nick.bdk

well im trying to sort out my engine ready for the track. I need to know what head gaskets to put on, steel 1.40mm or 0.55mm or what???

Broxi

iTrader: (11)

unfortunately it is NOT a Guessing game.

deciding what thickness headgasket to use depends on a number of factors.

First you need to know what the final compression ratio is.

To accurately calculate compression ratio, you must know several things:
1) The bore of the cylinder
2) The stroke of the cylinder
3) The volume of the combustion chamber
4) The compression height of the piston (Ask for this from the piston manufacturer)
5) The dome/dish volume of the piston (Ask for this from the piston manufacturer)
6) The piston-to-deck clearance
7) The thickness of the headgasket
8) The bore of the headgasket

Of course you want to know what thickness gasket to use, so you would do the above calculations, and input the various gasket thickness until you get the desired Compression Ratio.

a couple of factors which can change the CR of a std engine would be a Head and or Block skim. also known as Decking.

Although i am a mechanic, I do NOT undertake calculating the CR for any of the Subaru Builds i have done, I trust the experience of my local engineering firm to do this for me, but they have the Block and Heads when doing so, I just then order the reccomended gasket thickness.


So my best advice would be, go to a Subaru Specialist, or check with your local engineering company see if it's something they can do for you.

If you ar having your Block Honed, ensure they have Done Subaru engines before and that they will be using Deck Plates when doing so.

nick.bdk

Thanks for that! well its all std and im not skiming the head or block, so do you think i should put the std gasket in but a steel one??

Broxi

iTrader: (11)

Have you owned the car/ Engine from day 1?

are you certain the head has never been done / Skimmed?

Next have you checked the heads and block to ensure they are True? as you could be taking a costly chance if not.

I have an engineering Straight Edge, which I use to Check heads and Blocks. I have only pulled one set of heads that has NOT at least needed a light skim.

First off I will say the cheap gasket set's on the bay for £50 - £85 will Fail rather quickly, and not worth considering.

Either get Genuine Subaru or a Cometic / Cosworth one..
I would always go with the Cosworth or Cometic MLS Gaskets myself.

Devious

iTrader: (4)

another vote for Cometic here also