Papitto: The 4.6 stock has a fairly long stroke, and a good bit of the piston skirt comes out of the block at bottom dead center. Adding 0.200 inch of stroke pulls even more of the piston out of the block. In the case of the 5.4, the stock 4.165 stroke is long to begin with. This is one area where the small 3.572-inch bore is actually good. It makes for a light piston/wristpin assembly that lowers the tensile load on the connecting rod and rod bolts. It's common practice to use a 0.020-inch oversize piston, and this gives no problem. We have a few engines running around that are 0.040 inch oversize. In the case of the big bore, it requires resleeving the block to accommodate the 3.700-inch bore. This is made possible because the aluminum block has siamese-bore construction. The big-displacement engines won't show a large gain in power unless the heads/cams, intake, and exhaust system are modified to feed the larger displacement.
MM&FF: What are the best blocks to use and why?
Papitto: In the case of the 4.6, the OEM iron blocks are cheap, and they hold up well in limited-power applications. The early '92-'99 aluminum blocks (commonly known as the Teksid block) were cast in Italy and are regarded as the best of the 4.6 blocks. John Mihovetz has run 6.60s at over 210 mph using the production block. The later aluminum blocks, first cast in Canada and then in Mexico, are regarded as being less desirable than the early Teksid block, but I haven't had a problem with any of them. In either case, the aluminum blocks have the advantage by being 65 pounds lighter and having four-bolt main caps.
In the case of the 5.4, you really only have two choices: the early iron block used from 1998 to 2002 and the NVH block. The early block weighs 189 pounds. The NVH block has more metal on the sides and in the main webbing and weighs about 205 pounds.
The alternative is the aluminum block from the '05 Ford GT. These blocks have enormous strength, billet-steel main caps, and thick webbing everywhere. The Ford GT block weighs about 125 pounds. The drawback is they're expensive; there's no provision to use the standard modular-style oil pump as the Ford GT uses the dry-sump oil system with the external pump. The blocks were built in limited numbers and are becoming hard to find.
MM&FF: What's the best setup: Two-Valve, Three-Valve, or Four-Valve?
Papitto: Two-Valve engines can make good street engines with small superchargers, but they are rpm-limited by the lack of airflow. Three-Valve engines are prone to detonation caused by the spark plugs. There are only two choices for spark plugs, and they have a very hot heat range. They also have a weak spot in the cam phasers, which are not strong enough to deal with the increased loads associated with stronger-than-stock valvesprings. If you're looking for maximum modular power, the Four-Valve heads are where it's at. The efficient combustion chambers, big airflow, and lightweight valvetrain makes the Four-Valve heads the only choice for big power and high rpm.
MM&FF: Do you see a lot of people looking at the 5.4 instead of the 4.6?
Papitto: Not really. The 5.4 will physically bolt right in, but there are difficulties associated with the exhaust and intake manifolds. Sullivan Performance was the first and only company offering an aftermarket intake manifold. Its short runners work well with high-rpm or supercharged applications.
MM&FF: How hard is it to drop in a 5.4 where a 4.6 used to be?
Papitto: The 5.4 will bolt right in. Stock Cobra exhaust manifolds will clear the frame. I'm not aware of any aftermarket header that will work with a 5.4 and SN-95 chassis. The intake manifold presents a big problem. Sullivan Performance offers an intake manifold designed to work with Navigator heads and a 5.4 block. The Shelby GT500 manifold will only work with GT500 or Cobra R heads.
MM&FF: Are you familiar with Steve Erickson's 5.4 swap kit and, if so, what are your thoughts on it?
Papitto: Yes, I am. Steve has put a lot of effort toward making this work using all factory Ford parts. His swap is based around the Australian Falcon 5.4 intake manifold. This manifold has ports designed to work with the '03-'04 Four-Valve head.
Boss 330 offers numerous cam...
Boss 330 offers numerous cam profiles that are chosen based on your overall engine combination. Some are off the shelf, while others are custom designs. These billet steel bumpsticks are a mild grind that are already employed in the 5.5 that has produced over 1,400 rwhp. No, that's not a typo. Visit www.turbofordgt.com to find out more.
Taking a bandsaw to four brand-new...
Taking a bandsaw to four brand-new Navigator intakes might make some squeamish, especially at $470 each, but when you want to make more power than anyone else, you do what's necessary. Papitto used the rear runners as they offered the best overall design compared to the three forward pairs of runners.
We also got to photograph...
We also got to photograph Papitto's street car, which is a 5.4/Four-Valve Cobra that uses this prototype Cobra R manifold that he pieced together. It's one of four intakes produced, and Papitto actually found parts of it on eBay.
While we followed along on...
While we followed along on the 5.5 Four-Valve buildup, we also picked Papitto's brain on Ford's latest engine, the Three-Valve 4.6. He noted that the factory springs on the cam phasers (left) aren't strong enough to properly hold the phasers in position when used with stiffer valvesprings. In certain cases, the phaser will rock back and forth, making a lot of noise and even cracking the center of the hub. To remedy this, Papitto employs this adjustable cam phaser (right), which offers 22 degrees of timing adjustment, while removing the variable cam timing.
This is the second iteration...
This is the second iteration of the 5.4/Four-Valve intake. Here, you can see Papitto moved the injector bosses out of the runner to improve airflow. This is the last fuel-injected manifold he had on his groundbreaking '97 Cobra testbed, which made 535 rwhp.
The fixed cam phasers use...
The fixed cam phasers use ARP bolts and solid billet hubs for durability under load.
While we showed you the corrosive...
While we showed you the corrosive effects of leaded fuel, Papitto showed us this cylinder head, which has seen major amounts of water methanol injection. He put it like this: "The moral of the story is that if you want to play racer, you better maintain it like a racer, otherwise you'll end up with my phone number on your refrigerator."