Racing Headers - Header Talk

Stahl: Yes [to having multiple headers for different tracks]. I may be the wrong guy to ask that question, but I think it is unwise to have only one set of headers. I had a customer who would ordinarily use 1 3/4 to 1 7/8 primary tube sizes. But if he was racing and the track turned black and slick, he would put on a set of 2 1/8 headers and the car became easier to drive, almost like it had traction control. So, yes, it makes a lot of sense to have a selection of headers.

SCR: What should the racer look for in a header?

Boat: From a performance perspective, the primary tubes should be as close to the same length as possible. If you have a choice, a merged collector is better than a stamped collector, although a merged collector is a much more expensive proposition. You need to spend some time with your engine builder and see what he has found that makes better power on the engine you are running. If possible, do some dyno testing and get some data to help with the decision.

Stahl: The Saturday night racer should first look for equal-length primary tubes. Second, he should check the assembly methods used to construct the header. It makes a difference if the header is TIG or MIG welded or if it has gas acetylene brazing. Brass brazing never melts the parent material, so it is less disruptive. The heat from the torch has an annealing effect and you end up with a fairly large fillet, so you have a greater area to distribute the load. In my opinion, the worst method for welding headers is TIG welding. If you are going to TIG weld a header, then you need to anneal the header post-fabrication.

SCR: What causes leaks? Hardware, gaskets, thin flanges, poor maintenance?

Boat: The biggest problem with leakage is from the flange that interfaces with the cylinder head being too thin. The minimum thickness is 1/4 inch, and 3/8 is preferred. The weight differential is not that big of a deal in stock car applications, but the Sprint and Midget guys may gripe a bit about the extra weight of the thicker flange. You need to use a quality gasket that will take the elevated temperatures developed by racing engines. Quality hardware is also an issue. Using poor-quality bolts, studs, or nuts can also cause leakage problems. You need to make sure that the bolts stay tight. Safety wire is a good way to keep the bolts from backing off. But the biggest issue is still the flange thickness.

Stahl: We do not have problems with leakage. I would attribute most of the problems with manufacturing processes. One thing I would caution racers against is trying to tighten header bolts when the engine is still warm. Most header bolts are not made from the best steel. We have had people snap the heads off of header bolts when they tried to tighten them up while they were still hot.

SCR: How should a racer maintain headers?

Boat: First, it depends on the material the header was fabricated from. With mild steel, it is a good idea to keep them covered with either quality high-temperature paint or a ceramic-type coating like Jet-Hot or NitroPlate. The downside is that it is difficult to impossible to weld headers once they have been coated, unless you return the header to the coating house to have it removed. Other than that, keep them clean. If they are not plated or painted, keep the outside oiled to minimize rust. Headers made from stainless steel don't really require coatings. Just keep them clean.

Stahl: They need to be kept free from rust. They need to be properly cleaned in order to do that. If you are going to sandblast them, keep the blast pressure down to the minimum so you remove as little of the metal as possible. If you are going to paint the header, you need to get the header as clean as possible. This may require a chemical bath with a product like phosphoric acid.

SCR: What about ceramic coatings versus chrome or nickel?

Boat: Chrome plating is OK for show cars and bikes, but it has no place on racing headers. Nickel is not a real option, either.(Note: There are some data points out there that indicate some brands of coating actually increase horsepower. But the impact of coatings on durability is still an unknown at this point. -J.H.)

Stahl: The so-called ceramic coatings look nice. I have no hard data that confirms or denies if they add life to a header. The problem with these coatings is if for any reason you have to weld the header at a later date, the coating has to be removed; that's not something most guys can do at home. I will tell you that the header wraps that are on the market are the header manufacturer's best friend. The only way you could kill a header quicker is with a gun. Chrome plating can cause hydrogen embrittlement. So unless you are ready to bake the headers for multiple hours, chrome plating is not a real option. Nickel is not an option, either.