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1993 Ford Mustang LX SSP Edelbrock Performer RPM II Install - The Strip Performer - Tech
We Picked Up 2 MPH And Shaved Over Two Tenths Off E.T.'S With Edelbrock's Performer RPM II On Our '93 SSP LX.
As a project progresses, it tends to take on a life of its own. This is exactly what has happened with our '93 LX SSP. From its early days of 14-second e.t.'s, it's sure come a long way to its current 11-second status. Meant to be an everyday driver with enough gusto for slaying Brand-X muscle, our coupe has stood up proudly as an all-around performer.
In the Oct. '10 issue, we installed a Zex nitrous system on our resident SSP coupe. On the dyno, the 125-shot translated into an 86 rwhp and 84 lb-ft of torque gain. Certainly a nice increase, but the dyno graph revealed that the output flat-lined at 5,000 rpm. Looking to free up power a bit higher in the rpm range, we called up Edelbrock for one of its Performer RPM II intake manifolds.
Designed with larger and shorter runners, the Performer RPM II (PN 71233) is engineered for optimal performance between 1,500 and 6,500 rpm. It will also clear our SSP's stock hood, and it just looks cleaner and meaner than our current Cobra intake. It even comes with a removable plate so we can port the runners if we want to later.
Best output prior was 344 rwhp and 361 lb-ft of torque on the Dynojet at Ramsey's Performance (Lutz, Florida). Since dropping the timing to 14 degrees to complement the nitrous, our LX's performance on the street was lacking, so we called Chris Johnson of SCT for some help. He showed up with an SCT multi-program switch chip for our EEC-IV ECM.
After maximizing power output both on and off the nitrous (without having to change the timing manually), we replaced the intake with the Edelbrock Performer RPM II. We also took this opportunity to readjust the rocker arms and replace the valve covers with matching black covers from Edelbrock.
As expected, we noticed a drop in lower-rpm power, but that was only when running NA. That's because the Edelbrock intake's larger runners were not as efficient as filling the cylinders down low, but it's a different story up high. In fact, the power was up by as much as 25 hp at 6,000 rpm! On the nitrous, power and torque were both up above 5,100 rpm, and our Performance Automatic torque converter was certainly going to help keep our coupe in its new higher power band on the track.
For our track test, we expected the best, but scorching heat and near 80 percent humidity kept the SSP from running to its potential. Once we let it cool in the staging lanes at Gainesville Raceway (back to ambient temperature of 96 degrees Fahrenheit), we opened the bottle and heated up the Mickey Thompson drag radials. The first hit yielded an e.t. of 11.55 at 117 mph-a best ever for the little coupe, and that was with our big front tires and the front antiroll bar connected. Unfortunately, mid-August heat and traction issues (due to our newly found power) prevented another 11-second timeslip, but we were satisfied with the results. Next time, we'll set up the LX a little better and we expect lower 11s to boot.
Though some power was lost down low, it wasn't enough to be noticeable on the street. As always, we'll continue to tweak our little coupe one story at a time, so check back next month to see what we've done. And if you have any suggestions for what we should do next, send an to firstname.lastname@example.org.
On The Chip
Once a staple of 5.0L tech, the "chip" (which plugs into the computer to re-tune the engine) has been all but forgotten. But that doesn't make its affordability and effectiveness any less desirable. SCT makes chips and tuning software for EEC-IV processors like ours, and it's a great way to get a little extra or do simple functions like raise the rpm limiter for not a lot of money. The chip itself (PN 6600) plugs directly into the ECM, is programmable with up to four different tunes, and retails for $269.
Chris Johnson of SCT showed up at MM&FF headquarters with the chip and selector switch (included), the programming software ($349), and a chip programmer. The programmer (PN 7500) is separate and costs $300. On our Dynojet at the Source Interlink Tech Center in Tampa, a baseline pull yielded 262 rwhp and 287 lb-ft of torque.
After disconnecting the battery to clear the ECM's adaptations, power increased to 265 hp and torque to 291 lb-ft. "As you drive the car on the street, the computer learns and adapts to the conditions," says Johnson. So when we disconnected the battery, the computer was reset to factory settings-and a 3 rwhp and 4 lb-ft increase resulted.
The next step was to burn the tunes to the chip. Johnson downloaded the tuning software onto our computer and began picking tunes for our application. A mild naturally aspirated tune is already burned to the chip, so Johnson modified another version of that same tune by retarding the timing to 14 degrees; he burned it to the chip as well.
Now we can get the best of our engine with maximized timing and with the flip of a switch, turn on our nitrous-friendly tune. As an added safety feature, Johnson raised the idle of our nitrous tune to 1,200 rpm, so we know that it is on just by how the car idles.
Next, Johnson disconnected the negative battery cable and removed the ECM from its home behind the right kick panel. He then removed the computer cover, cleaned the terminals on the port, and plugged in the chip. The switch comes with a long cable, which plugs into the chip for easy placement anywhere in or under the dash (or console).
On our street tune, we made another pull on the Dynojet, which resulted in 273 rwhp and 304 lb-ft of torque-an 8hp and 13 lb-ft increase.