Cometic gaskets
#23
I would expect the Cometic to last longer.
Reason being, different materials expanding and contracting at different rates.
Cometic are all metal, and layers. Layers should allow faster cooling and less distortion.
More so, I would think that a composite gasket will fail sooner...because it's composite.
It is also metal, but coated. The coating expands and contracts differently than the metal it covers.
So, after however many heat cycles, miles, years, it is going to break down, and seperate from it's metal base.
Blowing the head gasket at the individual gasket's weakest point.
For whatever that's worth.
Reason being, different materials expanding and contracting at different rates.
Cometic are all metal, and layers. Layers should allow faster cooling and less distortion.
More so, I would think that a composite gasket will fail sooner...because it's composite.
It is also metal, but coated. The coating expands and contracts differently than the metal it covers.
So, after however many heat cycles, miles, years, it is going to break down, and seperate from it's metal base.
Blowing the head gasket at the individual gasket's weakest point.
For whatever that's worth.
#24
Another point they make is that less clamping force is needed to achieve the same sealing properties when compared to a paper gasket. This means less chance of stretching or stressing the block and distorting cylinder profile. With an aluminum block, this alone could make the cometic a better idea.
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#25
#27
Rover engineers might not be the brightest bulb in the chandelier, but they have more hands on experience with that specific motor than Buick did. And if Paul’s account holds water, it sounds like they had to make a change.
so, if Cometics are the best thing since sliced bread, why are we all running composites?
What other aluminum block & head engines run Cometics that are daily driver tasked, non high performance engines?
so, if Cometics are the best thing since sliced bread, why are we all running composites?
What other aluminum block & head engines run Cometics that are daily driver tasked, non high performance engines?
This Engine isn't an F22c though, so stories may differ here and of course I'm open to ideas but I did want throw in that my experience in a few other vehicles is that cometic is fantastic. Perhaps it's just a better option.
#28
Another option I’ve never heard of with the rover engines is to O-ring the heads. When I was heavy into drag racing it was all the rage for boosted applications. Machine a grove for the cylinders and water jackets, copper O-rings for the cylinders and rubber O-rings for the water jackets.
I built many high end sled motors with this system but the tolerance of head to cylinder was very tight. Also I never used sleeved cylinders, always nicasyl coated.
Not sure if it’s been tried on the rover v8.
I built many high end sled motors with this system but the tolerance of head to cylinder was very tight. Also I never used sleeved cylinders, always nicasyl coated.
Not sure if it’s been tried on the rover v8.
Fellow sledder here with a Turbo M1000. For sale btw if twin 500cc two stroke turbos are your thing. Currently at 470hp.
Last edited by 05TurboS2K; 07-17-2019 at 03:50 PM.
#29
Raceline
To my knowledge, steel head gaskets have been around for circa 20-30 years in various uses and forms for mostly modern performance vehicles engines where the engines are regularly stripped down. When someone proves they have used steel head gaskets for 100K+ miles without any issues I'll be convinced
To my knowledge, steel head gaskets have been around for circa 20-30 years in various uses and forms for mostly modern performance vehicles engines where the engines are regularly stripped down. When someone proves they have used steel head gaskets for 100K+ miles without any issues I'll be convinced
There's another interesting thing about cometic being that its all steel and the bead itself flexing is what provides a sealing surface, when a composite gasket fails, it blows out, this isn't true of a cometic. When a cometic fails it just allows leakage to occur but it doesn't mean it will worsen and no part of the gasket gives way causing catastrophic gasket failure. Now, failing is failing because it still will need to be replace but it COULD mean it fails in a very minor way and doesn't progress, this might equate to you making it home or continuing to drive it under failed conditions if you needed to. Perhaps that's advantageous enough for some?
Last edited by 05TurboS2K; 07-17-2019 at 03:55 PM.
#30