Well, it has been a long time coming-and believe us, it was no cakewalk-but Project Redheaded Step Child (a.k.a. our '96 Mustang GT) has officially cracked the 300hp barrier. A huge thanks goes out to all the companies that helped with the normally aspirated portion of the project, but especially Steve Ridout from Powertrain Dynamics. Ridout had to suffer through the endless testing performed during the development of my new intake manifold.
For the final round of dyno runs, he was kind enough to come back and reopen his shop after thinking he made it safely home without having to spend another moment with that damn red project car. Like a trooper, Ridout allowed yours truly to make those last few runs (naturally with tuning involved) to provide the necessary air/fuel and timing curves for the new non-PI combination. It was his dedication to the project (or maybe we just wore him down with all our begging) that allowed us to finally surpass the magical (and for some time seemingly unreachable) 300hp mark.
Before getting into the specifics of the new intake manifold that allowed our early non-PI motor to eclipse the 300hp mark, we should review what transpired to get us this far.
In Part 1, the modifications included a C&L plenum and 75mm throttle body. To that we added a set of BBK underdrive pulleys and a custom Powertrain tune, and were rewarded with gains of 14-15 hp.
Part 2 included just maintenance items (plugs, 180-degree thermostat and MSD ignition components), but we improved the power in Part 3 with a complete MagnaFlow after-cat exhaust and x pipe system (with cats). The exhaust mods showed gains of 15 hp, but things really got exciting after installing the XE262H Comp cams in Part 4. The cams allowed us to finally surpass the power output of a stock PI motor. After a complete Maximum Motorsports suspension upgrade in Part 5, we got crazy and swapped out the tired (200,000-mile) short-block for a fresh setup from Coast High Performance. Topped with a set of CNC-ported heads from Ford Performance Solutions and a set of even larger XE274H cams, the new combo brought us to roughly 275 rwhp. The nitrous upped that tem-porarily to 377 hp, but in all-engine trim, we were stuck in the 275-rwhp zone.
With nowhere else to turn in terms of viable street bolt on for our non-PI motor, I decided to take it upon myself to design a new intake for the early 4.6. With little else to choose from, I knew there was a great deal more power to be had from this combination with the right manifold. Previous testing on the engine dyno with a prototype unearthed a great deal of power, but now the trick was to get that combination to fit under the hood and be able to accept all the factory vacuum lines, EGR and IAC connections.
Not surprisingly, such an endeavor took some time. I can honestly say I have become an expert in the removal and replacement of the '96 intake system, having performed the task no fewer than 20 times during testing and development of the new intake. The design difficulty was not so much reaching a given power output, as eclipsing the 300hp mark would actually be easy on this combination. The real trick was managing to dramatically increase the peak power number without sacrificing all that wonderful low-speed torque production the factory intake had to offer. I'm a firm believer that losing power all the way up to 6,000 rpm is a poor trade-off for an extra 10 hp at the power peak (or beyond). Getting an intake design to provide a significant gain in peak power without sacrificing the low and midrange power is the real trick.
Making an intake to fit on...
Making an intake to fit on the engine dyno was a breeze, but making one to fit under the hood with all the factory components (vacuum lines, IAC and PCV) was somewhat more difficult.
Here's a shot of the pathetic,...
Here's a shot of the pathetic, stock non-PI intake. We can't wait to see it replaced with a twin-screw supercharger.
The VRI intake was equipped...
The VRI intake was equipped with the same 75mm throttle body used on the stock intake.
The VRI intake featured a...
The VRI intake featured a 3.5-inch inlet from the throttle body to minimize airflow restrictions. The large inlet was also used to enhance the plenum volume.
One of the performance tricks...
One of the performance tricks used to enhance the power offered by the VRI was to make sure all eight of the runners were identical in length and cross section.