Performance Camshaft Options And Installation For The Ka24de Engine

The Nissan KA24DE, a 2.4-liter inline-four engine found in vehicles like the 240SX, Altima, and Frontier, is a robust powerplant known for its reliability and decent torque output. While not inherently a high-revving screamer, the KA24DE responds well to modifications, and one of the most impactful upgrades you can perform is swapping out the camshafts. This article delves into the world of aftermarket performance camshafts for the KA24DE, exploring the different options, their effects on engine performance, and the essential steps involved in installation.

Understanding Camshaft Basics

Before diving into specific camshaft options, it's crucial to understand the fundamental principles of how a camshaft works. The camshaft is a rotating shaft with lobes that actuate the engine's valves. As the camshaft rotates, the lobes push on the valve lifters (also known as tappets or followers), opening the intake and exhaust valves at specific times and for specific durations. This precise control of valve timing is critical for optimizing engine performance.

Key camshaft specifications include:

• Duration: The number of crankshaft degrees during which a valve is open. Longer duration cams generally allow for more airflow at higher RPMs, increasing horsepower but often sacrificing low-end torque.
• Lift: The amount the valve is lifted off its seat. Higher lift also increases airflow, but requires proper valve springs and potentially modifications to valve clearances to prevent coil bind.
• Lobe Separation Angle (LSA): The angle between the maximum lift points of the intake and exhaust lobes. A tighter LSA generally improves low-end torque and throttle response, while a wider LSA tends to favor higher RPM power.
• Overlap: The period during which both the intake and exhaust valves are open simultaneously. Overlap can improve scavenging of exhaust gases and draw in more intake charge, but excessive overlap can lead to poor idle quality and increased emissions.

These specifications are all interrelated, and changing one will inevitably affect the others. Performance camshafts are designed to alter these parameters to shift the engine's power band.

Types of Performance Camshafts for the KA24DE

The aftermarket offers a range of camshaft options for the KA24DE, each designed for a specific purpose. Here's a breakdown of some common types:

Mild Street Cams

These camshafts are designed for daily driving with a focus on improving overall performance without sacrificing drivability. They typically have a modest increase in duration and lift compared to the stock camshafts. Expect a slight bump in horsepower and torque across the entire RPM range, with minimal impact on idle quality. These are ideal for those who want a noticeable improvement in performance without compromising reliability or requiring extensive supporting modifications.

Mid-Range Performance Cams

These cams offer a more aggressive profile, increasing duration and lift significantly. Expect a noticeable improvement in mid-range and top-end power, but often at the expense of some low-end torque. Idle quality may be slightly rougher, and supporting modifications like upgraded valve springs and a tuned ECU are highly recommended. These are suitable for enthusiasts who prioritize performance over daily drivability.

Aggressive Race Cams

Designed for dedicated track use, these camshafts feature extreme duration and lift figures. Expect significant gains in top-end horsepower, but extremely poor low-end torque and a very rough idle. These cams require substantial supporting modifications, including high-performance valve springs, upgraded fuel injectors, a standalone ECU, and potentially even head porting. Street driving is typically not practical with these cams.

Dual Valve Spring Considerations

When increasing camshaft lift and duration beyond mild upgrades, upgrading your valve springs becomes paramount. Dual valve springs offer higher spring rates and increased resistance to valve float at higher RPMs. Valve float occurs when the valve doesn't close completely before the next opening event, leading to power loss and potential engine damage. Dual valve springs are almost always required with mid-range and aggressive camshafts.

Installation Process: A Step-by-Step Guide

Installing performance camshafts is a complex procedure that requires a good understanding of engine mechanics. It's recommended to have experience working on engines or to seek the assistance of a qualified mechanic.

1. Preparation: Gather all necessary tools and parts. This includes the new camshafts, valve springs (if required), camshaft seals, timing chain, timing chain guides, and a new valve cover gasket. Ensure you have a torque wrench, feeler gauges, and a degree wheel for accurate timing adjustments.
2. Disassembly: Disconnect the battery and drain the coolant. Remove the valve cover, distributor (or coil packs), and any other components obstructing access to the camshafts. Carefully remove the timing chain tensioner and then the camshafts. Pay close attention to the timing marks on the crankshaft and camshaft sprockets.
3. Valve Spring Replacement (if necessary): If upgrading to dual valve springs, use a valve spring compressor to remove the old springs and install the new ones. Ensure proper seating of the valve stem seals.
4. Camshaft Installation: Lubricate the new camshaft lobes and journals with assembly lube. Carefully install the camshafts, aligning the timing marks on the camshaft sprockets with the timing marks on the crankshaft sprocket. Reinstall the timing chain tensioner.
5. Valve Lash Adjustment: With the camshafts installed, adjust the valve lash (the clearance between the valve stem and the rocker arm or lifter) to the specifications provided by the camshaft manufacturer. Use feeler gauges to measure the clearance and adjust the shims or tappets as needed.
6. Timing Verification:

   Accurately verifying camshaft timing is critical for optimal performance and preventing engine damage. Use a degree wheel and dial indicator to measure the intake centerline and ensure it matches the manufacturer's specifications. If necessary, adjustable cam gears can be used to fine-tune the timing.

7. Reassembly: Reinstall all components in reverse order, including the distributor (or coil packs), valve cover, and coolant.
8. Initial Start-up and Break-in: After reassembly, prime the oil system by cranking the engine without starting it. Then, start the engine and allow it to idle for several minutes, checking for any leaks or unusual noises. Follow the camshaft manufacturer's recommended break-in procedure, which typically involves avoiding high RPMs and heavy loads for the first few hundred miles.
9. ECU Tuning: After installing performance camshafts, especially those with aggressive profiles, ECU tuning is essential to optimize performance and prevent engine damage. A properly tuned ECU can adjust fuel delivery, ignition timing, and other parameters to compensate for the changes in airflow and valve timing.

Considerations and Cautions

• Valve-to-Piston Clearance: With high-lift camshafts, it's crucial to check valve-to-piston clearance to ensure the valves don't contact the pistons. This may require claying the engine or using specialized measuring tools.
• Oil System: Ensure your oil pump is in good condition and providing adequate oil pressure, especially with performance camshafts that require more lubrication.
• Professional Installation: If you're not comfortable with engine mechanics, seek the assistance of a qualified mechanic. Incorrect installation can lead to serious engine damage.

Conclusion

Upgrading the camshafts on your KA24DE can be a rewarding modification that significantly improves engine performance. By carefully considering your needs and choosing the right camshaft profile, you can unlock the hidden potential of this robust engine. Remember to always prioritize proper installation and tuning to ensure optimal performance and reliability.