Modified Mustangs & FordsHow To Engine
How to Build a Ford SOHC 3V Engine
SOHC + 3V = HP
When Ford introduced the single overhead cam 5.4L 3V Modular V-8 in 2004 in the redesigned F-Series trucks and the 4.6L 3V in the all-new ’05 Mustang GT, it was viewed as an upscale compromise between the 2V Modular and the mighty DOHC-4V Cobra and Mach 1 engines. Three-valve technology bolstered the SOHC Modular’s reputation as did Variable Cam Timing (VCT), and the SOHC-3V has become a proven mill in the 10 years it has been in production in performance applications like the ’05-’10 Mustang GT. The 3V has shown it can take a lot of punishment, make power, and come back for more. It also makes significantly more power than the 2V, however, should you consider the 3V SOHC for your vintage Ford?
Because Ford has produced so many SOHC-3V engines since 2004, these mills are plentiful and reasonably priced. There are a lot of them available from crash and theft recoveries. Sometimes, you can snap up the entire vehicle, part it out, and make money on parts for your engine-building project. The SOHC-3V will operate happily on 87-octane fuel and parts are generally more affordable, which isn’t true of the premium-fueled, DOHC-4V. There are also two fewer cams and eight fewer valves and rocker arms to sweat out, which makes the 3V cheaper to build. It is cheaper to build a 3V than it is a 4V and yet you can get nearly the same amount of power available from the DOHC-4V. The 3V isn’t as large as the 4V, so there’s more room if you’re trying to shoehorn the Modular into a Torino or Mustang.
There are also aftermarket shops like Modular Motorsports Racing building 3V engines and short-blocks. And because the 3V has an extensive application in the ’05-’10 Mustang GT, there’s a lot available from the performance aftermarket for this engine. If you want to build a 3V from scratch, Summit Racing Equipment has a huge inventory of Ford Racing Performance Parts (FRPP) pieces, as does other aftermarket sources like Roush, Brothers, BBK, Comp Cams, Edelbrock, and more. You can begin with a new factory aluminum or cast-iron block or the heavy-duty Boss block with larger bores and plenty of material down under to support huge amounts of horsepower.
The beauty of a 4.6L or 5.4L SOHC-3V is lightweight aluminum casting technology, if you decide on an aluminum block. In all- aluminum form, this engine weighs considerably less than a 390, 428, or 460 big-block and will make whopping amounts of power with the added benefit of fuel efficiency. Imagine one of these in your classic F-Series truck or fullsize Galaxie.
What makes the 3V a better bargain than the 2V is breathing and power for the same amount of money as the 2V. It is that second intake valve and variable cam timing that infuse real power into this engine. We’re talking 300 horsepower at 5,750 rpm and 320 lb-ft at 4,500 rpm of torque box stock in the ’05 Mustang GT. By today’s standards with the 5.0L Coyote, 300/320 is laughable, however, there’s more power available from the 4.6L/5.4L SOHC-3V with the right parts and technique.
Block Bottom Basics
All 4.6L and 5.4L SOHC Modular engines employ the same blocks, meaning you can bolt any SOHC head on any Romeo or Windsor block. This means you can mate any 3V head to any Romeo or Windsor iron or aluminum block, which gives you a lot to choose from. Romeo iron blocks are cast at the Cleveland Iron Foundry. Windsor iron blocks are cast at the Windsor Iron Foundry. Aluminum blocks are cast at the Windsor Aluminum Plant unless you’ve found a DOHC-4V Teksid block, which was cast in Italy.
The SOHC-3V engine has a bulletproof bottom end, meaning it can take a lot of punishment and serve you well for 250,000 miles with regular oil and filter changes with a stock bottom end. If you’re anticipating punishing performance, it’s a good idea to go with a steel crank, H-beam rods, and forged pistons with coated skirts.
A number of stock displacement and stroker kits available through the aftermarket for the 4.6L and 5.4L SOHC-3V Modular engines. Because these engines are very limited in terms of displacement growth, don’t expect a lot of displacement via bore and stroke, however.
The SOHC-3V cylinder head is completely different thanks to its innovative apex-shaped combustion chambers and one additional intake valve engineered to improve velocity and volume. This head makes significantly more power than the 2V head and is a close runner up to the 4V.
When you take this improved airflow port and valve design and marry it to variable cam timing (VCT), you have a great formula for power without additional cams and valves. VCT moves the cam on its longitudinal axis to advance or retard valve timing to improve both performance and reduce emissions. When you advance valve timing, you gain low-end torque, but usually at the cost of high-end horsepower. And when you retard valve timing, exactly the opposite happens with losses in low to mid-range torque and gains in horsepower. With VCT, you get the benefit of both without sacrificing power. Down low, you get more torque because VCT advances valve timing. And with the pedal to the metal, VCT retards valve timing to help you achieve more horsepower. This approach also improves emissions and fuel economy.
Another difference in the 3V is drive-by-wire technology. Instead of a throttle cable, throttle operation is electronic. The accelerator pedal is a variable resistor like a volume control on your stereo where resistance determines where the throttle is positioned. Step on the gas and the computer responds with an electrical signal to the throttle motor gear drive, which in turn moves the throttle—the days of goosing the throttle by hand are over.
The stock 3V head offers good flow right out of the box at 174cc intake runner volume and 62cc exhaust with 51cc chambers. Flow at 0.600-inch lift is 225 cfm and exhaust is 195.7 cfm box stock.
If you are seeking bang for your buck consider the CNC ported 3V head from Ford Racing Performance Parts (FRPP) available from any FRPP dealer. The M-6049/6050-N3VPA head is precision CNC ported to yield 202cc intake volume and 73cc exhaust with 53cc chambers. Intake flow at 0.600-inch lift is 272 cfm. Exhaust is 190 cfm. You will need the FRPP M-12029-3V coil packs with ’08-’10 12mm spark plugs for this head.
These heads have a suggested retail of $1,049 each, assembled and ready to install. To make the most of these heads you will want the FRPP M-6550-3V cam kit, M-9424-463V High Flow intake manifold and M-9926-3V twin 62mm throttle body. The M-9926-3V throttle body gives you 1,306 cfm with the butterflies pinned. You stand to gain 50-plus horsepower at the wheels with this combination of parts. You will need to purchase roller rockers and lash adjustors.
Though 3V engine production has come to a close, its plentiful numbers in Mustangs and F-150 trucks, as well as healthy aftermarket support, offers hotrodders a powerful, modern engine option in a lightweight package.
1 At first glance, the SOHC-3V isn’t much different than the 2V. It is built on the same block design, but its piston dish is different than the 2V and 4V due to valve configuration, and of course there’s an extra valve hiding under the camshaft at each cylinder . Cracked powdered metal connecting rods are the same. What makes the 3V distinctive are its three-valve heads with computer controlled/oil pressure modulated variable cam timing (VCT).
2 You can build a SOHC-3V on any Romeo or Windsor Modular V-8 block. There are plenty of block cores out there both new and used. This is a new 4.6L Romeo block with jackscrew fit cross bolted main caps, which is an excellent foundation for your 3V project. Later blocks are interference fit main caps instead of jack screws. You may also go with any of the Ford aluminum blocks.
3 This is the 4.6L Romeo iron block with jackscrew secured main caps. Side bolts are removed and jackscrews relaxed to remove main caps. Jackscrews on Romeo blocks are adjusted with an Allen wrench to where they are flush with the block pan rails once main caps are torqued. Side bolts are installed and torqued once jackscrews are set.
4 The #156-5901 stud kit is specifically for the 3V with a windage tray with longer studs.
5 Main studs have been installed finger snug and are not to be bottomed out. Note Number 5 main studs are the short ones because they do not secure the windage tray.
6 Modular Motorsports Racing (formerly Modular Mustang Racing) is building this SOHC-3V engine with a new cast-iron Romeo block as a foundation. Inside, this block will get a 4340 forged-steel stroker crank to achieve 4.75L or 5.0L. Reciprocating mass consists of MMR specification Manley forged steel H-beam rods and forged pistons dished for the 3V and fitted with Total Seal file fit rings and Clevite bearings.
7 This is the 4340 steel eight-bolt stroker crank that will bring displacement to 5.0L. The eight-bolt crank is what you want for any 3V build stock or modified.
8 Crankshaft endplay is checked and controlled by this shim on all Modular engines. Varying thicknesses are available depending upon how much endplay you need. Crank endplay needs to be between 0.006- and 0.014-inch depending on how hard you intend to work the engine. Crank rotation should take only your fingertips and there should be plenty of assembly lube on the journals.