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I was having a conversation with a friend regarding headers. I was considering the purchase of Belanger long tube headers and he advised me that B&B shorty headers make almost as much HP and tourque with no exhaust cutting (easier install). Comments from other forum members would be appreciated so I can come to an intelligent decision.
From: 26 NM out the 304 radial of the ORD VOR Illinois
Re: Long tube vs short headers (Buckmaster)
I would like to know how equal length long tubes can be a big help in schavenging when the LS1 engine fires twice in secession into the same header (instead of switching from side to side). Seems to me that most gains (long or short) are from the less restrictive design and not from exaust pulse schavenging. Considering the work involved with the long tubes, my vote (and my future plan for my car) is for the bolt in shorties.
Subject: Headers
Short tube headers are simply more efficient at getting exhaust out of the engine than the production manifold. These 'headers' are too short in length to perform the taks that long tube headers perform.
Long tube headers are not just longer versions of short tube headers. Their length has been determined by the timing of the exhaust and intake periods on the camshaft and the RPM band where the engine make max TQ.
Basically, a well desinged header connects three CAMshaft intervals in time. When the exhaust valve opens, a high pressure wave starts dwon the header. When the HPwave reaches the collector, it encounters a low pressure region. This causes a low pressure wave to reflect back up the header.
We want this low pressure wave to reach the cylinder at the same time the intake valve opens. This low pressure wave can begin to draw fresh mixture into the cylinder even before the piston starts down on the intake stroke. Unfortunately, since the exhaust valve is open, it draws fresh mixture into the exhaust pipe. Fortunately, this mixture is pushed back into the cylinder by the HP wave which follows.
Meanwhile, back in the collector, the high pressure wave has reached the end of the collector, and encounters a restriction we normally call the exhaust pipe. This HP wave reflects off this restriction, and runs back up the header. We want this HP wave to arrive at the exhaust valve just before it closes so the HP wave can push the fresh mixture which entered the exhaust back into the cylinder. Thereby achieving greater than 100% volumetric efficiency.
Summary: short tube headers are just less restrictive than production
manifolds, while real headers actually extract energy from the pressure waves which exist from the 4-stroke nature of our engines.
Simple and plane.......... Jim Hall of Halltec dynoed B & B shorties back to back on a 02' Z06, and they only made 3rwhp. Longtube usually makes about 15-20rwhp.
I looked at TPIS, Shorties, TTS , and Belanger and decided the Belanger's were the way to go. I got 21 RWHP and 18 RWTQ increase, but I also added the LS1 manifold intake at the same time so I can't tell which mod did what. Still - I'm satisfied - SOTP increase and deeper lower growl.