header, why?

I have been doing some studying on header for some time now, but i cant figure it out

how are the 4-1 better at higher RPM's
and 4-2-1 headers beter at the low and middle level.

Does it have to do with back pressure?
I mean how are they able to do better at diffrent levels.

yes, it has to do with back pressure. a 4-1 header is more free flowing than a 4-2-1 header. Just like single exhaust is better flowing than dual exhaust.



Hey, I'm not doing to bad for being half drunk hehe

what's the matter, not enough boozahol to go full-bore?

you're always half-assing things ;)

hahahahahaha lol...in the process of consuming more beer.

There are several factors to consider with a set of new headers. As GScivic7 said, 4 into 1 headers are definitly better for high rpm, and this is true for several reasons on top of reduced backpressure. 1. Typically 4-1 headers are flow more freely than 4-2-1's. 2. 4-1 designs scavenge the combustion chamber more effectively at high rpm because they allow the exhaust charge from each cylinder to carry more of it's enertia down-stream of the exhaust port before it meets to merge with another pipe. 3. Most designs create a momentarily higher vacuum during the gas exchange event (when both the intake and exhaust valves are open at the same time) in the cylinder allowing a more efficient charging of the cylinder with fresh air. 4. 4-1 headers are much easier to pulse tune during R&D (that is if tou are buying headers of a major performance manufacturer!) than 4-2-1's.

It's very important to note that these design advantages of a 4-1 over a 4-2-1 are most effective at high to very high rpm on a naturally aspirated engine that breathes well, like say a modified b18c5. The more of a screamer the engine, the better a 4-1 will work for you. However a low reving engine, like say a d16y8, will only begine to take advantage of a 4-1's attributes when it's running at the top of it's limited rev range, and you wont have the revs to compensate for the power that you might lose on the lower end or mid range.

4-2-1's are good for normal engines, with gains every on the torque curve.

4-1's are good for rev monsters with impressive gains up top, and low gain, maybe even losses at normal rpm's.

There are several factors to consider with a set of new headers. As GScivic7 said, 4 into 1 headers are definitly better for high rpm, and this is true for several reasons on top of reduced backpressure. 1. Typically 4-1 headers are flow more freely than 4-2-1's. 2. 4-1 designs scavenge the combustion chamber more effectively at high rpm because they allow the exhaust charge from each cylinder to carry more of it's enertia down-stream of the exhaust port before it meets to merge with another pipe. 3. Most designs create a momentarily higher vacuum during the gas exchange event (when both the intake and exhaust valves are open at the same time) in the cylinder allowing a more efficient charging of the cylinder with fresh air. 4. 4-1 headers are much easier to pulse tune during R&D (that is if tou are buying headers of a major performance manufacturer!) than 4-2-1's.

It's very important to note that these design advantages of a 4-1 over a 4-2-1 are most effective at high to very high rpm on a naturally aspirated engine that breathes well, like say a modified b18c5. The more of a screamer the engine, the better a 4-1 will work for you. However a low reving engine, like say a d16y8, will only begine to take advantage of a 4-1's attributes when it's running at the top of it's limited rev range, and you wont have the revs to compensate for the power that you might lose on the lower end or mid range.

4-2-1's are good for normal engines, with gains every on the torque curve.

4-1's are good for rev monsters with impressive gains up top, and low gain, maybe even losses at normal rpm's.

Wow I was just going to say resonance, but you summed it up nicely :)

For pressurized engines(supercharged, because turbo exhaust manifolds don't really matter) , don't worry about any of the other stuff I talked about earlier. Look for a header designed to flow maximum volumes. Look for large primaries, secondaries, unrestricted merges, gradual bends and straight pipe wherever possible.

Any more questions?

so you guys answered that exactly.
as you said the 4-2-1 hwould be good for the d16y8. that is exactly what i have. so i might notice a little boost with the headers.

my whole plan is to actually start a new exos from the headers back >>>>***

the DC 4-2-1 ceramic 2 peace seem to be what i want. what woud be good to finish it off. I would need somthing high flow (might supercharge it later)

something with a sporty or deeper sound.
NOT A WEED WACKER. i would have to shoot myself.

would an Apexi system be a good match.

if you are going to super charge it, look for a thermal R&D with 2.5" piping

To exman98 check out Powercore's stainless 4-2-1. They did really when in a couple of magazine tests a while back.

SC is something i have thought about doing. I wasnt sure the size i needed. I figured it was 2.5"

even if i dont SC my little D16. a new exost will still give me a liitle kick and the sound i am looking for.

so is this what i should be looking at
http://www.thermalrd.com/honda.htm
I have a 98 civic EX coupe (D16Y8)

Those are definitely good headers. A friend of mine had them. THey sound great, fit well, and free up power.

hee hee hee
this sounds promising

yup, those thermal units are so bad ass

amy ever heard thermal R&D's before.
I have been trying to get a sound clip, but no luck so far.
If i do i will post it

go to the 4th gen forum and ask them about thermals, you will get nothing but a positive response.

yeah, I have read some of the stuff off of a couple of web sites, but you never know who actually writes the crap. often time it is some one from the company. But i trust this forum