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Old 20 Aug 2007, 04:03 am
Jon Jon is offline
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Default whats the performance difference between 4-2-1 and 4-1 headers?

i know what they look like, i know what they do, i know how to put em in. im just not sure about the performance part. ive always used 4-2-1 just cuz it looks like the exhaust exits smoother. but which one is good for top-end, bottom-end, all-around etc. and do you think it matters what theyre coated with? ie ceramic, chrome, stainless steel
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Old 20 Aug 2007, 04:08 am
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4-2-1 header will give better all round performance because it will reduce pressure drop in the exhaust tract, however the amount of improvement depends on the rest of the engine, the type of cams used, if they have longer dwell angles as in full race cams then a bigger change over a 4-1 header will be seen. the coating is basically looks and extends the life but does nothing to help performance. If you have cams with long dwell angles the 4-1 header will cause some back flow of exhaust to the combustion chamber and reduce the amount of fuel and oxygen in the fresh charge to the combustion chamber
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Old 20 Aug 2007, 04:10 am
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You've got two choices: Accept what a particular header mfr states about their product's performance, or have a performance shop dyno test what you already have. In the real world of being the fastest badboy in the 'hood, 2-4 hp gain or loss is nothing compared to the ticket you'll probably get trying find out where the hp drops off...Chrome is always a good choice - Stainless is just overpriced chrome....
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Old 20 Aug 2007, 04:18 am
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Alright, so here is the main differences in a nutshell....The 4-2-1 is less free flowing and basically better for torque and lower end power.The 4-1 is much more free flowing and better for higher end power.For all-around performance, I guess it will all depend on what your going for. I desired a more free flowing exhaust when I was building my engine so I choose the 4-1. Plus, with the supercharger on my car providing excellent low-end power, I wanted the more free flowing exhaust to increase the higher-end.As for the different kinds of coatings....it doesnt matter, the coatings dont affect the performance. The ceramic coat looks excellent under the hood (I have a ceramic coated DC header on my 00 Civic Si), the stainless steel header also looks great under the hood and due to the constant heating and cooling, the header actually changes colors, it looks neat but I prefer the ceramic coat.
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Old 20 Aug 2007, 04:28 am
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IIII___=4-1II_II__=4-2-1
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