To answer the question by Henry, why did we decide to make our own Head stud? The proper answer should be, why did we decide to start making these again. We used to make and sell these over 25 years ago, before many others were making these. This was before the 993 studs came into existence, when all the Divalar issues were happening. Back then, the reasoning was easy to explain. Today, not so much.
I have gotten involved on this forum and Rennlist to help and give back to the community. I have my opinions on products and ways of building engines. I never assume I am right or it’s the only way, rather base it on what I see, what the engine application is telling me, all based on my knowledge and experience. This has been accumulated over many years and experiences, many of which I am truly humbled by.
My fondest memories are those that include my mentors, sharing their knowledge and experiences with me as I grew up in this business learning my “trade”. Showing me how to, why to, and when to. Then, as it is today, there were and are no books or papers to resort to when building brand new designs. However, there are the theories that are dated in time that give us benchmarks, baselines, foundations, known proven parameters that are used to guide design and development. But, in the real world you must know when to apply these theories appropriately, to match the results you are looking for. This means you cannot overlook or discard what you see. This is where the two worlds collide.
Applying this when rebuilding these Porsche air cooled engines, there are many critical issues that need to be considered. The material the engine case is made from, how old, how brittle, or soft it may have become with age and use. Does it have steel inserts fitted. Remember, just because it has steel inserts fitted, if the studs had pulled, the material holding the inserts is probably in the same condition as were the threaded bores. Are the decks level and straight where the Cylinders mate? Are copper or steel base Gaskets used. What is the class of the stud thread? Maybe a repair threading tap was used in the case? Was it a cutting tap or a proper roll type tap? Are the cylinders the same height? How soft/hard is the Cylinder head material. You can stretch the stud to its proper designed length but if the head collapse inwards around the stud, what have you achieved? This is where looking and understanding what you have in front of you is as important as any theory.
So, what does this whole rant mean. It means, without addressing these critical issues, it really doesn’t matter what stud you use. Certainly, the newer head studs are superior to the older ones. Also, I don’t hear about other brands of studs failing much either. Whenever this does happen, the background use and faults are never disclosed to fully understand the failure point. The fastener seems to get the blame always.
Why did we get back into the game? Simply, we are a company with a DNA that designs and makes our own versions of parts for these engines. Fasteners are one of many parts we have for these engines. Whenever we design something, it is always driven by a solid reason. Are we trying to solve a problem, create our own part under our brand, and can we improve on what is already out there? Whether its Head Studs, Camshafts, Connecting Rods, Crankshafts etc, we like to offer our own versions. But they are not for all builds. They must fit the build budget, the build end performance and fall under our ethos of a designed and engineered build. I started air cooled developments thread some months ago showcasing some of the new parts we have developed.
Our studs have several different features that others do not. I do not know what other stud makers make their studs from, but I would expect many use the same material as we do. Ours are made from 17-4 H-900 SS. This is one of the better materials to use in this application. We made our early studs from the same material. This new version of Head stud uses a 3/8” x 24 thread at the Cylinder head end. This is contrary to what others use. It is not a better thread than 10.00mm x 1.25, its purely so we can use a nut and washer that we use in other applications. Making 12point nuts is very expensive and requires large numbers to be made. These are made from Titanium. Titanium has been proven to withstand the heat cycles better than steel nuts do. It helps clamp the nut to the stud under heat loading better. The washer is also made from Titanium and acts as a heat barrier between the head and the nut. All to maintain the clamping loading we require. The only downside to this is, we supply those assembly hold down nuts for the Cylinders with the 3/8 thread. 12 come with each set of studs. We have added a hex’ed end making installation easier. You can install using a socket and not having to double nut them. Head stud installation, using Loctite or not, bottoming out or not is a totally different issue. I have made my reasoning on this known before. Its all about good building practices.
I’m turned off by all this back and forth over who’s studs are better. I at least have some knowledge of fasteners and their proper use. I cannot imagine how this comes across to those that just want good reliable information.
I have been drawn into discussions over the type of Ignition used. It got to the point where I just got turned off completely. Its not about which is better, it is always which is the better type in a particular application. I based my opinion on what I know and have proven on the dyno and in actual used in these large combustion chambered engines. If others have done the same research and testing and found other results, then that’s great. Then there are two types to chose from. I hope that customers come to me and require advice based on my proven results, not just what I think. I do my best to do this each time. When I do not know something, I tell them.
Are our studs better than 993 studs? Are our studs better than Henry’s. No is the correct answer as we have never tested any others back-to-back. We sell our studs based on our testing and the features we add and why. I never denigrate another stud sold by another company. However, I have been on the end of some who do. Don’t buy from them, period.