Project Apex: Building A Four-Valve Mod Motor On A Budget - Pt.1

Project Apex: Building A Four-Valve Mod Motor On A Budget – Pt.1

When our colleague, Ivan Korda came across a deal on this 2001 Mustang Cobra that was too good to pass up, he had to pull the trigger. The car was a roller but included a four-valve 2004 Mach 1 WAP (Windsor Aluminum Plant) engine in pretty rough shape. There were also some other desirable pieces on this very high-mileage project car.

The engine provided with Ivan’s Mustang had seen better days. It was not the original Cobra engine, which had been replaced at some point with a Mach 1 engine, and the mileage count was unknown. The black valve covers indicated it was a 2003 engine, and that the original engine had likely met an untimely demise. No matter, since the ’04 WAP was probably the same block as the ’01 (Ford went to the WAP in mid-’01 after they ran out of Teksid blocks).

The project has been dubbed Project Apex because Ivan plans to completely rebuild the Cobra into a road racing, track-day killer, competing in SCCA and NASA events as well as some other one-offs. While the car has 210,000 miles on the clock, the actual engine mileage is unknown.

Project Apex will be covered by EngineLabs’ sister publication, Here at EngineLabs, we’ll be documenting the engine build, being dubbed “The Boring 4-Valve” — a sarcastic twist on how the four-valve is regarded with the Coyote taking over the DOHC marketplace (along with a nod to Elon Musk).

The plan is to build a budget-conscious naturally aspirated performance 4.6-liter dual overhead cam engine, that produces around 400 horsepower at the wheels. While it is not an exercise in extreme engine building, it will illustrate what can be done to make a very solid naturally-aspirated engine as good as a crate engine Coyote.

The Mach 1 replacement engine that came with Ivan’s project Cobra was not the original engine and had seen better days. The crankshaft bit the dust and also wiped a bearing, probably due to an overzealous driver and poor lubrication. But Todd Warren from Apocalypse Performance took it all in stride as he set about rebuilding Ivan’s “Boring 4-Valve” short-block.

It’s The Apocalypse

Ivan enlisted the services of Apocalypse Performance‘s Todd Warren for the engine build. He’s a very experienced Ford guy who has a New Edge Cobra project car of his own, along with his own line of signature camshafts. As such, Warren is well-versed in setting up cams for the Modular engine. “Many people don’t like the Modulars because they’re only 281 cubic inches,” he says. “But they don’t need to be boosted to perform well.”

He says that Ivan initially called him about doing just the cams. “I told him that I do builds, too, and that I could spec out the engine with a trusted shop in Exigent Solutions in Ross, Ohio that can do the machine work and assembly.” Ivan liked that plan, and Warren ended up with the project.  “We agreed to do a naturally aspirated, ‘budget-friendly’ deal,” Warren recalls. “I had some Gen-3 Coyote rods with about 60 miles on them that I donated to the cause, too. It just kind of went from there.”

In stock form, the Mach 1 engine produced 320 horsepower at 6,000 rpm and 317 lb-ft at 4,750 rpm — at the crankshaft. So the mild performance build will bump the numbers up quite a bit and broaden the mid-range powerband to make it more suited to driving on road courses.

After tearing down the short block, it was cleaned thoroughly and the cylinders were touched up with a hone. The main bore was also checked for alignment and set up to handle the coated Clevite bearings, which were a splurge for this budget build.

Custom Pistons

Warren says the only pistons available in the desired compression ratio are heavier pieces designed for boost. So, they instead went the custom route with MAHLE Motorsport to get the weight down and compression up. “We wanted 11:1 — or a little more — to maximize the power. Ivan was a little concerned about going any higher than that, considering he is going to run it on 93 pump gas. But, I was willing to go to 11.5:1,” says Warren. 

It seems that many people are afraid of compression, but there is no reason to be scared of it with a 4.6- or 5.4-liter four-valve. The four-valve Modular combustion chambers are very efficient and are not prone to detonation. They are not unlike those of the Coyotes which now have 12:1 from the factory, with the addition of direct injection.

The only shelf pistons available in 11:1 were designed for boosted applications and as such, were heavy. So Warren decided to go the custom piston route with MAHLE. Even custom, the pistons were still within budget, partly because he chose to use 4032 over 2618. Forged 4032 will be plenty strong for this build.

On the Modulars, if you don’t have enough valve relief when you start adding duration, you have to retard the intake lobe center, and that kills all the mid-range power,” – Todd Warren, Apocalypse Performance

With Ivan planning to use the car for road racing, midrange power is required, and the reliefs allow for durations that will provide good horsepower/torque in that area of the powerband. “We ended up with an 11: 1 piston with large valve reliefs, which allowed me to get the cam specs I wanted. But everything we did was with keeping the budget in mind and making about 400 horsepower (or a little more) at the wheels. We also chose to build the piston from 4032 alloy, which is much better for naturally aspirated engines,” says Warren. He notes that the alloy doesn’t require as much piston-to-wall clearance, “so you don’t get any rattling on cold starts.”

Spec’ing the MAHLE 4032-alloy pistons with large valve reliefs lowered the compression a touch but will allow enough room for cam duration, and ultimately more power in the mid-range. The stock piston design prevents the ability to have any valve overlap, so Warren says to always buy the pistons with valve reliefs.

Ivan wanted the engine to perform like a Coyote engine, but on a budget. [The four-valve] can put out that same kind of power without spending Coyote money. – Todd Warren

Warren says he likes the 4032 alloy better for naturally aspirated applications and streetcars making 800 horsepower or less. “Over the years, people have been told that 2618-alloy pistons are required,” he says. “To the point where that’s all that anybody makes now. … 2618 alloy pistons. Everybody thinks that is what you need, but I know guys who are making 1,200 horsepower with 4032. I would never use it for over 1,000 horsepower, but some people do, and do it successfully.” 

After milling the factory heads a little, accounting for head gasket thickness and reduced combustion chamber volume, the final static compression ratio ended up at 11.2:1. “It’s not meant to run 30 pounds of boost at 9,000 rpm,” Warren clarifies.  He adds that the peak RPM will be around 7,200, max as dictated by the stock ECU and modified intake manifold from Matt Hayes of Never Enuff Performance. “That, with the intake manifold that Matt made for it [more on that later] will dictate a 7,000 to 7,200 rpm shift point. A stock intake kills power at about 6,300.”

ring gap

MAHLE’s reccomended ring gap is .0045 inch per inch of bore for the top ring and .0050 per inch for the second ring, in a high-performance street application. That works out to minimum ring gaps os .016-inch for the top ring and .018 for the bottom ring. Exigent decided to go with a little more than the “High Performance Street” specification calls for. .

In addition to having MAHLE make a set of lighter pistons, Warren opted to take advantage of a lightweight cast crank (which is lighter than a forged crank). Since it is strictly a naturally aspirated engine, MAHLE could use a little less material everywhere; less material in the dome, the skirts, and a lighter-weight wrist pin. In naturally aspirated applications lightweight components offer more efficient power production and are also a lot easier on the bearings.

Replacing Forged With Cast

For this build and this power level, Warren feels there is no need to go with a forged crankshaft. Add to that, the OEM cast crankshaft is a whopping 12 pounds lighter. “The cast crank doesn’t have the center counterweights that the stock forged crank has, and at this RPM and power level, the cast crank does just fine,” Warren adds. “We have naturally aspirated NMRA Factory Stock racers spinning to 8,500 rpm and higher with a stock cast crank.”

Going with an OEM cast crankshaft may not sound that exciting, but it reduces the rotating mass by 12 pounds. That large difference in mass is because there are no center counterweights on the cast versions.

Saving Weight With OEM Connecting Rods

“The Gen-3 Coyote rods are much better than the Cobra rods that were in there,” says Warren. “They have the same dimensions as the 4.6 rods, as far as the small and the big end, as well as the same length. As far as weight goes, they are lighter than your average H-beam connecting rod that’s out there on the market. They’ll handle over 8,000 rpm, and take 20 pounds of boost.”

One of the benefits of using the Gen-3 Coyote rods for this build, besides the fact they were donated to the project, was that the design uses beefier bolts. They were sized standard for the cast crank and will be paired with Clevite bearings that were coated by Calico Coatings. The bearing clearances were set at .002″ across the board for mains and rods.

The Gen-3 rods are powdered-metal like the OEM 4.6 rods, but one advantage is they have bigger rod bolts and are just made better, requiring no upgrades from how they were delivered off the Ford assembly line. Warren says this engine will mostly use stock hardware as it will hold up to mild performance upgrades. The only thing beefed up in the bottom end was the side bolts for the main caps. They used ARP bolts both for peace of mind and because stock bolts are not easy to find.

Oil Pan

Warren chose a Moroso road-racing oil pan with a higher capacity sump and the proper baffling in it for road racing, so you’re not sucking up air in a turn or under braking. “Road racing is unique in that you need to have the oil concentrated around the pickup because you’re constantly turning right, left and braking and accelerating. Even in a street car, I like using the road-race pan because the drag race pan is just too open.”

For the windage tray, Warren prefers the 3-valve windage tray, but it is currently not available from Ford or the aftermarket. The second-best option is the 2013-2014 GT 500 windage tray, which doubles as the oil pan gasket also. Most aftermarket windage trays require the use of two oil pan gaskets which increases the possibility of oil pan gasket leaks; fewer components reduce this chance considerably.

The Moroso fabricated steel oil pan not only offers more capacity than the stock pan, but is heavily baffled in order to control oil under all high-g conditions — acelleration, deceleration, and lateraly. It uses the factory dipstick and pickup tube, and has several 1/2-inch ports pre-drilled for various needs.

Everything in this engine has been designed from the beginning to work together in harmony. “The compression ratio, the intake manifold, the cams, the headers, with all of that in mind, they were all spec’d to work together to make good power from 3,500 rpm to 7,200 rpm without just making a good peak horsepower number,” says Warren. 

“Ivan had a horsepower goal in mind. I have no issues with this engine meeting that horsepower goal. But my goal is for something that has good average horsepower,” Warren notes. “Your peak horsepower number isn’t as crucial as the drivability and the mid-range that you can build into it for road racing. If you get that mid-range to come on earlier, and stay strong through to 7,000 rpm, you’ll have one heck of a motor for that application.”

So that is the basics of the short-block assembly and the plan behind Project Apex. Next, we will be zeroing in on the cylinder head rebuild and assembly of Ivan’s Cobra engine. Stay tuned for more as we document the progress of The Boring 4-Valve build and prove that it’s anything but boring.


With the shortblock completed, we’re ready to move on to the assembly of the top end. This configuration should make for a reliable, quick-revving engine, for a modest budget.

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About the author

Brendan Baker

Brendan Baker is an automotive writer who lives in Akron, Ohio with his wife and two dogs. He started racing and building cars at a young age, building his first "racecar" at age 12 (a quarter-midget), which he put on pole position in its first race.
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