what do longtube headers do for a 99 ss. and how much hp gain? thanks recommend any brands?

 

i believe longtubes with a 3" exhaust will usually net >20rwhp for an ls1. I know I felt a huge difference with mine, and love the sound too. I did pace setters, heard alot of complaints about the painted pacesetters so i bit the bullet and bought the coated ones with a tsp y-pipe. the ypipe had some clearance issues but the headers went right in with only a few hours of work. I think we (me and 1 buddy)had the manifolds off and the headers hung in about 3 hours. driver side needs either the steering shaft removed or the engine lifted slightly to get it in. You need to get the entire car off the ground, and its easier to have the rear end higher than the front to get the right angle to put the headers in

 

I will always first and foremost recommend Kooks headers/Y-pipe system, after that Dynatech, then Hooker, then Pacesetter. The first two are considered a "custom" header, they are tuned to get you the maximum torque and HP, Hooker and Pacesetter are not tuned as well, and will not fit as well, although they'll get you about the same HP, the real difference is in the low end torque that you get from the tuned tubes (I could go into the physics of it, but I won't bore people with that now, PM me if you'd like to know more). The Kooks and Dynatech are probably going to fit and seal a little better than the Hooker and Pacesetter as well. That's not to say that Hooker and Pacesetter make a "bad" produce, it's just worse, it's the whole "you get what you pay for" thing. I have heard some issues with people having to dent their Pacesetter headers to get them to fit right, apparently not everyone has to (Specter for example) but it does happen.

 

this was on an ls1 with EGR and AIR deleted. however i dont think either of those components will matter with the swap, just cant remember if they would get in the way. ls1tech guys like the pacesetters, its probably just that pacesetter got it right with the ls1, because i hear horror stories from v6 guys

 

Hey, I would actually like to hear more about the physics of this, as I think it would be instructional and benefit all interested...

Thanks!

 

Fair enough...

First off, why a tubular header makes more power than a cast iron manifold. We all know that headers "flow" better than the manifolds, this is partially due to an increase in internal area, and the bends are smoother, but the reason headers are a tubular design is because flow is due to temperature differentials. The faster you can cool off the tube of the header, the better it will flow, thus a tubular design is going to dissipate heat better than a cast iron manifold because it has more surface area. This is also why a coated header that is shiny will flow better than a header that is painted black with header paint, it can dissipate the heat better. Second, we all hear how "back-pressure" helps improve low end torque. This is saying that if you have some resistance in your exhaust system you'll have better low end torque because at low rpm's the charge doesn't go into the exhaust, unfortunately for headers, they're as close as we can get to a perfectly free flowing system for maximum HP, thus, we're trying to eliminate back-pressure. This is where the "tuned" header tubes come into play. If all the tubes are an equal length and all of them are tuned it gives two benefits. First off the header can help "scavenge" more exhaust from the cylinder when the valve opens, this is because the exhaust from each cylinder has a synodal pressure pattern (i.e. alternating low-high pressure bands), so if you can get the header tuned correctly it will resonate at the same frequency as the exhaust pattern, thus leaving a low pressure when the exhaust valve opens so it can pull out more exhaust faster. This also means that the high pressure is going hit during the valve overlap period when we could possibly have the charge blown out the exhaust valve, so it helps create a "back-pressure" to help improve low end torque. Obviously the header cannot be perfectly tuned to every RPM, but a good company can get them pretty close. Borla makes headers with merge collectors and mufflers to help tune them even better (if you ever go to professional drag races you see a lot of the comp-eliminator class running borla headers with their merge collector/muffler).

Science is fun isn't it

 

Chrysler did a whole lot of work back in the 60s with tuned exhausts and intakes. That is how they wound up having long tube intakes with 4 bbl carbs sitting near the fenders. The whole idea was to get intake, exhaust, heads, and camtuned to the same RPM band, and get the volumetric efficiency over 100%, like having a free supercharger.

 

LOL, I have to say those are some of the goofiest looking motors I've ever seen. At least they were trying new things to get power though. Good luck with trying to get over 100% efficiency too

 

are the hooker hearders any good?

 

Hooker headers aren't bad, but they won't have as high of quality as the Kooks or Dynatech systems. I can say from personal experience that my Kooks headers have better quality than my buddies Hooker Super Comps, but I also paid a little more for my headers as well. It all boils down to how much money you're willing to spend. You're going to get a bit more power and torque out of the Kooks or Dynatech systems, but you pay more for them too.