Bryce Mulvey and Mark “Poppy” Mulvey were first-time competitors at the ’13 AMSOIL Engine
Looking over the rules for the ’13 AMSOIL Engine Masters Challenge, Bryce Mulvey of Dr J’s Performance saw an opportunity. “The rules called for a street-style engine, and the cylinder heads portion restricted builders to replacement-style cylinder heads. This meant the cylinder head had to retain the factory port layout and position and use a production-style valvetrain. For a small-block Chevy, that meant no symmetrical port heads, no spread port or raised port heads, no shaft rockers, no altered valve angle—just a plain Chevy-style head. We make big port heads that require shaft rockers, but our AirWolf 220 head is just a basic small-block Chevy head that is all conventional and takes stud-mounted rockers. It fit the rules, and the Engine Masters Challenge seemed like a good place to show what our heads are capable of. The plan was to build an engine around a box stock set of our heads to show what they can do.”
Bryce started with a Dart Iron Eagle block, offering a top-quality foundation for the build. The block featured a raised cam position, adding clearance to ease the installation of a 4.00-inch stroke, and is virtually indestructible in a normally aspirated build. Though the block can take substantially more bore size, the bores were finished to a dimension of 4.165 inches for a displacement of 436 ci. Inside, a Callies crank took care of the stroke requirement, while Carrillo Bullet 6.00-inch rods linked the custom CP pistons filling the bores. Bryce relates, “I’ve built engines with pistons from a variety of manufacturers and find the CP pistons are the ones to use when every horsepower counts. Power, stability, and oil control are all going to play a part in how I judge a piston selection, and the CP pistons work on all counts.” The CP pistons were wrapped with Total Seal 1.2mm compression rings, with a 3mm oil ring completing the ring package.
Custom CP pistons are linked to the crank via a set of Carrillo’s new Bullet I-beam rods.
The pistons are cut for a low-friction ring pack from Total Seal featuring 1.2mm compressi
Achieving a compression ratio of 11.5:1 required a dished piston configuration. Note the D
The AMSOIL 5w/20 engine oil is circulated by a Melling oil pump. Bryce tells us the AMSOIL
A Moroso oil pan buttons up the bottom end, a unit that is designed to work with the wider
A full-flow Holley screen-type canister filter keeps the lubricant clean. Bryce relates th
To pump the AMSOIL lubricant in competition, a Melling high-volume pump pressurizes the priority main oiling system of the Dart block. Bryce added a Holley canister screen-style filter to the block, since the Iron Eagle deletes the factory filter provision. To fit the block’s wider pan rails, the bottom end was sealed off with a Moroso pan designed for the application. At the front, a Fluidampr crankshaft damper was squeezed onto the crank. All in all, the bottom end took top-quality aftermarket components and simply bolted them together. Bryce tells us, “We didn’t want to cut corners on the parts, so everything here was stuff proven to work. Other than the custom pistons, nothing was one-off or exotic. The parts in the bottom end were all just bolted in right out of the box.”
Cam, Valvetrain, Top End
The AMSOIL Engine Masters Challenge rules required a hydraulic roller cam, and here a custom spec ’shaft from Bullet Cams was shoved into the OEM-sized journals. The specifications were not mild at 264/268 degrees duration at 0.050 inch, but this was not a special one-off dyno competition grind—just their production hydraulic roller lobe profiles. The cam was cut on a 107-degree lobe-separation angle and installed at 102 degrees. Filling the bushed lifter bores of the block are a set of Isky retrofit hydraulic roller lifters. Bryce details, “Hydraulic rollers are very dependent on the lifter for rpm capabilities, and I can tell you for a fact they are not all created equal. Some definitely have an rpm advantage over others, and I’ve run quite a few. The Isky lifters deliver rpm capabilities, and that’s why I used them.” Converting the cam’s profile to lift is a set of Scorpion stud-mounted rockers at 1.7:1 intake ratio and 1.6:1 exhaust. The resultant valve lift is 0.680 inch.
The CNC-ported AirWolf 220 cylinder heads are replacement-style heads with all of the OEM
Air is directed to the cylinder heads via a Motown single-plane intake manifold. In ported
The Motown intake was fully ported by Dr J’s Performance, including the full plenum rework
Here we have a detailed view of the combustion chamber and seat machining of the AirWolf h
The AirWolf 220 heads accept standard Chevy-style stud-mounted rockers. Bryce went with a
Dr J’s Performance assembles its own line of high-performance custom carburetors under the
|Dr. J’s 436 Chevrolet Small-Block
|Team leader and members
||Bryce Mulvey, Mark Mulvey
|Bore x stroke
||4.165 x 4.00
|Connecting rod bearings
|Pistons and rings
||CP-Carrillo, Total Seal
|Compression and 2nd ring
||Bullet Racing cams
|Cam duration at 0.050
|Engine gasket set
||Dr J’s Colossus
|Spark plugs and wires
||Autolite, MSD Performance
|Hoses and fittings
|AMSOIL oil viscosity
Of course, the entire point of this exercise was to showcase the AirWolf 220 cylinder heads, and here Bryce just pulled a set from stock and bolted them on. These fully CNC-ported castings offer tremendous flow for a standard Chevy head, with intake flow capacity topping 330 cfm. As Bryce tells it, “I knew that almost every other engine would take advantage of radical custom porting, but I wanted to do it with heads we sell to customers every day. That meant no cheating up a raised port with a floor filled with mud or welding up and reshaping the head to a one-off port. The heads are hand-blended to the seat, but we do that with every set that we sell. I think we do about the best job possible with our development process for production and just let the heads stand on that.” Feeding the heads is a Motown single-plane intake manifold topped with a custom Dr J’s “Colossus” 4150 carb moving 1250 cfm of air.
To the Dyno
In Competition, the Dr J’s 436 Chevy came into qualifying on the first day of dyno testing, and the numbers were definitely stout. We have to say that 711 peak horsepower from a standard type of small-block is impressive—in fact, it was the highest output for an engine of this type seen in completion. With 628.5 lb-ft of torque, the engine was producing an incredible 1.44 lb-ft of torque per cubic inch. That is definitely full race territory, but without the high compression, solid roller, and race-style heads you might expect. The crew from Dr J’s came to the show to prove a point, and the numbers didn’t disappoint.
|Dr J’s Performance
Tested at UNOH
’13 AMSOIL EMC SuperFlow/DTS Dyno Data