For those with headers : Look into the collector. Are the primary ends
round with a diamond gap in the center ? If so that is cheap headers.
The center area should be pinched together to form a cross.
Dynomax (Walker) Super Turbo Mufflers have curved half pipes in each end
to direct the flow instead of the stampede bashing into the wall headon
and getting reorganised in the mayhem.
Mandrel bent tubing helps as opposed to exhaust bending machinery crimp
bends.
Gradual cone size changes, not abrupt adapters, are used to drop
diameter 1/4" every few feet or so.
Okay, look at a set of headers. Only one cylinders exhaust charge is
sliding through a primary at a time. This charge should reach the
collector at the same time as the cylinder firing previously just
finishes passing the collector. Once the charge just gets past the
collector is when you want the next charge to arrive there. This is why
equal length primaries are important. If off by even only a couple
inches, the header will not scavenge properly. Also considering only
one charge flows through say a 1-1/2" primary, and only one cylinder
fires at a time, and each goes into the exhaust pipe by itself, why have
a big 3" pipe to slow the velocity and ruin scavenging force and allow
the gas to expand and get lazy ?
Primary lengths and diameters, for most of us on the street driving
mostly in lower rpm range, long and skinny is better. I feel the
primary should hold one cylinder displacement. This means the shorter
you go, the fatter the tube should be. The reason is for scavenging
timing.
Four into one vs. tri-Y, If properly built both are okay. Tri-Y should
have a cylinder full of primary and also secondary tubes to continue
scavenging.
Scavenging is simply a flow charge exiting a pipe and sucking the next
consecutive charge through behind it. A yielding merge.
Now to go any further, look at the firing order and notice how a
cylinder will fire then one from the opposite bank of the engine, before
maybe returning to the first bank. Well that my friends is how the
development of 180° tuned headers came about. They are the best as
the entire engine is connected as one flowing pump working together
instead of fighting itself. Unfortunate header manufactures have only
concentrated the design on race cars. I would absolutely love to
develop a 180° header system for each Mopar V8 .
Thanks,
Eugene
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:50:45 EDT