Offenhauser is a good old school race manifold. Dual intake, if you get a double pumper with secondaries it's great for street/strip.
this is no good old school race manifold!!! edlebrock made a manifold called sp2p. this is the theory here... on the primary side very small port very high velocity lots of part throttle bottom end torque and response then a separate channel for secondary's so you still have the top end power of a good ole dual plain manifold. it has issues though. a lean primary channel and a rich secondary channel. most carbs are set up factory for good economy on the primary and make up for it on the secondary the power valve or enrichment system on the primary is not enough for full richness. it can be tuned and fixed but there goes the idea of good economy that you gain (the hole idea of this manifold)(although a good tuner can get both). with a rich channel and a lean channel the combustion chamber mix is horrible, especially with a chamber with very little squish and quench. end result a big sacrifice on top end power. some people say they like it. i say this... they spent time and had the knowledge or new someone that had the knowledge to work out the problems. or they went from a two barrel and even though there are issues the power was better thus satisfied. or maybe lucky and that even though a great thing don't happen very often, also the separation in the manifold is thick cutting the flow of the port by 25-30%, (fore sure not a power gainer)overall this manifold will probably help in the economy department and you will gain top end power over a two barrel so if that's all your after give it a try
