The crown down to the bottom...
The crown down to the bottom of the top ring groove (just below the ring land) has been hard anodized. This eliminates the "micro-welding" that occurs because the cylinder dries up so much from pulling a vacuum.
Going back to the piston coating issue, we've begun using hard anodizing on the top ring groove, from the crown down to just below the ring land. This is to eliminate the "micro-welding" that occurs because we've dried up the cylinder so much from pulling a vacuum. This is just about a "must" when you're pulling 15 or more inches of vacuum. The hard anodizing seems like the only thing that has helped in this area.
We've also seen a definite benefit from using the DLC (Diamond-Like Coatings) coatings on things like wristpins. For example, if you start with a good quality wristpin and apply the DLC coating, you can go through several rebuilds and use the same pins. It's hard to tell they've been run, even though this is a steel-to-steel operating environment. And even though the DLC coatings are a bit expensive, when you consider the long-term durability and cost savings in parts, we think it's worth the investment.
Also on titanium valves, we use the DLC coating on the valve heads. With a copper-beryllium seat, we've had remarkably good results from this combination. In fact, you can run thousands of laps, and where normally you'd be required to do a full valve job, it's not necessary when this coating is used. I guess when you're dealing with expensive parts to begin with, the cost of the DLC coatings makes considerable sense because of the extended parts life it provides.
I think this is going to become increasingly important as we see changes in fuel types being run today and in the future. Now that NASCAR is going to 15 percent ethanol (E15), we've done some experimenting with this and 85 percent ethanol (E85), finding out how to deal with the effects of these alternative fuels by the use of certain coatings.
This is just about a "must"...
This is just about a "must" when you're pulling 15 or more inches of vacuum. Dorton has found that the hard anodizing seems like the only thing that has helped in this area.
It's probably worth mentioning that with the coming of alternative fuels that contain ethanol, we'll need to address the corrosion factor, especially in carburetors. In fact, we're doing work with Calico to build some carburetors for the ethanol-blended fuels. We're looking for some corrosion reduction improvements that go beyond what's possible with anodizing that's being used. In particular, we want to address the fuel passages that include the emulsion channels and similar areas. I mean, no matter how much you preach to racers, it's unlikely they'll go through all the post-race draining, cleaning, and lubricating of areas that are exposed to the ethanol-blended fuels. The ethanol will sit in there until the next Saturday night race and cause ongoing corrosion.
Have you seen any cost-to-benefit coatings and applications over the years you've been working with them?
Some of the less costly areas we've found especially beneficial include flat-tappet lifters. Years ago, I found that no matter what type of camshaft break-in lube you choose to use, if you coat the camshaft and lifters with a dry graphite film (DFL) in combination with the lube, it'll improve your chances of a proper cam break-in. I know camshaft break-in problems have been around for a long time, and we've found this approach to minimizing premature wear or improper break-in has been successful.
What do you see in the future for coatings?
I don't really know. However, I would never have believed the benefits that we see today, even seven or eight years ago. This is especially true with the DLC coatings that increase parts longevity so much. So I'm not certain where it'll all go from here, although there's a possibility that other areas in an engine may benefit more, like with crank journals and that sort of thing. The benefits we've seen from coating bearings, valve seats, and valve stems just further validates how coatings can help.
I do know that there is a considerable amount of very aggressive testing going on right now. Of course, a lot of these exploratory materials don't work at this stage, but testing is the only way to find out what does and what doesn't. I'm certain we'll see new coatings and applications in the future. It's an evolving technology.