Camshaft tuning is a vital element of supercharger tuning. Camshafts orchestrate the valve closing and opening events within the engine and choose whether what comes out of our motor is beautiful high power music, or even a mess of dysphonics. The usage of the correct supercharger optimized cam shaft can go a long way towards Supercharger Porting and present considerable power gains for the money invested.
To understand camshaft timing and camshaft selection we must understand first:
Relativity: Changing when the valves open or close (intake or exhaust) changes the the valve timing regarding:
The piston position within the cylinder. Based on in which the pistons is in the stroke, and where we are in the combustion cycle, then opening the valves will exploit the stress difference between the cylinder and also the intake and exhaust manifolds.For example it would seem sensible that the ideal time and energy to open the intake valve is if you have peak vacuum inside the cylinder so that once the valve opens, the utmost level of outdoors could be ingested. Similarly, it seems sensible to not open the exhaust valve until peak cylinder pressures have been achieved in the combustion chamber as well as the combustion is complete and all sorts of the ability is extracted.
The high and low pressure pulses created by the design and runner lengths from the intake and exhaust manifolds.It could seem sensible to open up the intake valve just like the reflected pressure waves inside the intake manifold get to the intake valve as a high pressure portion of the wave, thus opening the valve at this particular high pressure point offers a ‘ram air’ effect through volumetric efficiency resonance tuning increasing air ingestion which increases power.Similarly on the exhaust side, it makes sense to open the exhaust valve, just as the reflected low pressure (vacuum) part of the exhaust wave (reflected back from the collector) reaches the back of the exhaust valve.
At this stage in time there exists both peak pressure in the cylinder, and vacuum in the exhaust which creates a higher pressure differential and a faster evacuating exhaust gas. With regards to the ignition timing event, such as a shorter duration or advanced exhaust cam, opens the exhaust valve sooner with respect to when the mixture was originally ignited, because of this although by advancing the exhaust cam we might have matched our header design and opened the valve using the lowest possible exhaust back pressure for the best efficiency, at the same time, we have reduced the amount of time the mixture is combusted and perhaps opened the valve before reaching our peak cylinder pressures and discarded some horsepower.
The intake valves with respect to the exhaust valves: and normally, this is described when it comes to lobe separation angles (the offset in degrees between the middle of the exhaust cam and between the center of the intake cam), or with regards to the amount of levels of overlap (the number of degrees that both intake and exhaust valves are open concurrently).
Because the combustion within the cylinder occurs in a much higher pressure than atmospheric pressure, and also, since exhaust valves are often smaller than intake valves (for this same high pressure reason) then exhaust gas velocity is much higher than intake gas velocity. So, in certain engines it is actually good for open the intake valve sooner than usual over the last portion of the exhaust stroke, this is called overlap.
During overlap – at the very end of the exhaust stroke – the quantity of pressure left inside the cylinder is low so it will be possible to breathe in new air under atmospheric pressure, at the same time, our prime velocity in the exhaust gasses exiting help attract even more outdoors from the intake side within an effect much like ‘syphoning’ in which the fluid (inside our case air) flows as being a continuous stream drawing in new intake air following the old exhaust gas leaves.
The other a part of phenomenon that concerns timing intake valves with regards to exhaust valves will be the period of time where both valves are absolutely closed, which is your power stroke. This is actually the area of the combustion cycle where the mixture could be compressed and combusted. If either (or both) intake or exhaust valves are open you may be unable to ebrtxr compress nor combust the mixture, as well as the absolute duration of time (in degrees of rotation) that the mixture is combusted and permitted to reach peak cylinder pressures is affected by camshaft selection and cam timing. Something to note is that the valve angle has a lot related to exhaust scavenging, obviously you will definately get maximum scavanging when the exhaust and intake valves had ‘line of sight’ i.e. in the event the valves were separated by an angle of 180*.
In that case, the exhaust air can directly pull in new air. Conversely, you will possess the least possible scavenging should you have had valves that have been in a narrow angle (zero degrees at the extreme) in between each other, so that the air would essentially need to make a U turn to can be found in with the intake and obtain pulled out your exhaust.