well below the power peak. In fact, street engines spend most of their time well under the torque peak and even during hard acceleration, the engine operates primarily between peak torque and peak power.
Holley’s single-plane intake was designed to optimize power production higher in the rev range than the dual-plane. Just make sure to apply it to the proper combination that can take full advantage of the top-end power production.
The choice ultimately comes down to where you value power production. For those new to LS performance (though this applies to every type of V-8 regardless of generation or manufacturer), the intake debate between single- and dual-plane manifolds is a simple matter of operating (engine) speed. The dual-plane was designed to enhance power production lower in the rev range than the single-plane. This simple fact makes the dual-plane ideal for the vast majority of street applications.
Run on the LS3 test engine (with mild Comp cam), the Holley dual-plane produced peak numbers of 544 hp at 6,900 rpm and 471 ft-lbs of torque at 4,300 rpm. After installation of the single-plane intake, the peak numbers changed very little to 552 hp at 7,000 rpm and 463 ft-lbs at 5,200 rpm. Despite minor changes in peak power, the power curves were decidedly different. Check out the curves and decide where you want your LS3 power production.
Most street and street/strip (carbureted) LS3 applications prefer the dual-plane design because of improved throttle response at lower RPM. The dual-plane was designed to maximize low- and mid-range torque production where it can be enjoyed most often.
Holley Single- vs Dual-Plane Intake on an LS3 (Horsepower)
Holley Dual-Plane: 544 hp @ 6,900 rpm
Holley Single-Plane: 552 hp @ 7,000 rpm
Largest Gain: 14 hp @ 7,200 rpm
The horsepower curves show a number of things, including the fact that the single-plane intake did indeed make more peak power than the dual-plane design, but not by much. Starting at 5,000 rpm, the single-plane pulled ahead, but the power difference was minimal. Run out to 7,200 rpm, the single-plane showed its worth by besting the dual-plane by 14 hp.
Holley Single- vs Dual-Plane Intake on an LS3 (Torque)
Holley Dual-Plane: 471 ft-lbs @ 4,300 rpm
Holley Single-Plane: 463 ft-lbs @ 5,200 rpm
Largest Gain: 54 ft-lbs @ 3,500 rpm
In terms of torque production, there really was no contest. Even though peak torque production differed by just 8 ft-lbs, the dual-plane offered gains that exceeded 50 ft-lbs down low. The additional torque offered by the dual-plane in the low- and mid-range is why it is usually chosen over the single-plane for most street applications. I even tested the dual-plane design under boost on a cathedral-port LS application with excellent results. If it’s better naturally aspirated (NA), then it’s better under boost!
Test 2: FAST LSXR vs Mast Carbureted Single-Plane
This test offered a comparison between a long- and short-runner intake design. In fact, I used nearly the same 468-stroker test engine to compare the Mast single-plane intake to the FAST LSXR LS3 manifold. The 468 featured a Darton-sleeved block stuffed with a Lunati crank and rods teamed with JE forged pistons. Unlike the previous test, the 468 was topped with Mast black-Label LS3 heads.
The combination also included factory LS3 rockers, Comp hardened pushrods, and Kooks 1⅞-inch stainless headers. Also present was a Milodon oil pan and windage tray, Meziere electric water pump, and FAST 75-pound injectors. The finishing touch was, of course, the FAST LSXR LS3 intake manifold and 102-mm Big Mouth throttle body. Equipped with the FAST LSXR intake, the 468 produced 732 hp at 6,400 rpm and 665 ft-lbs of torque at 5,200 rpm.
After running the FAST intake, I replaced the EFI system (FAST XFI/XIM) with the Mast single-plane intake. The Mast intake featured a two-piece construction, which allowed them to fully CNC port the internals. This thing was a work of art; the kind you hate to install and get dirty.
The Mast intake was flanged to accept a 4500-series Holley carburetor. To feed the 468, I installed a Holley 1050 Ultra Dominator. The Mast intake was also designed to run in injected form, so I plugged the injector holes with a set of 19-pound Ford injectors. Equipped with the Mast intake, the power output of the 468 increased to 761 hp and 645 ft-lbs of torque. Not that the peak power rose, but the peak torque dropped compared to the FAST intake. In fact, the long-runner FAST intake offered more power up to 5,900 rpm, but the Mast single-plane pulled away up to 6,700 rpm.
The two-piece Mast LSX intake was designed for high-RPM high-horsepower LS3 applications. (The company also offers cathedral-port and LS7 versions.)
Likely designed for slightly smaller and milder applications, the FAST LSXR intake performed well on this 468-inch stroker. It is hard to argue with more than 730 hp from any manifold.
FAST LSXR vs Mast Carbureted Single-Plane (Horsepower)
FAST LSXR LS3: 732 hp @ 6,400 rpm
Mast Carbureted Single-Plane: 761 hp @ 6,500 rpm
Largest Gain: 47 hp @ 6,700 rpm
The high-RPM nature of the single-plane intake was evident in this curve. The CNC-ported Mast intake was a work of art and boy, did it pull hard on the top end. Unfortunately, all the top-end power came with a trade-off lower in the rev range; in this case, below 5,900 rpm.
FAST LSXR vs Mast Carbureted Single-Plane (Torque)
FAST LSXR LS3: 614 ft-lbs @ 5,100 rpm
Mast Carbureted Single-Plane: 631 ft-lbs @ 5,300 rpm
