Testing Methodology

This test started with a simple premise: evaluate the available LS cathedral-port cylinder heads using consistent, controlled dyno and flow bench testing. Rather than rely on airflow numbers alone, the program included port-volume measurements and full dyno pulls to capture the complete performance picture.

This is part one of a series. The focus here is LS1/LS2/LS6 cathedral-port heads, with LS3 and LS7 testing to follow.

The Test Engine

With several heads in the group flowing beyond 300 cfm - enough to support more than 600 hp - a stock LS1 crate motor would have been the limiting factor. The test engine was a 408 stroker built with a 4.00-inch forged-steel crank, matching connecting rods, and forged dish-top pistons from Probe Racing.

The cam was a Comp Cams LSR cathedral-port hydraulic roller: 0.624-inch lift (with 1.7:1 rocker ratio), 239/247 duration at 0.050, and a 114-degree lobe-separation angle. Lift was slightly higher with the 1.72 roller rockers used on most heads.

Each set of heads ran with the same 1-7/8-inch American Racing headers and Fast XFI/XIM management system. Air/fuel was set to 13.0:1 at peak power rpm. All heads ran best at 30 degrees of total timing; sweeps in both directions (4 degrees each way) only lost power. Air and water temperatures were held consistent between runs.

Dyno pulls ran from 3,000 rpm to 6,700 rpm (some slightly higher where the power curve continued to climb). Data captured includes peak power, average horsepower and torque from 3,000 to 6,500 rpm, and torque at 4,000 rpm as a low-range indicator. Every head was also tested on the flow bench, with combustion chamber and intake port volume verified. Manufacturers supplied heads with 64cc chambers, and spring pressure sufficient for the 0.624-lift cam and 7,000-rpm potential.

Reading the Results

The manufacturers demonstrated confidence in their products by submitting them to this level of scrutiny. However, dyno results are application-specific. This combination of displacement, cam timing, and intake may favour certain head configurations over others. On a different engine, the results would differ. On many heads, the margin was only a few horsepower - within the range of test-to-test variation.

The dyno graphs provided with each head compare directly against the stock head curve.

Test 1: Stock LS1

Baseline

Retail price: N/A | Intake valve: 2.0" | Exhaust valve: 1.55" | Intake port volume: 205 cc | Exhaust port volume: 70 cc | Chamber volume: 68 cc

Peak power: 549.6 hp at 6,200 rpm | Peak torque: 517.2 lb-ft at 4,800 rpm | Average hp (3,000-6,500): 442.1 | Average torque (3,000-6,500): 488.7 lb-ft | Torque at 4,000 rpm: 499.8 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 32/24 | 0.100: 64/55 | 0.200: 137/106 | 0.300: 190/141 | 0.400: 216/179 | 0.500: 228/193 | 0.600: 238/203 | 0.650: 242/204 | 0.700: 244/206

The stock LS1 heads (241 castings) established the baseline. With 68cc combustion chambers, compression was slightly lower than the test heads, but the primary difference is airflow: the stock heads peak at 244 cfm. Despite being well below the aftermarket heads, the 241 castings still represent a significant step over traditional small-block castings - flowing 40 cfm more than the factory fuelie heads of the late 1960s. The 241 castings feature 205cc intake ports, 70cc exhaust ports, and a 2.0/1.55 valve combination. The LS6 (243 castings) would be the factory high-performance option, but even the stock LS1 heads respond well to proper porting.

Test 2: AFR 245

Retail price: $2,699 | Intake valve: 2.160" | Exhaust valve: 1.6" | Intake port volume: 244 cc | Exhaust port volume: 87 cc | Chamber volume: 64 cc

Peak power: 622.1 hp at 6,400 rpm | Peak torque: 558.3 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 474.9 | Average torque (3,000-6,500): 519.7 lb-ft | Torque at 4,000 rpm: 511.7 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 34/27 | 0.100: 68/55 | 0.200: 152/117 | 0.300: 225/176 | 0.400: 278/214 | 0.500: 318/230 | 0.600: 343/241 | 0.650: 352/240 | 0.700: 341/242

The Air Flow Research 245 heads registered 352 cfm at 0.650 lift - second only to the Mast LS3 heads in size. The AFR 245s feature 2.160-inch intake valves with 1.60 exhaust valves. These heads are likely better suited to a larger-bore motor and a more aggressive combination, but they performed well on the 408. Peak torque of 558 lb-ft matched the TFS and Texas Speed results, exceeded only by the Mast LS3 heads.

Test 3: Dart Pro 1 CNC 250

Retail price: $2,796 | Intake valve: 2.08" | Exhaust valve: 1.60" | Intake port volume: 249 cc | Exhaust port volume: 94 cc | Chamber volume: 64 cc

Peak power: 613.2 hp at 6,400 rpm | Peak torque: 554.6 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 473.9 | Average torque (3,000-6,500): 519.5 lb-ft | Torque at 4,000 rpm: 509.8 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 37/24 | 0.100: 70/54 | 0.200: 144/110 | 0.300: 216/157 | 0.400: 265/196 | 0.500: 304/225 | 0.600: 318/235 | 0.650: 322/238 | 0.700: 317/240

The Dart Pro 1 name is established in the LS market. At 250 cc, these are the largest cathedral-port heads in the test (eclipsed only by the Mast rectangular-port LS3 heads). The 2.08/1.60 valve package produced enough peak intake flow to support more than 600 hp. Despite the significant port volume increase, the Dart head still delivered 10 lb-ft more than the stock head at 4,000 rpm. The takeaway: the critical factor in power production is airflow relative to port volume, not port volume alone. The AFR heads flowed more on the bench, yet the Dart units with larger ports and less flow made nearly equal power.

Test 4: LPE Edelbrock

Retail price: $2,995 | Intake valve: 2.10" | Exhaust valve: 1.60" | Intake port volume: 234 cc | Exhaust port volume: 84 cc | Chamber volume: 64 cc

Peak power: 615.7 hp at 6,600 rpm | Peak torque: 553.7 lb-ft at 5,300 rpm | Average hp (3,000-6,500): 474.9 | Average torque (3,000-6,500): 520.9 lb-ft | Torque at 4,000 rpm: 516.7 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 32/24 | 0.100: 63/53 | 0.200: 129/110 | 0.300: 191/160 | 0.400: 245/196 | 0.500: 284/213 | 0.600: 318/222 | 0.650: 321/225 | 0.700: 305/227

The late John Lingenfelter was a serious racer and engine builder, and that commitment to quality has carried forward at Lingenfelter Performance Engineering. Starting with as-cast Edelbrock LS1 heads, LPE runs them through its own CNC program to improve flow and power potential. The completed LPE Edelbrock heads feature a 2.10/1.60 valve package, 235/84cc intake/exhaust port volumes, and 64cc combustion chambers. At 4,000 rpm, the LPE heads produced 516.7 lb-ft and gained more than 65 hp over the stock LS1 heads.

Test 5: Mast Black Label LS3 (Small Bore)

Retail price: $2,998 | Intake valve: 2.165" | Exhaust valve: 1.60" | Intake port volume: 257 cc | Exhaust port volume: 86 cc | Chamber volume: 64 cc

Peak power: 620.1 hp at 6,600 rpm | Peak torque: 563.3 lb-ft at 5,300 rpm | Average hp (3,000-6,500): 477.4 | Average torque (3,000-6,500): 523.4 lb-ft | Torque at 4,000 rpm: 514.3 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 34/24 | 0.100: 70/52 | 0.200: 142/110 | 0.300: 215/143 | 0.400: 274/205 | 0.500: 313/225 | 0.600: 342/239 | 0.650: 352/247 | 0.700: 335/250

This rectangular-port head does not strictly belong in a cathedral-port test, but its inclusion is deliberate. Like the cathedral-port heads, this small-bore LS3 head was designed for a 4.030-bore application, making it a direct market competitor despite requiring an LS3 intake and offset rocker arms. The second reason: testing whether the larger port volume would cost low-speed power. The conventional view holds that larger ports decrease cylinder filling at lower engine speeds. The data did not support that assumption. Despite 257cc intake ports and the largest 2.165-inch intake valves, the Mast heads produced the highest peak torque of any head in the test: 563 lb-ft at 5,300 rpm. The larger ports did not hinder average power numbers either. As this test went to publication, Mast announced a new line of 14 different LS heads, including cathedral ports.

Test 6: ProComp Motorsport LS1

Retail price: $1,875 | Intake valve: 2.055" | Exhaust valve: 1.60" | Intake port volume: 219 cc | Exhaust port volume: 79 cc | Chamber volume: 63 cc

Peak power: 629.1 hp at 6,600 rpm | Peak torque: 557.0 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 476.6 | Average torque (3,000-6,500): 521.3 lb-ft | Torque at 4,000 rpm: 509.9 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 34/25 | 0.100: 72/57 | 0.200: 148/113 | 0.300: 203/155 | 0.400: 261/195 | 0.500: 301/213 | 0.600: 321/219 | 0.650: 321/223 | 0.700: 306/224

This is precisely why dyno testing matters. The heads with the smallest port volume in the test produced the highest peak power. The CNC-ported LS1 heads from ProComp Motorsport are a new dedicated casting, engineered to compete directly with established heads at a lower price point. At 219 cc with 2.055-inch intake valves, the flow rates reached 321 cfm - more than sufficient for the test engine. The smaller port volume and intake valve traded low-speed torque for additional top-end power relative to other heads in the group.

Test 7: TEA LS6

Retail price: $1,320 (porting on customer-supplied castings) | Intake valve: 2.055" | Exhaust valve: 1.575" | Intake port volume: 226 cc | Exhaust port volume: 78 cc | Chamber volume: 63 cc

Peak power: 618.1 hp at 6,300 rpm | Peak torque: 555.3 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 476.1 | Average torque (3,000-6,500): 521.8 lb-ft | Torque at 4,000 rpm: 515.1 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 33/26 | 0.100: 66/60 | 0.200: 144/118 | 0.300: 214/163 | 0.400: 269/199 | 0.500: 310/223 | 0.600: 329/235 | 0.650: 330/230 | 0.700: 310/231

One set of ported factory castings was included to represent what is achievable with stock LS6 heads in the hands of a skilled porter. These Stage 2 heads from Total Engine Airflow feature CNC porting, a 2.055/1.575 valve package, and 63cc combustion chambers. The TEA LS6 heads flow 330 cfm with strong midlift numbers. The ported LS6 was also the lightest head in the test - a weight advantage that effectively translates to additional power at the vehicle level. Down only a few horsepower from the top of the group, porting a set of stock LS6 heads remains a cost-effective alternative to new castings, particularly for builders who already own a set.

Test 8: Texas Speed 237

Retail price: $2,199 | Intake valve: 2.10" | Exhaust valve: 1.60" | Intake port volume: 238 cc | Exhaust port volume: 85 cc | Chamber volume: 64 cc

Peak power: 621.3 hp at 6,700 rpm | Peak torque: 558.4 lb-ft at 5,300 rpm | Average hp (3,000-6,500): 477.5 | Average torque (3,000-6,500): 523.3 lb-ft | Torque at 4,000 rpm: 514.5 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 34/27 | 0.100: 72/59 | 0.200: 149/115 | 0.300: 226/176 | 0.400: 281/217 | 0.500: 317/234 | 0.600: 336/242 | 0.650: 345/243 | 0.700: 351/244

The Texas Speed 237cc heads are dedicated castings with additional head boltholes for use on aftermarket LSX blocks - a feature that provides extra clamping force for high-boost turbo applications. The 2.10/1.60 valve package combined with 238/85cc port volumes to maximise airflow. After the AFR 245 heads, the TS heads produced the highest 0.500-lift flow numbers. Power production was equally strong, with average numbers bettered only by the Trick Flow GenX head.

Test 9: Trick Flow 235

Retail price: $2,550 | Intake valve: 2.08" | Exhaust valve: 1.60" | Intake port volume: 234 cc | Exhaust port volume: 80 cc | Chamber volume: 64 cc

Peak power: 619.1 hp at 6,400 rpm | Peak torque: 558.2 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 478.4 | Average torque (3,000-6,500): 524.6 lb-ft | Torque at 4,000 rpm: 517.7 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 34/25 | 0.100: 67/57 | 0.200: 144/113 | 0.300: 221/172 | 0.400: 272/213 | 0.500: 309/230 | 0.600: 333/240 | 0.650: 323/240 | 0.700: 315/244

The Trick Flow Specialties GenX 235 heads have previously exceeded 700 hp on a larger 454ci stroker. On the 408, the 2.08/1.60 valve package with 234cc intake ports (measured at 234 cc) took top torque honours among the cathedral-port heads, though by only 0.1 lb-ft. Whether peak power or average power across a given range matters more depends on the application - which is why both metrics are provided.

Test 10: West Coast Cylinder Head Edelbrock 245

Retail price: $2,385 | Intake valve: 2.08" | Exhaust valve: 1.60" | Intake port volume: 243 cc | Exhaust port volume: 88 cc | Chamber volume: 64 cc

Peak power: 618.9 hp at 6,400 rpm | Peak torque: 554.0 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 475.5 | Average torque (3,000-6,500): 521.3 lb-ft | Torque at 4,000 rpm: 515.4 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 34/24 | 0.100: 69/54 | 0.200: 146/115 | 0.300: 203/171 | 0.400: 254/210 | 0.500: 300/231 | 0.600: 325/238 | 0.650: 323/240 | 0.700: 324/240

The second set of ported Edelbrock LS1 heads in the test came from West Coast Cylinder Heads. Like the LPE pair, these feature 64cc combustion chambers but differ in intake valve size (2.08 versus 2.10) and port volumes. The WCCH CNC program produced larger intake and exhaust ports at 243 and 88 cc. The larger ports improved flow, peaking at 325 cfm, and that additional airflow was visible on the dyno. With the exception of the stock heads, every head in the test produced peak torque at either 5,300 or 5,400 rpm - a consistent result despite dramatic variation in flow and port volumes. The Edelbrock casting's popularity among head porters is well founded.

Test 11: World Products Warhawk 255

Retail price: $2,790 | Intake valve: 2.10" | Exhaust valve: 1.60" | Intake port volume: 255 cc | Exhaust port volume: 87 cc | Chamber volume: 64 cc

Peak power: 602.3 hp at 6,500 rpm | Peak torque: 542.2 lb-ft at 5,400 rpm | Average hp (3,000-6,500): 466.6 | Average torque (3,000-6,500): 512.3 lb-ft | Torque at 4,000 rpm: 506.0 lb-ft

Flow Data: CFM at 28 Inches

Lift | Intake | Exhaust: 0.050: 35/25 | 0.100: 63/56 | 0.200: 137/115 | 0.300: 200/165 | 0.400: 260/198 | 0.500: 297/214 | 0.600: 313/224 | 0.650: 324/228 | 0.700: 328/233

The Warhawk heads from World Products are available in as-cast 235 and 255cc CNC-ported versions. Design features include a 0.750-inch-thick deck surface to minimise distortion and maximise sealing, a raised valve cover rail for aftermarket valvetrain components, and Manley stainless steel valves. CNC porting by Kuntz & Kraft produced peak flow of 325 cfm with a 2.10/1.60 valve combination.

One testing note: the raised valve cover rail prevented the use of roller rockers without grinding the rail. To avoid modifying heads scheduled for return, factory rockers were used in place of the 1.72:1 roller rockers. Previous testing has shown the roller rockers to be worth 8 to 10 hp, so these numbers are likely conservative.