winger are 1.3mm thick according to tech docs.

[Guest boostin]

Just do it properly Chris. Stop trying to guess at it!

[Guest]

Yo Chrisjunkie.....

I think your've been a little freak out. Yes, you do have to be carefull.

This is a example of my engine setup.

EJ22T Shortblock 98x75mm, 1.3mm Thick Headgasket and Dish size of my pistons is 46.6mm ontop of that is a set of Sti V4 Heads.

I shot to that webiste and put those numebrs in alone

(Not taking into consideration the actual Cylinder Head Dish size also. Estimated 20-30cc)

My answer is 11.029:1, obviously way to high. If I enter the Head dish in "30cc" it drops to 7.547:1.

and the setup im running is meant to be 8.5:1

[PhatRS]

I dont see how that is going to help honestly, If you dont put in the correct figures how do you expect to get the actual compression ratio?

[Glen]

 PhatRS said:

I dont see how that is going to help honestly, If you dont put in the correct figures how do you expect to get the actual compression ratio?

Oi. Stop making sense. It's not appreciated!