Header?

[Kim57]

I've got an LS2 going in my project. It's rated at 400/400 from the factory.
I'm looking at 2 different sets of headers.

http://www.sandersonheaders.com/Sand...s-Engines.html
These have 1-5/8 tubes with a 3" collector.

http://www.sandersonheaders.com/Sand...eader-Set.html
These I can get with a 1-3/4 tube with a 3" collector.

Is there going to any difference on a street driven engine with the smaller primary tubes?
Thanks for any input.
Kim

[Marv D]

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)

[Kim57]

Originally Posted by Marv D

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)

I can get the second set in 1-5/8 primaries also.
Kim

[Super73]

Yes this is a 6.2 liter motor but the Dino results are interesting..

http://www.performancetrucks.net/for...esults-496455/
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[Kim57]

From what I've seen on some other forums the LS engines need at least a 1-3/4 inch header so the 1-5/8 wouldn't be a good choice.
Kim

[BigDan3131]

If I was reading that right the 1 7/8 were falling on their face after 5200 rpm and the other set was but not so severely.

Can you not get stepped headers for ls based motors?

[Kim57]

Originally Posted by BigDan3131

If I was reading that right the 1 7/8 were falling on their face after 5200 rpm and the other set was but not so severely.

Can you not get stepped headers for ls based motors?

They make them but they are kinda pricey.
I'm looking at the Sandersons because I can get a good deal on them and if they don't fit they will take them back..
I'm probably being to anal about it because I wont be racing it but I don't want to choke it down either.
Kim

[Super73]

You are not reading that right. The 1 7/8 made more power from the start of the pull and then they were the same afterwards.
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[Super73]

I am getting away from my stepped header, 1 3/4 to 1 7/8 for a straight up 1 7/8 version. But with that said, I made 521rwhp through a locked up 80E with those 1 3/4 stepped headers.