georgiaz Posted September 3, 2003 Share Posted September 3, 2003 I recently put header wrap on my Summit brand block hugger headers and found that it makes a significant difference in underhood temprature. Now I can't seem to keep collector gaskets on them. I have burned the cheap paper ones, the slightly better Mr. Gasket ones and now the Flotech deadsoft aluminum ones. This is all in less than two months. I know the Summits are not the highest quality so I was thinking of the ceramic coated Hooker headers, but wondered if the coating contains the heat as much as header wrap. Suggestions or opinions? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted September 3, 2003 Share Posted September 3, 2003 The coating definitely keeps the heat way down. The header wrap will eventally make your headers rot, and is not recommended at all. Go with the coated headers, you won't regret it!! Tim Quote Link to comment Share on other sites More sharing options...
georgiaz Posted September 3, 2003 Author Share Posted September 3, 2003 I had heard that about the header wrap, but felt that something was needed to cool things off a bit. The Summit headers were only $79 so I figured if they would last a couple of years I got my moneys worth. I think the flanges on the header and collector are not fitting very flush together and the header wrap probably causes some warpage from heat at the collector where it is not wrapped. The best price I have found on the Hookers is $269.00 from Summit. I wanted to verify from someone who has run them that they would do the job before I spent that much for them. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted September 3, 2003 Share Posted September 3, 2003 The hookers are the most commonly used ones in the V8Z, I believe. not sure about the LT1 'D' ports fitment, though. Tim Quote Link to comment Share on other sites More sharing options...
Kimi Posted September 4, 2003 Share Posted September 4, 2003 Has anyone tried to put a ceramic paint on the headers? There is a ceramic paint called Black Satin. Costs here in Finland about $100. I have been thinking that I will paint the headers with this stuff instead of using Thermo-Tec wrappers. Quote Link to comment Share on other sites More sharing options...
dot Posted September 7, 2003 Share Posted September 7, 2003 Tim: I have found the thermo rap to be an asset to keeping the density of the exhaust gases high there by increasing the function of the header. I use stainless so rot is not a concern. If georgiaz were to use the ceramic coated Hooker headers with a rap do you think this would help reduce the corrosion problem but still provide horsepower gains and reduce under hood temperatures. There is a lot to be gained in this area. On the collector flanges I use hi heat silicone on very clean surfaces with out a gasket. I have not had a failure in many years. Cheers …:::Glenn PS Hybrid Zs in Finland…nice! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted September 7, 2003 Share Posted September 7, 2003 Glenn, When I took my headers in to get coated, I asked the guy at Rewarder Headers about coating and wrapping to decrease underhood temps even more. He said DON'T DO IT!! He was very emphatic about it. So that confirms everything else I've heard about using wrap. Tim Quote Link to comment Share on other sites More sharing options...
David K Posted September 7, 2003 Share Posted September 7, 2003 There is a thread on header wrap somewhere in this book of a site. Some of the guys who posted in the thread had problems with heads warping, etc. I would say if header wrap holds in enough heat enough to warp heads, then it would for sure burn out gaskets, etc. Give it a search, might find it. Quote Link to comment Share on other sites More sharing options...
georgiaz Posted September 25, 2003 Author Share Posted September 25, 2003 High heat silicone huh? I have never heard of using that for collectors. It is probably worth a try. Since the transmission bit the dust the Hookers are on hold for a while. I would not think that header wrap would cause the heads to warp, but I will definately do a search to see what comes up. Quote Link to comment Share on other sites More sharing options...
Afshin Posted September 25, 2003 Share Posted September 25, 2003 I can't remember for sure which of the turbo books (I think it was "how to turbocharge your car.." by David Wizard), but i distinctly remember the author recommending to stay away from wrappers for the very same reason that Tim mentioned. I have stayed away since. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 25, 2003 Share Posted September 25, 2003 David, that was my post. I put header wrap on my L6 not a V8 (which is why I didn't respond to this post) and immediately the motor got hot, especially when sitting. This still seems sort of backwards, because you are putting a lot more heat in the exhaust when at WOT, but that's what happened. I asked on the IZCC list, and got a response from an old ITS racer who said that since the flange was not insulated it puts lots of heat into the head and that his race team had warped a bunch of heads in the early '70s when they tried wrap. I don't think you would have any of those probs with a coated header. Jon Quote Link to comment Share on other sites More sharing options...
zbuild Posted September 26, 2003 Share Posted September 26, 2003 I'll throw my 2cents in. . . I agree about the hi-heat silicone. . .its magic stuff, I use it on my turbo'd L6 at the head/exhaust manifold face and also about 500mm down the dump pipe where I have a 3-bolt flange. On the dyno, my dump pipe glows orange right down to the 3-bolt flange, but when you take that flange apart the silicone is soft. . .amazing! Do make sure that the silicone is oxygen sensor safe if you run an O2 sensor though. I also run hi-temp ceramic coating on my exhaust manifold and on the shield under my inlet manifold. I cant tell what changes it made because Ive had it on since I built the car up, but after 6 laps round a track here in OZ with a mate who had a hot normally aspirated (webbers) L6. . . under my bonnet was like I'd been for a gentle cruise down to the shops, under his was stinking hot and mine puts out probably 150hp more than his. . .so Im a convert. Cheers Quote Link to comment Share on other sites More sharing options...
dot Posted September 26, 2003 Share Posted September 26, 2003 "One thing that is commonly overlooked by most racers is the matter of heat retention in the exhaust pipes. We have to remember that as soon as the combusted gasses leave the chamber, they start to cool down. As they cool, they lose velocity, and the scavenging effect is reduced. If the velocity of the gasses inside the pipes is kept as high as possible, the net effect will be a greater velocity, greater pressure drop in the system and higher efficiency. For the past several years we have been experimenting with many types of devices that can be used to insulate the exhaust pipes and hold as much heat in the escaping gasses as possible. We have been through all kinds of paints, brush-on coatings and laminated materials, and it took a lot of work before we finally found an effective heat shield that would be durable and trap enough heat in the exhaust to make a significant difference. The best heat-retention materials we have tested to date are produced by the Fiberfax division of Carborun- dum Company. This is a flexible woven material-like cloth and it is available in either tubes or in rolls of flat stock. You can either slip the tubes over the primary pipes-before the flange is welded on-or you can wrap the flat stock around the pipes, much like wrapping a bandage around the pipes. We use this heat shield on our small-displacement research engines where it has proven very effective and it allows the engines to be more effectively scavenged by the exhaust. This permits a less aggressive exhaust profile on the cam without a I loss of power and since this can usually be translated into reduced overlap and less draw through, the rate of fuel consumption is often reduced. As far as I know most racing organizations haven't yet decided to ban exhaust heat shields though they could change their minds at any moment and I think this stuff deserves serious consideration. It will, unfortunately, take some extra development work to get the entire dynamic flow system, induction, cam and exhaust-coordinated to the increased exhaust efficiency, but when the system is rebalanced, our tests show that the engine will produce more power from less fuel. About 10 years ago we were doing the same thing, but in a different way. Some people eventually noticed that we had drilled some 3/16-inch holes in the primary pipes, a short distance out from the header flange. The tech inspectors were crawling all over us. They had a helluva time trying to decide if, or why, it was illegal to drill holes in the headers, but this was simply another way to increase velocity in the header pipes. Once again, this was based on the fact that, in simple terms, heat is velocity, and maintaining heat in the header pipes will keep the flow velocity up, lower the pressure and increase the so-called scavenging effect. We had been experimenting with venturis in the exhaust in an effort to drop the pressure and increase the velocity of the escaping gasses. But this would not work unless we could also keep the gasses from cooling. However, we noted that the left over gasses leaving a high-speed engine still contain some combustible carbon, and we felt that if we could induce additional oxygen bearing air into the system, the gasses would continue to react in the exhaust pipe and maintain a higher heat level. The holes in the primaries were simply ports for inducting air into the pipes, and if the relationship between the air ports and the venturi was just right, the overall exhaust velocity in the pipe would be greater. Any knowledgeable thermodynamicist will tell you that this cannot possibly work, and I agree that it sounds a bit unlikely, but I also know that it works. When the system was tuned just right, there were obvious signs that the exhaust temperature and the scavenging effect was much higher with venturis than without them. We eventually stopped playing with this because there wasn't enough time available during those days to develop it properly. I mention it now simply to point up the fact that anything you can do in a racing engine to maintain the high temperature level inside the exhaust system will increase exhaust efficiency." :taken from Smokey Yunick's "Power Secrets" I am curious. How does the heat from the exhaust travel back from the header to the head with sufficient energy to warp a head? The heat from the flange to the head would be insignificant if the engine builder used the thick asbestos gaskets supplied by the header manufacture. The other source for heat transfer would be the studs. More than likely they would melt long before the heat required to warp a head could be transferred through them. They do torch them at junk yards and still manage to send out guaranteed motors. It is not uncommon to melt spark plug tips at WOT when an engine becomes fuel starved. Engines have also been known to drop an exhaust valve seat in every day driving if the timing is too retarded. More than likely the increase in volumetric efficiency with out the appropriate fuel and timing changes caused the engines to run in a lean condition over heating the combustion chamber and forcing the heads in question to warp. I’m sorry my rap stays on. I doubt you will talk Ferrari, Lamborghini and other manufactures to take their insulation off ether. Cheers…:::Glenn Quote Link to comment Share on other sites More sharing options...
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