PRODUCT DETAILS
Brian Crower Stage 2 Camshafts - K20A / K20Z / K24A2
Camshafts are where a K-series build stops being bolt-ons and starts being an engine. Brian Crower's Stage 2 profiles are machined from 8620 billet and come in two versions, one for naturally aspirated builds and one for forced induction, because those two applications want opposite things from a cam. Pick the right one and this is where the power you've been chasing finally shows up.
You Need Valve Springs, No Exceptions
Most important thing on this page, so read it before anything else.
These cams require Brian Crower kit BC0040 or BC0040S, which supplies dual valve springs, retainers, and seats. That's a hard requirement, not a recommendation.
Here's why it matters. Higher lift and more aggressive ramps ask considerably more of your valve springs than the factory profile does. Run these on stock springs and you get valve float at rpm, which means the valve doesn't close when it should. On an interference engine, that's a piston meeting a valve.
Upgraded valve keepers are also recommended while you're in there, since the retainer and keeper interface sees the same increased loads.
Budget for the spring kit as part of this purchase rather than a later addition. A set of cams without the valvetrain to support them is an expensive way to hurt an engine.
Naturally Aspirated Or Forced Induction?
These are genuinely different profiles solving different problems. Pick based on your build, not on which numbers look bigger.
Naturally aspirated (BC0042-2) runs 304°/300° advertised duration, 234°/228° at .050", and .525"/.472" lift. This is for high compression all-motor builds at 11.5:1 or above, and it also works on high boost setups running 18 psi or more. Pair it with a cold air intake, header, exhaust, ECU tuning, and fuel work to actually use it.
Forced induction (BC0041-2) runs 296°/300° advertised, 222°/224° at .050", and .520"/.497" lift. Shorter duration on the intake side reduces overlap, which builds cylinder pressure, while the high lift keeps air moving. That's exactly what a turbo or supercharged engine wants.
Why Boost Wants Less Duration
Worth understanding, because it's counterintuitive if you're used to naturally aspirated thinking.
On an all-motor engine, overlap is your friend. Exhaust gas leaving at speed helps pull the intake charge in, and more duration and overlap is how you take advantage of that scavenging effect.
On a boosted engine you've got a turbo forcing air in, so you don't need scavenging to fill the cylinder. What overlap does instead is let boost pressure blow straight out the exhaust valve while both are open, which wastes air and hurts cylinder pressure.
That's why the forced induction cam runs shorter duration. You're keeping the valves closed longer to hold pressure, while the high lift makes sure you're still flowing plenty of air when they are open. A big-duration NA cam on a boosted motor usually makes less power, not more.
Street Manners Aren't Sacrificed
The concern with any cam upgrade is turning the car into something you can't drive, and Brian Crower designed Stage 2 specifically to avoid that.
These deliver excellent street manners and idle quality despite the increase in lift and duration. The car still idles properly, still behaves in traffic, and still starts and drives like a car. That's a real engineering achievement on a cam this aggressive, and it's what separates Stage 2 from going further up the range.
Specifications
| Naturally Aspirated | Forced Induction | |
|---|---|---|
| Part number | BC0042-2 | BC0041-2 |
| Advertised duration | 304° / 300° | 296° / 300° |
| Duration at .050" | 234° / 228° | 222° / 224° |
| Valve lift (1.75:1) | .525" / .472" | .520" / .497" |
| Valve lift (mm) | 13.34 / 11.99 | 13.21 / 12.62 |
| Material | 8620 billet | 8620 billet |
You'll Need A Tune
Worth stating plainly. Cams change how the engine breathes across the entire rev range, and your existing tune was written for the factory profile.
Plan on dyno time after installation. That's not an optional refinement, it's how you get the power the cams are capable of and how you make sure the engine is safe while making it.
Fitment
Honda and Acura K20A, K20Z, and K24A2 engines.
Requires Brian Crower valve spring kit BC0040 or BC0040S. Upgraded valve keepers recommended.
Who Should Run These Cams
This is for the K-series builder who's done the bolt-ons, done the tune, and hit the ceiling of what a stock cam profile allows. High compression all-motor or a serious boosted setup, either way this is where the next real step comes from. Pick the profile matching your build, buy the spring kit at the same time, and book the dyno.
Fits: Honda and Acura K20A, K20Z, and K24A2. Part numbers: BC0042-2 (naturally aspirated) and BC0041-2 (forced induction). Material: 8620 billet. Required: Brian Crower valve spring kit BC0040 or BC0040S. Recommended: upgraded valve keepers. Also required: ECU tuning after installation.