What does advancing the exhaust cam do?

What does advancing the exhaust cam do?

Advancing or retarding the cam pushes the centerline of the camshaft to one side or the other of the crankshaft centerline. This changes the Timing of the valve opening and closing events, in relation to the position of the piston in the cylinder.

What will happen if the inlet and exhaust valves open before and after of the optimum timing?

Closing the intake valve either before or after the optimum timing for maximum torque results in a lower mass of air being trapped in the cylinder. As discussed previously, valve overlap is the time when both intake and exhaust valves are open.

Is exhaust valve open at TDC?

The piston is now at TDC, both the intake and exhaust valves are partially open. As the piston travels back down the cylinder, the exhaust valve goes fully shut and the intake valve goes fully open and starts to shut.

What happens when you advance timing?

The major benefit to advancing the timing of a vehicle’s ignition is increasing the horsepower of an engine. Advancing the ignition timing helps raise the high-end power while reducing the low end. It also helps get the spark past the ignition delay and run at peak power.

During which stroke does the exhaust valve close?

As the intake valve opens in the exhaust stroke, a portion of exhaust gas enters the intake port and will be sucked back into the cylinder in the intake stroke. The exhaust valve closes after TDC so that some exhaust gas will also be sucked back into cylinder.

Why do exhaust valves close after TDC?

The exhaust valve closes after a few degrees of piston reaching the TDC, i.e. when the piston starts to move down the cylinder in the suction stroke. This ‘overlap’ helps in better ‘scavenging’ or expelling the remaining exhaust gases from the engine cylinder.

Is Degreeing a cam worth it?

Pit Stop with Marlan Davis: Degreeing a custom cam ensures its maximum performance, helps prevent piston-to-valve contact, and protects against assembly error. The bigger the cam, the more important this is.

Should all valves be closed at top dead center?

Both valves should be closed if it’s TDC at the end of the compression stroke. If it’s TDC at the end of the exhaust stroke, you should be in the valve overlap zone, with the intake valve partially open and on its way to opening fully, and the exhaust valve partially open on its way to closing.

When should the exhaust valve open?

The valves are timed so the intake valve opens slightly before the piston reaches top dead center (TDC) on the exhaust stroke. Likewise, the exhaust valve is timed to close just after the piston starts down on the intake stroke.

What are the benefits of exhaust cam phasing?

Whereas the primary benefits of exhaust cam phasing are reduced emissions and greater fuel economy, intake cam phasing provides increased low-end torque and high-end power. Instead of moving the intake cam to effect overlap in the exhaust stroke (cylinder scavenging), intake closure is delayed at the bottom of the intake stroke.

How are cam phasers used in dual overhead cam engines?

Additionally, dual-overhead-cam engines, with one cam for the intake valves and another for the exhaust, can use these cam phasers to change their position relative to each other. This can allow the computer to increase or decrease “valve overlap” — the amount of time both the intake and exhaust valves are open simultaneously.

How does advancing the exhaust cam affect the supercharger?

Advancing the exhaust cam both opens and closes the exhaust valves sooner. Opening the exhaust valve sooner slightly reduces the power stroke, but at the same time it reduces overlap and makes better use of our supercharger.

What’s the sequence of events in a camshaft?

Looking at a camshaft, the sequence would be as follows: The exhaust lobe pushes open the exhaust valve and the piston comes up to push the exhaust out, then starts to close. The intake starts to open, just as the exhaust is closing, piston goes down, and the intake valve closes.