Why Valvesprings Matter on LS Cam Swaps

Installing a performance camshaft on an LS engine requires a valvespring upgrade. The factory LS1 springs tolerate roughly .520 lift (LS6 and LS3 slightly more), but aftermarket performance cams can reach .624 lift or higher. Running a high-lift cam on stock springs leads to coil bind and catastrophic valvetrain failure.

The spring upgrade addresses two variables: increased lift and increased operating speed. Higher-duration cams push the effective rev range upward, and the springs must provide enough pressure to maintain valve control at those speeds. Insufficient pressure leads to valve loft - where the roller lifter launches off the cam lobe during the opening event - or valve bounce, where the valve rebounds after seating on the closing side.

The Other Side: Excessive Spring Pressure

More spring pressure is not always the answer. Excessive pressure accelerates wear on cam lobes, rockers, and valve tips. On LS applications, the combination of high lift and excessive spring pressure can also shorten valve guide life, particularly with aftermarket bronze guides. Spring selection requires matching rate to the cam profile - enough pressure for control, without introducing unnecessary friction losses.

There is also a direct power cost. Compressing higher-rate springs consumes energy, and that energy comes from the engine's output. This dyno session was designed to measure exactly how much power valvespring upgrades absorb.

Test Setup: LS3 Crate Motor

The test engine was an LS3 crate motor from Gandrud Chevrolet, managed by a Holley HP standalone system with a complete Aeromotive fuel system. Air/fuel ratio was held at 13.0:1 and timing was optimized and held constant across all spring tests. The engine ran long-tube headers into a 3-inch exhaust with mufflers, and an electric water pump eliminated accessory drive losses.

Repeatability was confirmed before testing began - a critical factor when measuring changes as small as a few horsepower from a spring swap.

Test 1: Stock Springs vs. Comp Cams 26918 Beehive Springs (Stock Cam)

With the stock cam and stock springs, the LS3 produced 516 hp at 5,900 rpm and 501 lb-ft of torque at 4,800 rpm.

A Crane Cams valvespring tool made the on-dyno spring swap efficient - compressing the stock springs, removing the locks, and installing the Comp Cams 26918 beehive springs without pulling the heads.

With the beehive springs installed, power dropped slightly to 512 hp - a 4 hp loss concentrated above 5,500 rpm. Torque remained at 501 lb-ft.

Test 2: Beehive vs. BTR Dual Springs (Performance Cam + Speedmaster Intake)

For the second comparison, the LS3 received a cam and intake swap. The stock cam was replaced with a Brian Tooley Racing profile offering .624/.590 lift, 232/248 duration, and 114-degree LSA. The stock intake was replaced with a Speedmaster fabricated high-rpm intake manifold, modified with radiused port entries to maximize airflow at elevated engine speeds.

With the BTR cam, beehive springs, and Speedmaster intake, the LS3 produced 590 hp at 6,800 rpm and 493 lb-ft at 5,800 rpm - peak power shifted 900-1,000 rpm higher than the stock cam configuration.

Swapping the beehive springs for BTR's dual-spring upgrade produced virtually no change: 589 hp and 492 lb-ft. The additional spring rate required for the high-lift cam did not measurably affect output.

What the Data Shows

On the stock cam, upgrading from factory springs to Comp Cams beehive springs cost 4 hp above 5,500 rpm. On the performance cam with the Speedmaster fabricated intake, switching from beehive to dual springs produced no measurable loss. In both cases, the power absorbed by increased spring pressure was minimal.

The practical conclusion: a valvespring upgrade is a necessary part of any LS performance cam swap, and the power cost is negligible compared to the gains the cam itself delivers. On this LS3, the BTR cam and Speedmaster intake combination added 74 hp over the stock configuration. The 4 hp consumed by the springs is a small and acceptable trade-off for the valve control required to run that cam safely at 6,800 rpm.