Imagine you have built a very strong 996TT motor. All the things you have done in the past, knowing they work well. What happens if you make more power than you are suppose to? Imagine making 700+ AWHP on the dyno with the HP scale going up and up and all the sudden….well lets just say back to the drawing board. How do you keep the new motor together so that lifting doesn’t happen again. Well, like the bionic man, Steve Austin, we will built it better, stronger, faster….(enter music here) All joking aside this is a serious matter!
Lower end in these cars are fairly safe. We know what the limits are and almost never see a failure if the rules are followed. The heads and the cylinder assemblies are a different story. Like the early air cooled motors this continues to be an issue. In the air cooled arena we have been using what we call flame rings for years. This is an actual seal that is machined between the head and the cylinder so that if and when the cylinder head expands and lifts due to pressure and heat the gasket holds the integrity of the chamber together to avoid the cylinder or head or both from self-destructing.
The 996TT is a different construction and design, but the problem still exist. Solutions are a little tricker. We start with the head studs. We increase the diameter of our already fancy upgraded head studs up another 3mm. We also change the material and thread pitch both on the head side and in the case. This requires yet more machining to allow these larger studs to be fit.
Second part of the process we grove the head to accept an actual ring. Traditionally the head gasket has a small crush ring that serves to hold combustion in while the sandwiched outer gaskets create a barrier for oil and water to flow through their proper channels. We take those same gaskets and stamp out what use to be the combustion crush ring allowing our new much thicker and precise ring to be fit. As you can see from the pictures this is a two part seal, the outer copper seal lays in the groove while our “special material” second ring lays inside the cooper ring. This ensures that there is multiple sealing surfaces to keep combustion in should the head lift again. This is secondary as our new head studs will hold it all together.
Added with new valves, custom springs, retainer and custom stem locks we start to create the base of a bullet proof monster that can withstand the unknown! Stay tuned for more on this project as we continue our journey.