Rpm's fall faster than stock...?

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tarvin890

tarvin890
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This kinda sounds like a stupid question/discussion topic... but... here goes... It seems to me that a nice performance build engines rpms can audibly be heard and seen (tach) fall faster and rpm up faster than stock.... true or figament of the imagination???????? or can you hear when a motor has something special inside not only from the cam.... but the rpm characteristics?
 
Higher cylinder pressure will make an engine rev and drop quicker.
 
One other thing to think about is if it's an automatic and the tranny has a shift kit or is manual shift the gear change is (lets just call it) instant. So the RPM's will drop quickly when it goes into the next gear.

Ted
 
So, cylinder pressure is the constantly changing pressure inside the cylinder for all 4 strokes. There are certain characteristics of this pressure which people may want identified, like peak (maximum) cylinder pressure near TDC, or peak cranking compression pressure (pressure at TDC without combustion), or average cylinder pressure (IMEP, indicated mean effective pressure). They are all just measures of cylinder pressure at certain times (or averaged over certain times) in the 4 strokes.

It should be noted that for 3 of the 4 strokes, the engine is putting work into the process, and that only during Combustion/Expansion stroke is any work being output from the process. The work during the Combustion/Expansion stroke must make up for the other 3 strokes and still have enough left over to produce a net power. Luckily it works out that there is LOTS of work (or energy released) produced during Combustion/Expansion stroke.
 
Cylinder Pressure is the pressure in the engine cylinder during the 4 strokes of engine operation (intake, compression, combustion and expansion, and exhaust). You could argue that pressure during expansion is the most important, because that is the cylinder pressure pushing on the piston to produce power. But the cylinder pressure during all 4 strokes is necessary for accurate engine performance prediction.
 
Only one stroke where measured cylinder pressure takes place. The compression stroke.
 
Also lighter rotating assembly, crank, rods, pistons, converter/flywheel etc will help an engine rev up and down faster.
 
Changes in timing, free flowing exhaust relieving back pressure, lots of things can make a difference.
 
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