i'm Building a 2.0 zetec turbo engine at the moment and thinking of what headgasket to use.
Thought about a cometic one.
Gonna be running about 21 psi for now.
what do you guys recommend?

 

cometic

 

Standard Ford ones are fine at 500bhp.. and a lot cheaper!

 

Really??

like in other topics you said you only rely on things being tested rather then on stories...
Has this been done by many zetec turbo users?

 

Yes..

 

Hmzz Would save me some cash i can spend on some other parts....

Are the standard headbolts used here or arp ones?
thanks

 

Standard are fine

 

great ,

Thanks again

 

Put the cometic and standard Focus 2.0 gaskets side by side and you will not see much of a difference. Cometic has a wider selection of thicknesses though with Ford only having two to choose from.

 

It's for a silvertop zetec but i guess i can use the focus one or is the mondeo gasket the same?

 

Just go with a Focus RS one..

 

 

focus RS one bud

 

agreed focus Rs gasket is tried and tested

 

cheers Guys,

Wil get me one asap

 

mat lewis is doing ones on ebay,got mine for 20 quid

 

Hmzz.. but then there's always the p&p to holland.

Don't know what 1 will cost at the ford dealer.

 

About Ł30.

 

Focus RS gasket is the same than the nonturbo engines use. Only the ST170 gasket is thicker with fourth steel layer.

 

Hmzzz,
No i'm confiuzed
wich one to use then??
Just has to be good enough for my applacation.

 

Well, what gasket thickness does your piston/rod combo require to obtain correct squish?

 

st170 is what you need

 

go for the rs focus one for sure !!
st170 is thinner not thick as it is a high comp motor !!!

 

Does the thickness of these two make such a difference in CR?

Ok, this clears things up a bit ,lol

Wich one is stronger is more inportant or is strong enough for some reasonable boost ( minimum 21psi )

 

i had an st170 headgasket on mine for 5 years never any trouble 22 psi

 

It's very unconsiderate to make statements based on false assumptions. The difference in the compression rate is not made with the head gasket thickness. The ST170 gasket is on the order of 1.0mm and the other 2.0 gaskets, including RS, is on the order of 0.6mm thick. The thickness should be chosen so that the piston crown to cylinder head plane distance is optimum. Usually this is between 0.7-1.0mm depending on application. If you then end up with the wrong compression ratio, then you have an unsuitbale piston dish/dome volume.

 

Its right what you say about the pistons having a clearence to the head face but the thickness of the gasket does alter the compression ratio, the thicker gasket will create a larger squish area lowering the compression while the thinner gasket will reduce the squish area and increase the compression ratio. It wont make a huge difference but it does...FACT!

Thats why you can buy various thickness` of gaskets which makes up the "extra material" from having your head skimmed.

 

Very true. One thing must be kept in mind though. Usually CR is only reduced to counter detonation. One of the reasons for the proper squish clearance is to aid gas mixing and prevent detonation. Using a slightly thicker than normal head gasket can actually make an engine more likely to detonate because the squish is not working well anymore, but the CR is lowered too little to compensate. Using a spacer plate or similar to considerably reduce the CR is another thing.
Back to the point: The whole engine should be specced as a whole, including the gasket thickness. Extra care should be taken when mixing pre/post -95 or euro/us zetec parts.

 

I'll get the cvh head of first then and see how big pistoncrown to head distance is when i get either of the gaskets on.

 

If you are running low comp they should be well clear anyway, its high comp engines where you tend to get the most problems.

Place sum plasticine or mouldable wax on the highest part of the piston (if they arent flat), smear a small amount of oil on the head chamber, place the H/Gskt on, drop the head on, nip up the headbolts slightly, rotate the engine thru 2 revolutions, whip the head back off,slice through the squashed wax/plasticine in sections and mic up the thickness, try not to pull it off too hard (oo er!) as it will stretch and become thinner. (do this for all 4 to be on the safe side)

You are looking for around the 1mm mark, this allows for heat expansion and rod stretch at high rpm

Good Luck!

Oh...just to add, if you think the valves may come into contact, its the same principle but you will obviously need to put the cambelt on etc.... (solid followers would also be advisable to use as we all know the Hydraulic ones creep back in which will mean the valves wont be moving as much as if the engine were running!

 

Thanks for the advise,

CR wil be about 8.5:1

 

Well, went to the ford today,

They said the st170 was the same as the other 2 liter engines and only the RS was different.

Ordered the RS one and we'll see how it goes

Thanks for all the replies.

 

As I said in my reply to your PM, the RS is 3 layer (as is the normal 2L) and the ST170 is 4 layer..

Part Numbers

2L/RS = 1105772
ST170 = 1071744

I think your parts dept. needs a kick up the arse!

 

guess so...

well... wil let them have a look at the numbers..

thanks...

 

Same here Gasket looks very good quality too.

 

Me and a mate are currently building a zetec turbo, he has had it bored out to 86mm and has vauxhall c20let pistons fitted, the head has had one skim, he would like a cometic headgasket, there are currently four different thicknesses to choose from, does any one know which thickness is correct?

 

All depends what compression ratio your aiming for?

 

just buy a mk1 focus rs one lol

 

As Stu says, work out your CR and as a result what thickness you need.
No, don't just do that lol

 

What sort of compression ratio would be good to aim for?

Edit:
Ive just found this information over on fiestaturbo.com

With forged pistons there are a number of options for the Zetec. The cheapest is to use those originally designated for another type of turbocharged car. In this case the most common source for 2.0 pistons is the Vauxhall C20LET from the Cavalier and Calibra Turbo. Fitted to a Zetec these will give a CR of 7.4:1

The C20LET bore is 86mm, compared to the 2.0 Zetec’s 84.8mm, so a slight overbore of the block is required. This presents no problem as the block is likely to have some wear on it and there is enough material to maintain the wall thickness. This will take the original 1998cc to 2045cc. Also required is modification to the rods to accept the 21mm wrist pin.




The metal Series 3 (Focus) Zetec head gasket is fine for turbocharged use and has been used without problems a up to 2 bar boost. As far as I have been able to determine. The turbocharged Focus RS uses the same gasket as the NA engines.