header question
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Before you buy a header, you need to think about a few things
Where do you want your powerband to be? Midrange? high end?
How much power do you want your car to produce when you are all done modifying it?
Do you ever plan on forced induction?
Here are some aritcles to read on the subject
Header article I
Header article II
Where do you want your powerband to be? Midrange? high end?
How much power do you want your car to produce when you are all done modifying it?
Do you ever plan on forced induction?
Here are some aritcles to read on the subject
Header article I
Header article II
I don't want to start a new thread for my header question, so here it goes.
I've read the headers & exhaust articles and stil have a question about headers for my car. I have a 94 RS, not going FI. I am looking for low->mid end power. I have a 60mm (2.36") 5Zigen catback exhaust & OBX cat (2.25" ID) to be put on. (I can hear all you screaming about the OBX cat, but it's 2.25 ID & I'm not going FI & I don't race, I just like having nice pickup on highway)
I shouldn't get a header with a 2.5" collector because it is bigger diameter than the cat & exhaust. I should be getting a 4-2-1 design with at least a 2" collector which most are from what I've been reading (correct me if I'm wrong). My question is will the brand of the headers affect the exhaust flow out? Does anyone know if there are any headers with a 2.25" collector? Will I feel a difference between Comptech, DC, Greddy, OBX, or HP?
Any help would be great.
I've read the headers & exhaust articles and stil have a question about headers for my car. I have a 94 RS, not going FI. I am looking for low->mid end power. I have a 60mm (2.36") 5Zigen catback exhaust & OBX cat (2.25" ID) to be put on. (I can hear all you screaming about the OBX cat, but it's 2.25 ID & I'm not going FI & I don't race, I just like having nice pickup on highway)
I shouldn't get a header with a 2.5" collector because it is bigger diameter than the cat & exhaust. I should be getting a 4-2-1 design with at least a 2" collector which most are from what I've been reading (correct me if I'm wrong). My question is will the brand of the headers affect the exhaust flow out? Does anyone know if there are any headers with a 2.25" collector? Will I feel a difference between Comptech, DC, Greddy, OBX, or HP?
Any help would be great.
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If it was me I'd go with the factory ITR header. It is just as good as any aftermarket header. The flow is excellent and you'll get more top end. Like I've said time and time again - Honda knows what's best for its cars.
The factory ITR header is the exact opposite of what he's looking for bud, that's 4-1 optimized for top end, when he's looking for 4-2-1 optimized for midrange.
Unfortunately they don't make headers with 2.25" collectors... why not, I do not know. The DC, Greddy, and Comptech are all about the same, with the DC being cheapest which is why they are most commonly used. The OBX along with others can actually hurt performance... though no one seems willing to try them and prove it.
You usually want to step up the exhaust as it goes to the rear of the car. Going from a 2" collector to your 2.25 in cat to the 60mm exhaust would be exactly what you want to do.
Unfortunately they don't make headers with 2.25" collectors... why not, I do not know. The DC, Greddy, and Comptech are all about the same, with the DC being cheapest which is why they are most commonly used. The OBX along with others can actually hurt performance... though no one seems willing to try them and prove it.
You usually want to step up the exhaust as it goes to the rear of the car. Going from a 2" collector to your 2.25 in cat to the 60mm exhaust would be exactly what you want to do.
not only is the ITR header 4-1 and opposite of what he wants, but it is also a 2.5" collector which is too large for him.
and for the question of what is a better header between the five you named. no question about it, it is the comptech. you see the comptech has a stepped design, which the other four dont, which creates an anti-reversion affect, this eliminates backpressure. IMO comptech makes the best bang for the buck header out there. it has the performance of the big boys (well close to the big boys) with the price of the little tikes.
and with your sizing and hp goals i would look into a different exhaust. with a 2" collector you should get a 2.25ID cat (im not going to go into my rant on OBX as you already know my feelings), but your 60mm exhaust is a little too big. louse is right about wanting wanting to step up the exhaust as it goes to the rear of the car. but 2 3/8 is a little too big of a step up. a 2.25" OD exhaust would be the proper size. you would go from 2"->2.25ID->2.25OD. it is good to step up, but a drastic step is not a good one to take. hope that helps. oh and read the articles, all of this is explained in there, alot better than i have. and you will understand it alot more, which is better.
Thanks
alex
and for the question of what is a better header between the five you named. no question about it, it is the comptech. you see the comptech has a stepped design, which the other four dont, which creates an anti-reversion affect, this eliminates backpressure. IMO comptech makes the best bang for the buck header out there. it has the performance of the big boys (well close to the big boys) with the price of the little tikes.
and with your sizing and hp goals i would look into a different exhaust. with a 2" collector you should get a 2.25ID cat (im not going to go into my rant on OBX as you already know my feelings), but your 60mm exhaust is a little too big. louse is right about wanting wanting to step up the exhaust as it goes to the rear of the car. but 2 3/8 is a little too big of a step up. a 2.25" OD exhaust would be the proper size. you would go from 2"->2.25ID->2.25OD. it is good to step up, but a drastic step is not a good one to take. hope that helps. oh and read the articles, all of this is explained in there, alot better than i have. and you will understand it alot more, which is better.
Thanks
alex
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The Ultimate Answer to All Your Header Questions
my only concern with the comptech header is that the diameter of the primaries are smaller than that of other 4-2-1 headers with 2" OD collectors. the comptech header has the stepped design which helps the anti-reversion effect, but to step up as you reach the collector means that you have to start smaller. (i forget what the exact diameter of their primaries are, but they're in fact smaller than others)
going from 2" OD -> 2.25" ID -> 2.25" OD (2.12" ID) would be actually stepping DOWN going from cat to the exhaust. i don't recommend doing this. the exhaust gas has to flow into a small cross-sectional area when it goes through the cat and then enters the exhaust piping. the cat flange on the 2.25" OD exhaust can be knife-edged or ground out to make the transition a little smoother, yet you're still flowing into a small diamter tube. 60mm OD exhaust, which most aftermarket cat-backs are, might be a bit oversized for just mild bolt-on mods, but a lot of people don't stop at i/h/c/e anyway...
also, most aftermarket cat-backs have a bottleneck at the cat flange because they make it so that it would mate up to the stock 1.8" cat. what you need to do is to pick up a taper flange from SMSP when you get your 2.25" ID cat. cut off the cat flange from the cat-back and TIG weld the new flange on to remove the bottleneck.
i hope this helps a bit. have fun and drive safely.
sung
my only concern with the comptech header is that the diameter of the primaries are smaller than that of other 4-2-1 headers with 2" OD collectors. the comptech header has the stepped design which helps the anti-reversion effect, but to step up as you reach the collector means that you have to start smaller. (i forget what the exact diameter of their primaries are, but they're in fact smaller than others)
going from 2" OD -> 2.25" ID -> 2.25" OD (2.12" ID) would be actually stepping DOWN going from cat to the exhaust. i don't recommend doing this. the exhaust gas has to flow into a small cross-sectional area when it goes through the cat and then enters the exhaust piping. the cat flange on the 2.25" OD exhaust can be knife-edged or ground out to make the transition a little smoother, yet you're still flowing into a small diamter tube. 60mm OD exhaust, which most aftermarket cat-backs are, might be a bit oversized for just mild bolt-on mods, but a lot of people don't stop at i/h/c/e anyway...
also, most aftermarket cat-backs have a bottleneck at the cat flange because they make it so that it would mate up to the stock 1.8" cat. what you need to do is to pick up a taper flange from SMSP when you get your 2.25" ID cat. cut off the cat flange from the cat-back and TIG weld the new flange on to remove the bottleneck.
i hope this helps a bit. have fun and drive safely.
sung
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USDM collectors have to be 2 in. since they mate up to the 2 in. stock cat.jwong1268 on Aug/09/02 said:
The Comptech is stepped header. All are nonsequentially paired tri-Y's and they all have the same overall length which end at the stock cat location. There's not much separating the DC from the Comptech. OBX and HP primaries diameter will choke your flow.
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yeah, dude. apparently.StyleTEG on Aug/09/02 said:
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490 Posts
as far as ceramic vs. ss - don't bother with ceramic if you want your header to last. ceramic will crack if you ever bottom out.acuraFL on Aug/08/02 said:
comptech makes TIG and MIG welded SS headers. i don't see any benefits to paying more money for a TIG welded one. it would be stronger but with just mild bolt ons, a MIG welded one should more than suffice. dc sports SS header is also MIG welded. pricewise, the MIG welded comptech and the dc sports SS are pretty much comparable.
for future references, if anyone tells you to buy anything without fully knowing what your current set up and goals are, don't take his word for it. he doesn't know what the hell he's talking about. picking out parts is an art form. you should know what your goals are - na vs. fi, your ultimate hp goal, midrange vs. high end, blah blah blah...
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isn't it? don't feel bad. MD wasn't aware of that either...StyleTEG on Aug/09/02 said:
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jdm type r 4-1 is the best
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this is EXACTLY what i'm talking about. (see my previous post)ExtremeGSRteg on Aug/09/02 said:
OK, thank you to everyone for their help.
So a SS 4-2-1 header with 2" collector is fine. I will probably get a DC Sports (is Greedy comparable?).
As for the cat flange on the 5Zigen, I don't know what the ID is yet until I get it in. I will measure the ID to see if it is 2" or 2.36". If it is 2" I will just have my mechanic TIG weld a new 2.25" flange on.
I would have gone custom 2.25" mandrel bent but I got such a great deal on the 5Zigen that I couldn't pass it up. I also didn't want super "pull my @ss over" loud. 5Zigen is rather quiet. And yes I wanted a straight thru design.
Again, thank you for eveyone's help.
So a SS 4-2-1 header with 2" collector is fine. I will probably get a DC Sports (is Greedy comparable?).
As for the cat flange on the 5Zigen, I don't know what the ID is yet until I get it in. I will measure the ID to see if it is 2" or 2.36". If it is 2" I will just have my mechanic TIG weld a new 2.25" flange on.
I would have gone custom 2.25" mandrel bent but I got such a great deal on the 5Zigen that I couldn't pass it up. I also didn't want super "pull my @ss over" loud. 5Zigen is rather quiet. And yes I wanted a straight thru design.
Again, thank you for eveyone's help.
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???????ExtremeGSRteg on Aug/09/02 said:
After a whole pageworth of discussion and you chime in w/ a random comment like that? What is the basis for your claim? Let me guess, you don't have one. You probably "heard" that it was the best. So that MUST mean that it is.
Was it not perfectly clear on the page before, the author of the post has a 2.25" ID cat. How in gods name do you expect to bolt up a 2.5" collector to a 2.25" cat????? on an LS thats N/A a jdm 4-1 header is exactly what he doesn't want.
Comments like this one are what lead people in the wrong direction........
I just emailed 5Zigen USA & I got response within the hour, very impressive.
I'm not gonna post my email, the jist (sp?) of it was about the cat flange.
Response I got:
The Fireball catback exhaust is 60.5mm I.D., which is about 2.38", ideal for
a Japanese small engine car. The flange I.D. is also 60.5mm, so if it was
installed on a stock vehicle the major bottleneck in the system is the
catalytic converter itself.
2.25" I.D. is a U.S. standard, while 60.5mm I.D. is a Japanese standard.
Generally speaking, for any 1.8 liter - 2.4 liter engine, 2.25" to 2.5"
would be acceptable with minimal losses and good peak power gains.
So it doesn't look like I need a new cat flange.
I'm not gonna post my email, the jist (sp?) of it was about the cat flange.
Response I got:
The Fireball catback exhaust is 60.5mm I.D., which is about 2.38", ideal for
a Japanese small engine car. The flange I.D. is also 60.5mm, so if it was
installed on a stock vehicle the major bottleneck in the system is the
catalytic converter itself.
2.25" I.D. is a U.S. standard, while 60.5mm I.D. is a Japanese standard.
Generally speaking, for any 1.8 liter - 2.4 liter engine, 2.25" to 2.5"
would be acceptable with minimal losses and good peak power gains.
So it doesn't look like I need a new cat flange.
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it is the best because he says so...I don't know if he knows why but it just is...that's just the way it is....some things just never change...that's just the way it is...wait a minute, isn't that a song? yes, go right ahead and get a JDM 4-1 with a 2.5 in. collector and hook it up to a 2.25 in. exhaust..that'll work just great...great advice... keep it comin'...ExtremeGSRteg on Aug/09/02 said:
hey Extreme feelin kinda bashed up in this thread for sayin somethin yet? LOL
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