March 25, 2004

Step By Step

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0405mm_01z 2001_Ford_Mustang_GT Front_Side_Parked_Snow

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PI heads can be installed on either bank of the engine. There are provisions (on the front and back of the heads) for the hydraulic pistons that actuate the timing chain tensioners on the front and back of the heads. The pistons rely on oil pressure to apply pressure to the chain tensioners, therefore, you must block off the oil supply hole at the back of the heads to prevent an oil leak and loss of pressure.
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PI heads can be installed on either bank of the engine. There are provisions (on the front and back of the heads) for the hydraulic pistons that actuate the timing chain tensioners on the front and back of the heads. The pistons rely on oil pressure to apply pressure to the chain tensioners, therefore, you must block off the oil supply hole at the back of the heads to prevent an oil leak and loss of pressure.
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Next, the crankshaft was rotated so the keyway was straight up. This would ensure that none of the pistons were at TDC. This is not a problem since the cams were not installed, however, if the cams, lifters and finger followers were in the heads some of the valves would be hanging open and might hit the pistons since the engine would not be timed.
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Lacko inspected and cleaned the Patriot-ported PI truck heads then he placed the heads on the block.
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Bolting the heads on properly is critical to performance and longevity. To get a good torque reading, Lacko brushed ARP moly lube on the threads of the bolts. He also used the lube on the machined cups in the head where the bolts sit, along with both sides of each head bolt washer. The lube reduces friction and that allows you to get an accurate torque reading.
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Lacko torqued the heads using the following sequence: tighten to 30 lb-ft, then turn each bolt 90 degrees. Next, loosen each bolt one full turn and then tighten to 30 lb-ft. Lastly, turn each bolt 90 degrees, followed by another 90-degree turn.
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Before installing the cams we lubricated the cam with engine oil.
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Each cam was torqued in sequence to 10NM (about 100 in-lb). While torquing the cams, Lacko constantly checked to make sure the cams rotated freely.
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Next came the cam sprockets. The raised area, or boss, on the gear triggers a sensor that tells the computer exactly where the cams are in relation to the crankshaft.
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The Comp Cams camshafts required the use of larger cam retaining bolts (right). The larger bolts used are available from your local Ford dealership and they carry PN F1AZ6A340-A.

With today's technology and our intense desire for horsepower and speed driving us, we go-fast junkies continually find ways to improve the internal combustion engine. This search for power leads us to try different parts and pieces and we test and tune until we get it right. We sometimes work hard and fail, other times we find a combination that works so well that the results are shocking. This is one of those times.

The vehicle in question is MM&FF's own '01 GT, "Project Ice Box," which has been a test mule for many of the latest Modular parts on the market. It sported a Vortech SQ-supercharger with Aftercooler, ported Bullitt intake, BBK/SLP exhaust, Superchips performance chip, 3.73 gears and a Steeda suspension. It's laid down over 400 rwhp in previous tests and has run the quarter-mile at over 118 mph, albeit with only low 12-second times due to lack of sticky tires. Not to shabby for a little 4.6-liter 2V Mustang with nothing more than bolt-on parts. But horsepower is addictive and we wanted more.

To increase horsepower and torque we needed to pack more air in to those hard-working cylinders. This can be achieved by increasing boost pressure, improving the flow of the intake system, or a combination of both. We liked the idea of improving both so we decided to install a set of PI heads ported by Patriot Cylinder Heads, along with a set of Comp Cams camshafts. Basic hot rod stuff, right? Of course, and most of us would expect a gain of 50-70 hp from such parts. But as it turns out, our stock-block 4.6 made far more than we expected. I'd love to jump right in and give you the horsepower and torque figures, but before I do, I must digress.

The Install
When we arrived at JDM Engineering in Freehold, New Jersey, for the baseline dyno test and installation, we were aware of a substantial exhaust leak emitting from our headers. Because of the difficulty in changing the gaskets, which were blown out on two cylinders, we decided to test the car on the dyno "as-is." During a recent test the GT made just over 400 rwhp, so when the JDM DynoJet showed 399 hp, we knew the baseline power numbers were stable and we got to work.

We figured the exhaust leak was worth 5-10 hp, but after raising the Mustang in the air we realized there was more than a simple blown gasket. Somewhere along the way, the driver's-side BBK header was cold-cocked by a substantial object that did not move. We can't say the same about the header. The path of destruction started at the leading edge of the K-member, which was gashed, then it smashed into the K-member crossbrace, which was bent, along with the two lower header tubes on that side (see photo above). My guess is that the crushed header and the blown gaskets robbed the GT of about 20 hp.

With the problems noted and the dyno figures in the book, we jumped in and got to work. Rather than break his back leaning over the fender for three days, JDM's Shaun Lacko pulled the engine from the car. We'll note that it's not impossible to swap heads and cams with the engine in the car, but most technicians with Modular experience prefer to yank the plant.

With the 4.6 on the stand, Lacko removed the Bullitt intake, cam covers, water pump, and the timing cover. The system of chains and gears looks intimidating, however, if you follow proper procedure they are not bad to work with.

"Before removing the tensioners, cam sprockets, or the cylinder heads it's important to rotate the engine until the keyway on the crank is in the 12 o'clock position," explained Lacko. "When you remove the tension from the chains the cams can rotate, putting the valve timing and crankshaft out of sync in a rather quick, snapping fashion, and this can cause a valve to open and crash into a piston. By putting the keyway straight up, none of the pistons will be at TDC and you will ensure proper clearance. This goes for installation of the heads as well."

As we mentioned in part one last month, the heads are new PI castings from Patriot Performance. The Stage II heads, which we have, are CNC-ported and have 1mm larger valves, Patriot springs, a five-angle valve job and they retail for $1,295. Patriot also offers Stage I heads for $1,095 (both prices with exchange). The only downfall is that Patriot uses truck heads, which require truck valve covers and the tall truck cam covers may not fit on your Mustang. This should not be a problem unless you have a Bullitt intake and a Vortech blower with an Aftercooler--like we do. With this setup there is a clearance problem between the oil fill and the intake inlet tube from the Aftercooler to the throttle-body. We solved the problem using low-style truck covers and an oil fill S-tube from an Explorer.

Atop the heads are Comp Cams' Xtreme Energy camshafts and they are pretty aggressive with .545-inch lift and 234/238 degrees of duration at .050-inch lift. Comp says the cams are designed to work from 1,800-5,800 rpm and it offers one smaller cam and one larger one for the '99-up engines. The new JDM headers have 1 5/8-inch primary tubes and 2 1/2-inch collectors. The pipes were hooked to a JDM (cat-equipped) H-pipe and SLP's Loud Mouth cat-back. For more information on the heads and cams, including specs and flow data, see "Patriot Games, Part I" MM&FF, April 2004.

Dyno Time
After a few days in surgery the 4.6 was back together and breathing on its own. Lacko made some basic checks and then strapped the GT to the dyno. The combination of the JDM/SLP exhaust made for a loud exhaust note--it burbled at idle and sounded mean and nasty when the throttle was cracked. It's big-block, musclecar-like, not something for those who don't want to be noticed. If the bite turned out to be as big as the bark, we'd be in for some serious numbers.

With the GT strapped tightly to the floor, D'Amore connected his scan tool and the tuning began. The first few pulls were purposely cut short so he could check the air/fuel ratio and other vital signs. All systems were "go" so he pressed the green dyno button and pushed the throttle to the stop. The blown 4.6 jumped when the throttle was cracked and it revved in a flash, but D'Amore noticed the engine was lean and cut the run short.

Despite being shut down at 5,000 rpm the 4.6 spit out 473 hp and 434 lb-ft of torque. A change to the program was made and this time D'Amore rolled it up to redline. The DynoJet calculated a whopping 497 hp and 430 lb-ft of torque. We had predicted that the combination would be worth about 50-70 hp, but it was more like 100 hp at the wheels. Most would be satisfied with a 100hp gain, however, we knew more power was in there and we were going to get it.

The ported heads, big cams, and tuned headers caused an increase in airflow, thus less of a restriction, and this equated to a drop in boost (from 12 to 10 psi). We expected this and had a smaller Vortech pulley waiting in the wings. The smaller pulley is designed to spin the blower faster, therefore creating more boost pressure--and hopefully more performance. Lacko removed the 3.33-inch pulley and replaced it with the smaller 3.10-inch unit. Power climbed to 518 hp and torque went to 475 lb-ft. The smaller pulley showed immediate signs of greatness, until about 5,200, when the power curve went flat. The flat curve was a sure sign that the belt was slipping. Next stop, the parts store.

With the new belt in place (Napa PN 061066) we gave it another try, and this time the belt hung tight. Horsepower rocketed to 540 at 6,200 rpm and it was still climbing when the engine hit the rev limiter. Needless to say, we were stoked. We could have raised the limiter with the chip, but for fear of the stock connecting rods making an unwanted appearance on the shop floor, we decided to chill at 540.

Torque, by the way, peaked at 470 at 5,200. All on hand were impressed with the output. D'Amore then spent an afternoon with Ice Box improving the driveability. The 4.6 makes serious power and the cams make it a bit lopy at idle, but there is no stalling or detonation.

Out on the street the GT is simply amazing. Due to extreme cold weather in the northeast, we're dealing with great air, but also cold roads and cold tires. We couldn't let the GT totally loose, though we tried real hard. Unfortunately, giving it any more than half throttle made you feel like John Force on a burnout. Ice Box now rolls proud and can smoke, and I mean smoke, the tires at will.

This is one fast hot rod that drew big grins from the occupants--though I doubt it will draw any grins from the competition. Those who bemoan the fact that there are few aftermarket Modular parts to pick from can definitely take solace in the results offered by the Patriot heads/Comp Cams combo we installed. Who needs a lot of parts when those we have work so well?