At the risk of sounding very ignorant....what the hell is plenum? What is different about the crawford plenum vs. stock?

Thanks, i did a search but didnt find anything specifically explaining it. Just trying to learn here.

 

It is just the upper part of the intake manifold. The piece on top of the motor. The Crawford plenum is a cut and rewelded stock plenum that has shown very nice gains according to those who own them. Basically, they raised the front section of the plenum to allow more and more equal air flow to all cylinders. In addition to the Crawford, which has been out for some time now, a new version is coming out by Kinetix (lsdunique) that is made of "plastic" sort of like an LS1 intake manifold on the Vettes and F-Bodies. The claim is that the plastic molding process will allow a lower price and similar air delivery with less of an exterior change (the Crawford is too big to fit the stock strut tower bar). Should be the best of all worlds. Yet, it remains to be seen.