Many people ring and ask "why should I buy a billet sheet metal manifold?" & "what can I gain by buying a manifold?"
Obviously the answer has many variables. So on this page we will give a few examples
Before giving you 2 very good examples there are a number of questions you need to answer before your purchase:
Does your manifold maker have years of experience in the design of manifolds?
Does he have a flow bench and engine dyno for development and testing of ideas and theories?
Does he have years of racing experience?
Does he have an engineering degree?
Does he understand Fluid dynamics?
Does he understand wet flow vs dry flow design differences?
Can he design your manifold to work with other harmonics if runner length is compromised by design requirements?
At BG Engines we are Engine builders. racers and Engineers.
Runner length, taper and plenum size is designed to work with the specific combo in
While we do have off the shelf manifolds available for common engine
we prefer to consult with you and produce a manifold that will meet or
exceed your expectations.
All of our manifold
development starts with basic principles of fluid mechanics and CFD in
conjunction with actual testing via flow bench, the engine dyno, and
track data. . Analyzing all of these variables carefully is
where product refinement, knowledge, and experience increases
with each manifold we produce. We base the foundation of products and
applications around these principles.
small team is made up of someone who has been building race and
engines for 30 years, and who has been designing and building manifolds
since 1991. A CNC machinist and programmer with a degree in
Engineering, specialising in Fluid Mechanics and computational fluid
dynamics. Fabricator and welder with many years experience. We have
Flow benches, Fuel flow bench, Superflow 902 dyno and CNC machining
centres. We have years of experience in Drag, circuit and boat racing,
with our own cars and as crew chiefs, mechanics and engine
builders for both factory and private teams.
Back to a few real world examples
427 Small block Chev with AFR 227 heads.
These heads flow 309cfm which equates to 636 HP
Both engines were the same compression, had the same camshaft and used the same exhaust for dyno purposes
Both Engines used ICE 7 amp ignition systems (ICE Ignitions.com.au)
and ran on BP Ultimate 98 Octane pump fuel
Engine Number one
Edelbrock Victor Senior and Pro Systems dominator carb 628HP
Engine Number 2
BG Custom billet runner sheet metal manifold and 2 holley HP carbs 684 HP
You can see why it is referred to accoustic supercharging, as the
engine makes more HP than the potential of the cylinder heads due to
the ram effect of high pressure waves. A properly designed manifold
can make a huge difference. In this case 56HP, and just as
importantly 15 foot pounds of torque.
Overlaying The 2 graphs illustrates this difference. Some people are
concerned about losing bottom end power, but as can be seen the BG
manifold NEVER makes less power than the Edelbrock
Adding a small shot of nitrous this same engine
Overlaying the 2 graphs
Independent testing confirms and exceeds these figures
460 cubic Inch Big Paw Holden engine
Craig Bennett from Torque-Power
engaged us to build a manifold for twin 1150cfm throttle bodies on a
460 cubic inch Big Paw Engine.
The reults with a cast manifold and a 1450 cfm dominator Dambest carb were:
768HP @ 6300 rpm
665 ft lb
Impressive figures for the big paw dominator single plane manifold
With the BG Billet intake and 2 1150 cfm throttle bodies the same engine made
840HP @ 7200
700 ft lb
Craig's Big Paw Engine, blocks, heads and manifolds combinations are available at