warp2diesel wrote:
I Read through their catalog and their quality exceeds the Bean Counter Engineering of the Auto industry, no dispute. Their Carefully Engineered Studs for the TDIs that work great. If they Engineered studs for the CRD, they would work great as well. My point is, even their Wild @$$ Guess is better than trying to pick out fasteners from their catalog on your own with out their input.
A head bolt/stud for an aluminum head has to yield when torqued but not exceed the elastic limit. If the head bolt/stud does not yield when the head heats up the head gasket has yield to make up the difference and when it wears out from being over stressed the head gasket fails. ARP plugs all of this into their calculations to design the stud for the application, that is why they work so well.
I wasn't planning on picking a bolt by myself, but I am not going to pull my head just to get the required measurements. ARP has a rather detailed series of questions that they ask about hole depth, diameter, thread pitch, etc. etc. that you need to answer so that they can do the design. I knew that others had replaced heads and gaskets and was hoping to jumpstart the process by getting the bolts specs to start.
If they needed more thread engagement in the block for stud loads then I could ask for more input regarding hole depth. My hope was that just as with the D24T that the stock thread engagement would be sufficient for the increased load of the stud, but I am going to let ARP do the design. If you or RT are going to engage in talks with ARP, and you have all of that information, great! If you are going to do that, looking at their questionnaire is recommended, because they are going to want that information. been down that road twice, once with the D24T and once with a Honda Civic.