4-2-1 headers vs. 4-1 headers...what gains???

[habib_88]

Ok so i'm in a unique postion, I have the choice of getting either a 4-2-1 header off a 92-95 civic, and if that does fit right well there is a 4-1 header that will fit a 88-91 just fine so either one is really mine to use.

Ok the problem, i always thought 4-2-1 headers gave more mid-range torque, while 4-1 headers gave you more high end HP. Granted both headers are gonna give you a little more overall but i'm concerned where the majorty of Hp and torque is gonna end up. My racing friend keeps telling me 4-1 header is more for low end power? I'm confused here so can someone please clear up what the 2 types do and where does the HP and torque go in the RPM band with each one?

[Bleebdat]

You're right habib, in most cases(almost all) 4-1 is all about high end power, 4-2-1 is more for everyday light weight track or racing. Most of the times 4-1 is useless if not detremental to your performance.

[darolh]

The 4-2-1 is for broader improvement over the powerband. For peak performance the 4-1 gives more power but it's all at the top end at the expense of some in the mid band. For auto-x and street I'd go with the 4-2-1 (I have one which I have yet to install).

If you build a screaming bitch high rev engine you use a 4-1 header (note what motorcycles use).

[Setanta]

4-2-1 is the better bet habib, especially if you are limited to the factory redline. You actually lose midrange torque with 4-1s. I found this out the hard way with my '76 Civic that was producing 120bhp. Because it was s troked with a EN crank, it didn't rev as hard (only 7000 rpm, compared to the Mugen 1226's 8500rpm). I ran the 4-1 Jackson headers on it, mut found that I had better performance with Mugen street spec 4-2-1s as the Jacksons were tuned to make peak power at 6500-8000.

Put into context, my SiR has 4-2-1 config standard - that's in a car that is built to rev hard. I've been told it's better to go with a 4-2-1 setup running extended secondaries if I move to extractors, simply because it doesn't lose me the midrange that a 4-1 would.