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Marv D · 04-04-2012, 01:34 PM

I am not qualified to speak about the LS motors, but from a old school small block view,, and ESPECIALLY on the street driving at normal RPM's... a 1-3/4" header is more suited to 4000-7000rpm, 500+HP and USING all the ponies the motor can offer.
Torque is king on th estreet.. and long tube, small diameter primaries build better low ROM torque than large ones. A header is designed to carry exhaust away, BUT the scavaging effect of the port / header primary has a LOT to do with cylinder filling. If the exhaust over scavanges the cylinder (too small of a tube too much volocity) fresh fuel ends up burning in the exhaust. Too large of a tube and the volocity stalls,, and you get little to no scavaging effect and poor cylinder filling... spoiled intake mixture and poor efficiency, poor performance,,, poor idea. Size really does matter and too big hurts! (that sounds like a poorly chosen grouping of words doesn't it LOL)

04-04-2012, 01:34 PM	#2
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: Header? I am not qualified to speak about the LS motors, but from a old school small block view,, and ESPECIALLY on the street driving at normal RPM's... a 1-3/4" header is more suited to 4000-7000rpm, 500+HP and USING all the ponies the motor can offer. Torque is king on th estreet.. and long tube, small diameter primaries build better low ROM torque than large ones. A header is designed to carry exhaust away, BUT the scavaging effect of the port / header primary has a LOT to do with cylinder filling. If the exhaust over scavanges the cylinder (too small of a tube too much volocity) fresh fuel ends up burning in the exhaust. Too large of a tube and the volocity stalls,, and you get little to no scavaging effect and poor cylinder filling... spoiled intake mixture and poor efficiency, poor performance,,, poor idea. Size really does matter and too big hurts! (that sounds like a poorly chosen grouping of words doesn't it LOL) __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.