Originally Posted by tuan

We have single plenum IM induction systems in which the the TB is horizontally mounted and the IM uses ram resonance theory to swirl fill the chamber. V8's use top vertically mounted TB's which tumble fill into their chambers. Adding extra length from a spacer would help a carbureted top load engine that has poor filling properties...like a V8. Unfortunately you can't extrapolate it to the type of induction we have since a the thickness of the spacer doesn't add enough length to the intake ram tube on a single plenum system to make a difference.