Horse Sense: Of course, we know about Trick Flow's cylinder heads and intake manifolds, but the company has also expanded into several other product lines. These include intake spacers, valve covers, cams, diff girdles, 4.6 intake elbows, and even nitrous kits.
Three inches of runner length...
Three inches of runner length is the key feature of Trick Flow's new High Flow Intake Manifold. It really shows here in this upside-down view of the assembly, along with the 90mm throttle body opening. Total runner length with this upper and an R-Series lower intake manifold is 9 inches on a 302 and 10.3 inches on a 351.
The idea behind these intakes was simple. By reducing the long upper intake runners to mere stubs and fitting a blimp-hangar-like plenum area, screaming top-end power would result. True, their designers realized, torque and midrange power would be greatly reduced, but with unheard-of top-end power, the "box uppers" would make up for their missing torque with gears and top-end horsepower. These intakes were never designed for bolt-on-type cars that absolutely require runner length for reasonable torque in the real world. In fact, their application was mainly intended for supercharged drag engines where blower boost would make the day starting in the midrange.
You'll notice you don't see many of these early box intakes around today. We could be trite and say they didn't work, but that's only a half-truth. The thinking behind the box intakes was sound, but the execution always left insufficient runner length for the street. The result was a near total loss of low-end torque, enough so that the top-end power bonanza wasn't enough to make up the lack of low-end power.Keep in mind the early box intakes were designed for the stock or GT-40 intakes. The straw-runnered stocker was a nonstarter in this category, and even the otherwise great GT-40 didn't have large enough or straight enough runners to be a top-end star. But that's what was available in the early years.
Furthermore, enthusiasts insisted on bolting the boxes to bolt-on cars or mildly boosted street drivers with predictable results. The bad mouthing from these ill-advised, dissatisfied street stormers didn't help. Yet another factor was the lack of cubic inches. Early on, the 5.0 phenomenon was a 302ci party. The 347s were still in the future, and while a few souls had transplanted 351 Windsors into their Foxes, the widespread use of 392s and 408s was also years away.One place where the box intakes did well was on forced-induction cars at the dragstrip. There the combination of steep final drive gears, a duty cycle comprised solely of high rpm, and-most importantly-a big supercharger positively cramming the intake full of air ensured sparkling top-end performance and enough midrange to make a go of it.
 Looking inside the production...  Looking inside the production High Flow Intake Manifold plenum shows all sorts of good airflow features. The runners are evenly spaced and given straight runs to the lower intake manifold, and the air entry into the runners is smoothed and raised off the plenum floor. The O-ring seal between the upper and lower plenum castings is supplied by Trick Flow. A long section is provided, which easily lays into the groove, and then is trimmed to fit. The two-piece upper makes port-matching the upper to the lower a cinch. |  |  On the discharge end of the...  On the discharge end of the runners, the staggered rectangle spacing is apparent, along with the recessed mounting hardware between the lower casting and the billet flange adapter. The upper intake mates with either the R-Series 302 or 351 Trick Flow lower intakes. |