COLLECTOR EXTENSIONS

   
Deduct 10% on parts orders over $399.99 & under $525.00.

   
Deduct 15% on parts orders over $524.99 & under $650.00.

   
Deduct 20% on parts orders over $650.00.

    
Quantity Discounts do NOT apply to Header Kit Orders as they are already discounted over 20%.

    
Quantity Discounts do NOT apply to Header Orders either.
   

    Have added new "box" at
    bottom of this column to
     list the most important
     header design issues -
     information that can be
      referenced on almost
        all website pages.
  

================

   304 Stainless Steel   
        J-Bend & Collector
               S A L E.
  
   Discounts up to 50% off!!!
  
Sale limited to items on hand.  (You snooze, you lose.)

  
J-Bend & discount listing.

  
Collector listing.    
     
   

WEBSITE PROGRESS

A NEW PAGE - with an example Header Design Advice letter from the Header Design Service we offer is now available.  Lots of header design discussion in a very different format! 

===================

Lots still left to do to get everything transferred from the old website to this one. 

 Please be patient when things don't make sense or don't work correctly as many have told us that they wanted us to get this website back up and running even if it wasn't perfect.

 
Maximizing Performance
is accomplished by correctly
selecting the following header
design parameters (listed in
order of importance):
 
Header Tube Diameter
    - too big reduces bottom
      end and mid-range power

Header Tube Length
    - too short reduces bottom
      end and mid-range power

Equal Length Header Tubes
    - maximize power gains,
      minimize tuning problems

Collector Outlet Diameter
    - too big reduces bottom
      end and mid-range power

Collector (transition) Shape
    - improves performance over
      broad rpm range

Collector Length
    - very important if header
      exhausts to atmosphere

Port Match
    - exhaust port in head NOT
      blocked by header flange
 
Also VERY important is
making sure diameters and
lengths not only MATCH your
engine's needs but also how
your vehicle is equipped, its
intended use PLUS your
own expectations as well!
(See Header Questionnaire
to find out what needs to
be considered.)
 
(Note that no mention of
Brand Name nor Cost was
mentioned in the above
list of Performance Header
Design Parameters as
engines do not respond
to product names nor
product costs - they ONLY
respond to good design!)   
 
   ==================
 
 TUBE AREA DIFFERENCES
                   or
     Decreases in Exhaust
        Gas Velocities as
     Tube Sizes Increase

                                   Area
 Header        Area      Increase
  Tube       Increase       Over
Outside    Over Next   Second
Diameter    Smaller       Next
(inches)        Tube      Smaller
                                   Tube
  
  1.00            --               --
  1.125       29.6%           --
  1.25         25.8%        63.1%
  1.375       22.9%        54.6%
  1.50         20.5%        48.1%
  1.625       18.6%        43.0%
  1.75         17.0%        38.8%
  1.875       15.7%        35.4%
 
  2.00         14.6%        32.6%
  2.125       13.6%        30.1%
  2.25         12.7%        28.0%
  2.375       12.0%        26.2%
  2.50         11.3%        24.6%
  2.625       10.7%        23.2%
  2.75         10.1%        21.9%
  2.875         9.6%        20.8%
 
  3.00           9.2%        19.7%
  3.25         16.3%        27.0%
  3.50         16.6%        35.7%
  3.75         15.3%        34.5%
 
  4.00         14.2%        31.8%
  4.25         13.3%        29.4%
  4.50         12.5%        27.4%
  4.75         11.7%        25.7%
 
  5.00         11.1%        24.1%
  5.25         10.5%        22.8%
  5.50         10.0%        21.5%
  5.75           9.5%        20.4%
  6.00           9.1%        19.5%

Keep in mind that, as the tube
size increases, exhaust gas
velocity INSIDE the tube at
any given RPM decreases.
For example:  Looking at the
above chart, choosing a 2"
tube rather than 1 7/8" lowers
the gas velocity in the header
tube about 14.6%;  Choosing
a 2" tube rather than 1 3/4"
lowers the gas velocity in the
header tube about 32.6%. 
  
It has been our experience
(by listening to fellows
complain about headers
they've bought elsewhere)
that if one misses the correct
header tube size by two tube
sizes LARGER than needed
(one commits the infamous
"TWO TUBE SIZE ERROR"),
the gas velocities inside
the header tubes can be
25-50% (or more!) slower
than they should be.  These
much lower gas velocities
effectively take away
the headers' ability to
scavenge exhaust gases
optimally - resulting in
reduced bottom end and
mid-range performance and
sometimes even reduced
top end power as well!
      
Anyone who believes that
BIGGER IS BETTER has
obviously NEVER
experienced this header
design error!
 
   ==================
  
One comparison missing
in the above chart is the
area difference between
2 1/2" and 3" OD tubing.
3" is 46% larger in area
than 2 1/2".  This means
that, in a 3" exhaust
system, the gas velocity
is about 46% SLOWER
than it would be in a
2 1/2" system.
   
While the above Tube
Area Differences chart
compares inside areas
of various header and
collector tube sizes,
maintaining high gas
velocities in the exhaust
system is also important.
(Think of the exhaust
system as a secondary
scavenging system located
immediately behind the
headers!).  This is why
many switching to or
using 3" exhaust systems
often complain about
the poor bottom end and
mid-range performance of
their engines - the inside
area difference between
these two tube sizes can
end up simply too big
and the resultant much
lower gas velocities
inside these 3" systems
actually ends up
hurting performance
in many situations!
   
   ==================
   
(Tube Inside Area
calculations assume .049"
wall thickness on 3" OD
and smaller tubing and
.060" wall thickness on
3 1/4" and larger tubing.)
  
(The above Tube Area
Differences chart is a
smaller version of a much
larger chart found in our
Header Design InfoPak.)
   
   ==================
   
  RPM Range Definitions
 
Throughout this website
discussion often references
various engine rpm ranges.
Considering engines capable
of producing PEAK HP around
6000 rpm, we would define
the rpm ranges as follows:
 
"Bottom End", "Low End"
   - off-idle to 3000 rpm
 
"Mid-range"
   - 3000 to 4500 rpm
 
"Top End", "High End"
   - 4500 and higher rpm
  
(These rpm ranges are
approximate and would also
vary proportionately as peak
HP rpms go up or down.)
  
Referencing to actual use:

"Bottom End" covers rpms
of stock or near stock stall
convertors, rpms in town
driving or cruising down
highways, etc.;
  
"Mid-range" might include
max rpms normally used in
street driving, rpms of higher
stall convertors, some circle
track and road course racing
(rpms of engines as cars
accelerate off corners, etc.;
  
"Top End" might include rpms
of VERY high stall convertors,
engines of race cars whose
transmission and rear end
gears keep them running in a
very narrow rpm band, etc.