We can well remember the introduction of the new 4.6 modular motors in the Mustangs in 1996. Being die-hard 5-liter Ford fans, we were concerned about Ford's decision to abandon the little small-block that had served it so well since its inception back in 1962.
Ford offered the new 4.6 versions with two distinct powerplants. Though both shared the same displacement, the wilder SVT Cobra version had an aluminum block and was topped with free-flowing aluminum cylinder heads that featured double overhead cams and four valves per cylinder. The powerful and more expensive SVT Cobra was obviously the most desirable, but the vast majority of V-8 Mustang buyers opted for the GT.
These folks got a milder SOHC engine that featured just two valves per cylinder. The overhead cam configuration promised plenty of rpm potential, but unfortunately the mild Two-Valve modular never fulfilled that promise. In fact, the original Two-Valve 4.6 was less a revver than the pushrod 5.0 H.O. The maximum torque production came near 3,500 rpm-something that helped provide the motor with the illusion of performance, but things quickly went flat as the tach needle swept passed 4,400. Rated at 215 hp, the buying public reacted accordingly, and Mustang sales went in the toilet.
With the lowest power rating of all the available 4.6 Mustangs, the '96 (and '97) GT is unquestionably the redheaded stepchild of the modular engine family. Always seeing the glass half full here at MM&FF, we decided on a new project. While the '96 GT is certainly low man on the performance totem pole, there is a plus side to the lack of desirability-cost. Unlike the later PI motors or even the '97-'98 versions, a '96 Mustang GT can be had for a song. Our '96 five-speed GT was purchased for the paltry sum of $4,000 (from the original owner, no less). While the 260hp PI-motored Mustangs may offer better performance in stock trim, just how long do you think you will leave the new project stock?
The idea is to demonstrate that there is power to be had from the early non-PI motors (and Mustangs in general), even without resorting to the usual '99-up head and intake upgrade. We hope to take the non-PI motor (sans anything resembling PI components) to 300 rwhp in normally aspirated (pump-gas streetable) trim. After that, we may turn to PI upgrades but will certainly go for forced induction (we already got waxed by an LS1 Firebird). With power taken care of, look for a full suspension upgrade, big brakes, and maybe even a body kit. Given the lack of desirability of our Laser Red Mustang, we decided the ideal name for her was Project Redheaded Step Child (RSC).
RSC was purchased in stock trim. The '96 Mustang GT sported a five-speed tranny and nearly 200,000 miles. The original owner commuted nearly 140 miles per day to and from work. A discussion during purchasing revealed that the tremendous mileage logged on the freeway allowed him to use the original brake pads for 94,000 miles. He said he needed to stop only five times from his house to the freeway; the rest of the time was spent with the cruise control set at 70 mph.
The first step toward our normally aspirated performance goal of 300 rwhp was to install a few minor modifications. These basics are popular due to their price and ease of installation, but as we found out, the stock motor was not really airflow restricted-a fact we hope to change once we improve the power output with wilder cam timing, ported (non-PI) heads, and long-tube headers.
The list of performance upgrades for this go-round included a mass air meter and filter from C&L. C&L also supplied a cast-aluminum intake tube (from the MAF to the throttle body) to replace the corrugated rubber production hose. C&L was nice enough to include one of its upper intake (elbows) while Accufab supplied the matching 75mm throttle body. We know from testing that the throttle body and elbow are usually worth power on the later PI motors (especially modified ones), but would the stock non-PI motor take advantage of the extra airflow?
Before tearing into the motor...
Before tearing into the motor with reckless abandon, we thought it would be a good idea to start with a few basic bolt-ons. Our eventual goal for Project Redheaded Step Child is 300 rwhp from a non-PI engine, and these minor mods are the first step toward reaching that goal.
C&L supplied this mass air...
C&L supplied this mass air meter and filter assembly for our '96 GT. Not shown is the filter shroud designed to shelter the filter from engine heat, forcing it to draw ambient air from the fenderwell.
C&L also supplied this cast-aluminum...
C&L also supplied this cast-aluminum air-intake tube designed for installation between the MAF and throttle body.
The final performance product...
The final performance product supplied by C&L was this upper intake, or inlet elbow. The C&L inlet elbow easily outflowed the stock unit, but the real question was whether our stock 4.6 could take advantage of all that extra airflow.
C&L recommended a 75mm Accufab...
C&L recommended a 75mm Accufab throttle body to feed the inlet elbow. We had excellent results with this combination in previous testing on wilder combinations.
The gains offered by the BBK...
The gains offered by the BBK underdrive pulleys increased with engine speed. Like the throttle body and intake, the pulleys offered 6-7 hp past 5,000 rpm.
BBK stepped up with a three-piece underdrive pulley system to replace the crank, water pump, and alternator pulleys, while we relied on Steve Rideout from Powertrain Dynamics to custom tune the finished combination.
The first order of business was to test the 200,000-mile wonder on the chassis dyno to see if it was still in decent working order. Project RSC was strapped to the Dynojet, and we anxiously awaited the power numbers. Unfortunately, we had to abort the initial run as the air/fuel meter indicated the WOT mixture was excessively lean (over 15.0:1). Knowing the motor had plenty of miles, Rideout checked the MAF element and found it to be dirty (a common problem). Some brake cleaner cured the problem, and we were back in business.
The first dyno runs on the...
The first dyno runs on the DynoJet indicated that the air/fuel mixture on the stock non-PI motor was dangerously lean. The culprit turned out to be a dirty MAF element.
The stock engine was run once again, and we were quite surprised when we saw it produce 195 rwhp. The air/fuel curve started out at 13.5:1 at 2,000 rpm and tapered down below 12.0:1 at 5,500 rpm. There would obviously be some power to be had from tuning the air/fuel curve, but that would have to wait until the remainder of the bolt-ons were run.
With backup runs confirming our stock power output, we installed the C&L MAF, air filter, and aluminum intake tube. Though we have had success testing the C&L components in the past, the stock motor simply did not respond to the airflow and minor air/fuel changes-fairly typical of other '96 4.6s MM&FF has tested. The C&L components seemed to offer a few horsepower past 5,000 rpm, but 1-2 hp can simply be the difference experienced run to run.
Next up was the C&L upper intake (elbow) and Accufab 75mm throttle body. In terms of ease of installation, the throttle body and elbow ranked right near the top. Unfortunately, the peak-to-peak power gains were only minimal (2 hp), but out near redline (past 5,000 rpm) the induction upgrade improved the power output by as much as 7 hp. It should be noted that we removed the C&L MAF and intake tube and replaced them with the factory components before continuing. All subsequent runs were made with the stock MAF and inlet components.
The BBK underdrive pulleys reduced the parasitic losses associated with driving the accessories by reducing the speed of all the accessories with a smaller crank pulley. The gains offered by the system were further improved by increasing the size of the alternator and water pump pulleys. Equipped with the BBK underdrive pulleys, we managed to exceed 200-wheel horsepower while the power gains increased with engine speed. Near 5,500 rpm, the BBK underdrive pulleys offered 6-7 extra horsepower.
The final modification was to have Powertrain Dynamics burn a custom chip. By altering the timing and fuel curves (that is really all there is to tuning), Rideout was able to up the power output of Project RSC by as much as 6-7 hp and 14-15 lb-ft of torque. We left the dyno producing 209 hp and 286 lb-ft of torque.
The factory MAF electronics...
The factory MAF electronics were removed for use in the new C&L meter.
The wimpy stock motor just...
The wimpy stock motor just couldn't take advantage of the extra airflow offered by the C&L MAF and aluminum inlet tube. We will put these to better use after a few more serious modifications.
Once the new chip was cleaned,...
Once the new chip was cleaned, we plugged it in and were rewarded with as much as 7-8 hp and 14-15 lb-ft of torque.
Clean Stock MAF Element
The first thing we noticed after installing Project RSC on the chassis dyno was that the air/fuel mixture was excessively lean, despite running with all stock components. The high-mileage (just under 200,000) car was serviced regularly and seemed to be in good condition. We aborted the first run due to the air/fuel mixture exceeding 15.5:1. The culprit turned out to be a dirty MAF element (the hot wire). Cleaning with brake cleaner cured the issue, and the result was just over 195 wheel horsepower with the typical decreasing air/fuel ratio.
Stock MAF/Air Filter and Inlet vS. C&L
First up was a C&L MAF and aluminum intake tube to replace the factory components. Though the C&L MAF (with factory electronics) and matching intake tube (from the MAF to the throttle body) outflowed the factory components, the dyno indicated that the stock components were more than able to support the airflow needs of the anemic engine. The C&L components did lean out the mixture slightly (13.3:1 versus 13.0:1) but the stock components actually produced the best power curve up to 3,800 rpm. Past 5,000 rpm, the C&L components may have been worth a few ponies, but the difference was negligible. We know from prior testing that the C&L inlet system will pay larger dividends once we have modified the motor with cams, ported heads, and a new intake.
Stock Throttle Body and Inlet Elbow vS. C&L
One of the most popular performance upgrades for the 4.6 engine has to be the throttle body and inlet elbow (often called an upper intake). Some of the popularity has to do with the ease of installation, but testing has shown that upgrading the stock components with aftermarket systems can be worth significant power gains on modified motors. Unfortunately, the flow needs of our stock non-PI motor did not exceed those of the stock throttle body and elbow, as upgrading the stock components with a C&L elbow and Accufab 75mm throttle body showed virtually no gains in peak power. The additional airflow did make itself known by adding as much as 6-7 hp at near 5,500 rpm.
Stock vs. BBK UnderDrive Pulleys
Underdrive pulley systems have been a mainstay of the aftermarket since the introduction of the serpentine belt. This power absorbed by the accessories is power not produced for acceleration. Underdrive pulleys are used to decrease the speed of the accessories, thereby decreasing the amount of power required to drive them. We installed a set of pulleys from BBK. The kit included a smaller crank pulley (which decreases the speed of all of the remaining accessories) as well as larger water pump and alternator pulleys. The combination of these parts allowed us to retain the factory belt size. As we have come to expect, the power gains offered by the BBK underdrive pulleys increased with engine speed. Though the peak power was up only 2 hp, past 4,500 rpm the BBK pulleys offered as much as 6-7 hp.
Stock vs. PowerTrain Custom Chip
Using Chip Master Revolution software, Steve Rideout from Powertrain Dynamics dialed in our fuel and timing curves to maximize (pump gas) power. His years of experience tuning Mustangs showed as he nailed the tune for Project RSC on the first attempt. Using the Powertrain Dynamics chip, we were able to produce 209 hp at the wheels and 286 lb-ft of torque.