is ceramic REALLY needed?
03-07-2003, 03:53 AM
#1
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is ceramic REALLY needed?
just bought one of those intro-priced borla headers for my 2003 WRX. my friends and I have been in discussion about using ceramic coating or not. I don't see a need for it, except to possibly gain a little more performance from the header. they argue that the engine compartment will run too hot, but I've contacted borla and this is not an issue in their benchmark tests. plus, i have the advantage of having a CAI buried nicely in the right fender well. i assume the stock heat shield will remain in place...welded to the manifold. and i've not seen a single header for the WRX yet that was coated. bottom line....is it safe for the engine to bolt this thing on without wrapping or coating? thanks in advance.
03-07-2003, 09:33 AM
#2
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Frist of all, your CAI will do nothing for you in regards to making your engine run cooler. It will not even give you colder air into your engine as the air still goes into your exhaust gas driven turbine and gets heated up, negating your fancy cold air intake...
Now ceramic coating from the likes of JetHot or SwainTech do not radiate heat. It is designed to keep heat in and lower underhood temps. So ceramic coating WOULD benefit you if you did it. Even the header alone should lower temps a tad because thin wall steel retains less heat then stock cast iron manifolds.
Now ceramic coating from the likes of JetHot or SwainTech do not radiate heat. It is designed to keep heat in and lower underhood temps. So ceramic coating WOULD benefit you if you did it. Even the header alone should lower temps a tad because thin wall steel retains less heat then stock cast iron manifolds.
03-07-2003, 12:26 PM
#3
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ceramics
didn't know that the stock header would run hotter, i guess that's good news for me. BTW I did not expect the CAI to cool the air entering my turbine. The argument with my gear head friends was that with the header being so close to the air intake, that it would be sucking hotter air. I don't think that will be the case. I installed the CAI for 3 reasons...to hopefully get a little better gas mileage, to increase throttle response a bit, and mainly to hear the turbo spool up better without installing a BOV. I'm not running extra boost, so a BOV alone would actually hurt the performance vs. the stock bypass valve.
Thanks for the re-assurance though that the new header should run cooler than the stock one....makes sense. l8r.
Thanks for the re-assurance though that the new header should run cooler than the stock one....makes sense. l8r.
03-07-2003, 12:45 PM
#4
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Air intakes and headers
The theory behind CAI is to get colder are because it is denser (molecules closer together). Also the open filter allows your engine to suck in more air but it has to then add morew fuel to create good mixture (ie raising fuel consumption).
I decided to just use a K&N in stock box to prevent computer problems. I happens with my other car because of inconsisitent air flow leading to air/fuel mixture problems.
In the end the better move is a bigger intercooler to create colder, denser air ( but that comes with a cost $$$)
As for your header; exhaust gas works almost the opposite. Hotter air is better because it moves faster out of your engine. Using ceramic or my preference header thermo wrap helps keep the header red hot and heat away from your engine.
I decided to just use a K&N in stock box to prevent computer problems. I happens with my other car because of inconsisitent air flow leading to air/fuel mixture problems.
In the end the better move is a bigger intercooler to create colder, denser air ( but that comes with a cost $$$)
As for your header; exhaust gas works almost the opposite. Hotter air is better because it moves faster out of your engine. Using ceramic or my preference header thermo wrap helps keep the header red hot and heat away from your engine.
03-10-2003, 08:42 PM
#5
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I_Fry_Rice,
the most thermodynamically efficient headers are the best-insulated. Stainless steel is excellent because it has a very low thermal conductivity - i.e. it doesn't dissipate a lot of heat. The ceramic coat thickens the tube; ceramic also has a much lower thermal conductivity so the coating thickness + lower conductivity increases the header's overall thermal resistance. This means the hot flowing exhaust gas inside the header tube stays hot and the engine bay outside remains cooler.
Why is this good? It's about exhaust gas flow velocity. The less energy your exhaust gas wastes radiating heat into the surroundings, the more it can use to propel itself through the header. Think of a finite packet of exhaust gas flowing through the exhaust header and eventually out the tailpipe. It is imparted a fixed amount of energy that cannot be destroyed . . . only converted from one form into another. Gas velocity is one form of energy. Another is heat (i.e. wasted energy). Losing heat to the surroundings means your packet of gas loses some of its energy potential. Keeping the exhaust gas as hot as possible all the way through the exhaust system maximizes its flow velocity.
Why is flow velocity good? Because your engine needs to breathe properly to generate max power output. You want your combustion products to get the hell out of the cylinder so there's room for O2 + fuel. Faster flowing exhaust means less exhaust-line pressure near the cylinder. This "encourages" combustion products to move into the exhaust line. Also, faster flowing exhaust spools your turbocharger faster, which obviously reduces turbo-lag.
You might hear about problems with high exhaust gas temperatures (EGTs) and problems down the line . . . like in your catalytic converters. That's more from playing with your engine timing and A/F mixtures. I doubt a ceramic coated exhaust header alone would cause those problems, but you might wanna check just to be sure.
Dave.
the most thermodynamically efficient headers are the best-insulated. Stainless steel is excellent because it has a very low thermal conductivity - i.e. it doesn't dissipate a lot of heat. The ceramic coat thickens the tube; ceramic also has a much lower thermal conductivity so the coating thickness + lower conductivity increases the header's overall thermal resistance. This means the hot flowing exhaust gas inside the header tube stays hot and the engine bay outside remains cooler.
Why is this good? It's about exhaust gas flow velocity. The less energy your exhaust gas wastes radiating heat into the surroundings, the more it can use to propel itself through the header. Think of a finite packet of exhaust gas flowing through the exhaust header and eventually out the tailpipe. It is imparted a fixed amount of energy that cannot be destroyed . . . only converted from one form into another. Gas velocity is one form of energy. Another is heat (i.e. wasted energy). Losing heat to the surroundings means your packet of gas loses some of its energy potential. Keeping the exhaust gas as hot as possible all the way through the exhaust system maximizes its flow velocity.
Why is flow velocity good? Because your engine needs to breathe properly to generate max power output. You want your combustion products to get the hell out of the cylinder so there's room for O2 + fuel. Faster flowing exhaust means less exhaust-line pressure near the cylinder. This "encourages" combustion products to move into the exhaust line. Also, faster flowing exhaust spools your turbocharger faster, which obviously reduces turbo-lag.
You might hear about problems with high exhaust gas temperatures (EGTs) and problems down the line . . . like in your catalytic converters. That's more from playing with your engine timing and A/F mixtures. I doubt a ceramic coated exhaust header alone would cause those problems, but you might wanna check just to be sure.
Dave.
Last edited by Dave99; 03-10-2003 at 08:51 PM.
03-10-2003, 09:57 PM
#6
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thanks
wow...i finally met someone who's actually intelligent, and doesn't come back with smart remarks like some i've met.
been doing my homework too, the borla is going to more than likely run cooler than my cast iron stock header, so I'd rather save my $250 on the coating. As for the cats...i'll probably end up removing at least one of them in the future. Thanks for the advice.
been doing my homework too, the borla is going to more than likely run cooler than my cast iron stock header, so I'd rather save my $250 on the coating. As for the cats...i'll probably end up removing at least one of them in the future. Thanks for the advice.
03-13-2003, 11:05 PM
#7
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My header/upipe
is being JetHot coated. Haven't decided whether to wrap it or not. If you have a TMIC, I would think you would want to reduce under hood temperatures.
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