I have a Mugen header, but the stock header heat shield does not fit on anymore. I already have a heat shield for the brake fuild and that (by ARC) so I'm not so worried about that boiling.

I had to remove the stock header shield because it was knocking and did not fit on the Mugen header as the top two screws don't screw on anymore and only the lower screw on the shield could be screwed on, so it was making a knocking sound.

Could you tell me what the advantage/disadvantage of having the heat shield on the header is? The shop told me it could be an advantage to have it off, as it would allow heat to disperse quicker for more performance. And as mentioned, I do have a heat shield for the brake fluid already.

Any comments would be appreciated!

 

In the stock setup, the underhood temps can get up as high as 70*C in stop and go traffic. Without the header heat shields, those temps can get even higher. You have a shield for your brake and clutch fluid but this is only good for radiated heat. It won't provide much protection against convection heat, not that this is a big deal for brake fluid. However, with your engine bay getting that hot, imagine what your intake has to deal with, not to mention the added heat that surrounds the coolant lines.
I put on a Toda header and my engine bay temps got very hot. I put on a vented hood (Top Secret) to offset the lack of header heat shields.
If you cannot get those bolts on, you might try putting something in there to cushion the knocking. Maybe a wad of header wrap or something that can take such temperatures.

 

My Mugen header came with a heat shield, although it doesn't go down quite as far as the stock one. I could be wrong, but I recall the stock shield being two pieces, where the lower piece covers where the pipes merge from two to one. The Mugen lacks that lower piece.

Maybe a Mugen shield can be purchased separately.

 

Thermo Tech makes a wrap made to keep heat contained with the header and radiate a little as possible. It's a cloth-like strip 1 or 2 inches wide that wraps around the tubes and tied with metal traps. This might help you keep that engine bay a bit cooler. They also make various heat shielding products to keep things cool. I covered the stock air box with their heat reflecting product, keeping my Comptech air filter and air inside cooler.

 

Keep in mind that header wraps have been known to result in cracking of the header. That's the only thing that keeps me from wrapping my Toda header. I'll probably end up going xviper's way when I get the cash and get a vented hood to help reduce under-hood temps.

 

 

I'd like to make sure that noone got confused by this earlier statement. Use only a "wad" of header wrap to act as a "rattle cushion". At no time am I suggesting anyone wrap their header with this stuff. Most aftermarket headers are made of much thinner material than stock. A header wrap may hold much too much heat in to be a safe method of keeping heat out of the engine bay.

 

"Heat to disperse quicker for better performance"? Hmmmm. I wonder what engineering principle they were thinking of - this has no engineering validity in this context.

Higher exhaust gas temperatures result in high flow rates. so that can't be it
More heat in the engine bay is bad; the car will retard timing. so that can't be it.
More heat in bay warms the intake air more - not good for power. so that can't be it.

Yup - those "experts" have no clue - sounds like one of those "off the top of a clueless head" responses that the technically illiterate like to throw at people on the other side of the counter, in the hope that they are as technically illiterate.

With guys like xviper around, you are protected from technically illiterate musings by his invisible......... "Cone of Wisdom" (deep Don Pardo voice over, with impressive echoes for effect).

 

Thanks. I'll definitely have them put it back on then... and find out how to put the heat shield on.

 

The advantage is in weight reduction. The lower heat shield on the stock header weighs a little over a half of a pound. With that much weight being taken off, your are going to feel quicker acceleration and better throttle response.

Header wrap is a big on thin-walled headers if you are driving the car daily.