The experience of 40 years of engineering and producing literally millions of sterndrive and inboard engines lead to the development of MerCruiser’s ® innovative dry-joint exhaust systems. Featured on all MerCruiser V-6 and V-8 models through 425 horsepower, dry-joint exhaust systems virtually eliminate the opportunity for water, either from condensation or from sea water, to find its way into critical engine components. While externally the V-6 and small-block V-8 systems appear very similar to previous designs, the real new technology is hidden inside. The internal geometry is totally new and was developed using computer-aided modeling to contour the surfaces, reducing exhaust restriction while ensuring precise temperature control of crucial areas. Take a look at the results in the illustration to the right. Notice those two red rings? Those are special 4-lip high-temperature silicone seals that secure the coolant flow between the exhaust manifold and the elbow. Check out the distance between those seals and the large open area where the exhaust flows. There’s no way that coolant can find its way into the engine here. Those seals are mated to an engineered Grafoil® gasket that is made up of a stainless steel core bonded to a special graphite material that provides a precision high-temperature seal for the exhaust gases. The cone that you see on the gasket around the large opening is called a turbulator ring. Its job is to help catch any small droplets of water condensation that may collect downstream in the exhaust system that try to find their way back to the engine, where they can wreak havoc on internal engine parts. You might say: “Condensation! That means water!” If the exhaust system is so well-sealed, where does that come from?” Here’s the answer–water in the exhaust of a marine engine can come from two sources: one is the water that exits the engine through the exhaust system to help reduce the temperature of the exhaust gases and the exhaust system. The water also works to help reduce the noise level of the exhaust. The other source of water is the water created from complete combustion. Yes, water is a product of combustion and can condense on the inside of the exhaust system when the inside surface temperatures are not high enough to evaporate it. So, our exhaust manifolds and elbows are designed to run at higher temperatures on the inside, while still staying as cool as possible on the outside. Quite an engineering feat. There are still times when condensation could form, like when the engine is warming up or when operating in very cold water for long periods at idle. That’s why we incorporated the turbulator ring—for that extra margin of insurance. Our engineers didn’t stop there. Because the combination of heat and water work together to really speed up corrosion, we paid special attention to protecting all these critical exhaust components. We have had great success in using Electro-Deposition Paint or EDP to protect parts for decades. For some applications we also utilized a special high-temperature ceramic coating that provides an incredible barrier against corrosion in tough areas like the inside of an exhaust system. Our V-6 and small-block V-8 dry-joint exhaust elbows feature BOTH for double the protection. We’ve also gone the extra step to completely EDP each exhaust manifold, inside and out for even more durability. Our 496 MAG and 8.1S models utilize ceramic coated aluminum exhaust manifolds mated to 316L stainless steel elbows for superb corrosion resistance while producing incredible power and torque. If you option for a closed-cooled V-6 or small-block V-8 model, the exhaust manifolds are incorporated into the closed-cooling circuit as well, for the optimum in corrosion resistance. Add in our standard long-life (up to 5 years between changes) coolant, and you’ve got one robust total system. Our long-lasting dry-joint exhaust systems are just one more way that we’re working to ensure that you have the most enjoyable time on the water, year after year. And the reason why MerCruiser continues to be #1 On The Water™! top Grafoil is a registered trademark of Union Carbide Corporation. All other trademarks belong to the Brunswick Corporation.