What were you doing in 1991? The Gulf War was waged, Rodney King got a beat down, the Pittsburgh Penguins won their first Stanley Cup, the Minnesota Twins won the World Series, and Ford Motor Co. dropped the first 4.6L single overhead cam, two-valve-per-cylinder modular V-8 engine into a Lincoln Town Car, thus beginning its phasing out of the pushrod V-8.
The early mod motor was almost universally panned. As it rolled out across the other FoMoCo car lines, the critics became louder and more numerous. The most vociferous among them were Mustang owners, who largely despised the engine. The '96 Mustang, the first to boast mod motor power, carried the same 215hp rating as the previous year's car, the last with the venerable Five-Oh engine, but you wouldn't know by driving it. The power delivery was differ-ent from that of the outgoing pushrod engine, it had less low-end grunt, and it needed to rev higher to reach its powerband. As the Europeans are quick to point out, this situation is intolerable to Americans who demand the instant torque needed to win stoplight drag race wars. Mod motor Mustangs were getting their asses handed to them at intersections all across the country by smug Camaro and Firebird owners who had 275 hp from 350ci LT1s.
Ford responded by rolling out versions with more horsepower, but the company was a little too slow in doing so, and the unfortunate gutless, complicated, expensive stigma surrounding this engine remains in some segments to this day. One could argue that Ford may have prevented this by introducing the 280hp four-valve version first and putting it straight into the Mustang. Such was not the case, though, and the engine has struggled to gain the hearts of the masses. Compounding the problem, the aftermarket was slow to embrace the modular V-8, and that has kept many enthusiasts from building these engines. With the introduction of Trick Flow's two-valve heads, we think the tide is changing and that we'll be seeing more of the mod motor in performance applications.
This article is an overview of the performance potential of the mod motor. We received expert advice from the guys at Modular Mustang Racing (MMR) and Modular Head Shop. They gave us a few build options to consider and warned us of some traps to avoid along the way. This engine is a worthy platform and is capable of making an impressive amount of power. Let's investigate.
Engine Blocks
Specs 4.6L Engines 5.4L Engines Cubic inches 281 330 Bore 3.552 3.552 Stroke 3.543 4.165 Bore spacing 3.937 3.937 Deck height 8.937 10.078 Main journal diameter 2.657 2.657 Rod length 5.933 6.658 Bare block weight, iron 154 pounds Bare block weight, aluminum 86 pounds
Note that the bore and bore spacing are the same for the 4.6 and 5.4. Therefore, any cylinder head will fit on any block. You do need to check the head gaskets, though. The oil holes may be in different locations and could cause oil to leak into the coolant. Your best bet is to use Ford Racing's head gaskets.
Performance 2V Build No. 1
We talked with Modular Head Shop's Nick McKinney at length about his recommendations for a performance build. He told us nearly 60 percent of his customers are early Mustang, Crown Vic, Thunderbird, and Cougar owners. Since these are predominately two-valve cars, he's something of a 2V specialist and has several combinations he recommends to suit his customers' budgets. On his website, McKinney lists a parts combination that will make at least 300 hp at the wheels. Best of all, it costs less than $2,500, including new gaskets, timing chain tensioners, and sprockets. It's basically a cam, head, and intake swap, so you can reuse your bottom end. Assuming everything is in good shape, the stock reciprocating assembly will easily handle the increased power. We'll highlight some of the parts here.
You will bend your intake valves for sure if you run an aggressive camshaft. McKinney told us proper cam timing is critical. He recommended maintaining a 0.035-inch piston-to-valve clearance, and it is easy to exceed this spec. For example, installing a popular street cam with 225 degrees duration at a 112-degree intake centerline will give you 0.070 inch of clearance. Advancing that same cam 2 degrees to 110 will give you 0.035 inch of clearance. Advance it 2 more degrees to 108, and you will only have 0.005 inch of clearance. The problem is that these engines like more intake valve timing, and a popular option is to have the pistons notched for intake valve clearance. You can send McKinney your pistons and he'll notch them for $129. It's also a good idea to replace the intake valves with aftermarket ones without the perimeter ring. McKinney also stressed that the cam timing should always be checked. He said the factory timing sprockets are notoriously inaccurate and can be off by as much as 4 degrees either advanced or retarded. Degree your cams when assembling the engine. If the timing is off, you'll need to buy a set of zeroed or adjustable gears. Rounding out the 300hp combo, you can reuse your factory PI intake and add both a JLT intake with a 90mm mass airflow sensor and a performance exhaust system with a pair of long-tube headers: simple, cheap, and effective. If you still have some extra money to spend, McKinney recommends building all this on top of an aluminum 4V block out of a Mark VIII. In stock configuration, these were 10.0:1 engines. With PI heads, your compression ratio will be almost 12.0:1. That plus the nearly 80-pound weight advantage of the aluminum block will give you even better performance at the track. Whether you use the aluminum block or not, with this combination you'll be making more power at the wheels than the Camaro and Mustang guys are making at the crank.
Power Improved By The Numbers Engine Piston Dish Combustion Chamber Size Compression Ratio NPI 11 cc 51 cc 9.30:1 PI 17 cc 42cc 9.74:1 Ideal* 11 cc 42 cc 10.4:1 *Using a stock head gasket with 0.036-inch compressed thickness with -0.015-inch piston-to-deck height
Cam Specs NPI 201/208 duration at 0.050, 0.462/0.462 lift, 114/113 intake/exhaust centerline PI 200/209 duration at 0.050, 0.505/0.531 lift, 116/116 intake/exhaust centerline
Valvetrain Valve size 1.752/1.339-inch Cam follower Roller type with 1.80:1 ratio
Performance 2V Build No. 2
MMR's TWO-Valve Street Thrasher
Modular Mustang Racing is about two hours away from our offices, so we spent several hours poking around its shop for some more build ideas. Engine builder Alex Clochiatti outlined a cool build for us, which is a variant of the Street Mod 600 long-block the company sells as a crate engine on its website. This build starts with a new 4.6 block, a cast crank with forged rods and pistons, new PI heads, degreed PI cams, and ARP fasteners. This combination sells for $4,499.
The MMR 4V build
MMR's Rick Antonette told us that building a four-valve engine out of a two-valve engine is really no big deal. "Any cylinder head will go on any block. You just need to match the rest of the components to the block and head combination you choose." This is because some of the cam gears, chain tensioners, and timing covers are different from engine to engine. So pick your short-block (MMR recommends a stroker if you're building a 4.6) and add a set of heads.
Build It
We hope this article has given you a better look at the potential lurking within the relatively tiny 281 ci of Ford's modular V-8. We only scratched the surface, though, so we recommend readers hungry for more mod motor information read How To Build Max Performance 4.6-Liter Ford Engines by Sean Hyland and Building 4.6/5.4L Ford Horsepower on the Dyno by Richard Holdener. Both books are published by SA Design and provide a lot of excellent information that we couldn't fit in the space allotted this month. Also, go online to modularfords.com and search the forums. There's a lot of good info there, too.
Just because we are fans of this engine doesn't mean anything if our readers don't care. What do you think? Are we out of our OHC minds? Do you want to see a build? Or will you cancel your subscription if the words mod and motor appear next to each other again? Let us know at CarCraft.com.
