The race is on to build cylinder heads to handle more boost. Several manufacturers explain just how they are overcoming the current challenges.

Tony McAfee from Dart Machinery was at the Texas Motorplex earlier this year for TX2K, billed as the “super bowl of street car events” and where drag racing is the focus.

He noticed something that speaks to a continuing trend in the high-performance and motorsports industries. “I don’t think there was a naturally aspirated car on the grounds,” he said.

With more street enthusiasts and racers seeking a boost from nitrous oxide, superchargers, or turbochargers, cylinder head manufacturers are among those taking notice.

While the effect of power-adders on head development isn’t new, it is “heavily, heavily accelerated,” McAfee added.

“I think the trend is power adder.”

Certainly, the contacts we made for this story, including Dart in Warren, Michigan, would support that theory. All of them have recent news regarding cylinder heads for boost.

 

“The industry across the board is moving to mostly boosted applications,” said Jesse Meagher of Frankenstein Engine Dynamics, Weatherford, Texas. “There aren’t as many naturally aspirated engines out there because they might cost twice as much and make half the horsepower. That’s a hard argument to make.”

From circle track to road racing, and especially drag racing, we take a case by case look at what some of the biggest names in cylinder heads are building for boost.

Design Difference

Jamie Wagner of Edelbrock in Olive Branch, Mississippi, said racers using boosted applications are asking more of their cylinder heads, in particular larger valves—especially intake—and larger port sizes.

“Bigger, better designed exhaust ports allow the spent gases to be pushed out of the cylinder more completely, resulting in a better environment inside the cylinder to allow the increased volume of air and fuel to enter,” he explained.

Wagner said boosted applications require more focus on volume in the runners than port design. “Boosted engines can overcome some of the issues in cylinder heads that would be detrimental to a normally aspirated application.”

Wagner reported that Edelbrock’s Victor CNC-ported LS7, LS3, and Gen III Hemi heads are “well suited for boosted applications.”

Victor heads are designed to maximize airflow into and out of the engine with large port volumes, but also with appropriate cross-sectional areas to ensure efficient flow.

Added boost or pressure comes at a price, Wagner noted, with additional parasitic drag on the engine in the case of a supercharger, and higher exhaust back pressures in the case of a turbo.

However, “a well-designed cylinder head allows more airflow into and out of the cylinder, which can give an increase in volumetric efficiency without the cost of increased inlet pressures. [It can] increase the overall power output with lower boost pressures,” Wagner said in discussing the Victor line.

It is important that some design features cross over from normally aspirated to boosted applications to retain good performance and drivability in off-boost conditions, such as idle and off-idle-to-boost transition, Wagner noted.

Built for Boost

Stronger materials like aluminum alloys, thicker deck surfaces to improve structural integrity and gasket retention, and enhanced heat resistance to prevent warping and cracking under extreme conditions are all characteristics of cylinder heads for boosted applications, according to Mark Ward from Air Flow Research (AFR) in Valencia, California.

Also, designs often incorporate better water-jacketing and cooling passages to manage increased heat, and port designs are refined to maximize airflow and fuel mixture. “These features collectively ensure that the cylinder heads can withstand the demanding conditions of high-performance boosted engines,” Ward said.

AFR’s 100% CNC-ported 224cc Black Hawk Gen III Hemi aluminum cylinder heads are outfitted with a 0.750-inch thick head deck that enhances overall strength and rigidity, Ward said.

Also, “we have improved the water-jacketing for enhanced cooling while retaining a minimum of 0.200-inch port-to-water-jacket thickness,” he added.

AFR also offers a Black Hawk Gen III Hemi as-cast head with 185cc intake runners and 69cc combustion chambers for the 5.7/6.1 platform. That version also has the same head deck and port-to-water-jacket thicknesses.

One of AFR’s newest heads is a 200cc intake/69cc combustion chamber complete as-cast version for the small block Chevy. “They come fully assembled with the identical components found in our higher-end CNC ported cylinder heads,” Ward said, noting things such as ARP rocker arm studs and stainless steel valves.

Head Hunting

The Head Hunter Series from Brodix in Mena, Arkansas, is the ideal product for this topic, reported Mark Fretz. “That’s the most popular head right now for a conventional [24-degree], cast-style, boosted application” in many drag racing classes, he said.

Fretz noted that while cast is not as durable as billet, “with all the advanced technology we have in the casting, the HIP-ing [hot isostatic pressing] process that we do, they’ve come a long way. We have guys who run a ton of boost [up to high-50s in pounds].”

Fretz noted the Brodix Ported Head Hunter Big Block (BP HH BB) 395 MC is also made with a special exhaust port, adding an “X” to its product ID—and a lot of power to the engine.

“That combination of cylinder head is well into the 3,000-horsepower range at the hub,” Fretz said, noting its use in radial tire drag classes and grudge racing.

One step under the Head Hunter is the BP BB 3-Xtra 380, which Fretz stated is popular in NHRA Top Dragster. “It’s an index class that can only run so fast, so you don’t need as much power,” he said.

As for a step above the Head Hunter, that’s the Sonny’s Design (designed by engine builder Sonny Leonard) 14 1/2 degree BP PB 2002. Popular in power-adder applications, it has a conical or “softened” combustion chamber that widens the tuning window for the head.

“That is a cylinder head that will flow right at 600 cfm, and it is the top head that we have,” Fretz explained.

Boost Monsters

Meagher at Frankenstein Engine Dynamics further discussed differences between boosted and naturally aspirated applications and how they manifest in the cylinder head.

“With a naturally aspirated setup, it’s often important to have a particular control over the exhaust flow,” he said. “But when you get into a boosted application, especially turbocharging, the reality is it’s just about getting it out—just get that gas out and spin that turbine, and away you go.”

The increased pressures of a boosted application make engine material and component choices vital, Meagher stressed, “to let it survive the performance we’re able to unlock.”

Frankenstein is building off its budget-minded Monster Series cylinder heads with a line of Boost Monster and Boost Monster Plus heads. Its M311 and M712—Monster versions of its LS3 and LS7 heads with 11- and 12-degree valve angles, respectively—have been upgraded to Boost Monster status with CHE bronze guides, Inconel exhaust valves, and upgraded port-flow characteristics.

Also, the M311 has a Boost Monster Plus version, which has a larger intake port along with the CHE bronze guides and Inconel exhaust valves, and a Plus version is coming for the M712 later this year. “It’s a really nice little package,” Meagher said.

Frankenstein’s cathedral port LS1 head, the M115, will also have Boost Monster and Boost Monster Plus iterations later this year, he added.

Most Monster head sales were going to drag racers, but that has expanded to include drifters, road racers, and sports cars, plus classic car, show car, and restoration builders. “With the Monster series, it’s at a price point and a performance level that really makes it a lot more viable to other applications,” he noted.

Boost Specific

Dart made “extreme exhaust port modifications” to its Big Chief 2 and Big Chief 3 cylinder head lines for boosted applications. The company also released a power-adder exhaust port option for its 380 Pro2 24-valve big block head earlier this year. Both lines are “specifically designed and marketed to the power-adder guys,” McAfee said.

 

The goal is to achieve better blow-off when the exhaust valve opens to handle the extra air and fuel found with nitrous oxide, supercharged, or turbocharged applications. “As we modify the exhaust port or go larger at the exit side, it always tends to make better power and equate to a better ET,” he said.

The Pro2, meanwhile, is designed for big-displacement engines turning up to 7,500 rpm. It’s used in bracket racing, heads-up, and super classes and is billed as a more cost-effective version of Dart’s Race Series casting.

Dart also has a new version of its 10-degree canted-valve LS head, which McAfee said flows 500 cfm at the intake—matching with a small block what the Big Chief big block did five years ago.

“It’s more for either big cubic-inch stuff or big cubic-inch supercharger, turbocharger, nitrous applications,” he said about uses in drag, road racing, and circle track.

When it comes to LS engines, McAfee said, naturally aspirated, big-cubic-inch setups have become rare. “It’s power-adder one direction or another.”

Solid Change

All Pro Aluminum Cylinder Heads in Johnstown, Ohio, has been doing “an awful lot” of solid cylinder heads—with no water jackets—for methanol-powered drag cars. They are based on All Pro’s LSW-12-4 or LSW-12-5 heads. “[It] seems to be unlimited in what you can do with those,” Robert Williams said.

 

Cars are towed to the starting line and from the finish line, but otherwise there’s no need to rush the cool-down. It does help that methanol burns cooler than gasoline. “When you get to the end you might still be only 140 degrees, so it’s not a big deal,” he said.

The solid head opens options for port design—but bigger isn’t always better. “The turbo stuff actually tends to like smaller ports in a lot of applications. And the supercharger’s the opposite—it likes a big port,” Williams explained. “They’re two totally different animals.”

Another benefit of the solid head: “Just brute strength.”

Overall, Williams described All Pro’s LSW Series of symmetrical port heads as “stout” and able to withstand a lot of cylinder pressure—up to 3,500 hp in some applications.

The use of larger head bolts and their placement toward the spark plug side—where LS engines tend to blow head gaskets with 8-mm factory bolts—is important. “[It] helps clamp the head better onto the block, under extreme conditions, without distorting the cylinder wall,” he said.

Cast-iron Strength

World Products in Louisville, Kentucky, known for its cast-iron heads, is selling some ported versions for boosted applications in marine, pulling, and street markets.

Iron holds up better for saltwater marine applications in particular, where larger boats may use three supercharged big block engines. “And they’re more durable, stronger,” Jack McInnis said about cast-iron powerplants.

Salt corrosion, durability, or, more simply, rules, are reasons someone chooses cast-iron over aluminum, reported McInnis.

As to porting cast-iron, it’s a little slower than cutting aluminum, he said, but some of the same airflow improvements can be achieved.

New Design, Same Wisdom

McInnis said “power-adder stuff” is indeed prevalent, especially in drag racing. “So people are making design changes to accommodate that or to suit it—things like adding strength, adding deck thickness, adding material in places where it’s more prone to be distorted or damaged.”

He explained that engine building wisdom has always been that when using forced induction, it forgives a lot in the cylinder head. But don’t be complacent, he cautioned. “If you’ve got a hot street motor and you stick a blower on it, it’s going to definitely pick it up. But if you’re in a class where everybody’s running boost, then the guy with the better setup is going to be faster.”

 

Lessons From Diesel

Matt Ryce of D&J Precision Machine in Cambridge, Ohio, cited the power of diesel when talking about one of the full-billet Cummins engines the company designed for the fellow horsepower-crazed Ohioans at Firepunk Diesel.

“I don’t even know if we can call it a diesel engine,” he joked. “It burns more nitrous.”

 

The serious point is that the diesel market knows a thing or two about big boost. D&J has developed cylinder heads—such as the one in Firepunk’s sub-4-second (in the eighth-mile) Duster—to withstand massive cylinder pressures.

“We’re in a much different world than the gas side in that 100 pounds of boost is normal. I’ve heard people go as high as 190,” he said. “It really comes down to having the strength to withstand it.”

D&J upgrades 6.7-liter Cummins diesel engines for drag racing applications with its Stage 3 and 4 Cummins Performance Heads. Stage 3 has a billet intake manifold, oversized super alloy intake and exhaust valves, titanium valve spring retainers, heavy-duty extra-large intake seats and thread-in soft plugs. Stage 4 has those features plus a billet runner style intake manifold and reusable O-ring seals.

Stage 3 and 4 units start with factory cast Cummins steel heads, Ryce said, because they can better withstand porting and are more consistent than aftermarket heads.

Ryce noted diesels will produce peak cylinder pressures higher than those of a Top Fuel dragster, if for a shorter period of time. “So it’s important to have the quality of the components and the strength to handle that sort of cylinder pressure,” he explained.

Ryce said more interaction between the diesel and gas worlds is possible as it relates to cylinder heads, including with direct-injection technology. “I see a big connection with all the new direct-injection stuff, because with diesels we’ve been doing that for years. Can they use some of the things we’ve learned in our direct-injection systems?” —Andy Heintzelman

 

Is Big Block Back?

Dart Machinery in Warren, Michigan, is in the process of revamping its Pro1 Big Block Chevy CNC ported line, with “very significant gains” in airflow numbers and lift range.

The reason for the upgrade is that Dart sees a “large resurgence” in big block Chevy applications on the street and strip, Steve Rhodey said.

“It’s almost dominating our tech lines right now over LS or small block Chevy, small block Ford,” he said in March.

Why?

“I don’t know if the new school is starting to fall in line with the old school,” Rhodey answered, “and realizing that they can make big power for probably a lot less money than some of the high-end LS stuff.” —Andy Heintzelman

 

Sources

Air Flow Research (AFR)
airflowresearch.com

All Pro Aluminum Cylinder Heads
allproheads.com

Brodix
brodix.com

D&J Precision Machine
djprecisionmachine.com

Dart Machinery
dartheads.com

Edelbrock
edelbrock.com

Frankenstein Engine Dynamics
frankensteined.net

World Products
pbm-erson.com