dougn

why was the plastic intake manifold on the post 91 964 considered better than the earily alum ones? are they dimensionally different?

GG Allin

My guess? Less weight, less money.

Geoffrey

The plastic manifold flows better and does not heat soak as much as the aluminum manifold

Indycam

More info on heat soak please . When / how does that come into play ? Restarts ?

Bill Verburg

Both of the above are good answers, Don't know that heat soak is the best description, the plastic is just a better insulator and will keep the intake charge cooler longer.

An additional bene is the more unifornm flow cylinder to cylinder w/ the plastic manifold.

Steven C.

My car has 95 993 plastic manifolds and MAS on it and it runs great. Don't know how much difference there is between the 964 and 993 plastic manifolds?

Steve

Bill Gregory

The plastic manifolds were originally used on the 964 Cup Cars, and then went into the production 964's. They save 1.2 kg of weight.

Gus

If the plastic madifold was / is better then why did they go back to the aluminum intake on the 993 ?

Red rooster

Try making a Varioram manifold from plastic ! The 95 993 had a plastic manifold.
All the best

Geoff