Continuing with the previous post regarding cams, here is a brief explaination as to why I went the direction to purchase the pair of Crowers. The key parts of any camshaft are the lobes. As the camshaft spins, the lobes open and close the intake and exhaust valves in time with the motion of the piston. It turns out that there is a direct relationship between the shape of the cam lobes and the way the engine performs in different speed ranges.
If we leave say the intake valve open longer via larger camshaft lobes, the momentum of the fast-moving air/fuel continues to force the mixture into the cylinder as the piston starts to cycle a compression stroke. The faster the engine goes, the faster the mixture moves and the longer the wait for the intake valves to stay open. What a high performance engine wants is to have valves which open wider at higher speeds. This is what is called, VALVE LIFT.
The KA has a double over-head cam design, meaning that it utilizes both an intake and exhaust cam. The efficiency of this system allows for 2 intake valves, and 2 proportional exhaust valves. Due to the design of the all aluminum Head on the KA, the system does not utilize Rockers or Push Rods. This simplifies the combustion assembly and allows the head to be more durable. The Cam lobes hit the valve spring cap/bucket, activating the valve springs and valve, allowing for air/fuel intake and exhaust gas flow.
Regarding the valves, I decided to pick up a set of Dual Spring Titanium Valve springs with Titanium Retainers. The following is an excerpt from a Supertech Dealer. Call me lazy but as a novice car builder, I honestly would not know how to say this better.
“Supertech Dual Valvesprings and Titanium Retainers for Nissan KA24DE Engines. These are Dual Springs with fully CNC’d Chamfered Titanium Retainers. These valvesprings and retainers will reliably allow your engine to rev high without the worry of part failure, valve float, or coil bind. Aftermarket valvesprings are made out of superior metal alloy’s and optimized spring rates to make sure your valvetrain can keep up with your cams at high RPM. Whether you are rebuilding your engine, or building an all out race engine, replacing your valvetrain with Supertech components will allow you to rev higher, and go more aggressive on your cams. Supertech has been around for a long time in the Valvetrain industry, and has race proven their product year after year, and backed it up with world records and first place trophies. We use Supertech in our top level engine builds for good reason. We suggest Supertech Valvesprings and Retainers and actually use them in some of our very own cars.
There are 2 Major Issues with stock valvetrain, that can be prevented by using Supertech Components.
Coil Bind and Valvespring Failure – Factory valvesprings are made from cost effective materials that will survive normal driving, usually the entire life span of a un-modified car. The factory did not account for enthusiasts when they chose materials which is why it is common for high mileage factory valvesprings to crack or break when put through
the abuse of racing. High RPM, increased compression, aggressive cam profiles, and other factors can cause valvesprings to perminantly bend out of shape (coil bind) or even break and drop into the engine (spring failure), potentially causing irrepairable damage. Supertech’s valvesprings are made from carefully chosen alloys to stand up to the worst abuse.”
That’s all for now guys/gals.