Does a bigger cam mean more power? A comprehensive look

As an avid auto enthusiast and amateur engine builder, I‘m often asked if installing a bigger camshaft results in more horsepower. The short answer is yes, increasing cam duration and lift can dramatically increase peak power potential. But there‘s much more nuance to selecting the right cam profile and supporting mods for maximum gains. In this comprehensive guide, we‘ll explore cam design principles, supporting components, optimal configs, and real-world results. Buckle up for a deep dive!

Camshaft design fundamentals

Before jumping into bigger cams, let‘s review some key camshaft design fundamentals:

Duration – The number of crankshaft degrees (°) the cam keeps a valve open. More duration means valves stay open longer for more intake and exhaust flow.

Lift – The maximum valve opening height in inches (or mm). More lift flows more air/fuel mixture.

Lobe Separation Angle (LSA) – The angle between peak intake and exhaust lobe positions. Tighter LSAs increase overlap.

Overlap – The period both intake and exhaust valves are open, measured in crankshaft degrees. Overlap scavenges combustion chamber.

Intake Centerline – The crank angle position where peak intake lift occurs. Affects torque curve.

Exhaust Centerline – Crank angle at peak exhaust lift. Later exhaust improves top-end flow.

Installing bigger cams primarily means increasing duration and lift. But LSA, centerlines and overlap also change the powerband. Now let‘s see how…

How duration and lift affect engine power

More duration advances intake opening and delays closing for increased valve overlap. This keeps the cylinders scavenged for better breathing. Higher lift simply flows more air and fuel mixture into each cylinder.

• For example, increasing duration from 220° to 250° might add 30 horsepower, while adding 0.100" more lift nets 15 horsepower. Combining both can yield 50+ hp gains.

• Durations over 280° require supporting upgrades. Lift over 0.600" often needs new valves, springs and retainers to prevent valve train binding.

Key takeaway: Smartly increasing duration and lift makes more horsepower by improving cylinder filling and intake/exhaust flow.

Typical cam upgrade levels

Here are some typical camshaft upgrade levels and their advertised power gains:

• Stock replacement cams – Minor increase over stock. Improves throttle response. Gains of ~10%.

• Stage 1 cams – Entry performance. Adds 20-40 HP.

• Stage 2 cams – More aggressive. 30% gains or 60+ HP.

• Stage 3 cams – Serious power. Up to 100+ HP over stock. Race profiles.

• Stage 4 cams – Max effort racing. 450+ peak HP requires supporting engine build.

These are generalizations – exact gains depend on the engine combo. But the trend is clear – more aggressive cam profiles make big power. Now let‘s look at real-world results.

Cam test data on an LS engine

This cam dyno test on a 383 LS stroker engine clearly shows the power difference from mild to wild cams:

Duration increased by 44° and lift by 0.212" for a 111 hp gain! An aggressive cam nets major results, but a smart supporting build is crucial…

Supporting modifications

Here are some key supporting mods to handle the demands of high-lift, long-duration cams:

• Valve springs – Prevent valve float at higher RPMs. Use dual or triple springs.

• Rocker arms – Handle aggressive opening rates and high lift. Upgrade ratios available.

• Retainers & locks – Critical for valvetrain stability under acceleration. Titanium is ideal.

• Timing set – Gets cam timing events optimal. Use adjustable gear for fine tuning.

• Headers – Improve exhaust flow at peak lift area. Reduce backpressure.

• Intake manifold – Must flow enough to match increased airflow capacity.

• Fuel system – Supply adequate fuel for more airflow. Consider upsized injectors.

• Tuning – Optimize timing and fuel maps for new cam at all RPMs.

You can‘t just " Bolt a cam in it" and expect results. A complete optimized package gets the big power gains.

Diminishing returns of over-camming

While even more aggressive cams make peak power, the trade-off is often poor drivability. Here‘s what happens when you over-cam an engine:

• Rough/lopsy idle – Big overlap hurts idle vacuum.

• No low-end torque – Huge cams have little duration under 0.050".

• Won‘t start without tuning – Needs optimized cranking timing maps.

• Low RPM power loss – Big cams don‘t make power below ~4000 RPM.

• Increased valve train wear – Extra stress on components.

Key takeaway: Don‘t over-cam the engine for your application. Track cars need huge cams, street cars don‘t.

Expert tips for selecting a camshaft

Here are my top tips for choosing the right camshaft:

• Know your engine‘s intended operating RPM range. Don‘t over-cam for the street.

• Study dyno graphs to visualize the powerband differences between cams.

• Model the cam/valve event timing in modeling software. Tune before installing.

• Get cam recommendations from knowledgeable engine builders, not vendors.

• Validate your entire build plan supports the cam‘s requirements.

• Budget for the extra supporting parts you‘ll need. It‘s a system.

Choosing a camshaft is a complex exercise, but the results of a perfect match are incredible. That giant lumpy idle screams power!

Conclusion

While the old adage "no replacement for displacement" still holds true, optimizing cam timing events is one of the best ways to unlock an engine‘s performance potential. For massive top end power, aggressively increased duration and lift are key. But restraint must be exercised to retain drivability. Only by designing the entire engine system to support the demands of high-performance camshafts can big power gains be realized reliably. With smart cam selection and an optimized build, you‘ll be making power that truly puts a Bigger Cam in it!

Let me know if you need any other engine tech expertise. Happy wrenching!