Explain this to me:-

How is the external temperature of a header no different in the fast moving engine bay air of a car at 60mph compared with no air contact at all, encased in header wrap that reduces heat transfer by 70%

 

 

Pi x r2 ./. 70 x 60 mph - 85 (ambient) ./. insulation value x heat coefficient (assume 3.79 v for mean)...

when you get that equation, let me know.

 

So I see alot of posts, here and in other posts, about how bad the header wrap is, but wonder if most of the nay sayers have experience in actuality or in repeating what they have heard and read elsewhere, vs. those that have actual experience.

Just saying. Don't get your panties in a wad.

 

mikejpss + OP x bogus post + pompous drivel - goldens question = BS


See if you can work that out

 

What he is basically saying with that formula, in plain english is, enerhy has to come from somewhere. Heat is energy. The wrap istelf is not adding energy to the equation, so the headers, even wrapped, can only ever get as hot as they ever did without the wrap. That's physics.


The problem is, some of these old cars leak. Ever had a few drops of oil get on your pipes after changing out the filter? Every had a splash of anything get, pretty much, anywhere, while working under the hood? I know I have. Most of those compounds are highly corrosive to metal, and when heated, it accelerates that action. Or it just catches fire, and trust me, that wrap burns HOT. That doesn't happen often, though.

I have personally seen a set of hooker headers that were wrapped before instalation, brand new, then installed on a car that gets driven less than 3,000 miles a year, and the headers were junk 5 years later. And those were a 700 dollar set of big block headers. Is that gonna be everyone's story? Nope. But it's mine.

 

I think that is precisely the purpose of both items.

 

The same amount of heat energy is added to the header.

When you wrap it, it's not going to be able to get rid of the heat as efficiently or as quickly it does UNwrapped. The temperature of the header will be increased with the wrap. It's just as the surface of your skin is warmer in the winter with a coat on as opposed to wearing short sleeves.

 

That's a physical impossibility without some form of chemical reaction, or EXTREME pressure.

The exhaust gasses leaving the motor is what gets the headers hot. That exhaust gas, right out of the motor, not a few feat down the pipes, but right out of the motor, is going to be the same temp against those headers, wrapped or not. Since that gas is the source of heat energy transferred to the metal of the header, the header can NOT, without extreme pressure or chemical reaction, get hotter than said gas.

It CAN and WILL stay at that max temp for a much longer period of time, though, and heat accelerates almost all chemical reactions.

Ever watch myth busters? They tested a myth where a dude put hot sauce on his prison bars, and then heated it with electricity from a radio. The result? Bars with no heat source, just hot sauce, had NOT corrosion. Bars with sauce AND heat source had SIGNIFICANT corrosion. Substitute hot sauce for brake fluid, gas, antifreeze, power steering fluid, any number of the things can and most likely WILL get dripped onto those headers at some point. Or salt, either from the road or air. Even car soap.

All of these things will be absorbed by wraps.

It's a motor of pros vs cons, and how you plan to drive the car, where you live, etc.


I live in CT.

 

mikejpss has a lot to answer for, he's full of it.

He made a contradictory point to something that nobody said

I've just looked back through this thread and can't find where anyone has said there will be an increase in the maximum attainable temperature by headers being wrapped

Having said that, both mikejpfullofit and kevin are both making an irrelevant point. Anyone with a basic knowledge of physics knows that the maximum temperature of the headers where the exhaust gas hits them cannot be raised above the BTU value of the escaping exhaust gas.

But headers don't only have just the surface that faces the exhaust valve, the other side of that 1/8th inch thick piece of tube sits in a nice cold airstream (assuming you're not stuck in traffic). This cooling air is constantly wicking away heat from the headers.

By wrapping the headers and starving them of cooling air the exterior of the headers does indeed run hotter, causing the mean temperature of the header to be higher than an unwrapped set of headers.


So mikejpss, next time you want to show off your community college degree in BS, keep it to yourself and don't try to show off by arguing about something nobody said, or cares about.

 

got my headers coated, plus sprayed Lizard Skin under car, in engine bay, inside the car, and using a mat insulator inside also.



http://www.lizardskin.com/car-insula...lications.html

 

Hahahaha. This thread just gets better and better! I agree with Golden here, and I believe that is the point of the wrap. It keeps that temp on the header, not spreading to the rest of the motor.

My closing argument?


Header coatings FTW.

 

What we haven't mentioned yet is that header wrap can retain moisture and this may accelerate the rusting process from the outside.
Usually exhaust rusts from the inside as moist air is drawn I'm after engine shutdown and moisture condensates. Ever seen am exhaust pipe drip water after start up on a cool morning?

 

In case it makes any difference, I have decided to not do header wrap.

 

Heh...my car blows water out like it's a hose. It's parked next to the house, and the pipes dump out the side in front of the rear wheels, and every time I start it when it's been cool out, it splatters the side of the house with condensation.

 

I think this is one of those debates that'll never end. Kinda like displacement vs forced induction. Or import vs domestic.

Wrapping has it's pros. And it's cons.


Not wrapping has it's pros. And it's cons.

 

I'm still waiting for the rocket scientist to come along with another pearl of wisdom.

He seems to be avoiding this thread.........

 

I have heard that using header wrap will make you sterile. Is this true?


Scott

 

I've also heard that a roll of header wrap was the 2nd shooter on the grassy knoll

 

Maybe Sea Foam could save headers from the savages of the wrap...