Richard Holdener
December 13, 2006
Having logged over 200,000 miles, Project RSC received a bit of much needed TLC in the form of some high-performance/maintenance items.

Last month in Part 1 of Project RSC, we treated our '96 Mustang GT just like a red-headed stepchild, yanking it fresh from the orphanage and plunking it on the dyno without care or concern for its well being. The proverbial competitive father, we expected our child to rush out and hit home runs, score touchdowns, and win races, all without so much as a decent warm-up. Hardly the makings of a good parent!

I have to take the blame for this one. Being in an all-fired-out hurry to demonstrate the worth of the neglected mod motor, I forgot that this car has delivered some 200,000 miles of faithful service. It's all I can do to stop from turning myself into child services. But as adults we learn from our mistakes, so we take a step backward in part here by providing RSC with some much needed TLC in the form of maintenance items. In fact, some components even cross the line between maintenance and high performance (we here at MM&FF always plan ahead).

While the 4.6 Two-Valve was performing admirably, we decided to give the motor a quick once over. First up was a compression check. We also took a look at the color and condition of the oil, but since it was due for a change, we opted to step up to a synthetic blend (our boy deserved nothing but the best).

First on the list were the factory fuel injectors. The injectors were first flow tested and then treated to an ultrasonic cleaning on this ASNU injector machine. Injector cleaning is usually only necessary if the engine (or injectors) sits for an extended period of time. Ours were actually still in good shape with no leakage or unusual flow patterns.

The compression check was performed by removing all the spark plugs (something already on the to-change list) and inserting the compression tube down in the plug hole. We also took the liberty of disconnecting the injectors to eliminate fuel flow to the cylinder during cranking. With the throttle held open, we cranked over the motor using the starter eight or nine times in a row. The compression gauge was used to determine how well the cylinders were sealing (though a leakdown is more accurate).

Since a number of factors contribute to actual reading (static compression, cam timing, and ring/valve seal), what you are looking for is consistent readings from all cylinders. It is not uncommon for all the cylinders in the right bank to produce one number and all the cylinders in the left bank to produce another. This is an indication that the cam timing is off side to side. Our compression test revealed the motor was still plenty peppy (but by no means excessively powerful), with readings of 125 psi per cylinder.

With a seemingly healthy candidate (we expected as much given the dyno numbers from last issue), we turned our attention to the fuel system. Because of the excessive mileage, we decided to check the injectors for leakage and/or clogs. In most cases, injector problems are caused not by excessive use but rather by lack of use. Injectors sitting idle (filled with fuel) for extended periods allow deposits to form. These deposits can clog, alter the spray pattern or stop the pintle from sealing, causing the injector to leak when fully closed.

While we had the injectors and rail off, we installed this Accufab adjustable fuel-pressure regulator. Though tuning is best performed via the computer (through a custom chip), it is possible to adjust the fuel pressure to make global changes. This may come in handy during our test sessions when we don't have the ability to change the program.

The injectors were removed along with the fuel rail for installation onto the ASNU injector cleaning/flow test machine. The first order of business was to test the injectors for leaks, which was a simple matter of hooking up the injectors and applying pressure. The injectors all checked out perfectly. Next, we flow tested all eight injectors to both verify the flow rates and measure the flow balance between them. Ideally, all the injectors flow exactly the rated amount (19 lb/hr). Excessive or insufficient flow from one injector can play havoc on the air/fuel, as the computer will adjust by leaning out or richening up the mixture. Having seven cylinders suffer for the misgivings of one is obviously not good for performance. Thankfully, all the injectors from RSC received a clean bill of health.

Before reinstalling the stock injectors, we took the liberty of replacing the factory (non-adjustable) fuel-pressure regulator with an adjustable unit from Accufab. While proper tuning is best accomplished via the programming (a custom chip), the adjustable fuel-pressure regulator may come in handy if we are testing a component(s) and do not have access to programming. Of course, the Accufab adjustable fuel-pressure regulator will only allow us to make global changes in the air/fuel mixture, as we can't change the air/fuel at predetermined rpm points, only a broad change throughout the rpm range. Still, it is nice to have the ability to richen up the mixture even if only temporarily until we can employ the SCT tuning software. For now, the fuel pressure was set at the factory pressure reading of 43 psi.

Along with the new spark plugs, we also installed a fresh set of 8.5mm Super Conductor performance plug wires from MSD (PN 32229).

The final fuel-related component to be serviced was the fuel filter. We have no idea how long the current filter has been in service, so we opted to change it to eliminate any future problems. We plan on upgrading the fuel pump at a later date (with a Holley 255-lph unit), but the stock pump will suffice for now.

With our spark plugs removed for the compression check, we naturally replaced them with a fresh set. Normally we would simply put in a new set of factory replacement plugs and be done with it, but we decided to kick things up a notch. In this case, that meant a set of Denso Iridium plugs (IQ16s). We have always had excellent results with these plugs, especially on forced induction applications. Though they are probably overkill for this near-stock early Two-Valve application, they will be put to good use at a later date. We gapped the precious metal plugs at 0.045 (take care to not damage the ultra-fine electrode).

We gapped the Denso Iridium plugs to 0.045. We will likely be closing the gap once we install a blower or turbo, but for now, the large gap provides plenty of spark energy to ignite our mild mixture.

With our attention focused on the ignition system, we replaced the spark plug wires with a set from MSD. The 8.5mm Super Conductor plug wires offered a combination of low resistance, high EMI suppression, and a tough silicone sleeve for maximum heat protection. In addition to the Super Conductor wires, MSD also came through with a set of new high-performance coil packs. Having already tested the effectiveness of the coil packs up to 1,400 hp, we had every confidence installing them on the mild '96 4.6. We will probably include an ignition ampli-fier once the powerplant is subjected to boost, but for now, we should have plenty of spark energy.

In Part 1, we installed a set of BBK underdrive pulleys. One thing we noticed during the installation was that the factory serpentine belt had more than its fair share of surface cracks. Serpentine belts are one of the marvels of a modern mod motor, but the last thing you want to do is have the one belt that drives all your accessories (including the all-important water pump) check out on you. Can you say stranded? To put our fears to rest, the questionable drivebelt was replaced with a new Dayco unit (PN 5060975).

With our days getting warmer, we decided it was a good time to replace the factory 192-degree thermostat with a cooler 180-degree unit. Think about it-your motor will make more power with the coolant temperature at 180 degrees than 192 degrees. The 180-degree thermostat will allow your motor to run as much as 12 degrees cooler, since the minimum operating temp is determined by the thermostat. Testing back-to-back shows that the 12-degree drop can be worth 4-6 hp at the wheels. We will always welcome an extra 4-6 hp on the street. Though the temptation is there to go even lower (to something like 160 degrees), know that such a drop can keep the car in warm-up mode, where extra fuel is supplied-not good for daily driving.

The old coil packs were removed and replaced with the hot MSD units.

The final maintenance modification involved filling the crankcase with a fresh batch of synthetic oil. Lucas Oil supplied the necessary quarts of 5W-30 synthetic oil. Given the high mileage, we wanted to make sure the motor had plenty of lubrication. Synthetic oils dramatically decrease friction, absorb contaminants better, and offer a longer life between changing. This really shouldn't be a hard sell. High-performance motors deserve synthetic oil, and since we had every intention of transforming our near stocker into a real performance piece, why not start things off on the right foot? A new oil and filter should be on the to-do list every 3,000 miles (you can go longer between changes with synthetic, but I still try to stick with the 3K mark).

There you have it, Project RSC is now properly maintained and ready for some more dyno thrashing. Tops on the to-do list is a trip to MagnaFlow where we will install an X-pipe (with just two cats instead of the six that currently exist) and a new after-cat exhaust. After that, we plan on a set of Comp cams followed by a set of long-tube Hooker headers. Look for a new clutch, pressure plate, and flywheel system as well as ported (non-PI) heads and a new intake.

The 300hp mark is still a ways off, but stick with us, we'll get there-or someone's going back up for adoption.