5.0 Mustang & Super FordsHow To Engine
Mercury Cougar Cobra Hybrid - Mad Motor-World's Quickest Modular
John Mihovetz's Old-Head Cobra Motor Makes 2,300 Hp--That's 8 HP Per Cubic Inch! Here's How ...
Horse Sense: Will John Mihovetz sell you an engine? It's possible, but highly unlikely. Life is too short to spend locked in the engine-build room, says John, especially for a racing program that isn't totally committed to winning. A mere handful of customer engines have come from the Accufab engine room, a room that is dedicated to furthering John's racing.
This isn't a tale of overnight success. As you read this story, keep in mind that John Mihovetz has been harassing modular Fords since before they were sold in Mustangs. His accomplishments are truly spectacular, and it's best to recognize they've come at the expense of nearly 15 years of constant effort. And for those just checking in, John is the major blade at Accufab (www.accufabracing.com), a longtime performance manufacturer known for its polished billet throttle bodies. Under the same Accufab roof in Ontario, California is John's drag racing operation.
John started racing with pushrod 5.0s during the Fox era, and helped Jim Bell lay down impressive times with some of the first Kenne Bell-supercharged Mustangs. In 1995, a deal from a Ford insider put John in a 4.6-powered Fox Mustang. The car was an old FoMoCo engineering hack, and it set John on what's proving to be a life-long modular development program.
One of the modular pioneers, John has arguably gone further than anyone when it comes to extracting power from these somewhat intricate engines. For years now, he's been racing a tube-framed Mercury Cougar in NHRA and mainly PSCA, the Pacific Street Car Association. John was runner-up in the '07 PSCA Pro Street and slugged his way to the '08 class championship with four wins. He's also the three-time AA/AT and three-time BB/AT NHRA Competition Eliminator record-holder with the same car.
The Cougar is a dedicated Lenco-transmissioned drag car (see sidebar); to date, it's run a best of 6.31 seconds at 229 mph, and is a proven, steady laboratory for John's ceaseless modular engine development, which hovers at an astounding 2,300 hp. That makes it the undisputed horsepower-per-cubic-inch champion of the modular world, and one of two contenders for the straight-up most powerful modular engine in history. The accomplishment also puts the modular Ford far ahead of any current domestic engine in its ability to make and survive such power.
The "Stock" CombinationWhat makes John's power and speed so impressive is the small displacement and stock source for major portions of his engine program. Displacement is 282 ci--call it a stock 4.6 liters--using a stock aluminum Cobra block; stock old-style, "B" dual-port, Four-Valve cylinder heads, as found in a '95 Lincoln; and a stock 4.6 Cobra crankshaft. Twin Garrett turbochargers supply a mind-bending 52 pounds of boost on top of an over 11:1 static compression ratio on gasoline!
Frankly, the combination is so unbelievable that some members of Ford Racing recently came by to inspect the engine firsthand. They went away shaking their heads, with reset expectations of what regular production parts can generate. We'll admit to a similar reclocking, not only of how much power the stock parts can muster, but also by the attention to detail required by 8 hp per cubic inch, plus the amazing in-house capabilities of modern racers to manufacture their own supporting pieces.
Fred Grochulski is the other guy in the Accufab engine shop. Positive as a proton and able to talk an AM radio under the table, Fred brings the Accufab engine program near-fanatical attention to detail and a tireless enthusiasm for all things combustive. His background ranges from nuclear weapons in the Navy to martial arts, a stint at Livernois Motorsports, and a personal bent towards road racing and V-6 performance.
Generally speaking, John's combination is at the extreme edge. Being so highly tuned, it's easy enough to go too far, which at this level means certain detonation and instant engine death. Such was the case twice during the trying--although rewarding--'08 season. State-of-the-art also means further developments are frustratingly difficult to achieve. John invested many thousands of dollars in larger turbos and supporting headers in 2008, only to have them bog and run worse than the current combination. For now, those tubes and turbos sit ignobly in a large cardboard box in John's shop; in time they'll be modified in another attempt to benefit from their superior top-end power, while retaining the current combinations snappy holeshot action.
The ChallengesWith over a literal ton of horsepower, you'd think there would be enough, but John is racing against turbocharged big-blocks, so more is always better. But he must be careful not to give up his starting-line advantage. His relatively light, compact engine has been tuned for quick response, so it 60-foots quickly, like a nitrous car. There is a tradeoff: Even the sleek Cougar could use more outright horsepower during the second half of the quarter-mile when the competition's blown, 500-plus cubic inches makes itself known.
Backpressure is also an issue. There's over 60 psi between the exhaust valves and the turbos. This results in passive EGR, partially filling the cylinders with junk air, and killing power. More exhaust system tuning is definitely in the future.
Cost, of course, is a real issue. John is his own main sponsor, and if you count just half the time and most of the parts that go into it, then add the travel, entry fees, and so on, the fiscal challenge is clear. Racing being a disease practiced by the afflicted, we'll see John taking the treatments for a while yet.
John is also considering a displacement increase, albeit with mixed emotions. His 4.6 combination could be transferred to a larger-bore 5.4 block without excessive re-engineering, and considering the growing availability of aluminum blocks from Ford Racing, the move seems inevitable at some point. That said, a displacement increase will require bothersome retuning to say the least, and it's more fun to trip giants with the smallest possible engine.
In the meantime, few can approach the Accufab Mercury. Steve Matusek at Aeromotive is the only other modular racer in the same 6-second league, but his 323ci, destroked, 5.4 GT-based engine is a completely different animal. It uses a GT block, GT500 heads, and plenty of spending on the latest-and-greatest supporting pieces such as mechanical roller cams, a trick chaindrive, considerably larger turbos, and more. A shop towel would likely cover the small power spread between the two combinations--we'll give a slight power advantage to Steve because his heavier car has run a little more mph--but note that John makes his power with 40 fewer cubic inches and older technology, yet has run quicker e.t.'s. As Steve Matusek said, "The fact that they are both modulars is about all they have in common." In fact, John and Steve are friends, talk freely with each other, and are mutually complimentary about each others achievements.
And we're beyond impressed by what John has accomplished. Years of hard work and big bills have resulted in more power from a closer-to-stock combination than anyone could imagine. Plus, John has the behind-the-wheel talent and cajones to get it down the track quicker than anyone, and that's big when you have to pull into the lane next to him.
Driven by a quiet, powerfully focused personality, we expect John Mihovetz will be in the forefront of modular engine development for a long time to come. We can only imagine what sort of power will result, but it's bound to be impressive.
Quick KittyThinking he'd run in the then new NHRA Sport Compact series, John Mihovetz bought his race car eight years ago, but the V-8 section of the NHRA class was quickly eliminated, so John moved the program to NHRA Competition Eliminator, and eventually PSCA and FFW West Coast events.
Originally built in 1996 as a Mustang, the Accufab crew rebodied the tube-frame racer with Jerry Haas carbon-fiber Mercury Cougar panels during the winter of 2001, running the car for the first time in 2002. It has been modular-powered the entire time. The race weight is 2,650 pounds with John at the wheel. Of that weight, Accufab engine man Fred Grochulski estimates the completely dressed power plant accounts for a little over 500 pounds.
Behind the 4.6 is a now-four-speed Lenco transmission: a five-speed that John eventually fitted with a dummy shaft in place of Fifth as the car is faster with fewer gears. The rearend is a hand-fabricated, Don Ness titanium housing with 4.56 gears in a 9-inch final drive.
John leaves at 6,400-6,500 rpm; shifts at 9,400 rpm; and goes through the lights at 9,100 rpm. A Race Pak data acquisition system gathers the numbers, while a Koni shock controller with Lamb programming stiffens the shocks once it's in Second gear. A move to larger slicks and the wider tubs to accommodate them was required in 2008 to get the power to the ground.
Asked if he'd benefit from a newer chassis, John replied "not really." He certainly doesn't subscribe to the new metal chassis theory. He says there is certainly new technology available today, mainly in triangulation, to make a more rigid chassis, but all things considered, he's not convinced that it's automatically better.
"It depends on the track," says John. "It's a pretty flexible car, maybe more than it should be, but there is a place for a flexible car, depending on the track."
"It's pretty forgiving--goes down the track anywhere--but the really stiff cars tend to be more loose down track; it takes more wing to keep them planted."
"I'd like to have a new car, but I can make this one work. [This] one 60-foots as good as any car at that weight and power in the country. So there is no trouble." In fact, the modular Cougar 60-foots in the 1.0-second range, "really happy for a turbo engine. The nitrous guys are happy to have 1.0-second 60-foots. We get the same and the nitrous guys burn down trying to keep up."
John does admit to huge turbos: He has to watch his porting and valve sizes or the turbos are lazy to spool. This is important as John's advantage is quickness out of the hole and in the first half of the track. The disadvantage is that with only 281 ci, John can't give up his quick starts as the little engine--it's half the size of his competition--just can't make the raw power for the big numbers at the far end of the track. Hence future tuning requires careful turbo sizing and head porting, and ultimately, John could move to a 5.4-liter program if the need arises.
Here's another look at the connecting rod, as well as the custom-fit Total Seal rings. They are bought at 3.552-inch, file-fit, and measure a thin 1.2-, 1.5-, 3.0-mm thick; they sit well down from the piston crown. The dark piston pin is Casidiam-coated, as run in the drag car. Casidiam is a super-tough, diamond-like carbon coating useful in oil-dry environments, which describes John's highly evacuated, dry-sumped crankcase. Diamond Pistons supplies the Casidim under the Trend name. The piston is moly-coated on the skirt and features two small valve pockets on the crown.
You have to think an O-ring receiver groove is the first machining step when running 52 pounds of boost. It's followed by full chamber polishing, plus the porting, guide, and seat work. The seats and guides are the usual silicone bronze parts, but they are carefully installed using nitrogen chilling and diamond honing of the guides, which are held to 0.0001-inch accuracy.
Accufab does its own porting, starting with a CNC program and finishing by hand. The intake ports are not radically changed. The floor of the port is simply cleaned, while the roof and bowl are opened around the backside of the bowl. This makes more of an oval shape relatively deep in the intake port to keep the cross-sectional area the same throughout the port.
The exhaust ports are more rationalized than anything else, with a slight D-shape visible in the runner. Looking at this already-run head, it shows that port matching is clearly no big deal on the exhaust. It's also interesting how the square intake port's guide has been trimmed or set flush with the runner roof, but the oval port shows some guide to the intake wind.
At 52 pounds of boost, the head gaskets squeeze out no matter what, spraying water outward and downward--perfect for lubricating the rear slicks at 200 mph. As the catch pan under the engine can't capture this pressurized water, and even John can't drive on watered slicks at a football field-per-second speed, something had to done. For a while they thought trick gaskets, more torque, and dowel pins were the solution, but the gaskets still forcibly leaked.
The fix was to eliminate the water entirely at the block/head interface by blocking all coolant holes and routing the water externally using hoses at the rear of the block and heads. Here the blocking process is captured in mid-job, the passage at left having already been CNC'd to shape, and the passage to the right has its CNC'd plug nitrogen-chilled and installed. When all the plugs are in, the head is milled flat again. The same process is employed on the block deck, too, so even if the head gaskets give some--and they always do at 2,300 hp--they won't leak water.
In the beginning, John bought and ran other tuner's gear, but as he searched for more power, he's moved more and more to his own parts. The intake valve is one example: Considerable power was found by narrowing the lower stem and altering the transition to the head, so now Manley makes these valves for John. Interestingly no power was gained by fiddling with the exhaust valves.
Custom camming is obviously part of John's program. Comp Cams does the grinding, with the intakes measuring 256 at 0.050-inch lift and a total of 0.495 valve lift. It doesn't sound like much, but with all that boost pushing and a Four-Valve head, it doesn't take radical valve grinds to move literally tons of air. Fred says the cams feature easy ramps to keep the rocker arms alive. Like the stockers, there aren't any keyways retaining the cam sprockets to the cam, just 160 lb-ft of torque on Accufab-specific ARP retention bolts.
What's trick about the cams are their undercut lobes. This is done to dynamically balance the camshafts, as John tore the car apart to find a vibration at 6.500 rpm and higher. The parts-breaking buzz turned out to be the cams, which are now balanced in-house at Accufab by John. The actual cutting is done on old manual mills and is a real pain, according to John, but the results are worth it as the engine is now Lincoln-smooth and more powerful. We've never seen balanced cams before, but with four weighty shafts; large, heavy lobes; and high rpm, it's clear the cams could act like imbalance shafts.
Two Hogan Racing Manifolds have been used on the Accufab 4.6-liter recently. The first was named Anna Nicole, but it has since been replaced by this as-yet-unnamed second-generation intake, which flows an additional 20 cfm. Note that two injectors per runner are used, and the fuel is ingested from both ends of the fuel rail and balances in the middle. The injectors are placed as close to the combustion chamber as possible.
Ford has used large (common) and small (Cobra R, Ford GT, and GT500) lash adjusters. The older "B" head John uses employs the large lash adjusters, which he often grinds shorter on the bottom to put the lash adjustment where he wants it. The valvetrain is adjusted by way of valve-stem height, with each valve requiring individual adjustment, otherwise cylinder-to-cylinder breathing variations occur, says Fred, and getting the lash adjusters spot-on is part of the process. They've found these adjusters super sensitive to clearances, oil weights, and oil additive packages.
A single 90mm Accufab throttle body controls the airflow. It may sound small, but with 52 pounds of boost pushing things along, it can flow somewhere around 4,000 cfm. The black clamp and weld-on ferrule are Accufab's answer to the more complex and expensive Wiggens clamp previously run.
Dry-sump oiling is a given in the Accufab engine, along with what seems like powerful crankcase vacuum generated by this $2,100 Dailey Engineering dry-sump pump. It's a four-stage pickup pump and features a hex-socket drive, seen here at the far end of the pump. John runs a cable drive from this hex to the rear of the car, where it powers a high-volume mechanical fuel pump. The car is started using a small, electric boost pump, but once lit, the engine is supplied with fuel through the oil pump and cable drive.
As-installed, it's difficult to find the core engine under the air plumbing and wiring. Here the right cam cover--another stock part--plays host to the ignition coil packs. These are now Mercruiser-made Evinrude two-stroke coils, which are even hotter, lighter, and less expensive than their predecessors. Fred, who's gotten across these zappers, says they're "bad ass. [They'll] blow a hole in your arm!" Also seen is a fuel rail and bleed line, along with the tightly packed injectors.
He's run or experimented with various turbo configurations, but large-framed Garretts have proven the most powerful. This is the inlet side as it runs, with no air filter or other tubing other than the hoodscoops which feed directly to the turbo inlet. The large area around the smaller impeller inlet is a ported shroud; it bleeds some air off the impeller and back to the inlet to reduce surging when the blow-through throttle is snapped shut at the end of a run.
Yep, there's a single Accufab throttle body in all this. The stock 90mm unit is mounted behind the radiator on the intake's trunk-like entry.
So far, John's exhaust system has been upswept for packaging concerns. Eventually the heavy turbos will be low-mounted on a down-swept exhaust to improve the center of gravity for improved launch dynamics, but experiments in that direction have not worked so far.
Given up to 60 pounds of exhaust backpressure, tremendous temperatures, and generally hellish conditions all-around, the exhaust system is built of 321 stainless steel. Everything is exceptionally heavy-duty, including the -inch-thick flanges, 2-inch-diameter primary pipes, and Reid Washburn collectors. There's nothing stock, lightweight, or inexpensive here. The small ports are for the Race Pak V300 data acquisition system's EGT probes.
Even the starter motor has an Accufab twist. A Hitachi unit popular with racers, it features an aluminum adapter made by Accufab for Hitachi.
John had to make his own flywheel because none were available that would accept a Crower clutch. The result is this 14-pound CNC'd beauty. Starting life as a square slab of aluminum billet, the flywheel is whittled on the same in-house CNC machines that make the Accufab throttle bodies. The friction plates are segmented to avoid heat warping, and the bearing surfaces are diamond hardened. Accufab doesn't necessarily sell this flywheel, making it just for its own race car and a handful of engine customers.
With the transmission removed and looking forward through the firewall and missing bellhousing, the Crower three-plate clutch is front and center. The blue tubing is a water bypass running from the block to the back of the cylinder heads in support of the dry-deck modification. More mundane is the large, brown breather hose draped across the scene.
A wide-angle lens doesn't distort this detail of the radiator along side the oil tank; huge pressures inside the cooling system have deformed the compact heat exchanger. They're from combustion gas due to constant head gasket leaks from the unreal combustion pressures. Dry-decking the engine was the only way to put an end to this, but the bowed radiator remains.
Crawling on the shop floor and looking up at the right side of the engine compartment shows the Accufab CNC'd oil pan. It's part of a carefully controlled oil environment in the crankcase, plus its thick billet construction must aid block rigidity.