Seeing Red: Pro Line And Dart Team Up On A Brand New Engine Design

There’s no denying that racing pushes the advanced development of engine programs. Look at the Gen-II Hemi for example. Its legendary performances and the emotion the mere mention of the name “Hemi” evokes is due to how it was developed to become the preeminent powerplant in drag racing in its day, and even today.

However, it’s usually the horse that leads the cart. That is, the OEMs create an engine and then the aftermarket optimizes it. But, what happens when the aftermarket decides that, rather than modifying designs that have been around for 50-plus years in some cases, they just create something purpose-built, designed to be exactly what the market wants, with no compromises?

I’m sure you’re already thinking about Top Fuel-style, crazy billet custom engine designs, with price tags in the “if you have to ask, you can’t afford it” zone. But, what if a company’s idea was to create a no-compromise engine design, and then work on making it affordable and fit into racing classes that aren’t full of million-dollar programs? Well, then you’d have Pro Line Racing’s newest “Red” engine program. By standardizing “custom” options and working with their partners to keep stock of the Red-specific parts, Pro Line is creating an affordable engine program without crazy “custom” lead times.

This is the initial block used for the prototype engine. While it’s a Dart billet aluminum dry-deck block, Pro Line Racing is working with Dart to develop a cast-aluminum version in both water-cooled and dry-deck designs.

Developing A Different Kind of Hybrid

Ok, maybe we shouldn’t have used the word “hybrid” because of the emotions it stirs up these days. But, in the strictest terms, the Red project is a hybrid — taking the best features from a number of different architectures and racing programs and combining them into a single new design.

“Late 2018, a collaboration between Dart Machinery and Pro Line Racing was conceived with the primary goal to design a purpose-built engine application for the Sportsman, LDR, X275 type of drag racer,” explains Eric Dillard, Co-Owner of Pro Line Racing.

“Proline had worked previously with James Lawrence and ProCharger Superchargers, so this success drove the project from its conception to recent on-track testing, as seen at the recent SCSN 16 in Las Vegas. The Blown Z28 Camaro that Lawrence showcased has a full billet version of what we are now working on, which is a cast block, heads, and manifold.”

The project has been 18 months in design and production which might seem like a lot at first blush, but once you consider that this is the development of an entirely new engine platform, which has been hampered by a worldwide pandemic, you start to realize what a feat the development actually is.

“The project team’s overriding purpose is to design several competitive and affordable options with a suitable power range,” Dillard says. “Right now we are working to complete a cast aluminum version of the engine at a competitive price point. The offering will be available in both solid and water-cooled applications, keeping as many internal parts as interchangeable as possible.”

The camshaft belongs to a cam family of its own and is totally unique to Proline Red. — Eric Dillard, Pro Line Racing

Mike Sanders, Dart’s Product Development Manager, explains what all is involved in creating a new cast bock. “Fortunately we already had a high-quality aluminum BBC casting available. The only stand-out difference was the cam height,” Sanders explains. “The billet block we designed has a 1.000-inch raised cam location. Our existing castings could accommodate a +.400-inch raised cam location.” The cast version of the block will be available both wet and dry versions, and will undergo a hot isostatic pressing (HIP) process to ensure the best quality castings possible.

Designing a new engine is a lofty goal, for sure, but so far, one which has been successful so far, as evidenced by the prototype engine we’re sharing with you in these articles. “Initially, the design was shaped on the Limited Drag Radial rules package. However, over time we were able to incorporate other packages due mainly to rule changes and product evolution,” Dillard shares. “Right now we are focusing on the supercharged design, however, in time, we may develop a turbo version.”

MGP Connecting Rods are spec’d for use in the Red builds. While all of the particular rod specifications aren’t released, we do know they use a 2.200-inch bearing and are 6.535 inches center-to-center. A little math tells us that length allows for the piston to have a 1.415-inch compression height.

The Heart of the Matter

This article will be focusing on the bottom-end of the new Red engine, which is serendipitous, because that is where a bulk of the innovation has taken place. It should be noted that, while this engine in Lawrence’s car uses a Dart billet aluminum block, that is because it is simply a prototype. The project’s aim is a cast aluminum block from Dart, with all the same features that were “rapid prototyped” in this billet version at a price point far below a billet block, with a maximum bore size of 4.600 when all is said and done.

While the Pro Line Red is based on a big-block Chevy and has a 10.200-inch deck height, don’t be fooled into thinking it’s a standard block design. “The block is unlike any other product currently available,” says Dillard. “The key difference being the lifter layout, which is unique to this platform. It was designed to eliminate the need for an offset lifter. The capability to use a centered lifter allows for a better pushrod angle and improved rocker geometry.”

Basing a new design around an existing architecture can post some design issues since there are some hard limits already in place, vs a clean-sheet design. “It created some unique challenges, but because of our extensive knowledge of the BBC platform that we acquired from our 4.900-inch [bore spacing] Pro Stock engine development, we had a really good idea of what would work and what wouldn’t. Using this knowledge we applied it to the BBC 4.840-inch architecture and hit a home run,” says Sanders.

A Callies Ultra Billet crankshaft with center counterweights, Ultra-Shed profiling, and Aero-Shed finishing was used for this application. It has a 4.500-inch stroke, and is double-keyed to handle the power related to the supercharger the Red will be getting.

Pushrod angle has long been a challenge in big-power engine designs. Things like large intake and exhaust ports and oversized lifters and pushrods tend to get in the way of each other really quickly. The extreme angles and shapes of components that result tend to be prone to wear and breakage since they are essentially, compromises in order to make everything work together.

Since the Red design is starting with those larger components in mind, all of these changes incorporated by the minds at Pro Line and Dart are aimed at eliminating the compromises and enhancing performance. “The camshaft location is raised to one-inch from stock [BBC location]. These changes allow for an increased pushrod diameter which in turn allows for better valvetrain stability,” says Dillard.

Sanders elaborated on the process, saying, “We didn’t have any extreme challenges with the block or bottom end. The lifter positions and bank angles in the block were all dictated by the cylinder head. We were able to move the lifters and bank angles enough to straighten the pushrod angle and increase the pushrod diameter for increased strength and reliability at high-RPM.”

Those design changes allow for a 1/2-inch diameter pushrod on the intake side and a massive 9/16-inch diameter pushrod on the exhaust side. Between the improved pushrod angles and the tree-trunk pushrods, valvetrain stability in the 9,000-rpm range is achieved. Yes, you read that right: nine thousand RPM.

To accommodate the one-inch-raised cam location, the Red program uses a Donovan camshaft gear drive unit. Besides being raised in order to straighten out the pushrod geometry, the 65mm cam bores allow for a much beefier cam core to be utilized in the creation of the Pro Line Racing custom camshafts.

The lifter bores are .937-inch right out of the gate, while the cylinders retain the standard big-block Chevy 4.840-inch bore spacing to comply with class rules and weight-breaks for altered bore-space combinations. As Dillard mentioned, the cam bore has been raised 1.00 inches from the standard big-block location.

In addition to the altered location, the journal diameter has been beefed up to a massive 65 millimeters. This is done not so much to be able to run larger lobe lift (although a larger base circle does allow you to run more lobe lift and less rocker ratio, to achieve the same lift at the valve with less leverage) but for its additional core strength and bearing surface.

And speaking of the camshaft, due to the unique lifter arrangement, the cam lobes have to be matched to the lifter locations. “The camshaft belongs to a cam family of its own and is totally unique to Pro Line Red,” Dillard explains — but more on that in the next article where we dive further into the top-end and valvetrain.

One of the Red program’s biggest features is the revised lifter locations. Besides the .937-inch lifter bore standard, the new locations allow for a much straighter pushrod and a centered rocker arm compared to a standard big-block Chevrolet, with a 1/2-inch diameter intake, and 9/16-inch diameter exhaust pushrods.

Rotating The Earth

In addition to the standard big-block Chevy bore-spacing, the PLR Red block design retains the BBC main journal spacing and sizing. While in theory, that might allow a standard big-block Chevy crankshaft to be used, for this engine and its specific operating parameters, a billet piece was chosen.

Using the standard main journal size of 2.750 inches, Callies machined one of its center-counterweighted Ultra Billet crankshafts out of Timken EN30B steel with a 4.500-inch stroke for the Red project, incorporating all the goodies one would expect from a Callies billet crank, like Ultra-Shed anti-windage counterweight profiling and Aero-Shed surface finishing. Pro Line specified a dual keyway on a standard BBC snout for the additional loads encountered with the supercharger.

At first glance, this might seem like a simple flat-top piston. However, the dome and the valve relief were painstakingly designed to be perfect, thanks to a 3D scan of the Red combustion chamber. Notice how deep that valve relief is sunk into the piston crown.

Standard 2.200-inch rod journals were specified for this particular engine, with Dillard explaining, “We have found that the big-block Chevy rod journal works well in a lot of applications.” This highlights Pro Line’s design philosophy with the Red program of making changes where needed, but not making changes just for the sake of being different.

Getting into the connecting rods, the team turned to a tried-and-true source of aluminum rods, MGP Connecting Rods. While some of the details of the connecting rod are being played close to the vest, Dillard did share that the rods are 6.535 inches long, center-to-center, but beam width and wrist pin specs weren’t disclosed. However, it was mentioned that the Clevite rod bearings have been narrowed and the rod bearings have a little extra clearance built into them.

While Pro Line hasn’t released the specs on the wrist pins, we do know that they are beefy and they utilize stronger (and more supportive of the oil ring rails) pin buttons to retain the pins within the pistons. Also note, even though we don’t have any specs on the piston ring package, they appear to be relatively thin, and lower on the piston, as you would expect in a big-power forced-induction application.

The pistons are 4.500-inch forged 2618 pieces from JE Pistons, and while at first glance look relatively plain, upon closer inspection you notice a very smooth dome and an incredibly deep valve relief for a massive 2.400-inch intake valve. “The pistons are designed specifically for this Pro Line engine program,” says JE’s Bryce Mulvey.

“The largest thing we focused on with this design was the valve pocket to ring groove distance. If you look at the back of the valve pocket where it intersects the ring groove, that can normally be a weak point under extreme loads. We had to ensure that the top ring land and the edge of the valve pocket left adequate material, to make sure the piston will be something that lasts.

This is the result of ultra-precise 3D scanning of the combustion chambers to incorporate into the design process. “The process [of developing these pistons] was relatively normal for us. The only challenge was creating a piston around a brand new head design from Dart on the project. We wanted to make sure this was something that would last an entire season, and not be lifting ring lands every few races.”

Real-World Testbed: BlownZ28

Since this engine is a prototype being designed for performance in one arena, it only makes sense that it is tested in the real world, not just on an engine dyno. For that, Pro Line dropped the engine between the frame rails of James Lawrence’s Limited Drag Radial 1969 Camaro, known as Project BlownZ28. You can check out the entire build series over on our sister site, Dragzine.

Additionally, Mulvey worked his engineering magic on the piston’s skirt design, in order to reduce piston rock at top and bottom-dead-center. “If your piston rocks a lot at the bottom, it can wreak havoc on your rings. So you want to make sure that the rings have the best chance of sealing at the top and bottom of the stroke,” Mulvey says.  The rings used are from Total Seal and are built to Pro Line’s exacting specifications but details beyond that are trade secrets.

A beefy Donovan cam gear drive designed specifically for the raised camshaft location is utilized to keep the cam in sync with the crankshaft. The oiling system is a dry-sump unit by Moroso built specifically for the ProCharger gear-drive unit. Using two tri-lobe scavenge stages and a single spur-gear pressure stage, the Moroso pump stack is about 40-percent more energy efficient when compared to similar gerotor designs. With -16 inlets and -12 outlets, the Moroso pump assembly is mounted to the supercharger gear drive for motive power and utilizes an off-the-shelf dry-sump oil pan from Moroso.

The 572 cubic-inch short-block in all of its glory. As you can see, it has a dry-sump oiling system utilizing an off-the-shelf big-block Chevrolet dry-sump oil pan from Moroso. On the right is the three-stage (two scavenge, one pressure) pump unit from Moroso which is mechanically driven off of the supercharger gear drive unit. Moroso says the tri-lobe scavenge sections and spur-gear pressure section are significantly more efficient than gerotor designs.

What all of that adds up to is 572 cubic-inches of 9,000-rpm-capable (no, that’s not hyperbole) short-block, which will serve as the base upon which to prove out Pro Line and Dart’s collective brainchild. Stay tuned in the coming weeks as we bring you the details on the top-end of the Red engine, along with details on its power adder and dyno results. This impressive package stands to really shake the market up.

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About the author

Greg Acosta

Greg has spent seventeen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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