If you’ve been following my comparison posts you’d see a lot of valuable information given on quality and fundamentals pertaining to certain engine internal parts that I like to use or use on a regular basis. The internet is filled with a considerable amount of misinformation and its important that I clear up a lot of details and myths so to speak pertaining to components and their use and features.
Today I’m going to be discussing the two main MLS head gaskets we typically use for the VG30 engine platform. These two companies I’ll be showcasing the head gaskets from are Tomei and Cometic. There are some pros and cons everyone needs to know and realize pertaining to each gasket and why they are better/worse than each other.
Tomei on left / Cometic on right
The first gasket I am going to discuss upon is the Cometic MLS Head Gasket. 3 layer in design and a dual (top & bottom) layer. Riveted corner tabs to keep the gasket together. Features a embossed compression bore area for added sealing ability and a full nitrile rubber coating to aid in creating and maintaining a solid sealing surface to both the decks of the block and heads. As with all MLS gaskets they require a R/A of approx 55-65 for proper sealing.
The upsides of this Cometic gasket. Its quite affordable, on average ranging from $145-170 for the set. Primarily always in stock and readily available, these can be had very easily. Come in a variety of bore dimensions and thicknesses and are most widely sold by aftermarket vendors. Just as with all MLS gaskets these can be used up to a total of 3 times before the embossed areas are flattened/worn beyond use which results in having to replace the gaskets.
The downsides are that the compression bore area of the gasket is and open layer design. This alone is a major concern for ensuring the seal is accurately done. Unlike the OEM gasket which has a sealed fire ring, the cometics open layers offers up chances for combustion gases to find a breaching point in the compression area of the gasket and begin its assault on separating the layers and causing a compromised area in the seal under compression & combustion. I’ve had this happen to me on 2 different occasions as well as many others resulting in the same failure. Some have had great success but the number of failures pertaining to this particular gasket is more than I’d like to see and more often than not the a common cause of gasket failure.
Now moving on to the Tomei MLS gasket. This is the premium gasket on the market bar none. Between the two the Tomei is by far the better gasket for a few excellent reasons. We all know the quality of Tomei, everything they produce in the industry for any import car they develop parts for is of the highest quality we’ve seen. For that reason its to no surprise that Tomei would develop the superior head gasket for the VG30.
So whats good about the Tomei? Well for starters its the ONLY MLS gasket on the market that has a sealed fire ring. This is, in my opinion the most important feature of the gasket that sets it apart from any and all others. It is fully embossed around all coolant and oil passages just like the Cometic, however, the middle stainless steel layer they use is a much higher quality steel than that of what Cometic supplies. The smallest bore size available is in an 89mm bore and come in a variety of gasket thicknesses just like Cometic. Tomei head gasket is also nitrile rubber coated to ensure proper sealing on both upper and lower outer layers as well.
Please excuse this image as I use this particular gasket when I hone my engine blocks. This is showing the fire ring but on a used Tomei unit.
So right from the start you are dealing with a different class of gasket construction. The implementation of the fire ring is unique to the design much like the OEM composite gasket we’ve grown to love using. The fact Tomei spent the time to add this feature into their gaskets shows true attention to detail in their gaskets.
**Higher grade stainless mid section of the Tomei Gasket**
**Embossed sealing areas throughout the gasket surface**
Being that this gasket has already superceded the Cometic variant, this gasket does have a downside. Pricing for this gasket kit is around $465…yea I know…ouch! It also takes approx. 2 weeks to ship in from Japan unless Tomei USA happens to have a few sets on the shelves, which isn’t likely. So if you are up to invest into a higher quality product Tomei is the best choice for your build. I swear by them over Cometic if customers inquire about which MLS gasket to use. The manufacturing process in building the sealed fire ring into the gasket is more costly, the outcome though is a far better designed unit. Even though the gasket does cost more you absolutely get a better made product that holds up a lot better than its competitor.
I’ve read on many forums and else where online that many ppl like to copper spray coat their MLS gaskets. This is frowned upon for the simple fact that it the nitrile rubber coating isn’t given its chance to seal and the copper acts as a buffer layer to the rubber itself. This can cause sealing issues between the head and block. So I advise that you do not use copper spray on the nitrile coated surfaces. You can however use copper spray on any and all composite gaskets. I use copper spray on all my OEM composite gaskets and they seal phenomenally well using the spray addition.
So in closing I hope a few details have been explained well to you and I hope you understand and see the differences between these two gaskets. As always its important for me to educate my current and future would be customers on systems/components that can better help them make more educated decisions about what products they choose and purchase for their application. I hope you’ve enjoyed this comparison write up and I hope you’ve learned something new today.