UNCLE_DADDY0911

can anyone out here tell me what is the better header to get i have a b20 with itr header and 2.5 inch exhaust back no cat...im curious to know the differences between headers 4-1 2-1 etc....

MPR

4-2-1 will give you all-around better power range (wider torque curve). 4-1 generally give you more mid-top end gains.

I have a b16a2 with a ported ITR header and full 2.5" exhaust. It definitely lost torque below 2500-3000rpm because of the slower exhaust gas velocity due to the larger diameter piping. On the contrary, this allowed for noticeable gains across the rpm range from about 3000rpm up, especially on the vtec cam right up to the limiter at 8200 due the the allowance of increased exhaust gas volume flow at higher rpms (less bottle-necking/restriction).

There is a lot of science behind header design. The primary, secondary diameter, length, taper, collector style, etc... all has an effect. All in all, the ITR header gives decent performance for it's low cost. If you re-weld each primary to the head flange from the outside, then port (grind) the factory welds down (inside each primary where it meets the flange) so that it makes a smooth open passage, you'll pick up a few more poines up top (dyno proven).

In other words, be happy with the ITR header (port it to get a little more from it) and call it a day. The gains achived by buying a $400+ header is really not worth it unless you're building an NA race motor.

UNCLE_DADDY0911

i can pick up a 4-1 header for $40 than maybe sell my itr for? probally the cost of instalation eh ? but since the price is cheap is it worth it?

PurpleStuff

itr is 4-1. why do you want to get another one?

MPR

^Exactly. The ITR header is a 4-1 and a decent one at that. Just keep it. It's probably better than that $40 header...lol.

Plus some aftermarket headers have a smaller 2-1/4" collector which is more restrictive. The ITR header already has a larger 2-1/2" collector, which is what you want.

UNCLE_DADDY0911

ahhh ok ok see now its because of guys like you 2 y I like forums lol thanks guys ok next question is injectors ...i have itr injectors on my car now ...wihats better ? and how will it help my car?

ol Dusty

iTrader: (2)

you're gonna need to do come calculations for this one. too big and you flood, too little and you'll starve but really getting ones able to out put enough flow for your motor and then dyno tuning how much fuel they're spraying is really the only way to get any gains. Adding more fuel without somehow getting more air, won't gain anything but a rich condition.

MPR

All B and D-series honda engines have the same 240cc injectors (with the exception of a few.

In other words, your b20 already has the same injectors as a type-R. They are well suited for your type of setup.

Unless you're going to install larger cams, rev it higher or add boost, you don't need different injectors. There is no gain to be had changing the injectors in this application.

EF.Hatch

get a Megan 4-1 header because they make your car sound like a subaru. This might help: http://www.hondatuningmagazine.com/t...r_install.html

MPR

^The megan isn't tested in that article.

I've seen the megan racing header (they make 4-1 and 4-2-1 headers) and they are decent for the price (and will not make your car sound like a subaru). You're thinking of some other brand 4-2-1 header which joins the wrong two primaries.

For optimal scavenging, a 4-2-1 header uses the pulses from one cylinder to help draw the exhaust out of another cylinder. On b and d-series honda engines, because of the firin order, this mean joining the primaries of cylinders 1-4 together and 2-3 together first, then joining those secondaries together after that to a single pipe.

On some other aftermarket brands, they joined cylinders 1-2 and 3-4 or 1-3 and 2-4 which results in the pulses collecting differently, creating the "subaru" sound. This can actually cause a loss in power, so I don't recommend doing this just to sound like a subaru. OBX used to be one brand that got this wrong initially. After a quick search, it looks like they've changed their design to properly match the primaries 1-4 and 2-3.

A 4-1 header gives a little bit different sound than a 4-2-1 header, but nothing drastic or subaru-ish.

EF.Hatch

^ you are 100% correct except for megan not sounding like subaru, I'll clearify. You can only get the subaru sound on a b-series. My friend has the 4-1 on his b17a teg and I heard a b16 on the net and the sound similar to subaru's.

The best header ever made is the Hytech Tri-Y, then comes the SMSP. These will run you over a grand. The Hytech replica is good to and can be picked up for hundreds. BUT you will have fitment issues with a swapped civic.

jdm_77

Just keep the itr header it's a pretty decent header n it's 4-1 n I don't think your building a b20 all motor so you really don't need it because that header is giving good enough flow for probably your basically stock b20. But if you were honestly going to upgrade headers or w.e y don't you get something better then probably a shitty eBay header thats pancaked to the point that your actual stock exhaust manifold can make more power then it lol but thats just my 2 cents Good luck on decided what you are gonna do.

jdm_77

I just read the thing about the Megan header makes your car sound like a subaru okay well the Megan headers are pretty decent headers but they don't not make your car sound anything like a Subaru how do I know this is because I actually have a Megan header on my b16a2 right now n I don't hear any difference in sound I may have got a few more ponies but that's about it. What MPR saying is right this guy is a Honda guru.

iTaLiAn_vIrUs

im in the same boat as you,
i personally was going to purchase a vibrant 4-2-1 race header, but that was around ~$500. That's too expensive for me just for a header.

Then i got offered a replica Hytech for $300. 4-2-1.... this is something ive considered, its going on a stock b18c1.. im just curious to know what the power gains would be like.

ive always preferred a 4-2-1 header cause of the low/mid range gains.. as opposed to mid/high gains a 4-1 provides, only because i do alot of city driving so its always a stop and go

its a b series into a civic.. so now im a

MPR

You can make any 4 cylinder engine sound like a subaru if you make the primary tubes a certain length before the collector. If you put
4-1 equal length primaries on a subaru, it doesn't sound like a "subaru" anymore.

I have an itr 4-1 on my b16a2 and it sounds a bit different than it did with a 4-2-1, but not much like a subaru at all.

Hytech replica for $300 is a good price, provided it is in good condition.

EF.Hatch

To me this sounds like a Subaru.

On topic: Here's dyno's http://www.honda-tech.com/showthread.php?t=2239644

MPR

They sound a little bit like a subaru...

My car sounds a little bit like that only a bit smoother. Not quite so choppy. Most of the civic's I have heard with 4-1 headers didn't sound quite like those vids, hence my previous comments speaking from experience.

Would be interesting if you post a vid of a WRX or STi for comparison. I know their H-4 layout and firing order accompanied by the stock un-equal length manifold gives them their distinct "lobbing" sound.