are the greddy headers any good? i'm kinda in the market for some headers right now... I was lookin' at the SMSP's, but they kinda expensive

 

The only headers that add any HP are custom jobs. SMSP, Hytech, RMF.....all expensive, and all beautiful. But they are the only headers that add any power. Greddy are similar in design to the DC Sport, but don't break all the time. The DC Sport header not only breaks all the time, but I think it may actually make you lose a couple HP. $150 is not a deal for something that is just going to crack and hinder performance IMO.

 

Prelude 1897 I've been to NTPOG website years ago, didn't know you had a meet. Are locations & times listed on the website?

As far as DC Sports headers go, I wouldn't install one if it was free. As far as headers in general go, I don't believe you'll gain any significant hp unless you use it in conjunction with other modifications i.e. exhaust, cai, turbo or supercharger, ecu upgrades etc. If you just want to add a header, the only real difference I've been able to notice is the weight difference between aftermarket & stock due to the materials used. It would be a waste of money. Of course, I've never seen before and after dyno results. I could be wrong.

 

correct. those custom headers are worth every penny if you're looking to make as much hp as possible. but, the header is only part of the system. you have to get the rest of the engine inhaling and exhaling better.

 

I'm seeing a lot of inaccurate statements about headers here (and I don't mean to put anyone down). Here's a pretty indepth explanation of headers, how they cause an increase or decrease of hp, how they can change the effective rpm range, etc.
It starts at the valves. The exhaust valves open and exhaust gasses start to travel out of the cylinder and into the header/manifold. When the piston nears TDC, the INTAKE valves open (while the exhaust valves are still open). Due to the negative atmospheric pressure in the intake and the positive atmospheric pressure in the exhaust header/manifold, the exhaust gasses are expelled more quickly and the intake charge is pulled into the cylinder (this is known as the scavenging effect).
Obviously exhaust is not a constant pressure. It is a pulse traveling out of the engine at near the speed of sound. The leading edge of the pulse is high-pressure and it trails off to low pressure (as the pulse travels it becomes low pressure). The design of a header uses tube diameter and length to manage this low pressure pulse. The idea is to have low-pressure feedback for the next exhaust port as it is opening to expel exhaust.
Essentially a long tube length and small tube diameter will assist in low rpm torque (this goes back to the scavenging effect). Large tube diameters and short tube lengths promote upper rpm power (because the scavenging effect is lost to lower rpms but gained at upper since the exhaust flows so freely).
This said, header design (tube size, style, length) is the most important factor when it comes to selecting one for your application, not 'who made it' or 'how good it looks'. Selecting the wrong header leads to an engine that can be a real DOG (because the engine is designed to build power at "X"rpm and the header is designed to promote power at "Y"rpm).
Another 'myth' is that a turbo needs HUGE tubes to operate. Again, this is a MYTH. Too small of tubes makes the exhaust back up into the engine (meaning that you are contaminating the intake charge) and too large of tubes means that the turbo is not spinning optimally. Everything AFTER the turbo can be 20" diameter for all it matters as long as it flows well.
In conclusion (don't fall asleep yet) most aftermarket manufacturers design the headers around certain engine combinations (this data is usually readily available through the manufacturer).
Again, I did not mean to step on anyone's toes here or belittle anyone for their opinions. I think that should about clear things up about headers... class dismissed. Any questions?

 

yes these mass produced OTS headers like dc and greddy are basically a one size fits all type deal. if it makes power, it'll be very little. if it doesnt, chalk it up as a lesson learned i guess.

but the top custom header makers, smsp, hytech, rmf, etc., custom build a header to your engine specs and power goals. taking into effect tube lengths, diameters, collector size, and cylinder pairing. all of which play a big part in the header making or losing power in the part of the powerband you want it.

my 2 pesos

 

"Essentially a long tube length and small tube diameter will assist in low rpm torque (this goes back to the scavenging effect). Large tube diameters and short tube lengths promote upper rpm power (because the scavenging effect is lost to lower rpms but gained at upper since the exhaust flows so freely).
This said, header design (tube size, style, length) is the most important factor when it comes to selecting one for your application, not 'who made it' or 'how good it looks'. Selecting the wrong header leads to an engine that can be a real DOG (because the engine is designed to build power at "X"rpm and the header is designed to promote power at "Y"rpm).
Another 'myth' is that a turbo needs HUGE tubes to operate. Again, this is a MYTH. Too small of tubes makes the exhaust back up into the engine (meaning that you are contaminating the intake charge) and too large of tubes means that the turbo is not spinning optimally. Everything AFTER the turbo can be 20" diameter for all it matters as long as it flows well."

After reading this, I've got a question (most likely a dumb one). If one were considering installing a turbo, then would it be effective to install headers with long tube length and small diameter to increase low end torgue to offset the "lag" turbo's create while they spool? If this is the case, which headers would one choose?

 

you wouldnt use a header with a turbo. you'd use a turbo manifold. different designed manifolds will have different spool times. also the size of the turbo will play a factor in spool.

 

Snoopy is right, commonly you would be using a turbo manifold rather than a header. I wrote that in there partly because there are always those out there that have a custom setup (or simply want a custom look) and so opt for a header instead of the manifold, and partly because a lot of people believe that a tuned header provides the turbo better power (the truth to that is questionable). I once saw a beautifully done turbo header... all stainless steel and powdercoated, but it had darn near 2.5" pipes... Rediculously oversized because the guy was told that the turbo HAD to have HUGE tubes in order to work. After many troubles the guy changed to a manifold and found a lot better response time and power. It just didnt look as good.
The refrences about tube lengths is for N/A engines. Turbos generally need to be as close to the exit ports as can be (or you get a lot of lag). Now, I have heard a few experts claim that they can mount the turbo further than normal from the engine and still maintain low lag, but since I haven't seen it and dont know how to accomplish this, I cannot elaborate.
I also want to add on to what Snoopy said... The exit pipe will have something to do with spooling time as well. If there is backpressure there, then the turbo is having to force the exhaust out... thus losing efficiency and creating some lag. In other words, on the exit side of the turbo, bigger is definitely better.