Muscle Mustangs & Fast FordsHow To Engine
We Spent $22 per Pound and Got 35 Extra Pound-Feet of Torque
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If you're reading Muscle Mustangs & Fast Fords magazine, it's likely you're after an increase in power for your pony or other beloved Ford. Whether you own a time-honored 5-liter, a 4.6 Mod machine, or any other Ford or Mercury product, there's a way to add power to increase the fun of driving. In the last few years Ford has delivered a fun product, albeit one that's a little harder for gearheads to extract extra power from.
In 1999, Ford itself hopped up the 4.6 SOHC, which is now capable of getting a stock 5-speed GT into the 13s, despite only having a little 281-incher under the hood. In stock form it makes 260 horsepower and 302 lb.-ft. of torque, which is 20 horsepower better than the best EFI 5-liter94-95 Cobra).
Nevertheless, Mustang owners are always looking for more. In fact, we've received dozens of letters and e-mails asking how to get a few extra ponies from these Modular engines. You could add nitrous, a blower or a turbo kit, but most owners want to start with the basics. You know, the bolt-on parts that install quickly and don't cost too much.
But the term "bolt-on" is pretty vague these days. That's because just about everything you can buy, including nitrous and superchargers, simply bolts on. Today's parts are engineered so well that they do not drastically alter the stock configuration, and in most cases you can install the parts and be back on the road in a few hours.
Thankfully, "simple" bolt-on parts exist for the latest breed of ponycar. We wanted to find out what the effects of simple bolt-ons were on a 2001 GT so we rounded up the usual stuff and set off to do some dyno testing.
Our list of components included Steeda underdrive pulleys, a Steeda Timing Adjuster, a C&L 80mm meter with K&N filter, and a 70mm throttle body, which we received from Downs Ford in Toms River, N.J. The test vehicle was an '01 GT with an automatic--even the air intake silencer was in place (notice we said "was"). The odometer showed 7000 miles, so the 4.6 was broken in.
As with any test, we first had to establish a baseline. The car was strapped down to the DynoJet chassis dynamometer at Crazy Horse Racing (South Amboy, N.J.) and the engine was warmed up to 170 degrees, as noted by the Snap-On vehicle scan tool. Using the scan tool allowed us to monitor ECT (engine coolant temperature) so we could begin each dyno pull at the same temperature and eliminate a potential variable.
The first pull was smooth and the stock 281 pumped out a respectable 219.1 horsepower at 5200 rpm, and 265.6 lbs.-ft. of torque at 3300 rpm. We backed this up with a run of 218 horsepower and a torque reading of 263 lbs.-ft. And if we figured in a loss of 18 percent through the powertrain, we come up with the advertised 260 horsepower and a slightly larger torque number of 312, which is close to the advertised figure of 302.
An important note is that the engine was pulled from 2500 rpm to 6000 rpm. In addition to peak numbers, we also took a close look at average horsepower--that was 183, while torque was 220. This is significant because a higher average is far more important than just a higher peak, since the engine does not stay at one particular rpm during a run. As you digest the information in this (or any other story) pay close attention to the average power, not just the peak, because it shows a bigger part of the picture.
Every racer knows that free horsepower is the best kind of power, so we decided to pull apart the air filter box and remove the rubber air intake silencer. The purpose of the silencer is to draw in air from the inner fender and direct it into the plastic filter box. The rubber silencer has a funneled opening to improve flow, but the opening is small and removing it opens up a larger hole in the plastic filter box for the engine to breathe through.Best of all, removing the silencer is as simple as removing the box and prying the rubber silencer away with your hands. We did just that, and then we replaced the filter box, still using the stock filter.
And as expected, removing the silencer worked, increasing power to 223.6 from 219, while peak torque fell a hair to 263 lbs.-ft. However, average power climbed to 184.8 horsepower and the torque average also climbed to 223.5 lbs.-ft., even though the peak was down. An added bonus was that we could now hear a big whoosh of air as it rushed into the 4.6 mill and it sounded good.
Throw It Into Underdrive
The first of the aftermarket parts to be installed was the Steeda underdrive pulley kit. The kit includes an SFI crankshaft pulley, water pump pulley and alternator pulley. The reason underdrive pulleys add power is that they reduce parasitic drag on the engine. Drag, or friction, is created by engine accessories and by slowing the speed of the accessory drive belt, the accessories spin slower, thus reducing friction or parasitic drag. The result is usually increased power to the wheels.
While it's possible to install the pulleys with the vehicle on the ground, we elected to put the Mustang on a lift so we could also install the Steeda Timing Adjuster and save a little time. It's important to note that the timing adjuster was set to 10 degrees, (which is the stock timing setting), so we could first test the pulleys.
Our first pull with the pulleys and the timing adjuster showed no increase in power, so we placed a call to Steeda to see if we may have done something wrong. We learned that despite setting the timing adjuster to the stock position of 10 degrees, the engine may not have actually been at 10 degrees. Dan Carlson of Steeda explained that because the timing adjuster relocates the pick-up sensor, it may be a degree off, even if the placement of the timing adjuster is set to 10 degrees. Therefore, we may have actually backed the timing off to 9 degrees BTDC. To remedy this we added one degree of timing and tested again.
This time we noticed a gain of three horsepower, but even more impressively, torque jumped to 275 lbs.-ft., for a gain of 12 lbs.-ft. And while we did not find a huge gain in average horsepower, our torque average rocketed from 223.5 to 232 lbs.-ft.
Timing Is Everything
Our next move was to cool the engine, bump the timing and try again. We decided that four degrees would be a good starting point so the adjuster was moved from the mark of 11 degrees to the 15-degree position and the result was awesome. The GT now produced 229.9 horsepower, a gain of six, but once again torque rocketed, this time up to 290 lbs.-ft., for a gain of almost 15 lbs.-ft.
If some timing advance was good, then more is better, right? Wrong. We added two more degrees (17 total), but the engine detonated during the pull and we aborted. As you can guess, we turned the adjuster back to 15, the point where we made maximum power.
We concluded this part of the test with a new total gain of 10 horsepower and 25 lbs.-ft. of torque and an average of 190 horsepower and 239 lbs.-ft. of torque.
Next up to the plate was the 80mm C&L meter. The meter was probably the easiest and quickest of all the parts to install. All we needed was a flat-head screwdriver, a 1/4-inch nut driver and a small Allen key to get the job done.
The C&L meter measures 80mm across and it has no restrictions except for the sample tube, which channels the airflow over the sensor wires. While the stock Ford meter also measures 80mm, flow is impeded by a wide restriction that runs across the meter. Before installing the new meter, you must remove your old meter and unscrew the 4-wire sensor. We recommend that you handle this with care, so as not to damage the sensor. When installing the sensor in the C&L meter be certain that the rubber O-ring seats perfectly into the meter. If not, an air leak will result and the engine will run poorly.
With the C&L screwed down, we got the engine back to 170 degrees and followed our normal testing routine. And again, we noticed a gain. The little 4.6 was becoming more and more efficient and now horsepower was up to 237.5 and torque was up to 292 lbs.-ft. As you may have guessed, the average was also up to 193 and 246 respectively.
Last on our list of bolt-ons was the 70mm throttle body. The stock unit measures 65mm and if our 4.6 was starving for air then a larger throttle body would certainly help. Like the C&L meter, the throttle body was also easy to install, taking only a few minutes of our time.
To install the 70mm throttle body it is necessary to disconnect the throttle cable, throttle return spring, along with the TPS wire. Next, you'll have to remove the four retaining bolts, and the stock throttle body can be taken off.
I'll admit it, I didn't have a load of confidence in the larger throttle body, namely because big throttle bodies never showed big gains on similarly modified 5-liter engines. But this was no 5-liter so we let the numbers speak for themselves.
Once again, we got the test temperature to 170 and we spooled up the roller on the dyno, running the engine from 2500 rpm to redline (just over 6000 rpm). The GT spoke loudly again, shooting out a peak of 238.5 horsepower and a whopping 300 lbs.-ft. of torque. Average power reached a peak of 202 and torque finished with an average of 250 lbs.-ft.
Testing parts and finding the results is one of the best parts of this job. Thankfully, with the advent of the chassis dyno, we can do valid testing both at the track, and in many shops across the country. Hopefully you found our tests entertaining and educational, all of which will help you to make vital decisions on the parts you buy.
In this exercise we did some simple things including improving airflow, reducing parasitic drag and increasing the spark advance of the 4.6. Based on the results, we got more air into the engine and that's one reason the 4.6 developed more power. This is especially noted in the mid-rpm range, because torque jumped up by 35 lbs.-ft. at the peak and 30 lbs.-ft. across the entire rev range.
Likewise, we picked up almost 20 horsepower at the peak and virtually the same on the average, from 2500-6000 rpm.
Best of all, driveability was not compromised and we can't wait to see what this GT will do on the strip. In the coming months, we'll continue this exercise in airflow by testing a couple of exhaust systems on this GT. We'll also get to the track and see how the dyno numbers translate into elapsed time.Then we'll add some new gears, sticky tires and see just how fast this pony can run, still with a stock engine and no power adders.