Sr20det Compression Test Question???
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ive seen as much a 30psi of increased compression through retard cam timing a few times. it only take a few 100ms for the whole combustion process to occur as it is anyways. when you have you timing not in sync with the stroke of the piston you can get a increased pressure due to a compress extra air but releaseing it late.
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if you havent been in a small plane its worst, cause your eyes and brain say we are moving and your body says oh no we are not. eyes and brain go asshole we are moving, cant you see? body says fuck you we are not moving at all. so they fight and fight and eventualy your body says, you know what fuck you brain, see if you can stop this!! then you throw up.
if you havent been in a small plane its worst, cause your eyes and brain say we are moving and your body says oh no we are not. eyes and brain go asshole we are moving, cant you see? body says fuck you we are not moving at all. so they fight and fight and eventualy your body says, you know what fuck you brain, see if you can stop this!! then you throw up.
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ive seen as much a 30psi of increased compression through retard cam timing a few times. it only take a few 100ms for the whole combustion process to occur as it is anyways. when you have you timing not in sync with the stroke of the piston you can get a increased pressure due to a compress extra air but releaseing it late.
The entire combustion process has to occur a whole lot faster than a few hundred milliseconds.
A 12:1 CR gasoline engine at 1500 rshared_pm would have a flame speed of about 16.5 m/s.
At that speed, with a cylinder radius of 43mm, the entire combustion chamber has completely burned in 2milliseconds.
The type of intake timing you're talking about happens at much higher mass flow rates, associated with higher engine RPMs. The effect is called "inertial supercharging". You can read up on it a bit here:
Dune-Buggy.com - Fuel Injection Intake
This effect is tuned by intake manifold design, and is why aftermarket manifolds produce better top end power - they have a higher natural frequency at which the pressure waves resonate.
I assure you no manifold has a designed natural frequency down around cranking RPMs.
Here's some more reading on the issue:
Volumetric efficiency - Wikipedia, the free encyclopedia
