Yep, the itialian guys, never looked how to spell it.
Here is a bunch of good stuff.
Mustangs have come with both Romeo and Windsor engines. The 1996 thru 1998 Mustangs came with Romeo based engines. The 1999 thru 2000 Mustangs came with Windsor engines. Then just for fun, Ford went back to Romeo engines in the 2001 thru 2003 Mustangs. Be sure to check the engine no matter what year it is. It seems that Ford carried over some engines into the following model year.
4.6L DOHC engines have come with blocks cast in both iron and aluminum. You can find the aluminum blocks in Mustang Cobra's up to year 2002, Lincoln Continental, Lincoln Mark Series and the Lincoln Aviator. These blocks are cast by Teksid in Italy for Ford. All of the aluminum engines are assembled at
the Romeo plant. No SOHC engines have ever been cast in aluminum, although the blocks are generally interchangeable between the DOHC and SOHC. The only exception to this is the Continental engine which is front wheel drive. This block will not work in rear wheel drive vehicles. One of the motor mounts is not drilled, the bell housing is different to allow mating up to the transaxel, the oil filter is located on the opposite side of the block, the front cover and accessories are different. The oil pan has a front sump so
this may help with some swaps that require a front sump. If you get stuck with one of these engines, you can still use all of the internal parts, cylinder heads and intake. These parts will bolt up to an iron or aluminum rear wheel drive block. Be sure to evaluate the time and expense associated with this kind of swap, all of the necessary parts needed to complete this conversion will add up quick.
The Lincoln Mark series are probably the most popular 4.6L DOHC engines, due to the relatively low
price compared to the Cobra engines. What are the differences between these two engine's? Following
are some, but not all of the differences.
The Cobra comes with a forged steel crank using 8 flywheel bolts, the Lincoln comes with a nodular cast iron crank with 6 flywheel bolts.
The Lincoln uses a different oil pan with a reservoir on the side.
The oil filter/water outlet castings are different.
The Intake cams on the Lincoln are a slightly different profile.
The Intake on the Lincoln is different from the one used on the Cobra, although they do use the same cylinder heads and a Cobra intake will bolt on.
The 6.8L V-10 has never been cast in aluminum except for a limited number that Ford did for a Mustang concept vehicle. The 5.4L DOHC has been cast aluminum but has, up to now, only been available in the supercharged GT40. We will have to wait and see if Ford offers this block through it's performance parts division. Just a guess, but you probably won't find many of these at your local pick-a-part yards
Crankshafts
DOHC & SOHC Cranks will interchange. Some blocks may require minor block modifications for counter weight clearance when installing a forged crank in a block that previously contained a cast crank. The
most common cranks for 4.6L engines are the nodular cast iron units. They come in both 6 & 8 bolt flywheel configurations. Note that just because a crank has 8 bolts does not mean that it is forged. The
2-valve Windsor engines use both a 6 & 8 bolt flywheel, the Romeo engines use 6. The only factory forged cranks available for the 4.6L DOHC engines are installed in the Cobra. These cranks are manufactured by Gertach in Germany for Ford. Ford Racing Performance Parts (FRPP) offers these cranks for sale under part # M-6303-D46 for 425.00. The correct 8-bolt flywheel for this crank is sold under part # M-6375-G46
for 250.00. This is a billet steel flywheel.
The cranks in the 5.4L DOHC and SOHC engines are also available in cast or forged. Most of the cranks are forged, but not all. The only way to know for certain is to look at the parting line. Thick line for forged, thin line for cast.
All 6.8L V10 engines have forged crankshafts.
Cylinder Heads
SOHC
The most in depth evaluation of sohc cylinder heads can be found at the previously mentioned link
http://www.babcox.com/editorial/ar/eb40228.htmFor performance applications the choice is more clear. These heads can be separated into pre-1999 non-performance improved (NPI) and post 1999 performance improved (PI). If you have a set of pre-1999 heads and want to use them, understand that a fully ported set of these heads will perform a little better than a
set of PI heads out of the box. There are good reasons for using the early heads, mainly cost. To convert
to the PI heads on a non PI head engine will require not only new heads but intake and associated
hardware as well. If your willing and capable of doing your own porting work you can build a strong SOHC engine with these heads, just understand that these heads will never perform as well as a set of ported PI heads. Be very careful when porting these heads. There is not much material to play with. This applies to
all castings.
The post 1999 heads (PI) are excellent castings. These heads work well as is, but really respond to a
good port & polish job. After porting these heads can flow as well as the FRPP heads listed below. For supercharged applications or hi-performance engines these heads are a good starting point. The moral of the story is: if you are looking to buy an engine, buy a 1999 or newer.
There is one other option, the FRPP hi-performance heads for the early (1996-1998) engines. These are probably the best heads available for the SOHC 4.6L engines. They also respond well to a good port & polish job. These heads have never been offered on a production vehicle but they can be ordered through FRPP under part # M-6049-D46. Be sure to shop around before purchasing these heads. Prices vary from vendor to vendor but expect to pay about 800.00 each without cams. Ouch!
The numbers listed below are for reference only. Your results will vary depending on who does your
cylinder heads and whether or not they were drinking beer at the time. These are not our flow numbers
so take them with a grain of salt.
Heads Stock Intake
Flow @ .50 Lift Stock Exhaust
Flow @ .50 Lift Ported Intake
Flow @ .50 Lift Ported Exhaust
Flow @ .50 Lift
1991-1998 NPI 150 CFM 150 CFM 190 CFM 170 CFM
1999-2004 PI 165 CFM 150 CFM 220 CFM 190 CFM
FRPP 215 CFM 150 CFM 235 CFM 200 CFM
The 4.6L SOHC and the 5.4L SOHC use the same basic heads. The difference in these heads is not whether they were installed on a 5.4L or 4.6L, but whether the engine was built in the Windsor plant or the Romeo plant. The Windsor heads use 14 bolts for the valve covers while the Romeo engines use 11. That is the easiest way to tell them apart but there are a lot of other differences. The two heads share the same basic archetecture but thats about it. Chambers and port dimensions are the same for these 2 heads. Valve sizes and combustion chamber volumes are as follows:
Heads Combustion Chamber
Volume Intake Valve Exhaust Valve
1991-1998 NPI 52 cc 43.69mm (1.752) 34mm (1.339)
1999-2002 PI 44 cc 43.69mm (1.752) 36mm (1.417)
FRPP 51 cc 46.74mm (1.840) 35.81mm (1.410)
Everything stated above regarding the 4.6L cylinder heads applies to the 5.4L and 6.8L V-10. The
difference being, the 5.4L and 6.8L V-10 did not receive the PI heads until year 2000.
After looking at the cylinder head combustion chamber volume and the varying amount of dish in the
factory pistons it's easy to see that changing heads and pistons from different years will result in a compression increase or decrease. The following chart will give you a guide when scrounging the junk
yards for engines. Your compression ratio will vary depending on combustion chamber work, head gasket thickness, decking of the block, & milling of the heads.
Dish CC 1991-1996 NPI 1999-2004 PI
Flattop 10.3:1 11.2:1
2.66 cc 10.0:1 10.9:1
4.54 cc 9.8:1 10.7:1
10.49 cc 8.9:1 9.5:1
15.80 cc 8.5:1 9.0:1
18.10 cc 8.3:1 8.8:1
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