The shape and position of the runners all but dictated a new fuel rail. This billet rail o
Not surprisingly, the 3.5-inch inlet tube eliminated any and all airflow restrictions. In retrospect, we should have replaced the factory mass air meter with the C&L unit we tested in Part 1. Given the power level, we suspect the factory meter was now the restriction in the inlet system. The inlet tube was fed by the same 75mm Accufab throttle body used on the stock intake. It should be noted that the VRI was tested against the stock intake using the Accufab throttle body and C&L plenum, which was worth considerable power compared to the stock throttle body and plenum at this power level. Thus the power gains offered by the VRI would have been even greater had we run them against the stock intake, throttle body and plenum. The 75mm throttle body was fed by a 3.5-inch inlet tube (positioned between the throttle body and MAF). The tube featured provisions for the PCV line from the driver-side valve cover and the IAC motor. The second PCV from the passenger's side cover was fed behind the throttle body.
The equalized runner length and cross section required a new fuel rail. The billet fuel rail (in prototype form) was configured to work with the stock 19-pound injectors. That this motor managed to exceed 300-wheel hp with just 19-pound injectors (and a stock pump) shows just how much power the stock stuff will handle. The custom fuel rail required an external (adjustable) fuel-pressure regulator, but a new design is in the works to allow use of the stock fuel rail and regulator. Note from the photos that alternator, thermostat housing, and ECT sensor are all intact. Having realized our goal of producing 300 wheel horsepower with a non-PI motor, we can now turn our attention to bigger and better things, namely forced induction. We enjoyed dealing with all the normally aspirated modifications, but the power available with boost has to be experienced to be believed. While we kicked and scratched to get a few horsepower here and there (and spent endless hours on a new intake design), these gains pale in comparison to those available with a simple pulley change on a Kenne Bell supercharger. It's amazing what a few extra pounds of boost will do for the power curve.
Now that we run the gamut of normally aspirated mods for the non-PI motor, we can step back and take a realistic look at the buildup. Was it difficult? Sure, coaxing this kind of power from the pathetic non-PI motor took every trick in the book. Was it worthwhile? Sure, it's always beneficial (certainly to the readers) to examine and (accurately) test the merits of different performance components. Would we recommend this route to our readers with '96-'98 Mustangs? Probably not, unless (like us) they are looking to prove a point. It would make much more sense (and power) to simply equip the engine bay with the later PI components, the most important of which would be the PI cylinder heads.
Even in ported form, the early non-PI heads simply do not flow as much as a well-done set of PI heads. The flow difference can be as much as 30-40 cfm per runner, especially since the later PI heads can be run with 0.550-lift (or greater) cams while the early heads must make do with 0.500-lift cams. Limiting the lift to just 0.500 is the same as limiting airflow since either head (in ported form) flows more at 0.550 than it does at 0.500. We would expect an easy 40-50 hp were this combination run with ported PI heads and attending cams instead of the non-PI stuff.
Power Train Dynamics
15628 Graham St.