[Eric_Oz_S2]

Anyone have experience with MLS Head Gaskets (Cometic) for boosted 968's? Mine seems to have developed a small leak and is blowing some combustion gas into the cooling system under hard (track) use.



Interested in sealing ability vs stock gasket vs surface preparation level.



There is a composite alternative from 928Motorsports as well, but more expensive and perhaps (?) not as robust.

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[968cabx2]

I'm also interested if any one has experience with these "new and improved" head gaskets. I am going to do the head gasket in both of my 968's within the next year and want to do it right.

I've been tempted to use the one from 928 motorsports that promises all sorts of benefits, but I'd like to hear from anyone who has first hand knowledge if these benefits are real or just marketing hype.

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[flash]

the 928 motorsports gasket is also not either one of the OEM thicknesses, so you may need to adjust head thickness



there have been some issues with cometics, but i also know people successfully using them.



there is a wide fire gasket out there that will probably work better. however, it is only available in standard thickness. it is what most racers and those who do forced insuctions use:



http://www.pelicanparts.com/catalog/Supe....htm#item2

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[968cabx2]

I apologize for this question because it possibly shows how ignorant I am on this topic. The stock head gasket is listed as .060 thickness and the 928 motorsports gasket is .065. Is the .005 difference that much of a concern, and does the alleged increase in quality and sealing ability override that concern for the thickness difference. I'm going to be doing two of them soon and I want to make sure I make the best decision as far as quality of the materials I chose so I'm not wasting my time twice. What is the conventional wisdom as far as the best choice for a street driven pretty much daily driver for 7 or so months of the year?

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[JWahlsten]

If you're not doing forced induction, I am not sure what is to be gained by going to a non-standard material for the headgasket. Mine lasted 120,000 and 21 years... I am replacing mine right now and have the head out for rebuilding. I thought about using the wide fire ring, but in the end opted for the standard gasket. I'm not sure what I'd gain since my engine is pretty much stock except for exhaust, airbox, and tuning.

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[968cabx2]

My cars are pretty much set up the same. Air box mod, performance chip and one might get a "performance" exhaust. Otherwise as stock as it gets. I'm assuming if no forced induction there is no benefit to the 928 motorsports head gasket or the gasket with wide fire rings as sold by Pelican. If that is the case to go with the stock head gasket, is any one brand better than the other?

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[flash]

the stock gasket is 1.1mm (.043") not .06



the thicker gasket for a shaved head is 1.4mm (.055"). this gasket on a stock height head drops compression about a half point



a .065" gasket would drop it even farther. further, there is no data regarding effectiveness or longevity. just seems to me to be pointless when there is a good gasket out there now.



a wide fire ring cools better, preventing detonation. this could be advantageous for anybody running a lot of timing advance or prolonged high revs

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[968cabx2]

flash,



I guess what I'm getting from your post is for a mostly stock, street driven car that you should stick with the standard head gasket. Do you have any particular brand recommendation and or supplier? Thanks as always.

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[flash]

victor reinz is an OEM supplier

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[Eric_Oz_S2]

The wide fire gasket also results in less clamping pressure around the sealing ring. A lot of people don't favour the wide fire rings at all. The Cometic does come in multiple thicknesses though: 0.04", 0.051", 0.06", 0.075".

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[flash]

actually, it doesn't result in less clamping pressure. what it results in is less gasket compression. the wide fire ring is the sealing ring. it actually results in more even pressure than the standard.



some people don't prefer it because it requires a perfectly smooth head. many people (particularly independent shops) don't want to clean up the head surface, and just want to slap it back on there, because having to clean it up means at least a day at the machine shop, and the bay tied up with that car in the meantime. it costs them money due to not being able to get the car in and out quickly.



so, it really depends on how you are doing the job. a on a standard gasket swap, with no head work, and a less than perfect head or block surface, i'd probably run OEM.



as for cometic, i've heard mixed reviews, but i have no data to point to why those that had issues had them. some guys love them. some guys hate them. no idea why.

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[Eric_Oz_S2]

I've read up on the cometic, and it seems without very specific surface finishes they have a tendency to fail. I'll probably ho stock but with hylomar this time.

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