Cometic Head gaskets?

[Yellow4g63]

Who uses them? I didn't use them a while back because I didn't hear any good things about them. Someone enlighten me please.

[2_Liter_Turbo]

Who uses them? I didn't use them a while back because I didn't hear any good things about them. Someone enlighten me please.

It's been awhile since I've dug into this, so I don't remember details. But in short, they aren't made as well as the other gaskets. Apexi is one of my favorites, but expensive. Cosworth is the best/cheapest gasket (at least for the SR series) out there. Regardless of what metal gasket you get, make sure the have the head/block surfaces decked to a mirror finish. You need to run a smoother finish than factory for a proper seal. If the machine shop asks what surface finish, using a new mustang cobra as a reference works great, as they have mirror finish for their gasket surfaces from the factory. I used to remember the number, but not at the moment. Ha ha

[RRRRB]

Who uses them? I didn't use them a while back because I didn't hear any good things about them. Someone enlighten me please.

It's been awhile since I've dug into this, so I don't remember details. But in short, they aren't made as well as the other gaskets. Apexi is one of my favorites, but expensive. Cosworth is the best/cheapest gasket (at least for the SR series) out there. Regardless of what metal gasket you get, make sure the have the head/block surfaces decked to a mirror finish. You need to run a smoother finish than factory for a proper seal. If the machine shop asks what surface finish, using a new mustang cobra as a reference works great, as they have mirror finish for their gasket surfaces from the factory. I used to remember the number, but not at the moment. Ha ha

Im not sure why people hate on Cometic.. i think there great.

You dog them but cant come up with any facts as to why there inferior, thanks for that

50 or lower RA (roughness average)

Ive used cometic in 3 different engines my orginal RB25, same RB25 now with RB26 head swap and an H22A

H22a sees regular 30psi on pump and meth makes over 600whp

Never had an issue with my RB25's either, they kept stable temps.. NEVER push coolant etc..

Like you always should.. i always have a clean straight surface and will retorque head studs. RA is important, these gaskets don't give

[2_Liter_Turbo]

It's been awhile since I've dug into this, so I don't remember details. But in short, they aren't made as well as the other gaskets. Apexi is one of my favorites, but expensive. Cosworth is the best/cheapest gasket (at least for the SR series) out there. Regardless of what metal gasket you get, make sure the have the head/block surfaces decked to a mirror finish. You need to run a smoother finish than factory for a proper seal. If the machine shop asks what surface finish, using a new mustang cobra as a reference works great, as they have mirror finish for their gasket surfaces from the factory. I used to remember the number, but not at the moment. Ha ha

Im not sure why people hate on Cometic.. i think there great.

You dog them but cant come up with any facts as to why there inferior, thanks for that

50 or lower RA (roughness average)

Ive used cometic in 3 different engines my orginal RB25, same RB25 now with RB26 head swap and an H22A

H22a sees regular 30psi on pump and meth makes over 600whp

Never had an issue with my RB25's either, they kept stable temps.. NEVER push coolant etc..

Like you always should.. i always have a clean straight surface and will retorque head studs. RA is important, these gaskets don't give

Didn't want to sit here and do some research as I am out in the garage working on stuff, but I did a little quick search, lol.

Article as to why cometic's suck
http://www.motoiq.com/MagazineArticles/ ... locks.aspx

And also, after talking to a friend of mine who also happens to build a TON of SRs up here in the NW (he did my bottom end), this is what he had to say:

I have used a few cometics back in the day. They always leaked. Specially around the front cover. You can blame it on installer error, but I have done hundreds of head gasket jobs using everything from oem to tomi greddy hks cosworth and even circuit sport headgasket from phase 2 and I have literally never had a single one fail.... So I think the argument of installer for me is pretty proven it's the gasket and not me

[2_Liter_Turbo]

Also,

Eric Hsu, former owner of XS-Engineering and current engineer of Cosworth published this in his blog back in 2008 (The image referenced is no longer up unfortunately, but may be the same one on the MotoIQ link above... as he was the one who wrote it, ha ha).

We’ve been doing a lot of product testing at Cosworth recently which is a good thing. Real company = real products = real research & development = real engineering. No Ebay made in China sh*t here man. However, just because something is made in the USA by a reputable company, it doesn’t mean that it is a quality product. You find out all kinds of things in testing.

Cosworth has been coming out with some kick a** head gaskets lately. They provide the engine builder with Japanese multi layer stainless steel quality, but priced 1/2 way in between the JDM and USDM gaskets. As we develop more applications, we have more testing to do since we must validate our designs and sometimes also check a competitor’s product. To do this, we take some expensive a** pressure film and sandwich it in between the block and head gasket. Obviously, all sealing surfaces must be perfectly flat and free of imperfections. Then we torque the head on top of everything with the head bolt/stud of choice. The pressure film creates a color coded imprint that shows how well the clamping force is distributed. Obviously you want a high clamping force around the cylinders. Of course you can’t forget the water/oil jackets either. The higher the pressure, the brighter the imprint. We’ve found some very surprising results. A leading US multi-layer stainless steel gasket manufacturer actually manufactures some pretty weak gasket designs. In some instances they are worse than stock.

Here are some results from a popular Japanese 2.0L in-line 4 cylinder iron block/aluminum head factory turbocharged engine. No names, models, or manufacturers in this blog post. You figure out which engine. If you can’t, you’re probably either a dumb sh*t or a non-enthusiast in which case I’m not sure why you’re reading this. Ok, here’s a hint: it’s four wheel drive. No not the one with the flat engine.



This test was performed with 8740 ARP 11mm studs with torque at 90 ft./lbs.
LEFT: This US made multi-layer stainless gasket has a thin sealing line around the cylinder and distortion right around the head bolts which compromises the strength seal. You’ll also see the color is dull which means the clamping force is low. The funny part is that the primary seal (immediately around the piston) is very light whereas the secondary seal (around the primary) is darker and wider. They got it reversed.


CENTER: The OEM multi-layer stainless gasket. It only needs to seal 280hp so the engineers don’t seem too concerned with with a perfect band around each cylinder. However, you can notice that the clamping force is significantly higher than the Co…(oh **** sorry, no names, huh?) the gasket on the left.
RIGHT: The best of the bunch. The sealing area around the cylinders are round, consistent, wide, and the force is the highest. What does this mean to you? Proper cylinder sealing whether your engine is stock or you’re running 40psi boost on methanol with L19/H11/MP studs.

So next time you want to save a couple bucks and buy that cheaper gasket, don’t do it. You’ll be sorry you did. At the same time, there’s no need to break the bank for that over priced JDM gasket. Remember: JDM isn’t always the best choice. Have fun in boost (if you don’t have one of the gaskets on the left)." - Eric Hsu, 10/9/07

i hope this helps you understand why mike has been flooding the forum with news of this new development. also another reason why to buy the brand and not the "Ebay made in China sh*t".

[RRRRB]

I've been in the automotive industry for 10+ years as a tech myself, i build all my own s***, and others.. I'm no rookie either, there is no reason for me to stray from Cometic from some article that a company makes comparing there own s*** to others.. I'm sure its in there best interest to praise the "US gasket maker" right....

External leaks around the front cover could possibley be resolved with copper spray which i have experimented with, and have had no negitative effects.

To each there own, im sure the others make a good gasket as well but i have yet to have an issue with mine..