H3 Headers

Are these headers really for the H3 and do you think they will give you the 20-30 hp? Anyone already do the research?
 
http://www.teakatoys.com/Hummer_H3_Header_p/3303-3645.htm

Note the term Header............singular is used when only refering to a one piece in line exhaust flange.  Headers refers to two pieces as in V exhaust banks on each side of the motor, hence two flanges.  Typed with pinkies up!
 
That part is for the 3, and you can get the darn near identical part for the Colorado/GMC.  The factory exhaust manifold is designed with much better flow than typical exhaust manifolds of years gone by so IMO the claims of 20-30 HP is puffed and inflated.  If the exhaust Cat was nixed, maybe 10-15????  That's my story and I'm stickin to it til somebody has AWD dyno results that prove me wrong.

I agree Doc. Most modern exhaust manifolds are just cast "headers". I mean a cast "header". So maybe 10 h.p without removing cats. So if you have ever installed a set of header(s) on anything, and dealt with keeping them tight then you know why I'm saying it isn't worth the hassle. Considering the H3 doesn't spend a lot of time near 6000 rpm, depending on the header style, it can actually hurt low end performance. Like when rock crawling or trail running. I will now get off my soapbox.

absolutly.headers are really for the rigs that see 5000 +rpm alot,really no advantage to anything with less then that

I don't know about snakes on an H3...The exhaust manifold on the H3 has a built in Catalytic Converter, read "Close Coupled Catalytic Converter:.

The reason you don't get a Header or Headers on your vehicle from the Factory is due to cost. Almost all of your as casted exhaust manifolds are restrictive. Longtube header (s) tend give you more low to mid range torque and increase flow, short tube tend to give more mid to top end. As far as getting 20-30 Hp not on a 5 cylinder but on a V8 you will. I also found on the net if gut your catalytic convertor you will gain 10-15 Hp depending on the exhaust system, OEM or Performance. If you supercharge then going with a Header (s) you will boost performance as well. With Turbos the catalytic convertor (s) are your restriction then exhaust.  

Absolutly no disrespect Gunny, but I think you have that backwards. Long tube headers are for high rpm performance, and short tube for low end torque. Also, take a look at your stock manifold. Most new vehicles have a tubular design. They're not perfect, but way better then the cast ones of previous decades.

Header configuration is a favorite, long-running debate amongst enthusiasts.  However, it is generally agreed that:
 
· Longer header tubes tend to increase power below the engines torque peak and shorter header tubes tend to increase power above the torque peak.
· Large diameter headers and collectors tend to limit low-range power and increase high range power.
· Small diameter headers and collectors tend to increase low-range power and limit high-range power.
· "Balance" or "equalizer" tubes between the collectors tend to flatten the torque peak(s) and widen the powerband.
 
This list is an except from an article on exhaust theory I have.  It addresses most of the issues we discuss when contemplating headers and explains theory behind exhaust system design.  It agrees with pretty much all the theory I was taught in my engines theory courses in my mechanical engineering training and in my experiences since.

Maybe I do, but I had a set of TTI long tubes on my 07 Hemi and increase to about 50 (Stock exhaust) ft lbs of Torque down in the 3k & up rpm range. When they tested them on a dyno in the Sport Truck article they got 61 ft lbs of Torque @ 3500 rpm, that is why I bought them and put them on.  Your right when it comes to HP but torque moves you.

Good info, and I should have been more specific. Not all, but most long tube headers tend to be on the large diameter side. Not all but most short tube headers tend to be on the small diameter side. And Gunny, what did you expect. It was a Dodge. That thing was jusk when it left the assembly line. Of course headers where going to help. Really I'm just kidding. I'm try'n to get you rialled up this morning. They say that's good for the circulation. Those were impressive numbers on the dyno. That means like like 75 ft/lbs of torque at the crank.

Yeah, they gave the truck an even more kick on take offs, wife hated that, I have a heavy foot. Though the Hemi is pretty impressive IMO. I've had a few Dodges and there is always room for improvement. Though I would like to see if those JTR longtubes would fit on the Hummer due to its close comparison to the Colorado. I bet you would get some decent torque out of that I5. The only thing though is the underside setup. I found pics with it on a 2wd Colorado but not a 4wd.
 
As far as the as casted manifolds they are restrictive and with the designs going or moving towards putting Cats closer in order to heat them up faster it doesn't matter how good you make them. It still comes down to COST.