One of our engine builder customers made an unusual discovery. In looking at our Hurricane for Vortec heads, he noticed that the inner design of the manifold was different from our standard Hurricane. He felt that this difference was significant enough that if could adapt the Vortec manifold to a regular 23° head, he could make more power.
So that's what he did and sure enough he got nearly 20 more horsepower out of his modified Vortec compared to our standard Hurricane. Now considering that the regular Hurricane consistently makes significantly more power than any of the leading names in manifolds of this type, this was an amazing result. The results were so great that this engine builder hand made a number of these modified manifolds for his top racing engine buyers at a cost of about $1,500 each. The performance was so strong that users gladly paid for these handbuilt manifolds.
So we decided to take this design and make it as a production manifold which we call the Hurricane+Plus. However, it has taken us two years of constant tweaking and modifying to get the exact same shape and design to where we could equal the power producing results of the hand made models. The changes are very subtle and it is very difficult to even visually see what is different.
The new Hurricane+Plus is intended for small block Chevy engines up to about 400 cubic inches. Also, when directly compared to a standard Hurricane, the main improvements will occur over 7,000 rpm. In numerous dyno tests, we have seen anywhere from 12 to 20 horsepower increase over the standard Hurricane. These differences were due to variations in component combinations in the different engines used for testing.