Head gasket water channels ??? cometic,hks,standard

R

radiobar

New Member
hi !

looking at cometic and hks gasket i cant see any difference in quality.
so i will install the cometic.

please note that gaskets are not exatly the same !!!
i was told that they are made by same company with
different stamp on it - khs or cometic.

the cometic has one more useless waterhole(than hks)
and the waterchannelholes are little smaller than hks(cyl 1,2,3)
(cometic 1mm,hks maybe 2mm)

pics:
http://www.weidewaren.de/comHG.JPG (new)
http://www.weidewaren.de/hksHG.JPG (used)
http://www.weidewaren.de/orgHG.JPG (used)

the standard gasket has no holes for the waterchannels(cyl 1,2,3)
i mean the bigger ones like on cyl 4.

any idea why ?

would you recommend to make the waterchannels little bigger ?
maybe like hks ? or can i make them same size like on cyl. 4 ?


take a look at the cometic here:

http://www.weidewaren.de/comblock.jpg
useless holes are marked white.

4th cyl has all bigwaterholes,while all other are closed(only 1mm hole)
3rd cyl. has 3 closed and 1 open.

for me its all very strange. why arent all cyl. like the 4th one ?


thanks
 
O

Odin

Guest
You must be either mad or stupid mate :shock: :doh: , With the amount of documented problems people are having with the cometic gaskets why risk it :der: , Just pay a little extra for the known to be excellent HKS gasket.

Unless of cause you like pulling your engine out or struggling to get the head off in situ, Once your cometic gaskets fails, Notice how I said when and not if lol lol lol.



Rob
 
CruiseGTi-R

CruiseGTi-R

Member
I used a cometic in mine, spec'd it before all the fuss came up.

The fuss by the way, is mostly bollocks.

Cometics have been used in massive power applications with no problems. These things flare up now and again on anecdotal evidence.

The Cosworth comparison was interesting - although in my book with less pressure on the Cometic gasket means that the metal is less stressed. The higher stress on a gasket, the closer to failure it is as a material. Everyone forgot that.

A gasket needs to be at the right pressure once bolted down that it carries sufficient stress (pressure) to form the correct seal but probably crucially, being far enough from yield failure stress, particularly once it is subjected to temperature.

My two pence...
 
R

radiobar

New Member
hi !

i will install the cometic and we will see.
we had already a blown hks here...

but what about the water channels ?
maybe its better for cooling if i make them bigger...
 
O

Odin

Guest
radiobar said:
hi !

it wasn't my engine.

had a standard one for around 20000 miles(400hp)
and it was fine.
Click to expand...

I suppose it depends on whether they skimmed the block/head before fitting it, Or just bunged it on and old engine :lol: :lol: :lol: .

I kinda agree with most of what Toby said, Their is a lot of variables to think about when judging whether a type of head gasket is any good or not, But their has been a lot of negative press about the cometic gaskets for it to all be rubbish.

They probably work very well on a newly rebuilt engine with perfectly flat surfaces ;-) .



Rob
 
J

Jonnie R

Member
I have a cometic for sale if anyones interested in putting it to the test.

Heard that the block and head have to be perfectly flat before they are installed
 
Last edited:
CruiseGTi-R

CruiseGTi-R

Member
My head and block have both been skimmed, so fingers crossed.

I got the Cometic gasket from Eric's Performance Parts which just lists it as that for the GTIR RNN14. No idea if its actually the right one with the right water holes, I never compared it to the old one, have to trust Eric :roll:
 
Last edited:
stumo

stumo

Active Member
I've just recieved a 90mm Cosworth gasket having previously used a Cometic. (cost was $320 inc postage directly from Cosworth, they also do std bore gaskets)

The difference in quality is immediatly apparent .

As with any multilayer gasket the surfaces have to be perfect
 
R

radiobar

New Member
hi !

still no idea about the water channels on cyl. 1-3?
is it better for cooling to make the holes bigger - may 3mm or 4mm ?
 
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