Newb question regarding aftermarket catalytic converters
 

Pardon my ignorance, but I'm curious about aftermarket catalytic converters, specifically the ones that have been coming out on headers and over pipes for our cars. I understand that cats generate a lot of heat as part of their function. Naturally, the stock headers and catalytic converters have a lot of heat shielding, which I assume is to keep all the excessive heat away from its surroundings (ie oil pan for the headers, etc). I've noticed that a lot of the aftermarket options don't have any heat shielding at all. I've noticed a handful of folks heat wrap their parts, which I would have thought would be more common, but almost everybody just installs them as-is.

Why is wrapping not as common? Why don't people put any adhesive heat shielding on other components like the oil pan? Do aftermarket exhausts have the heat shielding already build in?

The answer to all of your questions can be summed up in two words: BECAUSE. RACECAR.


But seriously I have wondered some of the same things. Free bump!

I have seen plenty of photos of people using adhesive heat sheilding on the oil pan. A large number of people also get their headers ceramic coated to reduce the heat it dumps into the engine bay. People tend to shy away from wrapping headers due to the fire risk they pose and the increased risk of corrosion. Although i have read some people talk of a sealing spray you can use on the wraps that improve that situation.

Could it be that the wraps contain the heat so well that it leads to speedy deterioration of the exhaust components being wrapped? I've heard of headers cracking due to the heat being contained.

I was told the cracking had more to do with wrapping them too tightly and preventing expansion of the metals than holding too much heat.

That is true, I believe one of the headers (I'm not sure which) came with heat shielding to go on the oil pan.

I believe there is some type of high temperature spray you can spray over over the heat wrap to reduce the fire risk.

Do folks just think that the headers and parts of the exhaust just don't get hot enough to need any shielding?

the OE is generally very cautious about heat. not necessarily worried about performance, but risk of fire (ie, parking your car in tall grass, leaves, etc). also heat in the engine bay leads to a higher rate of degradation in rubber components (belts, hoses, wire insulation, etc) and are making cars to last a long time with fewer problems. at least that's their intention. aftermarket companies generally aren't worried about other stuff lasting, so long as their part holds up.

and btw your catalytic converter gets waaay hotter than the manifolds, but the manifolds are right up in your engine bay, hence the heat wrap on headers.

This is great info, I also hear about people saying the cats don't last long in after market headers/front pipes. If they must be replaced don't header cats also need the same?

I toasted my cat at track into a marshmallow