How much overlap requires Headers?
Thread Starter
Teching In
Joined: Dec 2006
Posts: 34
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From: Bastrop, Texas
How much overlap requires Headers? I've noticed the difference between before & after header HP #'s, without much more mods, is minor. So the idea is to pump up the flow.
Say you have a budget motor in mind: PRC 5.3l Heads, LS6 intake & the usual misc. mods (lid, remove egr-air, etc) & you have optimized the exhaust with 3" into 4" Magnaflow type merge collector, + good flowing Cats & Muff--
How much overlap @.050 gets you where stock exhaust manifolds begin to be too much restriction? Or is it more of a valve event / header primary length tuning issue that makes them essential to obtain any measure of a cam's max potential?
I moved this from External section hoping to get a response from the heavy hitters around here. So how 'bout it JRod, Patrick G, Old Stroker SS & the rest of you fine fellows?
Say you have a budget motor in mind: PRC 5.3l Heads, LS6 intake & the usual misc. mods (lid, remove egr-air, etc) & you have optimized the exhaust with 3" into 4" Magnaflow type merge collector, + good flowing Cats & Muff--
How much overlap @.050 gets you where stock exhaust manifolds begin to be too much restriction? Or is it more of a valve event / header primary length tuning issue that makes them essential to obtain any measure of a cam's max potential?
I moved this from External section hoping to get a response from the heavy hitters around here. So how 'bout it JRod, Patrick G, Old Stroker SS & the rest of you fine fellows?
TECH Enthusiast
Joined: May 2007
Posts: 538
Likes: 0
Stock engines need headers. All of the above.
Originally Posted by bwana
I've noticed the difference between before & after header HP #'s, without much more mods, is minor. So the idea is to pump up the flow.
Say you have a budget motor in mind: PRC 5.3l Heads, LS6 intake & the usual misc. mods (lid, remove egr-air, etc) & you have optimized the exhaust with 3" into 4" Magnaflow type merge collector, + good flowing Cats & Muff--
How much overlap @.050 gets you where stock exhaust manifolds begin to be too much restriction? Or is it more of a valve event / header primary length tuning issue that makes them essential to obtain any measure of a cam's max potential?
I moved this from External section hoping to get a response from the heavy hitters around here. So how 'bout it JRod, Patrick G, Old Stroker SS & the rest of you fine fellows?
Say you have a budget motor in mind: PRC 5.3l Heads, LS6 intake & the usual misc. mods (lid, remove egr-air, etc) & you have optimized the exhaust with 3" into 4" Magnaflow type merge collector, + good flowing Cats & Muff--
How much overlap @.050 gets you where stock exhaust manifolds begin to be too much restriction? Or is it more of a valve event / header primary length tuning issue that makes them essential to obtain any measure of a cam's max potential?
I moved this from External section hoping to get a response from the heavy hitters around here. So how 'bout it JRod, Patrick G, Old Stroker SS & the rest of you fine fellows?
Thread Starter
Teching In
Joined: Dec 2006
Posts: 34
Likes: 0
From: Bastrop, Texas
Why's That? Comparisons I've seen, on this site, don't create more than 10hp on a stock engine. So why would a stock engine need headers? And at what point would you, is the real question?
Theres not gonna be any set number where it hist a wall. Its going to be gradual. Yes, some cam grinds like the CheaTR will work without headers, but in the end, youre doing yourself a great disservice if you dont get them first. Gotta walk before you run. There are plenty of affordable choices out there.
I put a new intake mani, k&n, corsa cat back, maf, 1.8 rockers, plugs, wires, tb mod, valve springs, but no cam. Car felt a little more responsive but a huge let down from what I thought....
So I was thinking heads and cam but first let me....
Enter LG pro headers....
WOW!!
OOOOOOO that's what was holding all that other work up......
car dynoed with above mods on a stock cammed 97 ls1 6 spd vette at 370rwhp and 379 rwtq
Headers made all the difference, and was holding back all the other mods, in the end saw over 50 hp and tq and wasn't in a hurry to cam it any more.... BTW the PCM didn't need tuned to get this power
Good Luck!!
So I was thinking heads and cam but first let me....
Enter LG pro headers....
WOW!!
OOOOOOO that's what was holding all that other work up......
car dynoed with above mods on a stock cammed 97 ls1 6 spd vette at 370rwhp and 379 rwtq
Headers made all the difference, and was holding back all the other mods, in the end saw over 50 hp and tq and wasn't in a hurry to cam it any more.... BTW the PCM didn't need tuned to get this power
Good Luck!!
TECH Resident
Joined: Jan 2003
Posts: 855
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From: AUSTIN TX
Headers and an LS6 intake netted me an additional 30 hp on an otherwise stock with minor boltons motor. And that is without a real tune, only altered what had to be done to make up for the 28.8 injectors (mine had the 26's originally).
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I have most bolt ons now and hope to do H/C next weekend. Once you get all the bolt ons together they work really well. I think the sound and performance gain with headers was the most impressive 'bolt on' to me so far but it was the last mod I did. A dyno tune from a trusted tuner is also a big help. Personally I would not do the 1.8 rockers because they won't work with a lot of cams.
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Staging Lane
Joined: Jul 2007
Posts: 73
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From: fresno, ca
Originally Posted by bwana
Comparisons I've seen, on this site, don't create more than 10hp on a stock engine. So why would a stock engine need headers? And at what point would you, is the real question?
