RustyRatRod's Guide To Hot Rod Bliss
Filling the cylinder is more VE
This is also for the new to engines guy, PScamp74
Not exactly. It is though. The VE is limited by the intake tract (mostly) from carb to valve and will hit a ceiling (mostly) by how much time the valves are open. Let me put it in another way.
A bigger cam allows more in this increasing how effective the engine runs in terms of more power by a greater cylinder fill. But the parts themselves hav not changed.
Valve diameter for door size
Valve Lift for how wide the door opens
Duration for how long the door stays open
CFM for how fast people can go through the door
The door is 1.78 (1.78 feet) wide.
It’s enough for one person to go through EZ enough.
The door only opens up enough for 1 person to get in at a time, let’s use stock valve lift as how wide the door opens in feet. .400, am so half a foot. Plenty for a thin fella to get through.
Now the door stays open for a short time, this is duration and we will use seconds for degrees. In a stock cams case, 198 (or so) seconds. They walk in at a rate of 125 people per event of door opening time.
This is the amount of volumetric efficiency of this scenario.
(We’ll call it a stock 318 head)
Increasing the volumetric of efficiency of the system can not be done since the actual parts are cast steel but you can increase the cylinder fill but rearranging the previous perameters of the door openings with a wider door opening that lasts longer. And here is the beauty of a wider door, it not only allows more people through the wider and loved door openings, but it allows the people to move through faster since there is less chance of hanging into the door. The equals to a cylinder head being able to flow more air and fuel via a higher lift since the port can allow more air and fuel. The change in efficiency is as only as great as the door or head port allows.
To suggest to someone that you have to change the efficiency of the engine isn’t a good idea because of how it’s worded and what you said earlier and as well as what you said the person should be after.
Changing the cam is taking advantage of what is there already and not altering the efficiency of the parts already there but simply just taking advantage of what’s there to fill up more of the cylinder.
In a way, yes it does create more efficiency but only within its limits as cast. Otherwise it’s porting heads, replacing bolt on parts.
So with this, how is the cam not important and making more power? It’s allowing more people through the door! But only an amount to slightly alter the power curve by a few hundred rpm.
This works on any displacement engine. While a bigger engine is better at specific torque output, there is t a need to suggest a engine swap be done or major over hauling or ported parts be done.
The idea of a larger camshaft is to create more power and this is torque!
