pulsenpal wrote:
ARP fastener company specifically distances itself from the 2.8 crd engine--
they point out never offering head studs designated for use in crd 2.8
Ok, yes this is technically true. You have to remember that this country has too many lawyers though. ARP is a company made up almost entirely of engineers. Scientific measurement, material development and metallurgy are what they do. Just because they haven't specifically MARKETED studs for this engine, doesn't mean that they were not integral in the selection OF existing products for this engine.
Manley has been consulted on valves, and the only thing they will offer (even though they have a large collection of existing sizes right on their shelving) is to custom-cut valves for our engine at great individual cost. Why? Because they don't want the potential liability of not-the-right-application or grey-market usage of their valves to come back on them. Custom cut valves are offered with NO WARRANTY OF ANY KIND.
Back to the studs. Some very smart engineers in this group worked with ARP to specifically measure and test the existing head bolts and select options that existed which could do the same job - better. The existing bolts were determined to be putting down about 19,000 PSI of force when installed as instructed. Even the FACTORY INSTALLATIONS have not been found to be consistent after time! The research thread that I started asking for data points has shown even within the same engine, to be variations on release (and ergo, clamping) forces. The studs are MUCH higher engineered than these bolts, but no - they don't come with anything that might be construed as a guarantee or warranty, b/c there are just too many lawyers that would use that as justification to go after ARP for problems that are not theirs.
NOT ONE CRD ENGINE HAS FAILED BECAUSE OF ARP STUDS.
The CRD has a number of design issues. Every engine or vehicle does. The ARP studs are at about 75% of their elastic range and exerting about 21,000 PSI with how we are installing them, and this installation methodology was developed in close consultation with ARP. Were they going to produce a "specific kit" for an engine that has a theoretical maximum of 16k kits? No. There are FAR more TDIs out there, and 4 generations of the same block that can utilize the same studs, so even more than just the specific ALH engine that we sourced the kits from. This is just marketing and business.
NOT ONE CRD ENGINE HAS FAILED BECAUSE OF ARP STUDS.
If you want to cast aspersions at a manufacturer... Why not do it against VM who specifically made exhaust valves that weaken under the very conditions that they are designed to experience on a daily basis in a stock engine? 1200 degree exhaust temperatures because of excessive exhaust timing and multi-fueling and excessive EGR usage to "make less emissions" by making the exhaust hotter than it needs to be... All to overheat the stupid catalytic converter? The valves COULD have been made with stronger alloys, instead of one that softens around 1200 degrees.... But they didn't.
WE had to discover this problem as a community, and WE had to come up with a solution (which frankly is an enormous amount of work) to replace all the valves... With the same ones. The ONLY reason this isn't a dumb idea, is we usually are also simultaneously solving the rest of the design issues and lowering the peak cylinder temperatures to protect these valves. Is this the ultimate answer? I don't know. But I do know: NOT ONE CRD ENGINE HAS FAILED BECAUSE OF ARP STUDS.