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Discussion Starter #1 (Edited)
This topic comes up so frequently, it is getting kind of old for many of us who frequent the Bolt On Section. So, I am creating a thread specifically related to race headers and attending questions that often follow.

Here is a thread I did about my Vibrant race header install: http://www.8thcivic.com/forums/bolt-ons-all-motor/79725-mother-all-vibrant-race-header-installs.html

Race Header availability by price in descending order:

1. Hytech -http://www.hytechexhaust.com/





Price: $1300

Material: Stainless Steel

Collector Size: 2.5"

Impressions: A true, race header that is custome made. The Gold Standard of headers. Features anti-reversionary tubing. The stuff of legends.

http://www.8thcivic.com/forums/bolt-ons-all-motor/42018-hytech-header-pics.html

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2. SSR-http://www.sixsigmaracing.com/kseries.htm





Price: $1200

Material: Stainless Steel

Collector Size: 2.5"

Impressions: Similar to a Hytech with slip joints.

Videos: http://www.8thcivic.com/forums/bolt-ons-all-motor/52282-ssr-r-h-sound-clips.html

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3. J's Racing-FD2 header-http://www.excite-webtl.jp/world/english/web/?wb_url=http%3A%2F%2Fwww%2Ejsracing%2Eco%2Ejp%2Fjs3%2Findex%2Easp&wb_lp=JAEN&wb_dis=2



Price: $1200 special order from Japan

Material: Titanium

Impressions: A true Japanese tuning company that will drop over 12 pounds from the weight of a stock header/downtube.

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4. Toda-http://www.todaracing.com/jp/product/ex_mani.html



Price: $1200

Material: Stainless Steel

Collector Size:

Impressions: JDM goodness

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5. ASP 4-1 header: Advanced Street Performance

Header with test pipe and defouler:


2.5" stainless steel exhaust with magnaflow muffler


Dyno before and after header and exhaust


Cost: $900

Material: Stainless Steel

Collector Size: Can be tailor made for buyer

Impressions: All headers are made custom to the motor spec that the customer gives us. So the primary and secondary lenght/diameter and collector size changes with every order. A true "custom design"


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6. T1R FG2 header for Si:-http://www.aj-racing.com/shop/product.php?productid=1444&cat=402&page=2



Price: $812.91

Material: Stainless Steel

Impressions: A bling-bling header with the T1R name.

Finally, some T1R goodness for your new Si. This header utilizes large 45mm primaries to optimize power. The header replaces the stock 4-1 portion and the stock catalytic converter. This header was developed and intended for race and track use only. A T1R O2 Fix (mechanical O2 simulator) is supplied with this header.

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7. Skunk2 -http://www.skunk2.com/mm5/merchant.mvc?Screen=PROD&Product_Code=412-05-0930

Features primaries that go into two separate merge collectors, then two collectors which end in 2.5" collector. This may be the best header for the money out there. It is a classic 4-2-1 header.





Threads: http://www.8thcivic.com/forums/bolt-ons-all-motor/153844-skunk2-header.html

Price: $700-$800

Material: Stainless Steel

Collector Size: 2.5"

Impressions: The most beautiful merge collectors ever on a mass produced header.

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8. BuddyClub-http://www.buddyclub.us/





Price: $769

Material: Stainless Steel

Collector Size: 2.0"collector, then a 2.5" flange

Impressions: Incredible street cred. Just saying BuddyClub sets heart to palpitating with the Tuner Crowd.

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9. Vibrant race header with high flow cat]-http://vibrantperformance.com/catalog/product_info.php?cPath=1021_1029&products_id=1152



Price: $663

Material: Stainless Steel

Collector Size: 2.5"

Impressions: The only header available with a high flow catalytic converter. This header can at least make one feel good about not polluting the environment too much.

*Caveat: This header is an OBDI compliant header. It is not OBDII compliant. Vibrant has made it clear that it is for "off road use only". Anyone thinking that this is an emissions legal header is sadly mistaken. Take it for what it is worth.

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10. Vibrant race header w/o cat: -http://vibrantperformance.com/catalog/product_info.php?cPath=1021_1029&products_id=1151



Price: $581

Material: Stainless Steel

Collector Size: 2.5"

Impressions: Donovan Griffith of Vibrant says that it is worth about 4-8 hp more than the version with the cat, maybe more depending on the mods.

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11. Strup -http://www.strup.us/honda.html



Price: $480

Material: Stainless Steel

Collector size: 2.0"

Impressions: How about a new affordable stainless steel header designed by Charlie Wenstrup of early DC Sports fame?

4-2-1 collection design, Stainless Steel HeaderT-304, #1 grade stainless steel tubing, polished to a bright luster, 1 5/8" x 1 7/8" x 2" mandrel bent tubing provides 12 to 15 HP

Threads: http://www.8thcivic.com/forums/bolt-ons-all-motor/169011-my-review-strup-race-header.html

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12. KiddRacing Si Dominator Race Header: Club RSX.com: KiddRACING Si Dominator Header



Cost: $450

Collector size: 2.5"

Tubing material: Brushed Stainless Steel

Threads: http://www.8thcivic.com/forums/bolt-ons-all-motor/167025-kiddracing-header-review.html

http://www.8thcivic.com/forums/bolt...cing-06-08-si-header-dyno-installed-pics.html


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13. CT Engineering Shorty header-http://www.ct-engineering.com/store/product1546.html



Price: $529

Material: Stainless Steel

Collector Size: Same as stock

Impressions: The only way to fly if you live in a state like Kalifornia, with their smog Nazi type rules. Will work with stock cat or aftermarket high flow cat.

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14. DCSports header: Price: $375



Price: $375

Material: Mild rolled steel, ceramic coated

Collector Size: 2.0"

Impressions: DC Sports put tuners on the map and are synonymous with Hondas.


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15. EZR Race Header: ERZ performance 06-08 Honda Civic SI Race header 4-2-1 1 piece



Cost: $225.00

Collector size:

Tubing Material: T-305 Stainless Steel

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16. Megan Shorty Race Header: -http://www.ct-engineering.com/store/product1546.html Honda Civic Exhaust / Headers - Megan Racing Stainless Steel Headers Honda Civic Si 06-09 Free Shipping



Price: $179

Material: Stainless Steel

Collector Size: 2.5"

Impressions: A cheaper alternative to CT Engineering.



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Here is some info on collector size: http://www.8thcivic.com/forums/bolt-ons-all-motor/103291-race-header-collector-sizes.html

This from Corsport:
Strup 2" collector and flange
BCRH 2" collector then a 2.5" flange
DCRH 2" collector and flange
Vibrant 2.5" collector and flange


If you want that extra degree of performance, get the Hytech or SSR.

If you want a header similar to the Hytech or SSR, but priced more reasonably, get the BuddyClub.

If you want a header that is value priced and comes with a cat that is OBDI legal, get the Vibrant RH w/hfc. It also will improve the smell greatly.

If you want a good quality header w/o a cat, get the Vibrant race header or the Strup.

If you want a good bang for the buck, get the DCSports header.

Now that we have the headers out of the way, next question to deal with is legality. All of the systems, save for the Comptech and Megan, which will use the stock cat, will be either illegal or non-compliant for many emissions' tests.

If you have a race header, one of the issues that keeps coming up is CEL's. In order to prevent a CEL, the best policy is to use a defouler. For BuddyClub and Vibrant, one should use an angled defouler. Remember, most race header manufacturers have a caveat that it is for "Off road use only".

You can also use a ScanGaugeII to remove CEL's. However, they will probably keep appearing until you get a defouler.

There are also electronic O2 simulators that can trick the ECU, but they are much more expensive than the defoulers.

Another question that pops up is about the noise. Generally, adding a race header will increase the sound level unless you are using a stock exhaust system. If you go aftermarket, it will be commensurately louder, especially with a Skunk2. I therefore went with an extra resonator which I got from SCTuned and is made by Vibrant. My system now has 2 resonators in it to suppress noise, although in VTEC, it is still loud.

A race header is a great way to enhance the power of your Si. It will not make massive horsepower gains, but it is a difference you can feel. Coupled with a larger cat-back exhaust system, the gains will be greater. If you add an intake or cams, the improvement will be greater still. For me, it is a great value.

I would appreciate everyone who has experience with the above mentioned headers to chime in and add to anything I have said, or correct any mistakes.

This thread is being done as a service to the 8th Gen Community. Hopefully, it will answer most questions people have. :vtec: :badger: :dancing: :dance: :spinning:

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Addendum. I am posting this great stuff from BTRobertson. Kudos to him for helping to explain the differences between a 4-2-1 header and a 4-1 header. :thumb:

Header Design – the “Tri-Y” and “4-1”

When you’re in the market for a new long-tube Honda header, there are basically two designs: the Tri-Y – more commonly known as the 4-2-1 – and the 4-1. These names, while largely uninspired and bland, are 100% functional in that they simply describe the way the tubes – called “runners” – are arranged to provide scavenging for the exhaust gases during the combustion cycle.

A header is much more than tubes welded together in a cool-looking fashion, with springs and chrome to make them look sexy and provide tension for stress reduction. Adding the proper header to your car can add much-needed exhaust flow and additional power by means of the scavenging process, which is simply the way exhaust gases are drawn from the combustion chamber. The goal of a header is mainly to decrease flow resistance – known as back pressure – and to increase the volumetric efficiency of the engine.

But before we get to the actual design differences, pros, and cons of each design, it’s high time we stop and do some more physics to understand WHY and HOW a race header makes more power. Some people put larger diameter exhausts and headers on and lose torque, then in turn blame the lack of back pressure. This is a myth, explained below.

The state of an amount of gas is determined by its pressure, volume, and temperature according to the equation PV = nRT

Where:

P is the absolute pressure
V is the volume of the vessel
n is the number of moles of gas
R is the universal gas constant
T is the absolute temperature

Analyzing this formula, we can easily see that if the volume decreases (V) and all the variables on the right side of the equation remain constant, pressure (P) must increase to satisfy the equation. In other words, the pressure in the combustion chamber will increase if we decrease the volume in the chamber (move the piston toward the cylinder head). This makes sense to most people, but the process involved is important to understand because this Ideal Gas Law and the Combined Gas Law are two laws which govern the scavenging process. Read this next section carefully and envision each of the steps in your mind – you will be able to see the amazing science behind what a performance race header does to make more power based on the formula above.

When an engine starts its exhaust stroke, the piston moves up the cylinder bore, decreasing the total chamber volume. Since pressure is inversely proportional to volume in our Ideal Gas Formula, the pressure will be rising as the volume in the exhaust stroke is decreasing. At some point during the exhaust stroke the exhaust valve will lift and open. The high pressure exhaust gas escapes into the exhaust header, creating an exhaust pulse. We sometimes hear people talk about exhaust resonance or pulsing…this is that part and it’s important to understand.

An exhaust pulse is a release of exhaust gas, containing three main parts, a high pressure "head", a medium pressure "body" and a low pressure "tail". The high pressure "head" is created from the huge pressure difference between the exhaust in the combustion chamber and the atmospheric pressure outside of the exhaust system. As the exhaust gases equalize between the combustion chamber and the atmosphere, the difference in pressure decreases (remember our formula – pressure is decreasing because volume is increasing between the combustion chamber and the area outside the chamber, which is the header space) and the velocity at which the exhaust is leaving the engine decreases. This forms the medium pressure "body" component of the exhaust pulse. The remaining exhaust gases form the "tail" component. This tail component may initially match in pressure to that of the atmosphere, however, the pressure is further reduced by the siphoning effect created by the momentum of the high and medium pressure components. The end result may be a pressure at the low end of the exhaust pulse that is less than the atmospheric pressure. This creates a greater pressure difference between the intake manifold and the combustion chamber, which increases the velocity in which air is brought into the engine. This increase in intake air velocity leads to an increase in the amount of air in the combustion chamber, which allows the engine to add more fuel and thus make more power.

As you can see, the way pressure and volume interact during this “scavenging process” is critical in understanding how the design of a race header affects the intake of air and fuel to create more power. The effectiveness of the exhaust scavenging process is a direct function of the velocity of the high and medium (head and body) components of the above-explained exhaust pulse. Create more velocity in the scavenging process, you create negative pressure in the intake manifold and a larger gulp of air and fuel to compensate = more power.

So now we come to the 4-2-1 – Tri-Y – and the 4-1 header designs. First the Tri-Y:

As the name Tri-Y implies, the four runners (the tubes attached to the engine block) are arranged in such a way that three groups of “Y” shaped runners are formed. Runners one and four form one Y section, runners two and three form a second Y section, and finally those two Y sections (now forming two new runners) dump into a single section of the header called a collector. This is why it’s called the 4-2-1 – four runners collect to form two runners which collect to form the final pipe that runs to the cat then exhaust, or for cat-less systems, straight to the exhaust.

In contrast is the 4-1, where all four runners form into a single short collector; four runners into one, the 4-1. Simple enough, right?

On Honda headers, Honda Tuning magazine (thanks guys, awesome job) mentions several other design criteria that can be altered to affect performance. They don’t test each of these in turn, but here they are listed. With either primary design, you can change both the primary and collector tubing diameters. With the tri-Y, the secondary tubing’s diameter can also be altered. Again, remember that these tubes can’t just be increased because you think that will open up the exhaust…it’s all about balance, figuring out the exact combination to improve the exhaust’s velocity out of the combustion chamber. Bigger is NOT always better people, let’s all remember this concept because it’s the same with intakes!

So how did the tests turn out? Tri-Y designs by and large have a much broader RPM spectrum so increases showed up throughout the range on the B16 rebuild tested by Honda Tuning Magazine, but the 4-1 passed it up in the peak range because the 4-1 design is mostly used for high RPM (they have a narrow range of effectiveness) racing applications. Note how we all have 4-2-1 designs because our cars aren’t race cars!! The tri-Y design for our cars is definitely the best even though the 4-1 will beat it up top; the key is that the tri-Y hangs with the 4-1 all the way through the RPM range, giving more torque and whp at the low end than the 4-1, only losing at the very top and only by a small margin (3 whp and 2 torque). Since we all don’t drive our cars daily at 7,200 RPM, my guess is that this won’t change the trend for tri-Y headers being chosen over 4-1 for our application.
 

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Thanks for the great summary. Your making it more and more tempting for me to ggo ahead and order the Vibrant w/ HFC. If we still had rep you would get :1:
 

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Thanks for the great summary. Your making it more and more tempting for me to ggo ahead and order the Vibrant w/ HFC. If we still had rep you would get :1:
You should do it. Really, it is one of the best mods you can do on your car. As you know, making hp gains is really hard on the K20z3 motor. As you combine this with a cat-back and intake and possiblty Hondata and cams, you should have a pretty strong running car. :thumb:
 

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You should do it. Really, it is one of the best mods you can do on your car. As you know, making hp gains is really hard on the K20z3 motor. As you combine this with a cat-back and intake and possiblty Hondata and cams, you should have a pretty strong running car. :thumb:
:yeahthat: What Bill said.:thumb:

I see you've been mighty busy with your "Mother" series of threads Bill.:thumb:
 

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I think adding accurate inner diameter measurements will be helpful. It'll be even better if the members give the measurements instead of the listed size at the manufacturer/supplier website.
 

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I think adding accurate inner diameter measurements will be helpful. It'll be even better if the members give the measurements instead of the listed size at the manufacturer/supplier website.
I can give the specs on the Vibrant, but I need info on the other headers. Anyone want to help so that I can update the thread?
 

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Heya Nitrous, maybe we can put other information in here, like the difference between a 4-2-1 and a 4-1 header. There's been tons of analysis and tests done, so even though we all know the 4-2-1 design is better for our K20, I'm sure a lot of people ask "well, why?" I have the latest Honda Tuning magazine where they discuss this very thing and compare the designs - both have their strengths and weaknesses. Just a thought. Great write-up, though...I didn't even know about the top two race headers. :smile:
 

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Heya Nitrous, maybe we can put other information in here, like the difference between a 4-2-1 and a 4-1 header. There's been tons of analysis and tests done, so even though we all know the 4-2-1 design is better for our K20, I'm sure a lot of people ask "well, why?" I have the latest Honda Tuning magazine where they discuss this very thing and compare the designs - both have their strengths and weaknesses. Just a thought. Great write-up, though...I didn't even know about the top two race headers. :smile:

If you can post it or get it to me, I'll update the thread. Great suggestion as people do want to know the differences between the 2. Let me know.
 

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Well, how do you want it? :smile: I can PM you or just post it, then you can do what you want with it and I'll edit my post when you incorporate. Is that how it's done or do Mods help us out with the logistics? :smile:
 

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Well, how do you want it? :smile: I can PM you or just post it, then you can do what you want with it and I'll edit my post when you incorporate. Is that how it's done or do Mods help us out with the logistics? :smile:
You can do it either way. If you PM me, I will just copy it and add it to the thread, or just post it and I'll take care of it.
 
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