Does size matter?
#2
01-13-2006, 11:43 AM
RE: Does size matter?
OK, after posting this question I kept researching on my own and found the answer. Since I figure there are probably others who do not know the answer either it basically comes down to this:
"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. "
For those looking to learn more click here. There is a lot to pick through, but if you can pick through it all there is some good information in there.
-JAK
"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. "
For those looking to learn more click here. There is a lot to pick through, but if you can pick through it all there is some good information in there.
-JAK
#4
01-13-2006, 12:53 PM
RE: Does size matter?
I posted this another place here a few day ago in response to basically the same question, and just copied it again for here, here goes
---------------
Headers provide more power through two means. First, they provide a smoother path for the exhaust flow and make it easier for it to exit the engine: hence more power. All headers do this, but this adds only about 5-10 HP. Second, they "tune" the exhaust for a type of exhaust pressure resonance which actually assists the exhaust valve function within a certain RPM range usually a range from some RPM (say 3000) to about twice that RPM (say 6000) adding a further 15-20 HP.
This gets very complicated as to how and why this resonance works, but it really does work and on some gran prix racing engines, almost a third of the exhaust outlet timing in the power band is accomplished by header resonance, not valve action (one reason why a FI race car is dead meat if its headers break). The resonant tuning is a combination of tube length, tube idamter, and collector diamter, elgnth, and taper, as well as the characteristics of the engine is is matched to.
The overall engineering rule is::: the longer the length of the header tubes from flange to collector, the lower the RPM at which this tuning kicks in with added power, and the lower that RPM limit where it stops helping the engine. On a typical LS engine, headers about 28 inches long gradually kick in with this extra HP starting at about 3000 RPM, peaking at about 4500, and gradually stop providing that power gain beyond about twice that RPM (6000), by contrast, shorty headers (say 16 inch length, only kick in at much higher RPM, about 5500-6000, and would peak at about 8000 RPM, and would only stop providing gain at around 10000 RPM. But since the LS1 engine is typically only run to 6500, this means shorty headers provide only a little added power at the very top end RPM, so its not very usable.
It is also best not to get to wide of a tube, otherwise you kill low end torque: 1 3/4 inch is best unless you have a heavily modded engine at more than about 400 RWHP, then you want 1 7/8 tubes, and above about 800 HP you want 2 inch tubes.
---------------
Headers provide more power through two means. First, they provide a smoother path for the exhaust flow and make it easier for it to exit the engine: hence more power. All headers do this, but this adds only about 5-10 HP. Second, they "tune" the exhaust for a type of exhaust pressure resonance which actually assists the exhaust valve function within a certain RPM range usually a range from some RPM (say 3000) to about twice that RPM (say 6000) adding a further 15-20 HP.
This gets very complicated as to how and why this resonance works, but it really does work and on some gran prix racing engines, almost a third of the exhaust outlet timing in the power band is accomplished by header resonance, not valve action (one reason why a FI race car is dead meat if its headers break). The resonant tuning is a combination of tube length, tube idamter, and collector diamter, elgnth, and taper, as well as the characteristics of the engine is is matched to.
The overall engineering rule is::: the longer the length of the header tubes from flange to collector, the lower the RPM at which this tuning kicks in with added power, and the lower that RPM limit where it stops helping the engine. On a typical LS engine, headers about 28 inches long gradually kick in with this extra HP starting at about 3000 RPM, peaking at about 4500, and gradually stop providing that power gain beyond about twice that RPM (6000), by contrast, shorty headers (say 16 inch length, only kick in at much higher RPM, about 5500-6000, and would peak at about 8000 RPM, and would only stop providing gain at around 10000 RPM. But since the LS1 engine is typically only run to 6500, this means shorty headers provide only a little added power at the very top end RPM, so its not very usable.
It is also best not to get to wide of a tube, otherwise you kill low end torque: 1 3/4 inch is best unless you have a heavily modded engine at more than about 400 RWHP, then you want 1 7/8 tubes, and above about 800 HP you want 2 inch tubes.
Thread
Thread Starter
Forum
Replies
Last Post
92 CaMaRo RS
82-92 General
1
08-26-2009 06:05 PM
