High-level engines are using a compacted graphite iron (CGI) for today's competition.
As the block preparation work continues, the elements to produce power start to come together. As Jenckes emphasizes, good ring seal is critical.
"You have to look at the cylinder kit, which is the bore, piston, rings-those components," he says. "Some of the things that are critical in getting good ring seal are the finish of the bore, what level you hone it, how you hone it, even what you hone it with, and not the least of which is the guy honing it. Machines make a lot of it easier. Back in the day, I can remember a guy standing on top of the block with a 11/42-inch drill motor, and that's how blocks were honed. It worked fine. Part of that was the guy operating it. He was so skilled he could feel a block burnishing just by the increase in the motor speed. When they came out with machines, you could watch a load meter run while you were honing the block. There are a lot of machines out there now that can help the average guy hone a block than ever before."
There was some discussion last month about coating bearings. According to Jenckes, there has been some experimentation in applying coatings to cylinder sleeves.
Racing-engine blocks can be composed of various materials. Popular choices include aluminu
"Nickel silicone carbide is a ceramic that coats either the parent metal of the block, or the sleeves are coated and placed in the block," Jenckes explains. "Coatings are difficult. Whenever you coat something, you have to be very careful that the coating sticks. There's a substrate on the parent metal you're applying a coating to that's an integral part of the chemistry. In a cylinder block, the iron itself is not homogenous. As they pour the iron and it cures, it's not consistent throughout the block. The chemistry of applying a coating to an iron block is problematic at best. A sleeve is easier to coat because the material can be completely homogeneous. It can be a tube that is specially made to be coated. The chemistry is much easier, but even then, you can have coating slips and that can be a problem.
"It used to be that people didn't use sleeves, thinking a sleeved block was a bad block. Today, they're different sleeves. Some of the sleeves they're running in motorsports are 0.0004 inches, and that's not much of a sleeve.
"There are some significant advantages to running sleeves. Many people don't believe in them and say they're a bad addition, [but] many people have had good luck with them. So we're not going to find anyone saying sleeves are perfect, or they're great, or they're junk. There's still a lot of debate over it. Like anything else, you can build winning engines with or without them, but you have to be careful how you handle each side of it.
Boring for cam bearings is a precision step in which modern engine builders rely on high-c
"As far as friction reduction by using a nikasil coating, I don't know that I have personally seen power gains just by doing the nikasil. In and of itself, it may not be a power gain, but you may be able to build power you couldn't have without it by using other technologies."
Jenckes found a possible advantage of using sleeves: They come with bigger bores. "Today, people find that particular bore and stroke combinations are very effective," he adds. "Typically, people are running bigger bores and they find that, no matter what the application, a bigger bore may be helpful. I'd certainly say that's the trend in Nextel Cup. Obviously, if you want to make a block last a long time, you can't go to the big bore size immediately. You'll get one rebuild, and then it's junk and you've just spent all this time building this nice block. A sleeve can allow you to go to your optimal bore size. When you have problems, just replace the sleeves.
"Some teams in Nextel Cup use sleeves, and some don't. In Nextel Cup, the well is deep money wise, but it's not endless. Consider that you can use a smaller number of pistons and crankshafts, and that means less money tied up in crank and piston inventory. Some teams might approach it from that standpoint."