We're always talking about next-level performance for late-model Mustangs. Handling and engine-performance are the main points of focus, and typically, our mantra is the more, the better. This never- ending quest for performance has us always on the lookout for new products or methods of increasing-and-improving performance for '89-'13 Ponies.
In 2011, commissioning Coast High Performance to build a fuel-injected, 408ci Windsor with Trick Flow's new PowerPort 225cc Cleveland cylinder heads and R Series intake manifold (a Clevor engine) was one of the ideas we followed through on. Since that project's first report ("Hot In Cleveland," July '11), Greg Montoya nailed the hammer to the mat in our hard charge to learn more about the potential of this unique combination.
On this particular leg of the continued effort, we want to see the impact--negative or positive--of a simple intake- manifold swap on this Pony's unique bullet. This idea came about after Tech Editor KJ Jones and Gregg Changet at Trick Flow--although pleased with the Clevor's initial chassis-dyno results (432 hp/428 lb-ft without nitrous)--thought there was "a lot more power where that came from." We thought the Box R upper plenum intake manifold would be the best place to find it.
As we've explained in past reports, Trick Flow's Cleveland-style heads offer bigger valves, canted valve angles, large intake/slightly raised (0.100-inch) exhaust ports, and closed chambers. That makes them comparable to the Ford Aussie 2V and 4V heads of the '70s--heavy breathers that proved to be great performers on stroked engines.
Horse Sense: The dragstrip segment of this test, while successful, left us just on the edge of crossing one of the major performance plateaus for any regularly driven street/strip Mustang--the 10-second zone. Post-track investigation showed us that the clutch in Greg Montoya's '89 GT was thoroughly fragged, and it more than likely had been since our first runs on the chassis dyno. We're noting all this to reinforce how important it is to seat a new clutch before hammering a 'Stang on the chassis dyno or track. A new Centerforce Dyad will be backing up the 408 Clevor engine by the time you read this.
While Trick Flow's R-Series upper plenum definitely served our 408 Clevor well, we believe
Standing the plenums side-by-side, their runner differences are quickly discerned. Basical
Here is a close look at the interior layout of the Trick Flow Box R plenum, from the top a
Since air exits through a staggered runner arrangement on both R upper intakes, there's no
Unlike the R Series upper, fasteners for securing the Box R do not pass through any of its
Here is another example of the Box R's perfectly straight, 3-inch runner design (total run