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.”

Beefy Bottom

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.

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.

Vital Specs:
Dr. J’s 436 Chevrolet Small-Block
Qualifying score 2,604
Team leader and members Bryce Mulvey, Mark Mulvey
Engine type small-block Chevy
Claimed displacement 436 ci
Block Dart
Bore x stroke 4.165 x 4.00
Compression ratio 11.5:1
Compression height 1.00
Crankshaft Callies
Engine bearings MAHLE Clevite
Connecting rod CP-Carrillo
Connecting rod bearings MAHLE Clevite
Pistons and rings CP-Carrillo, Total Seal
Compression and 2nd ring 1.2, 1.2
Camshaft Bullet Racing cams
Cam duration at 0.050 264/268
Valve lift 0.680/0.680
Head gasket Fel-Pro, 0.041
Cylinder heads AirWolf 220
Valves (in/ex) Manley 2.125/1.60
Valve lifters Iskenderian
Pushrods Manley
Rocker arms Scorpion, 1.7/1.6
Engine gasket set Fel-Pro
Intake manifold World Products
Carb Dr J’s Colossus
Carb spacer Moroso
Ignition system MSD Performance
Spark plugs and wires Autolite, MSD Performance
Fasteners ARP
Flywheel PRW
Engine damper Fluidampr
Water pump Meziere
Headers Schoenfeld
Valve covers Pro Header
Hoses and fittings BSB Manufacturing
AMSOIL oil viscosity 5w20
Oil pump Melling
Oil pan Moroso
Mufflers Flowmaster

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.

Dyno Results
Dr J’s Performance
436-cid Chevrolet
Tested at UNOH
’13 AMSOIL EMC SuperFlow/DTS Dyno Data
3,000 511.5 292.1
3,100 504.4 297.7
3,200 489.2 298
3,300 489.6 307.6
3,400 508 328.9
3,500 529.2 352.6
3,600 545.2 373.7
3,700 558.2 393.3
3,800 570.3 412.6
3,900 580 430.7
4,000 588.1 447.9
4,100 594.1 463.8
4,200 597 477.4
4,300 597.8 489.5
4,400 600 502.7
4,500 600.1 514.2
4,600 603.2 528.3
4,700 610.3 546.2
4,800 616.4 563.3
4,900 620 578.5
5,000 623.6 593.7
5,100 626.6 608.5
5,200 628.4 622.1
5,300 628.5 634.2
5,400 627 644.7
5,500 624.4 653.9
5,600 623 664.3
5,700 619.9 672.7
5,800 617.9 682.3
5,900 614.5 690.3
6,000 610.4 697.3
6,100 604.4 702
6,200 598 705.9
6,300 591 709
6,400 583.8 711.4
6,500 573.7 710.1
6,600 564.5 709.4
6,700 553.3 705.9
6,800 542.3 702.2
6,900 533.2 700.5
7,000 524.2 698.7

Flowmaster Inc.
100 Stony Point Road
Suite 125
Santa Rosa
CA  95401
Moroso Performance Products
80 Carter Drive
CT  06437
925 Tower Ave.
WI  54880
Dr. J's Performance
436 S Montgomery Street
CA  92868
Comp Cams
3406 Democrat Road
TN  38118
180 Zoar Valley Road
NY  14141
CP Pistons
1902 Mc Gaw
CA  92614
CA  92870
Manley Performance Products
1960 Swarthmore Avenue
NJ  08701
5555 Garden Grove Blvd., Dept. CHP
CA  92683
VP Racing Fuels
P.O. Box 47878
San Antonio
TX  78265
Scorpion Performance
Callies Performance Products
901 South Union St
OH  44830
Melling Engine Parts
2620 Saradan Dr
PO Box 1188
MI  49204
MSD Ignition
Bullet Cams
8785 Old Craft Road
Olive Branch
MS  38654
Isky Racing Cams
16020 S. Broadway
CA  90248