Any knowledge on Cometic "Phuzion" head gaskets?

[JGK]

Any knowledge or experience out there with the these head gaskets? I hear they've been used on racing and performance engines for years but haven't been available for the CTD until recently due to the need for special equipment to make one for the longer length of a straight 6.



They are a multi layer steel (MLS) gasket (stainless steel sandwiched between viton coatings) and use a gas-filled o-ring which eliminates the need to cut the o-ring groove. The gas is sealed in a tube at 500 to 600 psi at room temp. As it heats, it expands for improved sealing.



The only spec I note that raises an eyebrow is that their compressed operating thickness is . 051", so a fair amount of material may need to be removed from the head to avoid low compression.



Thanks,

-Jay

 

[AMassaro]

I know everything that you stated about them. I think they were designed for high boosted turbo charged engines in the pro-street arena a few years back. State of the art in technology, but I don't think they have anything for the Cummins... yet. Maybe a phone call to the company might peak their interest?

 

[pwerwagn]

Are you sure they are available for the cummis? Last I heard, they said they were not going to invest the time/money into the machine to make them, but they considered making a 2 piece HG.



If they are available, I want one!!!



--Jeff

 

[JGK]

I understand they are, in fact, now available for the 12 valve and 24 valve 2nd gen trucks. A friend just put in an order for one, though it did mention it would be a few weeks before he'd get it. I was just wondering if anyone else had done so already, or had experience with them on other engines. I believe they've been available for the Ferds and possibly the Chebbys for a while now.



Maybe I'll do a search/post over one one those sites.



Thnx.

 

[BILLVO]

The only spec I note that raises an eyebrow is that their compressed operating thickness is . 051", so a fair amount of material may need to be removed from the head to avoid low compression.



Thanks,

-Jay

The cummins head is flat.

 

[Turbo Tim 1]

Within the last couple months I e-mailed Cometic about this and they said they had tried and couldn't make them because of length and didn't have any plans to in the near future.

 

[pwerwagn]

Within the last couple months I e-mailed Cometic about this and they said they had tried and couldn't make them because of length and didn't have any plans to in the near future.

Thats what I was told too. They mentioned to me the the possibility of making a 2 piece setup, but the fact that they could be incorrectly installed pretty easily made them decide not to.



--Jeff

 

[12V Ford]

My brother talked to them about a month ago on the phone and they said that they would have a hdgskt for the cummins in a month or two. Maybe they got enough interest to do it?

 

[JGK]

The cummins head is flat.

My point was, that in most cases a . 010 or a thicker . 020 gasket is typically used, depending on the amount of metal removed to true up the head's mating surface. Since this gasket is . 051 thick, more material would likely need to be removed to compensate without sacrificing your compression ratio. I think...



As to the availability, I guess we'll find out in 2 or 3 weeks, when (if) one arrives for my friend's truck. I'll let you know.



Did some searches on the Ferd forum but found no mention of Cometic and only a couple about multi layered steel gaskets. Nothing noted about gas filled o-rings such as these have. May do some more searches as time allows.



J.

 

[Idaho CTD]

A stock gasket is over . 051. When I ran a copper gasket it was . 084 thick and it did reduce the compression but it ran and started fine even without being plugged in.

 

[pwerwagn]

My brother talked to them about a month ago on the phone and they said that they would have a hdgskt for the cummins in a month or two. Maybe they got enough interest to do it?

Cool, call me as soon as you hear anything Clayton. I emailed cometic yesterday, but no response yet... ...



Also, Sorry I forgot to return your call a while back. I was working and didnt hear it ring, and didnt write the number down. Call me again if you still have questions...



***EDIT***

Just got a response from Kevyn:



It is not quite ready yet but is in the final stages of R & D. I will put

your name on a list and contact you when it is ready for public use.



Kevyn Kistner

Technical Sales

Cometic Gasket





--Jeff

 

[SMorneau]

Keep us posted I would like to try an MLS gasket.

 

[zstroken]

The Dmax that used just put down 1000 HP used the gas filled rings I think.

 

[Glen Pratt]

I just got an e-mail response from them. I inquired about a 12 valve head gasket. They said it is in development and should be ready within the next 4 weeks. As far as 24 valves and 3rd Gen. trucks I don't know. -Glen

 

[BILLVO]

My point was, that in most cases a . 010 or a thicker . 020 gasket is typically used, depending on the amount of metal removed to true up the head's mating surface. Since this gasket is . 051 thick, more material would likely need to be removed to compensate without sacrificing your compression ratio. I think...

J.

With a flat head,Shaving the head doesn't really affect compression. The reason for the thicker gasket is for clearance as the valve to piston clearance will be less. Resurfacing the deck of the block will affect compression as combustion area just got slightly smaller.

 

[zstroken]

With a flat head,Shaving the head doesn't really affect compression. The reason for the thicker gasket is for clearance as the valve to piston clearance will be less. Resurfacing the deck of the block will affect compression as combustion area just got slightly smaller.

I am confused, typically . 006 or more is take off of the heads to true them up. So to keep the compression from increasing a . 010 head gasket is needed.

 

[JGK]

I think you're both right. My mistake was that I didn't realize when someone mentioned a ". 010 gasket" or a ". 020 gasket", what is meant is a . 010 or . 020 over stock thickness, which is about . 051, as IdahoCTD said. So the over-thickness gasket is used as as Billvo says, to keep valve clearance in a safe zone after the head is shaved. But if you raise the head with a much thicker gasket (or lower it by using a stock gasket) it stands to reason the cylinder volume will increase (or decrease) and therefore lower (or raise) your compression, per Zstroken's line of thought.



The question is, how much does a raised head (by 5 or 10 thousandths) lower the ratio, and is that really a problem considering you're doing this whole thing to strengthen the sealing capability to handle higher pressures from boost and fuel burning anyway, which would offset the slightly lower compression? Right?



-Jay

 

[paulb]

I am confused, typically . 006 or more is take off of the heads to true them up. So to keep the compression from increasing a . 010 head gasket is needed.

As BILLVO said it's a flat head, and shaving them doesn't increase the compression. For performance reasons lowering the compression can help, and that can be done by adding a thinker head gasket. It does have side effects though. Adding a thicker head gasket to replace the amount removed from the head will also keep the piston to valve clearance the same.



Paul

 

[Eric_B]

How much piston to valve clearance do we have or don't have in a stock 12 valve that . 010 makes that much of a difference? I understand the compression part.

 

[paulb]

Plenty with a stock cam, running stock rpm...