Recently we've taken a look at header coatings and even showed you a no-buck way to rust-proof your mild steel headers. So we thought it was only appropriate to hit the trifecta and take an in-depth look at a third option for protecting your headers and controlling heat: header wraps.
Header wraps are definitely old-school, and honestly, you don't see them on race cars too often any more. But Design Engineering Inc. (DEI) has been bringing some pretty cool new technologies to the table recently and we thought it deserved a closer look.
DEI's newest wrap is known as Titanium Exhaust Wrap and the premise is pretty interesting. Instead of a fiberglass-based material, DEI says the Titanium Wrap is made from pulverized lava rock and stranded into a fiber material that is then woven into the wrap. This is supposed to create a wrap that is stronger and capable of withstanding a greater temperature range. DEI says it has also addressed one of the greatest complaints about wraps--this new material is resistant to abrasions and isn't very absorbent. That means that it won't tear apart with a little contact and it won't become oil soaked as easily as other wraps. What we do know is the wrap has a cool metallic sheen that looks pretty high tech.
Of course, looks mean nothing in circle track racing. If it doesn't help you go faster, make your equipment more dependable or save you time, it's practically worthless. To find out whether--and just how much--a header wrap can help your racing effort, we put DEI's new Titanium wrap to the test on a real racing engine on the dyno. Here's what we found.
1 DEI sells its Titanium...
1 DEI sells its Titanium Exhaust Wrap in multiple sizes, but we chose two rolls, 2 inches wide by 50 feet each. That’s the recommended amount to wrap two small-block V-8 headers. We’re also using DEI’s stainless steel locking ties to secure the wrap and a can of DEI’s HT Silicone coating to help repel any oil that may drip on the headers.
2 For the test went went...
2 For the test went went to Keith Dorton’s shops at Automotive Specialists. Dorton was doing R&D work on his own spec engine which is used in several different series and allowed us full access.
3 The test engine is a small...
3 The test engine is a small block Chevy with a 600-cfm Holley carb that produces 530 lb-ft of torque at 5,200 rpm and 620 horsepower at 7,000. Dorton had mounted up a set of stainless steel, uncoated headers to the 23-degree cylinder heads. The first step was to get a baseline, so the engine was revved to peak torque and held there until the temperature stopped rising. By that time, as you can tell, the header tubes were beginning to glow red.
4 Once the engine was fully...
4 Once the engine was fully heat soaked, Automotive Specialists’ Justin Bryson used an infrared temp gun to check the engine temperatures in several places. We monitored temps at the valve cover, the header tubes near the exhaust ports and just past the collector. We kept repeating the process until the temperatures stabilized. By the way, the temperature we measured at the collector was 750 degrees F.
5 The uncoated headers leveled...
5 The uncoated headers leveled off at 1,156 degrees, while the valvecovers were in the 750-degree range just above the headers. We checked the valvecovers because the headers are obviously heating them which, in turn, heats the engine oil.
6 The headers were still...
6 The headers were still hot when we pulled them off and started the wrap process—but to be honest, we held the camera and tried to look busy while Bryson did all the work. Begin by using the stainless steel tie to secure the wrap near the header flange. DEI recommends overlapping the wrap by only 1/4-inch or so to keep from actually holding in too much heat and damaging the header.
13 Dyno testing means constantly...
13 Dyno testing means constantly pulling the valvecovers to change springs or check valve lash, which means oil is always dripping on the headers. DEI makes an excellent high-temperature spray paint that contains silicone. The silicone helps reduce the absorbency of any material it is sprayed on. DEI doesn’t actually recommend it for the Titanium Wrap, only because the super slick material the wrap is woven from can sometimes allow the spray to flake—but it isn’t a performance issue and doesn’t affect either the wrap or the headers. So we figured we’d give it a shot and Bryson laid down a few light coats. The spray actually cures at 400 degrees once the headers are on the engine. Also, if you are wrapping mild-steel headers, use the spray first to seal the headers from moisture before applying the wrap.
14 Back on the dyno, the...
14 Back on the dyno, the freshly wrapped headers certainly looked good. It’s time to put them to the test.
15 We repeated the previous...
15 We repeated the previous testing process, holding the engine at 5,200 rpm and checking our test points until the temperatures held steady. The first time around the header tubes near the cylinder heads measured 1,156 degrees, but with the wrap that number dropped to 972.
7 Even in 50-foot lengths,...
7 Even in 50-foot lengths, there isn’t a lot to spare, so avoid the urge to cut the material into shorter lengths. With V-8 headers, wrapping is practically a two-man job. Conventional wraps are stiff and require soaking in water to make them pliable enough to wrap, but the Titanium Wrap is easy to work with. Just make sure to keep the wrap nice and tight so it won’t slide around later.
8 This set of headers have...
8 This set of headers have bungs welded in to install sensors to monitor EGT’s on the dyno, but they were easy enough to wrap around. With Chevy headers you will have to wrap the center two tubes as one. DEI says that doing this is no problem.
9 Wrap the header tubes individually...
9 Wrap the header tubes individually as far as you can and then tie them off. You can cut the material with either scissors or a knife, just be careful because it unravels easily. Then continue by wrapping all the tubes together. You can see the gap that doing this can leave. That’s unavoidable but not a problem.
10 Bryson ties off the wrap...
10 Bryson ties off the wrap near the collector using safety wire. Make sure to use either DEI’s stainless steel ties, hose clamps or safety wire—not plastic zip-ties because they will melt.
11 Here’s where you can learn...
11 Here’s where you can learn from our mistake. We tied off the end securely with both a stainless tie and some safety wire. But that doesn’t keep the end from unravelling. When it is your turn, make sure to fold the end of the wrap under before strapping it down.
12 Here’s a look at the finished...
12 Here’s a look at the finished product.
16 Before the valvecovers...
16 Before the valvecovers were around 750 degrees, but by wrapping the headers the radiant heat was significantly cut down. This time around they were only 619 degrees. This should make a big difference in the oil temperature.
17 And unsurprisingly, we...
17 And unsurprisingly, we saw the same results at the merge collector. What was originally around 750 degrees dropped to 552.
18 It’s worth noting that...
18 It’s worth noting that wrapping the headers doesn’t get rid of the heat of engine combustion, it just holds it in the header pipes. As you can see, they are still glowing inside the wrap. We didn’t see any horsepower gain on the dyno, but that was because the engine is being fed temperature-controlled air into the carburetor. In a race car the wrap will significantly reduce under-hood temps, and if you don’t have a hood scoop it means the air going into the engine will be cooler. Using a wrap or some type of coating to keep heat inside the headers will keep components, oil and even the air/fuel charge cooler, which should make for a healthier, stronger racing engine.