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Old 01-09-2010, 09:01 PM   #27
gokart2
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So what do you think? Would a wrapped header/flex pipe retain enough heat to warm a retail aftermarket HF cat (OR a racing cat) as quickly as the OEM setup?
^--No. Its too far down stream as compared to oem. It would be delayed, but i dont know by how long.

Would a cold header/flex pipe act as a heat sink initially to rob the cat of startup heat?
^-- Most definetly

Is +750*c (1382 degrees Fahrenheit) typical for a gas engine? Or could you obtain the EGT of a Duratec engine? Is that the light-off temp for a cat?
^--Not at start up or idling. Decent rpm and alot of load can yeild those temps. But it depend on what engine (i4 or v8), catalyst placement, etc... I can possibly get egt of a 2.3 at start and for a few sec. But then we go to a specific rpm and load, then alter timing and fueling, ect...i will see if i can dig some data up. Wont be right away though.
We refer to lightoff as an overtemping of a catalyst, so i cant tell u exactly when the cat reaches the optimal conversion temp. We age gas catalyst to what would normally be about 150-200k miles in about 85-100hrs, depending on the aging requirements. But i have seen catalysts reach 2400*f for long periods and live. But i have also seen then melt.

I specified header wrap as from my reading it retains more heat (I.E. works better) than a jet coat or similar.
I did not specify wrapping the cat as I don't know if doing so is recommended. Would the cat burn out prematurely?
^^yes header wrap retains heat (and moisture) better. So idealy you would want wrap on the cat, but im not 100% sure about the header...maybe both coating and wrap? You'd want it to retain heat as well as get it to the cat. The wrap on the cat will speed up the aging of the cat, but i dont think a noticable amount. Im not 100% sure what precious metals and chemistry are in aftermarket/high flow cats so that one im not too sure about
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