The Aussiespeed® Plenum Pig is an easy way to increases torque, horsepower and make your engine behave on the street. It can be easily removed if your daily drive doubles as you strip stompin weekend warrior.
The Plenum Pig was designed be fitted to a Cain 4 barrel manifold or an Aussiespeed® AS0019 4 barrel Hemi performance manifold. The Plenum Pig insert needs to sit flat on bottom of manifold, sometimes trimming of Plenum Pig or manifold may be required.
It is very important that the manifold and Plenum Pig insert are absolutely free of contaminants. These include fuel, oil, sand, filings etc. It is a good idea to use a degreaser or cleaning fluid before installation.
It is also recommended that the pig and bolt have a small amount of fuel resistant sealer on the bottom. Once installed fuel mixtures will need to be checked due to better atomization in most cases your carburettor may require leaner jets.
The pig comes drilled and supplied with 2 bolts, 1 short for when the Pig is removed and a longer bolt to hold the Pig in place. It is recommended that the 2 nuts supplied are used as a lock nut on the retaining bolt on the underside of the manifold.
Manifold not included.
To fit the Aussiespeed® AS0084 insert, there arw some modifications required to fit the Plenum Pig the black coloured in area needs to be cut out.
With the material cut out the plenum pig drops into the manifold, one in position a single hole of 6.5mm needs to be drilled to hold the AS0084 Aussiespeed Plenum Pig in place.
The Holley 4 barrel carby base has had the butterflies removed to show where the insert sits in the manifold.
The underside of the manifold with washer and nut supplied a small amount of sealant should be used to seal the bolt hole.
What we achieved by developing the plenum pig:
The Hemi 265 engine we used as our dyno mule was a good strong street engine that powered a Chrysler Centura. The engine belongs to a customer of Outlaw Speedshop in Adelaide the customer wanted a tough street engine that he could also use to run quick 1/4 mile passes at the drags .
The engine combo was a solid Crow cam, Big Block Chev roller rockers, standard size valves porting of the cylinder head was bowl and short turn work with porting to be considered a good street port job.
With a few different inlet manifolds tried we were trying to see if our long runner manifold could produce low down torque and still make the numbers up top. We tried a list of different carbies from 465 Holley, Barry Grant 650 Demon and the best performing was the Holley 650 HP Series with a 12mm spacer under the carb and the Aussiespeed® 4 barrel AS0019 manifold .
Highest horsepower reading was recorded 304.4 HP with 300.2 ft lbs of torque. The maximum torque was achieved @ 4600 RPM and maximum horse power @5800 rpm.
The Aussiespeed® Plenum Pig gave an increase of around 20 horse power with the combo. It is for the Cain Hemi and early Aussiespeed® AS0019 manifold and is not required in the later AS0265 and AS0298 Hemi 6 manifolds.
In a nutshell, on a good hot street motor with a camshaft duration of .244 inlet and .244 exhaust the Plenum Pig increased horse power from 277 HP to 304.4 HP and torque from 268 ftlbs to 300.2.ftlbs.
For a investment of around $100.00 bucks a few hours work and some carby re jetting an increase of around 20+ horsepower is well worth the effort. The plenum Pig helps increase air speed and is simple and easy to fit.
Bang for buck if you are using and early John Cain or Aussiespeed® Hemi 6 manifold it will be the best 100 odd bucks you will ever spend.