Dyno Testing Naturally Aspirated Two-Valve Performance - Modular Revolutions
It's Time To Dig Into The Naturally Aspirated Side Of Two-Valve Performance-So AFM Spun The Dyno Rollers, And We're Here To Tell The Tale
From the November, 2009 issue of 5.0 Mustang & Super Fords
By Steve Turner
Photography by Courtesy of Anderson Ford Motorsport
Horse Sense: Modular GTs have come a long way since 1996, but considering the 4.6 debuted in the Crown Vic in 1991, it's taken the aftermarket quite a long time to get excited about modular performance. Of course, most of that blame should be shouldered by the asthmatic, 215hp Two-Valves found in the '96-'98 GTs. Those certainly slowed down the excitement. Since 1999, however, these babies have been cranking out 260 horses, and it's time to get with it.
Rick Anderson finally decided...
Rick Anderson finally decided to get serious about 4.6 performance, so he needed to buy a car to use as a test mule. He headed out to the used-car auction and scored an '00 GT with only 37,000 miles. It has more mileage on it these days, primarily courtesy of Rick's DynoJet rollers, and it also sports some slick Bogart wheels to separate it from the crowd. When we began, this car was bone stock, right down to the stock paper filter and factory mufflers. The only modification along for the ride during the whole test was an Autologic chip ($299), used simply to raise the factory rev limiter-not for tuning-as Rick wanted to test parts, not tune-ups.
It's about time. Yeah, we know, we've had it too good for too long with the 5.0, so that meant there was less pressure to become aggressive with 4.6 performance. But there's more to life than power adders (and, believe us, we love power adders). Naturally aspirated performance is the cornerstone of making power. Once you can make power without boost or juice, you can make even more when you add either to the mix.
So why has it taken us a while to really explore naturally aspirated performance? Well, there's the aforementioned success of the 5.0, but there have also been a few parts missing from the mix-noticeably, intakes and camshafts. In 2003 that all changed, as cams began coming out of the woodwork, and the intakes were starting development outside the confines of the Blue Oval. Meanwhile, people were still busy pushing the 5.0 envelope, where the edge seems to get farther away every day. So it was just easier to add a blower, some bolt-ons, and a chip and go have some modular fun.
How would you like to own...
How would you like to own K&N Engineering? It sells the one product that everyone puts in their performance car first-the K&N air filter. These filters capture dirt in the air with a pleated cotton mesh caged in a wire mesh, and coated in dirt-grabbing oil. In the process, the filters allow more air into your engine, allowing it to make more power. We've seen this filter many times on 5.0 machines, and it proved itself again on Rick's stock 4.6, with 3 hp and 3 lb-ft at the peaks. The direct-replacement filter for the modern 4.6 will set you back $48. Removing the factory snorkel didn't help on the dyno, but Rick says that may change when going down the track.
Additionally, modular engines are perceived as newer and more complex, just as EFI was back in 1986. The new voodoo always keeps the skittish away for a while, until they figure out the black cat can actually be friendly if you treat it right. So more and more every day, the Ford aftermarket is getting the modular cat to purr. And when Rick Anderson of Anderson Ford Motorsport called us, we knew the timing was perfect. Rick was about to embark on one of his dyno learning missions, but this time it wasn't a blower 5.0 or high-rpm 347. This time Rick wanted to finally see what kind of potential was locked up in these modular engines. He bought an '00 GT to thrash on, and we were excited to go along for the ride.
Longtime readers know we often peer over Rick's shoulder while he spins the dyno rollers. Rick is the kind of guy who's happy to spend his off-hours and weekends trying parts, tuning, and just plain experimenting to find more power from our beloved Fords. Back in the day, I got this wild idea to do a blower test and flew out to the cornfields of Illinois to see the whole process. Eventually, Rick got smart, bought a camera, and now he doesn't have to see me every day for a week.
Obviously, we have great confidence in Rick's consistency and numbers, but if you're skeptical of his tests-particularly on his AFM parts-we wouldn't blame you. Just keep in mind Rick is keenly aware there's a dyno on every street corner these days, and if parts don't work as advertised, he's just one message-board post away from a black eye. That's why he does all this testing-to make sure the parts he sells works the way he says they do.
As we all know by now, moving...
As we all know by now, moving more air through the engine usually begins at either end. After uncorking the air-inlet system with the K&N filter, Rick's next step was to add a Bx Performance after-cat system. Talk about paying instant dividends. Meeting those federal noise limits must require a fairly restrictive factory muffler. The Bx systems added almost 10 hp and a whopping 15.3 lb-ft of torque at the peaks versus the K&N filter pull. Better yet, the after-cat allowed the 4.6 to make more power and torque throughout the powerband, justifying its $479 price tag.
We're car guys, right? So...
We're car guys, right? So if some is good, more must be better! If the after-cat was so worthwhile at this moderate power level, would opening the exhaust further multiply that result? Not exactly. While adding a Bx Performance off-road X-pipe improved power at the top of the tach-adding 5.1 hp-it did soften the bottom end. This has never bothered Rick, as he just gears his cars for torque. And we've seen it before, as X-pipes tend to bias toward higher rpm. Furthermore, removing the cats tends to eliminate backpressure, which does help torque to a point. So the Bx X-pipe ($249) might have looked better if added later in the test, but for the power levels we were aiming for, it was definitely a plus, and it sounds way cool.
We've tested many of these...
We've tested many of these parts in the past-particularly on 5.0 engines-and we've always had good luck with underdrive pulleys. So we were expecting a huge boost from the Auto Specialties pulleys here. Don't get us wrong, the pulleys made more power-2.3 ponies-at the peak, and pulled harder up top. However, they didn't give us the 10 hp or more we've seen on 5.0s. Rick says this is no fault of the pulleys; Ford has simply become more aggressive with its own pulley ratios to help power and fuel economy, so there's a less drastic change when adding underdrive pulleys. Of course, Rick is hoping to spin this engine 7,000 rpm and beyond. At that rpm, you definitely want underdrives to prevent overspinning your alternator and other drive accessories.
OK, 5.0s had puny 55mm mass...
OK, 5.0s had puny 55mm mass airs, but the modern 4.6 meters are 80 mm and larger on the Cobras. Why would Rick try a Pro-M mass air meter at this stage of the game? To begin with, he's seen how efficient the Pro-M 80mm meter is from an airflow standpoint. And, as the power grows on this engine, he knew he'd need to increase fuel-injector size, which would require a recalibrated meter. Sticking with the stock injectors, Rick added the Pro-M 80 ($299), and saw a nice boost throughout the powerband. The peaks jumped up 5.1 hp and 8.6 lb-ft of torque. It seems the factory meter and airbox are a little restrictive.
You gotta love Rick. He could...
You gotta love Rick. He could have added his beloved Power Pipe much later in the test to really make it look good, but he was confident it would help at this power level, and it did. While it wasn't like a shot of nitrous, the Power Pipe ($232.66) improved the numbers across the board, and stacked 2.5 hp and 1.3 lb-ft onto the peaks. If you aren't familiar with AFM Power Pipes, these are mandrel-bent inlet tubes designed to smooth and enlarge the inlet path. They are popular additions to superchargers, often yielding more boost, but Rick also has a selection of naturally aspirated parts as well.
Accufab's main man John Mihovetz...
Accufab's main man John Mihovetz told Rick flat out that his 70mm wouldn't do much combined with the restrictive, factory upper-intake elbow. Of course, Accufab now has a fancy, high-flow upper elbow, but we'll get to that in a minute. We figured most people would try just the 70mm throttle body ($225) to save a little cash. Well, not that Rick questioned him, but John was right on the money. The throttle body did a barely noticeable 0.7 hp at the peak, but power and torque were down until 4,500 rpm.