header question
03-12-2011, 08:50 PM
#1
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header question Does the diameter of the tubes matter much in terms of horsepower/torque gains? I watched someone struggle today mounting Kooks 1 7/8 longtubes in an 05 V with brand new LS6 longblock crate motor. Tubes are actually touching in several spots, including steering shaft. These headers are wrapped in fiberglass tape BTW. I'm thinking headers for my 06, but would it be wiser to buy the smaller diameter model-is it 1 3/4, I think?
03-13-2011, 10:34 AM
#2
Aren't you doing a blower? If so it's 1 7/8 all the way. I have 1 7/8 and mine dont hit anywhere at all so his motor mounts might be way past gone. I think 1 7/8 is the general consensus now as there hasnt been any proof that they hurt hinder low end performance.
03-13-2011, 05:33 PM
#3
Generally speaking, smaller primaries are better for lower-mid range torque and larger is better for mid to upper rpm gains. The length and sequencing (e.g. tri-Y vs. 4 into 1, etc.) make a difference, as well and then there's equal length primaries. I haven't seen any for the LS-series engines (but also haven't looked; Hedman makes them for others), but they also have stepped headers, where the primary starts off smaller, then increases; they even had some where it had like a smaller tube in a larger tube and had supposedly help with anti-reversion or something like that (been years since I read about them)...not sure how popular or well those work on something like an LS though. Finally, if you can get something that matches the exhaust port of the head (some are 'O', some are 'D'), that would help too...
So, really it depends on your goals...I would think 1 3/4" or 1 7/8" could work on even a stock engine and when you step up the cam, the larger for sure. However, there is a lot to consider more so than just the primary sizing, but seems Kooks are pretty good in that respect and it's not like we have much choice. You can go too big too, of course, but the ones offered for the LS seem decent...Just avoid the shorties, as you're not going to gain much there; modern exhaust manifolds are pretty decent (i'm not 100% familiar with what the CTS-V manifolds look like, but the GTO ones were decent), but typically long tube headers can get modest gains, with a tune...
The only real exception is if you were to have turbo(s), where a cast iron manifold typically works better for the heat retention to the turbine wheel, but ideally you'd want the compressor (turbo) close anyhow..
So, really it depends on your goals...I would think 1 3/4" or 1 7/8" could work on even a stock engine and when you step up the cam, the larger for sure. However, there is a lot to consider more so than just the primary sizing, but seems Kooks are pretty good in that respect and it's not like we have much choice. You can go too big too, of course, but the ones offered for the LS seem decent...Just avoid the shorties, as you're not going to gain much there; modern exhaust manifolds are pretty decent (i'm not 100% familiar with what the CTS-V manifolds look like, but the GTO ones were decent), but typically long tube headers can get modest gains, with a tune...
The only real exception is if you were to have turbo(s), where a cast iron manifold typically works better for the heat retention to the turbine wheel, but ideally you'd want the compressor (turbo) close anyhow..
03-14-2011, 04:16 PM
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leo
03-14-2011, 04:26 PM
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Ive been this way for several months, few thousand miles now. The steering wheel "sticks" when turning the car and there is a TON of vibes. I was just under the car and there appears to be nothing but cosmetic damage to the steering shaft and some annoyance on my part.
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03-14-2011, 09:40 PM
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I just decided! Goin' with OBX or Pacesetters so when I whack 'em I won't hold back as much as Kooks or American!! But seriously, think I'll use the smaller diameter just to be on the safe side. What about wrapping? Where are you guys with that philosophy? And I guess it's a good idea to use a higher grade spark plug wire to avoid melting.
leo
leo
03-14-2011, 09:49 PM
#14
Rather than wrapping them, I'd get them ceramic coated, inside and out (if you plan on going turbo, then don't do the inside) at a place like swaintech...I'd go pacesetters before the chinese ripoffs, personally though, if you're on a budget; just save up and get the real deal, IMO.
03-15-2011, 11:52 AM
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03-15-2011, 10:23 PM
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Rather than wrapping them, I'd get them ceramic coated, inside and out (if you plan on going turbo, then don't do the inside) at a place like swaintech...I'd go pacesetters before the chinese ripoffs, personally though, if you're on a budget; just save up and get the real deal, IMO.
