john5f

iTrader: (3)

Can anybody please tell me the thickness of the standard head gaskets on a MY95 jdm WRX Wagon?

joz8968

iTrader: (13)

99% it's 1.6mm. But check with your specialist to make sure.

If you are doing a HG replacement, it's a good idea to upgrade to STi v.1-4 multi-layer shim steel ones. Or decent aftermarket jobs like Cosworth, ARP or Cometic.

sonic93

iTrader: (16)

how comes cosworth 1 on ebay is 0.7 mm surely they should be thicker than that as i need 1 who sells them don t trust ebay lol

joz8968

iTrader: (13)

Well, I think the MY99/00 cars use 0.6mm ones. You sure the ad is not for those MYs?

sonic93

iTrader: (16)

na just under wrx or sti head gasket. what brand and who supplys the cheapest

sonic93

iTrader: (16)

any1

joz8968

iTrader: (13)

I wouldn't buy HGs on the basis of how cheap they are. That's flawed thinking regarding such a major, fundamental component of the engine.

You are best off with the stronger STi MLS ones, as the lesser WRX-fit composite fibre jobs actually aren't that much cheaper... if at all!

You should be looking at around £100-130 the pair, for the MLS types.

john5f

iTrader: (3)

I've looked around flea bay and, for my engine as above, found Cosworth HGs at .7mm and 1.1mm, Cometic HGs at 1.2mm and 1.3mm and other un-named makes at .55mm and 1.0mm. All in multi-layer steel, hence my confusion and a reason for the question.

I can understand why thicker ones would be used if the head is skimmed, but why would the other thicknesses be used?

joz8968

iTrader: (13)

Don't know.

But if you search more, you should see the Cosworth and/or Cometic offered in 1.5mm, as well (unless they're not available at the mo ). I don't think 0.1mm/4 thou difference will be problem as regard the CR. Theoretically the 1.5mm ones will cause the CR to increase a tad (all else being equal), but don't know if it will be enough to compromise the engine?

Personally, I'd play safe and get STi v.1-4 ones from somewhere like API or RCM... that way you know they'll be the correct 1.6mm thickness....

sonic93

iTrader: (16)

cheers joz na wasn t gonna buy a cheap non brand 1 i wanted a cosworth or something around the same quality but do u think sti 1 just as good

joz8968

iTrader: (13)

Yes, the STi ones are just as effective as the branded ones. API supply/fit them as matter of course in rebuilds, so if they advocate them............

john5f

iTrader: (3)

Thanks for the info Joz, much appreciated as I don't want to stress the engine with too high compression.

Still scratching my head about the other thicknesses though.
Anybody else got any ideas?

rossmc

You can get the STI ones from here for £90!

http://importcarparts.co.uk/parts_in...en=&searchKey=

joz8968

iTrader: (13)

Doesn't say, specifically, what the thickness is for those ones ^^^.


They do do the 1.6mm ones too, though:-

http://importcarparts.co.uk/parts_in...en=&searchKey=

rossmc

That's the better link above.

I ordered quite a few bits and got a good discount on the price, so worth phoning the guy up. Great service and fast delivery too

joz8968

iTrader: (13)

Yeah that company does OEM parts at good prices.

£89 for a set os STI metal HGs - can't go wrong.

merlin24

iTrader: (1)

As joz said above - go for the OEM STi Version 3~4 1.6mm MLS head gaskets and you wont have any problems provided the head and deck faces are prepped correctly ( clean and flat/no distorsion). Dont use the standard carbon composite head gaskets as fitted as standard on the WRX - they tend to fail around the lower coolant areas of the head gasket.
The other thickness of head gaskets on the market are for different combinations of pistons/compression height and head volume - normally used when you have worked out your CR on a Forged build.

Mick

john5f

iTrader: (3)

Ah, hadn't thought of worked heads.
Wish advertisers wouldn't let you think that other thicknesses are standard - that can be dangerous.

joz8968

iTrader: (13)

Oh sorry john, I didn't realise that you wouldn't have known that. Otherwise I would have mentioned earlier that's why there are various thicknesses.

As Mick says, it's so that you can work out the C.R. after a rebuild with aftermarket pistons/rods/heads - any combo of which could alter the C.R. - and then be able to choose an appropriate thickness, so as to restore as close to the std C.R. as possible...

john5f

iTrader: (3)

Thanks again Joz. I was aware of it but obviously had a brain dead period.

I have been researching some more and a main point for consideration in the calculation seems to be the compressed thickness of the gasket. As the standard 1.6mm gaskets are fibre wouldn't they compress more than the MLS ones?
The cylindrical volume created using a 1.6mm gasket is 10.64cc and, for example, a 1.3mm gasket would give 8.645cc. Using the calculation to get the CR, this reduction in compressed volume would increase the CR from 8:1 to 8.2:1.
However, if as I suspect, a fibre gasket would compress more than an MLS then would the actual difference when compressed to be minimal if using the 1.3mm MLS?

Also, are the thicker ones less prone to blowing under pressure?

Or am I trying to be too clever for my own good? - just trying to get a thorough understanding.

joz8968

iTrader: (13)

Interesting point re the fibre and metal ones compressing down to different heights. Unless the fibre ones are actually thicker, so that when torqued up, they become exactly the same height as the metal ones???? Pass. You'd have to speak to a specialist to get him to explain it, etc.

The way I understand fibre v metal:-

fibre - more likely to fail under increased boost pressure. More fragile. But when they do fail they typically fail 'slowly' so can 'hold up' for longer, due to the malleable nature of the composite fibre material.

metal - much tougher. Can handle high boost pressures. But if they do fail, they tend to fail immediately , due to their unmalleable nature.

v-limited195

guys at eclipse say 0.051 all day long will c u no troubles at all...

john5f

iTrader: (3)

That must be 51 thou (0.051") which works out at about 1.3mm, right?

Cometic MLS at that size are £89.95 delivered on ebay - is that a good price?

Thanks for the info, much appreciated

joz8968

iTrader: (13)

Anything under £100 for a pair of metal multi layer jobs is a great price.

I'd double check with API David re HG thickness for your MY. As said, I thought it was 1.6mm...and if it IS, but you fit 1.3mm ones instead, then obviously the CR will be raised somewhat. As said, best to get the 'all clear' from a well known specilaist, befor diving in...

john5f

iTrader: (3)

Will do. Thanks again Joz.

David? - or I'll call you.

trell

What would be the thickness of my HG?? Its a v2 JDM STi 95??

Woiuld be grateful for your knowlage guys

john5f

iTrader: (3)

Check earlier in the thread and follow the link.