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noone on the uk forum knows an awful lot about header so i thought i`d ask you guys.
with my main aim to get the engine as much cool air as possible i hsve ordered a hondata intake gasket and a muz air intake. an ex race engineer who works for itg filters recommended wrapping my header with thermotec wrap.
Has anyone used this on their s or any other cars.whats your opinion on this. it basically insulates the engine bay from the heat generated by the manifold. my main concern is that the manifold will overheat as it is lagged and it may crack as someone suggested. can that happen? btw im am planning do this on a ricks manifold.
my main concern is that the manifold will overheat as it is lagged and it may crack as someone suggested. can that happen? btw im am planning do this on a ricks manifold.
This has always been my concern also. With the cost of replacing a cracked header on this car, I decided not to do it. Also, it will be a bit hard to do a good wrap and still be able to bolt the heat shields back on.
Here's what I know and have heard about adding header wrap.
1) The "reflected wave" in the exhaust is affected by the temperature in the exhaust. The header wrap increases the mean temperature of the exhaust gases and therefore increase the speed of the exhaust gases. This may or may not be a good thing for your particular application. Some drag race guys (V-8 small block Chevy) claim to pick up 4-8 hp with header wrap (on 700-900 hp engines). Other guys claim just the opposite.
The reason is that the extra heat creates a new "ideal" tube diameter and tuned tube length. So if your header was slightly too big or slightly too small the header wrap could improve you or hurt you. The only way to know is to try it.
2) The underhood temp. will likely be reduced by 10-20 degrees F (I think this is a reasonable guess). The tradeoff is that if your using mild steel tubes (I think the OEM tubes are 304 stainless steel) the headers will virtually crumble apart after a few thousand miles. The constant heating and cooling causes moisture to become trapped between the insulation and the header tube. The "heat effected zone" near the welds are the weak link and they begin to crack/deteriorate first. I have heard that even headers with the ceramic coatings crumble (although they take more time before crumbling). I have seen guys use it on stainless steel headers with good results (on drag race cars that only run 30 miles per year), but I can't promise you that they won't eventually deteriorate. Stainless steel is rust resistant not rust proof.
Hi xviper. it would be easy for me to wrap the header up at the moment as its not on the car.the heat shield is more for personal safety than to keep the engine bay cool. i think someone mentioned that u could actaully touch the wrap while the car was running it was that good at insulating the heat.
i have actually ordered the bits. they only cost $100US dollars which was about a third of the cost here. this includes a sleeve for the air intake pipe between the manifold and airbox. i can still use that if i decide against the wrap.
You can jet coat the header with about the same results as a wrap. I had my Comtech header done inside and out. Having the inside done will help reduce heat by 50* to 75*F and it will be very smooth inside
Originally Posted by S2KPUDDYDAD,Aug 27 2005, 11:30 AM
You can jet coat the header with about the same results as a wrap. I had my Comtech header done inside and out. Having the inside done will help reduce heat by 50* to 75*F and it will be very smooth inside
how many miles have you done since you had the header coated. have you noticed any problems since you had it coated and have you seen any benefits since coating it?
i was a bit sceptical of the coating but coating the inside makes more sense as it prevents the header itself from heating up.
Wrapping the outside of your header isn't a good idea, and here's why:
Our headers are likely made from 309S or a Japanese equivalent (most headers are), which has very good high temp corrosion resistance, Wrapping the header will significantly increase the temperature which will accelerate the oxidation rate of the metal. Unlike 409 stainless that forms an oxide layer, 309S is an austenitic stainless that has a higher thermal expansion coefficient, and the oxide layer "powders", or exfoliates the oxide layer as a powder. The oxidation rate and powdering rate increase with increasing temperature.
The high thermal expansion coefficent of this type of stainless steel means that stresses increase with temperature. Since the header is not symmetrical, the the added thermal expansion will cause stress risers at critical locations. Thermal cycling with higher temps will eventually result in fatigue cracks. How soon? That depends how high the temperatures get, and how many times it cycles to high temps.
The strength of all metals decrease with increasing temperature. So the higher the temperature, the weaker the header. Along with high vibrations and temps at high RPMs, you're shortening the life of the header and if the temps and stresses get high enough, the header will bend or sag.
And if you ever get this wrapped header area splashed with road salt, you will see the corrosion rate of the header accelerate dramatically. These salts tend to wick into the space between the wrap and the header (capillary action). A wrapped header will get hot enough to actually melt sodium chloride and calcium chloride. Molten salts are far more corrosive than brine (saltwater).
Coating the inside of the header may actually reduce the header wall temps, which would increase the life of the header. As long as the coating doesn't come off and clog your catalytic converter, that would be a good way to go.
how many miles have you done since you had the header coated. have you noticed any problems since you had it coated and have you seen any benefits since coating it?
i was a bit sceptical of the coating but coating the inside makes more sense as it prevents the header itself from heating up.
I have a Comtech header which is a very good, well made header. It is about 8 to 10 lbs lighter than the OEM unit but still has some weight to it.
There is more under hood heat now with the new header but not as much as I would have thought. The coating is working well, looks great with a nice shine to it. The header has been on for about 1000 miles or so with no problems of any sort. The coating will lose some of it's shine after time or sooner if you run too lean but, it will not lose it's cooling benefit, it will just dull a little. I do not think that it will come off on the inside or out for that mater so as not to worry about clogging up your cat. if you run one.
As for the benefits of the coating, it looks great and works well at what it is intended to do cool the engine bay down
Puddydad what sort of material was your header coated with and what sort of place coated it for you? was coating the inside and outside expensive and difficult?
i wouldnt know who to ask in the uk! the tuning places here havent even heard of this!
Puddydad what sort of material was your header coated with and what sort of place coated it for you? was coating the inside and outside expensive and difficult?
i wouldnt know who to ask in the uk! the tuning places here havent even heard of this!
Ceramic coating, Jet coat, Jet coating as a brand name has been around for a good long time.
I first saw an ad in the back of Hot Rod magazine in the 80's for the service and at that time it was big bucks($1000 US) to have it done. It has been used in Top Fuel on down the line to Pro street drag racing with great results "Wins" over the guys not using the prosess "It works!!"
The price has come down a lot since then I paid $120.00 US to have mine done, and that was inside and out
It is not hard to do and the inside is done with a wand that can reach far inside to spray the chemicals. There are guys here in the States that do this as a side business "It's not rocket science". medea blast to get it to stick, Spray it on, bake it, and polish it... finished.
The guy that did mine works out of his garage at home. Let me know how you make out finding a place to do it. Also J.C. Witney sells a home kit for the "do it your self guys" it's ok but not the best.
08-26-2005, 02:56 PM
Header wrap
