Well, I have been hearing mixed opinions on headers. Some say they provide nice gain, some say they just rob the power. What is the truth?

Also, would proper tuning make the header beneficial even if you lost power initially without any tuning?

Thanks.

 

i didn't loose any power. picked it up all throughout the band.

 

Its really dependent on the header design, how the rest of the exhaust flows, and whether you are N/A or FI. If you have a stock catback and stock cats, a typical header like DC sports, alphaworks etc will make some nice gains because it provides equal length and some scavenging effect. But if you have test pipes and a true dual catback, headers may lose some low end because the higher cross sectional area of the system requires more RPM to get the velocity up to the 240 ft./sec needed for max torque. Thats why that combo will gain in the upper RPM range.

It will also be very beneficial for any FI application because turbines like to dump to atmosphere or as little backpressure as possible, and you really need about 1 sq.in of cross sectional area for every 60 crank HP you plan to have. So, it really depends on what you have now and what you plan to have to say what the result will be the day you slap them on. Just think of them as a foundation for future flow mods.

 

get em

 

I think they are good IF you are looking for added top end power. The stock headers are much more restricted. If you plan on racing and the such, I think they are a great investment. Otherwise, I think money can be spent elsewhere for more noticable, drivable improvements.

 

You will rev quicker and pull harder up top for sure. You shouldn't lose any low end tq to be honest as headers should help to balance exhaust gas pulses and help scavenging. When my headers get here and I get them on I will let you know. Even with just test pipes installed my motor rev'd much more freely and pulled a lot better up top. It did seem to lose a little down low, but I could sometimes chirp going into third, couldn't do that with the cats in. It was a little chirp nothing big(car didn't gain that much power)

Another benefit is they should lower cylinder temps over stock manifolds. This is a good thing. Forced induction setups like Stillen superchargers, prochargers or vortechs will see even better gains. I am not sure if you can use these headers with turbo setups, I don't think the piping would clear, plus they would need to be ceramic coated to handle the heat from a turbo.

 

Headers typically show gains of 5-8whp. Headers are a bit of a pain to install, some worse than others. The biggest downside I see to headers is increased underhood temps. Header coating and header wrap will help, but it still won't be as good the OEM design with thick cast piping and heat shields. The increased underhood temps can make for quicker engine heat soak and potentially quicker wear on rubber components.

 

If you get headers, definitely ceramic coat them whether they are stainless or not. It will reduce the radiated heat quite a bit and keep the heat in for better gas velocity. But the stock manifolds are not cast at all, they are a 2-layer welded assy with sound/thermal damping between layers. But they ARE restricted. Only 1.5" exit diameter vs. 2.25" for a typical header collector.

 

Where does the 240ft/sec come from? Can you show us how that is calculated to be optimal for max tq?

 

This http://www.team-integra.net/sections...sp?ArticleID=2
does a pretty good job of explaining it. The main thing is that the header is just part of a "system". If the rest of the exhaust is not sized/designed properly, the header will not perform well. That probably explains why the original poster is getting mixed messages about headers in general. Most guys just slap on some headers with what they have and that's how it turns out. Some work well with what's behind them, some dont. Its a crap shoot unless its all been tuned to work together.

 

i def agree with all hes said. and especially above about the coated headers. wraps may work, but header rot is possible, however theres a new spray to "seal" header wrap that may work a bit better. however metals expand and contract when heated and cooled, hence the coating is better than a restrictive wrap.

 

Nice pic and thanks for the correction.

 

Even with more potential heat under hood you are removing more heat from the cylinder head. I would coat a header long before I wrapped one, wrap can trap in moisture and cause them to degrade.

 

For me, in my researach and live testing, the bottom line in headers is that you will lose some bottom end and gain in the top end. That is ultimately what they are designed for to begin with.

If you have a properly setup and tuned exhaust 'system', they can work beautifully. If you are modded appropriately or FI, they will also work VERY well. The problem is that most will put them on in a bad combination and see little to gains and very commonly a loss, until way up in the high band.

Most wont spend the money to have a complete system done right. You almost have to tune your system for headers, so if you really want them, you need to plan on headers first, then design the rest of your breathing mods around that point of the system.

Planning is key when it comes to headers.

Rick

 

Ideally, you want to keep as much heat in the heads and piping to keep up the exhaust flow. Hot heads, block, exhaust and a cold intake manifold and intake charge is about as ideal as you can get.