If the ls6 intakes only flow 275 ish...
If the ls6 intakes only flow 275 ish... do we really see a gain by putting on heads that flow much more? May sound like a weak question, and maybe 275 for intake flow is not correct as i've been told...but IF this is the case, what case is there for 300+ cfm flowing heads? Just a thought////
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Joined: Nov 2002
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From: Orlando
What you are saying is to some degree true and there is a point of diminishing returns. You can only get so much into the engine, but...what you can do is maximize components to take advantage of the flow the best way. A good cam with good lift and duration values will maximize the amount of air going in to get the best power. If you increase the duration and lift on the cam, you can get the valve timing events working in your favor to fill the cylinders in the most efficient way possible using all of the flow rate of the intake. Keeping the intake valves open longer and allowing the cylinder to fill with more of that ~275 CFM coming is what you want. For stock cubes, the intakes are pretty efficient but this is what some of the stroker guys are wondering. Is the stock intake a cork to a stroker? Maybe, maybe not but at some point in displacement, it will.
Reasons are...
Head Loss
sum of individual components != end result.
Think of it this way. A 3" diameter pipe that is 10" long will flow X amount @ pressure A. Add a second 3"x10" pipe to the end of that first pipe and your flow will decrease by amount L due to an increase in Head Loss. Head Loss is flow energy lost due to friction, increasing the length of the pipe increases friction, and Head Loss, and decreases flow @ at pressure A.
Now take a 4" diameter pipe that is 10" long. It will be capable of flowing X+Y amount @ pressure A. Add this pipe onto the first pipe and your flow loss will still decrease, but not by as much the two 3" pipes because Head Loss in a 4x10 pipe is less than Head Loss in a 3x10 pipe.
Now, our heads and intakes are more complicated than a couple pipes, but the same principles of fluid dynamics are applied. I hope I didn't confuse things with the variables. Pressure remains constant in all cases. You can increase flow by increasing pressure, but that's not applicable to our engines (let's not get into boost) and the pressure in the case of a naturally aspirated engine is the intake vacuum generated by the piston's intake downstroke.
Head Loss
sum of individual components != end result.
Think of it this way. A 3" diameter pipe that is 10" long will flow X amount @ pressure A. Add a second 3"x10" pipe to the end of that first pipe and your flow will decrease by amount L due to an increase in Head Loss. Head Loss is flow energy lost due to friction, increasing the length of the pipe increases friction, and Head Loss, and decreases flow @ at pressure A.
Now take a 4" diameter pipe that is 10" long. It will be capable of flowing X+Y amount @ pressure A. Add this pipe onto the first pipe and your flow loss will still decrease, but not by as much the two 3" pipes because Head Loss in a 4x10 pipe is less than Head Loss in a 3x10 pipe.
Now, our heads and intakes are more complicated than a couple pipes, but the same principles of fluid dynamics are applied. I hope I didn't confuse things with the variables. Pressure remains constant in all cases. You can increase flow by increasing pressure, but that's not applicable to our engines (let's not get into boost) and the pressure in the case of a naturally aspirated engine is the intake vacuum generated by the piston's intake downstroke.
