Cylinder Block
Choosing the appropriate 4.6-liter block for a race or performance application is not too challenging
of a proposition. We at Sean Hyland Motorsport (SHM) have successfully used the ‘96-‘98 Cobra
aluminum block as a basis for drag-race engines of up to 1500 hp. This block, part number F6LZ-
6010-AB, was also used in the ‘93-‘98 Lincoln Mark 8. Originally this block was cast in Italy by
Teksid, a supplier to Ferrari and other manufacturers. The block is cast in SAE 319 modified alloy
aluminum before it is heat treated and aged to achieve the desired characteristics. Overall, we
have achieved good results with this lightweight (85.40 lbs) alloy block, as long we use care in its
preparation. In 1999, Ford changed the main cap detail, eliminating the jackscrews that preloaded
the side of the main cap. They also changed the width of the cap, and switched to a different side
bolt with a higher torque value. The diameter of the hole for the knock sensor was also changed
from M8x1.25 to M12x1.50. We simply drill and tap these holes if we are using the ’99-up block in
an earlier chassis. The part number for the ‘99 block is XR3Z-6010-CA.
In 2001, Ford changed the design of the block to a lighter-weight (80.40 lbs) casting utilizing SAE
319 modified alloy, incorporating some interesting design changes. This block is known as the WAP
(Windsor Aluminum Plant) block. The oil drain-back holes were changed to keep the oil as far away
from the crank as possible, and the main bearing web area was changed to create a beefier
structure.
The WAP block on the left has been cast
at Windsor Aluminum Plant since 2001.
The Teksid block on the right was cast in
Italy from 1993 to 1999. The WAP block
shows the extensive ribbing that was
added to compensate for a thinner case
section. The WAP block is 5 lbs lighter
than the Teksid block on the right. The
Teksid block is the strongest production
aluminum case available.
Extra external ribbing detail also contributes to a beefier appearance, although the lighter weight
means that the extra ribbing has been added to compensate for a reduction of section thickness in
the case. The NVH (noise, vibration, harshness) block is a derivative of the WAP block, but features
a thicker pan rail for decreased noise. This seems to be the current block in production on the
Marauder. At this time, we have not used the later block for any extreme horsepower applications,
and some attempts by others have resulted in block failure. Our recommendation is that the early
block is the best foundation for power levels above 900 hp, although the later block certainly should
be adequate for moderate power levels of up to 600 hp.
The WAP block has more
material in the main bearing
web area. The windows in the
web area are the weak point
in the lower end of the case.
The windows require
deburring to prevent stress
cracks from occurring.
Another version of the aluminum block that you may come across is the front wheel drive (FWD)
block. This block is modified for use in the FWD Lincoln Continental. Changes include a different
coolant flow, additional bosses for engine mounts, and a unique bellhousing bolt pattern. The FWD
bellhousing bolt pattern renders this block useless for rear wheel drive applications, as no
rear-drive transmission bolts up.
Cast-iron 4.6-liter blocks have been produced since late 1991, and are found in the Crown Victoria
sedan, beloved by taxi companies and police forces everywhere. The first block, now out of
production, is distinct because it uses a two-bolt starter mounting instead of the current three-bolt
starter design. The bolt pattern on the bellhousing is also unique on the first year blocks, because
they were bolted up to AOD transmissions that used the 5-liter bolt pattern. The iron block released
for the ‘96 Mustang GT and the ‘97 F-150 is part number F6AZ-6010-CB. This block is referred to
as the Romeo block, as it is used in 4.6-liter engines assembled at the Romeo factory. In a move
reminiscent of the 351 engine, Ford also has a 4.6 iron block, assembled in the Windsor engine
plant, hence the Windsor designation. Primarily, the Windsor plant has produced the 4.6-, 5.4-, and
6.8-liter modular engines used in the Ford trucks, while the Romeo based engines were slated for
use in the car lines. Changing demand and availability, however, has resulted in the Mustang in
particular being produced with both versions since 1999. The major difference between the two is
the main bearing caps and the main bearings themselves. Each of these engines uses different
main bearing sets that are not interchangeable. It is difficult to mess this up, because the tangs are
different between the two main caps.
The 4.6 Windsor iron block is readily
identified by the large W cast in the
valley area and also in the front of the
block. The other 4.6 iron block is the
Romeo. The main bearings of the
Windsor and the Romeo are not
interchangeable.
The iron blocks have cylinder wall thickness in the .110-inch range on the thrust side, and .165 inch
on the front and rear sides. The iron block does not have Siamese-bore construction like the
aluminum block, and in either case, we would not recommend overboring past .040 inch. These
blocks weigh 154 lbs, so one can see the advantage of using the aluminum block if the rules permit.
The 5.4-liter Windsor
iron block is similar to
the 4.6-liter version.
The deck height is
10.079 versus 8.937
inches on the 4.6.
The 5.4-liter iron block, part number F75Z-6010-AF, has been used in the Ford trucks and the
2000 Cobra R. It has a 10.079-inch-tall deck height to accommodate the longer 4.165-inch stroke,
versus the 8.937-inch height of the 4.6-liter block. Particular care should be taken to sonic test a
5.4 candidate block to ensure adequate wall thickness on the thrust face, as the loads are higher
due to the longer stroke and greater rod angle of the 5.4. High-mileage 5.4 engines have shown a
pronounced bore distortion, which creates a cold-start engine knock until everything warms up and
expands into place. In 2001, Ford added 18 lbs of iron into the 5.4 block in an effort to improve the
NVH characteristics of the block, and also changed the part number to 2L1Z-6010-AA.
The iron block uses 2 main
bolts plus 2 precision
dowels to locate the main
cap, through which go the
side bolts. All the bolts in
the iron block main caps
are one time use only.
With some simple modifications, all of the 4.6 and 5.4 blocks can be used with both single overhead
cam (SOHC) and double overhead cam (DOHC) heads.
