LT headers increase low end?
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Joined: Aug 2005
Posts: 306
From: Canada
LT headers increase low end?
Like it says:
I heard people say that they lost low end torque and gained more top end power when they installed their headers.
Anyone lost low end with lont tube?
I heard people say that they lost low end torque and gained more top end power when they installed their headers.
Anyone lost low end with lont tube?
Registered User
Joined: Feb 2006
Posts: 102
From: NC but stationed in WA
Honestly I don't know why so many people ask about low end after installing headers. Who are you racing at 2k rpms? Once your in the powerband, after 2-3 seconds tops, your going to stay there until your done.
Last edited by JCCamaro; Feb 29, 2008 at 11:13 AM.
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Joined: Sep 1999
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Because 90% of the time is spent in that RPM range for normal driving, merging, accelerating from street lights, pulling out in traffic, going from 30-45 mph in an open spot.
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Joined: Mar 2005
Posts: 12,312
From: Aurora, IL
It would be interesting if someone had a dyno graph of a before/after LT install. Judging from the SOTP, I really didn't notice a decrease in low end torque, it felt like a nice power increase all throughout the powerband.
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Joined: Dec 2005
Posts: 313
From: Harrisburg, NC
If anything, your low end power would stay the same. You will not lose any power adding longtubes, it may feel like you lost some power because you have more power higher up in the rpm band. If that makes any sense.
Registered User
Joined: Feb 2006
Posts: 102
From: NC but stationed in WA
Registered User
Joined: Feb 2006
Posts: 102
From: NC but stationed in WA
What leads you to believe I'm saying that? My point is why are you worried about low end torque when your just cruisin your way to work? Is that .01 second longer it took you to pass that semi gonna make you go shorties instead of longtubes?
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Joined: Sep 2007
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From: CA, home of the smog nazi
I think this thread is more of a curiosity thing than debating getting longtubes.
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From: Hell was full so they sent me to NJ
Its hard to separate the "variables" when you install headers. Typically, you are changing at least two things..... 1) primary diameter, 2) primary length.
Larger diameter primaries can hurt low end torque because they reduce exhaust velocity, and decrease scavenging. The cure for some header manufacturers is the "step" designs. So it is conceivable you might lose low end torque with larger diameter primaries. A set of 1-7/8" primaries on a stockish LT1 isn't going to be very happy at low RPM.
Longer primaries favor lower RPM, possibly at the expense of high end HP. Short primaries favor high end power.
If you add a set of well-designed long tubes, and try and compare them to stock manifolds on the dyno, you aren't going to be able to determine what caused the resulting torque curve.
A good reference:
http://www.burnsstainless.com/TechAr...ry/theory.html
Some excerpts:
Larger diameter primaries can hurt low end torque because they reduce exhaust velocity, and decrease scavenging. The cure for some header manufacturers is the "step" designs. So it is conceivable you might lose low end torque with larger diameter primaries. A set of 1-7/8" primaries on a stockish LT1 isn't going to be very happy at low RPM.
Longer primaries favor lower RPM, possibly at the expense of high end HP. Short primaries favor high end power.
If you add a set of well-designed long tubes, and try and compare them to stock manifolds on the dyno, you aren't going to be able to determine what caused the resulting torque curve.
A good reference:
http://www.burnsstainless.com/TechAr...ry/theory.html
Some excerpts:
Gas speed is a double edged sword as well, too much gas speed indicates that that the system may be too restrictive hurting top end power, while too little gas speed tends to make the power curve excessively 'peaky' hurting low end torque. Larger diameter tubes allow the gases to expand; this cools the gases, slowing down both the gases and the waves.
There are many ideas about header pipe sizing. Usually the primary pipe sizing is related to exhaust valve and port size. Header pipe length is dependent on wave tuning (or lack of it). Typically, longer pipes tune for lower r.p.m. power and the shorter pipes favor high r.p.m. power. The collector package is dependent on the number of cylinders, the engine configuration (V-8, inline 6, etc.), firing order and the basic design objectives (interference or independence). The collector outlet size is determined by primary pipe size and exhaust cam timing.
