Headers

[MarkWebb]

So I am looking for a set of headers for my old style SBC with AFR cnc 210 heads installed in a CanAm so the up and over style no good. Currently run a set of the "blue flame" ones that some people fitted instead of the factory spec. These are rubbish and leak around the collectors which are badly welded to the headers. I am wondering and would like to start debate as to whether the longer style a la AB LS style would give any benefit or whether the factory style is the way to go?

[Justaredbadge]

Last time the ab headers were mentioned someone brought.up a very good David Vizard article which said that matching the primary lengths was not as important as the collector length. differences in primary length of up to 25% made little difference on the dyno.

These tests were done on a sbc with a known power output.

Anyway, the factory set up is a known quantity. The ab setup is over the top for the negligible gains that it may make. i would suggest the fabrication by an exhaust specialist (specializing in chevy engines) or the factory setup.

But at the end of the day it is your money.

[356Speedster]

I'll wade in here seeing as I have an AB exhaust and it's been dyno'd...... Car is a Can Am, crate LS3 motor, GM E67 ECU, no internal mods. I have an AB carbon intake and the AB exhaust. When the car was on the dyno & the GM ECU re-mapped, the motor made 480bhp with the cats in place and IVA friendly emissions. That's a significant upgrade over stock LS3, so I'd certainly say the exhaust is contributing to the power hike (along with the mapping, of course). I'm now running de-cat, but the car hasn't been back on the rollers, so not sure how that's changed power. Hope that helps.

[MarkWebb]

Was me who mentioned the Vizard article.

[Storer]

On the exhaust topic, does anybody know if headers designed for an LS2 will fit an LS3 or LS7?


Paul

[DHGTR]

Hi Paul,

No they won't. LS2 has different exhaust ports. LS2 are cathedral/arched type.
LS3 are rectangular.

Dave

[Storer]

Thanks Dave

I thought they wouldn't but wasn't sure.


Paul

[petrol head ash]

I think DHGTR is referring to the inlet ports being rectangular and cathedral? The headers will fit LS2/3 and 7 although they do have slightly different valve angles.

Tubular headers on an LS7 will require the early type exhaust gasket due to the bottom of the exhaust port having a flat edge.

hope that helps

Ashley

[Storer]

Now I am confused!


Paul

[MarkWebb]

So getting back on topic. Mr Vizard article suggests that 1.75 primaries and 3 inch secondary pipes will suit my heads nicely. He then suggests a collective resonator box or non restrictive silencer followed by silencers which will flow the amount of exhaust produced and not much more otherwise noise will result! So I am looking for a factory set of SBC headers! Anybody?
I will then probably get them coated.

[ROWDYRENAULT]

if you go on the Burns Stainless steel web sight, they have a very detailed input form for engine displacement, compression ratio, valve diameter, ect ect that will calculate your header and primary pipe dimensions for free. I agree with the thought that we are only speaking in small percentages but I think if you paying to have the headers built why not get it as close as possible. If you are buying off the shelf headers I would think I would want them to be equal length and the correct diameter. Lee