4 in-line Intakes
This is what is commonly refered to as a 4 in-line manifold. it was standard on the 84 and early 85 (maybe) late 85. these are considered to be the less desirable intakes. as the runners are smaller than those on the 86 and every 2.3 manifold to follow.
4 Square Intakes
This is the more common and most favored 4 square style intake. The 86 svo was equipted with thiis style of intake however it did not have the 2.3 markings on it. it was a smooth serface. this is a shot of intakes off an 88 T-Bird Turbo Coupe. These intakes are often used as upgrades for early svo owners.
The 86 Intake
this 4 square intake was found in mid year 85.5 and 86 2.3T cars it is a very desirablt upper intake manifold as it does ont require a spacer to be made to clear the un-grooved valve cover. also when rotated forward it sits higher and makes it easier to clear the alt. for intercooler piping
Time To Rotate
When using a front mount intercooler, it is opinioned by some to cut and rotate the upper intake manifold 90-100 degrees. With the intake rotated it alows less piping to be used in routing the intercooler tubes. In theory the less the air has to travel and the straighter it travels the more efficient it becomes.
Compare the Runners
these are two unported intake manifolds. The 4 in-line and 4 square. see for yourself the 4 square has a slightly larger advantage.