If you have, or are thinking of buying an Aussiespeed manifold and then spending time porting it or giving the manifold to your engine builder and getting them to port it, please get them to read this article before they go near it with a die grinder or stones.

 

Brads 265 6 cylinder recently ran a 9 second 1/4 mile pass using an AS0265 manifold. Many hours of r&d go into our products as we want to help you to go faster and make your engine more efficient.

This is not a personal attack on any other manufacturer of manifolds, individual or engine builder, but some info we think may help our customers with understanding the reasons we would rather our customers not port our manifolds.

 

With this being said, there are engines that may find improvements from porting our manifolds. Our experience has shown this is not the case, with a turbo charged Hemi 265 making over 500 rear wheel horsepower with an AS0265 manifold out of the box, 250 crossflows making over 350+HP and Slant 6 and Holden sixes also making figures that shouldn’t be sneezed at. Some may disagree with what is written in this article and are entitled to there opinion. Being the founder of Aussiespeed Performance Products, I still have the same passion for my products as i had on day 1 and want to give our customers and users information straight from the horses mouth and not from the horses arse. If you are reading this you might have already purchased an Aussiespeed Manifold and this may give you more confidence in our products, as we want you to get the best results from using Aussiespeed Performance Products

 

 

 

 

A Ford crossflow round port responds different when reshaped to a rectangular port of a Holden 6 red, black or blue 6 cylinder. A square port slant 6 or Hemi six port is totally different again. We will look at these 3 engine types here and explain what we have learnt over recent years while developing the range of Aussiespeed street and race manifolds.

 

The first manifold we will look at is a Holden 6 cylinder 202 black and blue motor. The manifold is a Aussiespeed supercharger manifold to suit the m90 Eaton style supercharger, the AS0009 looks very similar to the AS0002 red motor manifold. The blue, black motor is taller in the port and the manifold has been designed the same way. Inside the plenum on the inside closest to cylinders 3 and 4, you will notice centre divider and the unusual shape how it points towards the inside closest to the cylinder head. We tried filling it in to a flat section and it didn’t like it, It upset balance of flow to all the cylinders so it is advised not to touch it.

 

The Plenum floor with the plenum “PIG” filler, This is cast into the manifold so it can not be removed this was done to stop guys from unbolting it and ending up with an engine that wont pull from a moderately low rpm and can also cause pooling of fuel on the port and plenum floor, removing it slows air speed and velocity and also makes engines boggy. The shape was designed to increase the performance and not reduce to much volume, at higher RPM it also directs air and fuel. The shape was changed many times and the correct location, height and tail length along with the centre divider all work together to deliver optimal port flow and velocity.

 

If you start grinding any of these areas you have undone the many hours we have spent perfecting the manifold.

 As the AS0009 was cast to obtain optimum port and plenum size to deliver good torque over a wide rev range, shown is the Aussiespeed east west carb adapter that allows the carb to be run eastwest

Picture of a manifold that was modified by a engine builder, We were told our manifold didn’t work. as the engine was sluggish down low, fouled plugs and had fuel dropout on the port floor. This is normally caused by incorrect power valve sizing & when the cross sectional area of the manifold has been increased and is to large.

You may notice the different tail lengths on the plenum pig, this is done for a reason, If you are going to compete in a 500 mile reversing race, please contact us.. so please do yourself a favour and don’t change it..

 

Note the bell mouth on the port on the left hand side also the extra distance the calipers go into the port, We didn’t even check the height of the port the evidence of the width was bad enough. Plus the removal of material from the port floor

The middle runner on the AussieSpeed Holden 6 manifolds are different size than runners 1,2,5 and 6 for a reason, It is important that they are left this way. Match porting & polishing looks good when you show people or at a bench racing session but does more harm than good with our Holden 6 manifolds

 Abracadabra they even hit the port floor on this one and look at the amount removed to the left port side wall.

 So in short after seeing the pictures of the manifolds above here are some important points

The ports on the Aussiespeed Holden 6 manifolds differ in size on the port mouth for a reason.

This is done to balance cylinder fill to give good velocity and an even flow on all cylinders

 The dividing wall in the plenum in front of cylinders 3 and 4 and the runners are matched to the port sizes on cylinders 1, 2, 5 and 6.

The reason the Aussiespeed 2 and 4 barrel manifolds can deliver high levels of performance is due to the balance of flow on all 6 cylinders.

When picking your carb and manifold be sure to not go to big. We had a customer ring and complain that his engine went real hard with his old carb and manifold, after installing our manifold and a 750 vac Holley it went backwards. When asked what was the old carb and manifold he replied ” stock single barrel Stromberg on a factory manifold” with a  “standard head standard cam”. So please do your self a favor and select a car and manifold suited to your combo..

 

Many hours of research has gone in to developing our range of manifolds, we have many different ways we like to test manifolds in which has caused some critics to disagree.