In line compressor selection and timing Cam
![Exhaust System]()
Tuning camshaft is an essential part of tuning the compressor. Orchestrating the camshaft opens the valve and closing events in the engine and decide if what comes out, our engine is nice dysphonics high power density or a mixture of music.
Choosing the right compressor optimizes camshaft can go a long way toward the development gains of the compressor and considerable power for the money invested.
To understand, camshafts and camshaft selection, we must understandFirst:
Relativity: change when the valves open or close (input or output) for the valve timing in relation to the changes:
The position of the piston within the cylinder. Depending on where the piston is intact, and where we are in the combustion cycle, then open the valves, the pressure difference between the cylinder and the intake and exhaust valves manifolds.For to exploit, for example, would make sense that the time the ideal intake valve is open when peak loadinside the cylinder so that when the valve is open, the maximum amount of fresh air to be fed. It 'also best not to open the drain valve when it reaches peak cylinder pressures inside the combustion chamber and the combustion was complete and that all power is derived. The pulses of high and low pressure generated by the rotor design and the length of the intake and exhaust would be created manifolds.It way to keep the intake valve, as reflected pressure waves in the openReach intake valve input as a high-pressure part of the wave, so the opening of the valve under high pressure at this point is a "ram air" effect of taking resonance volumetric efficiency of the air mass on the rise , which increases power.Similarly on the discharge side, it makes sense that the drain valve open, as reflected in low pressure (vacuum), the unloading wave (reflected by the collector) has reached the rear of the valve drain. At this point it isboth peaks of pressure in the cylinder and the vacuum in the exhaust, the pressure differential generates a higher and more rapid evacuation of exhaust gases. In relation to the event start, as a shorter or extended exhaust, the exhaust valve opens earlier in the report, if the mixture was originally lit, this means that, while advancing the exhaust cam, we have adapted our design header and opened the valve with the least possible exhaust back pressurefor better efficiency, we have the same time that the mixture is burned and can reduce the open valve, first to reach our peak cylinder pressure and threw out some horses. The intake valves in relation to the exhaust system and is usually described in terms of lobe separation angle (in degrees between the center between the center of the exhaust and intake camshaft offset), or in relation to the degree of overlap (the number ofExtent to which both the intake and exhaust valves are open simultaneously).
Since the combustion in the cylinder at a pressure much higher than atmospheric pressure, and exhaust valves are usually smaller as the intake valves (high pressure for the same reason), then the speed is much higher gas velocity exhaust as revenue. So, on some engines it is advantageous that the inlet valve opened earlier than usual during the latter part of the exhaust stroke, this is called superposition.While overlap - the end of the race exhaust - the amount of pressure inside the cylinder on the left is low, so you can breathe the air again under atmospheric pressure to draw the same time, the high gas velocities exhaust after leaving the aid still leaving the cooler air from the suction side in a similar effect to 'lift', where the flow of liquid (in our case air) as a continuous stream of new design inlet old drain.
The other part of the phenomenon thatTiming refers to the intake valves exhaust valves in relation to the length of time that both valves are closed completely, the power of your shot is. This is the part of the combustion cycle, in which the mixture can be compressed and burned. If either (or both) or A-. The exhaust valves are open will not be able to burn or compress the mixture and the duration of absolute time (in degrees of rotation) that your mixture is burned and allowed to reach peak cylinderThe pressure is influenced by the selection and timing of the camshafts. It should be noted that the angle of the valve to do too much with gas flushing, of course, you were digging to get the most when the exhaust and intake valves had "seen", that is when the valves were separated by an angle of 180 * . If so, the exhaust air directly to draw in fresh air. On the contrary, it would be clear as little as possible when the valves in a narrow angle (zero degrees in extreme cases) between them, hadso that air is essentially doing a U-turn to enter through the grip and pulled out the exhaust.
So different engines react differently to the function of the exhaust valve overlap and the corner.
Duration:
Cam duration is the number of degrees of rotation of the entire * 360, the intake and exhaust valve is open. The longer the maturity, the air entering the engine can overlap, which more (which helps more with the fastest performancePower), the lower your power stroke (the focal length and reduce peak cylinder pressures reduce speed fuel efficiencly low and minimal clean .... etc.
The duration (with its overlapping increments and put in order) is also an opportunity to get to the exhaust air to the input or suction gas leak in the exhaust, and therefore more sensitive to the timing of events otherwise we could have some effect negative "overcammed"
Elevator:
A lift ishow far or deep to open the valve in the cylinder. The more you lift, the valve is not a restriction to incoming air, because it is farther from the direct path of air in and out. Add lift usually more for all speeds, depending on how well the camshaft (and ramp), the valve lift to accelerate to a higher number in a short period. It 's like a ramp, the lower the duration, the greater the lift, the steepest ramp. So what happened here, that if yourThe valve train is not bright enough and well-controlled (through suitable valve springs or hydraulic lifting and suspension) to operate the lift quickly and then get better performance at low speed (where there are a lot of time to lift the valve at the top to move), but decreased performance at higher speeds, where there is more revolutions per minute and requires less time per lap, and thus less time to climb the steep ramp and slide the valve at maximum extension.
Elevator is good, but not usually find peopleto radically increase the lift on the cams aftermarket for some considerations:
Make sure that this new momentum, there is still enough space between the valve (fully extended) and the cylinder (at TDC) to avoid any catastrophic failure Mechanical. They upgraded to lighter valve train with stiffer springs and valve springs, more control on the valve cam profile with this steep. And 'to add power, but does not shift the power curveor down as radical as changing the length of the cam is not, and so in many aftermarket applications that we really want a cam to our excellence in a certain range of revolutions, so we worry more about the best time running (and some additional lift).
I know this is a rather complex topic, but I have to make sure that we speak the same language before you go this way with compressors. Before you decide to use the camshaft (or how to set the time on your stock cams) must seesomething very important:
The exhaust system and exhaust:
If you're one share log type exhaust manifold, having a cat-piece, with a dual cat exhaust system, exhaust pipes of small dimensions, and some restrictive muffler on your car, then it is possible at full capacity, up to 10 bar of back pressure.
If this is the case, would be my first recommendation, to a high flow, low-pressure exhaust system wins for updating the power potential, but IWe know that some of our readers who are self created for their parents or dual-use goods, in which their partners or the laws in force ... etc. are very strict when it comes to having any additional noise or exhaust systems exhaust. In this case, where the exhaust upgrades are not an option, then you must select your vote and your camshaft timing, which was absolutely the minimum possible amount of overlap. If you have a significant overlap, then rises above about4500 rpm, the compressor suffer more and more waste of power. When the compressor is designed for 7 psi boost, for example, then during the overlap, the cylinder sees boost 7 psi on the suction side and pressure 10PSI on the discharge side, the result is that the air flow from the high zone Pressure (discharge) for the area of lower pressure (recording) and then the cylinder begins to fill with smoke. As the rotation continues, the outlet in the vicinityand ends overlap, and the intake valve remains open for the rest of the intake stroke (for the rest of the length of your intake camshaft), and the rest of the cylinder is filled with fresh air.
What happens here is that we filled a cylinder filled to 30 * overlap with the exhaust air, and then (from the original cam 240 * duration of a typical street) * for an additional 210 with fresh air. The result is a cylinder of only 85% is full of fresh air, or an engine that isliterally 15% less capacity! On the other hand, if our magazine for 18psi, for example, oriented, then during stacking, we need to 18psi on the suction side and our exhaust pressure of 10 psi output, the result is this overlap that our compressor only the production of value 8psi differential pressure between the intake and cylinder, and so we are just going to a performance improvement during the overlap 8psi. Thus, during this 30 * of overlapCompressor is only efficiently produce 8psi boost and then once the exhaust valve closes, the compressor will be able to return to the operating system complete with pressure for the other 210 *. The result is something like 16psi so fine at 2 psi (or about 12%) of our energy has been wasted.
Compressor from the tune selection and cam timing
Camshaft intake:
Because of the negative impact of overlap on the performance of the compressor and a car especially for high-drainAgainst the pressure, as most factory turbocharged vehicles, we find that the optimal duration of the cam intake cam * Duration is usually 30-40 less than a camshaft aspirated engine RPM for the same peak power. The decision to reduce the length of the intake camshaft, rather than divide the duration is reduced between the inlet and exhaust camshaft, the intake camshaft is equipped with air pressure flow conditions (the addition the compressor and increasing the intake manifoldPressure) at a time and then reduced the intake camshaft, the engine is still able to get is full share of the intake. At the same time, high speed is to increase the efficiency of the reduction of duplication and promote the generation of a cam with more conservative. Finally, if we like to get more flow from the camshaft intake, there is the possibility of a higher lift camshaft (with a steeper slope due to the limited time frame) with the support of the valve train to ensure changesFlutter valve does not occur at higher speeds.
Taking timing:
The timing of the intake camshaft would ideally be delayed, which would move the camshaft intake opening event to further reduce exhaust valve closing event so or to eliminate overlap, and as a side effect duration of the power stroke by delaying the taking to increase the cam that has lost the power to compensate for the reduction of the length.
Exhaust:
The exhaust camshaft duration and lift for aSupercharged version of the engine should be similar to a cam of nitrogen, in the sense that the exhaust cams are nitrogen is based on specific:
1 - Very healthy, very healthy and duration cam cam for a greatly increased amount of exhaust gas to be able, doubling the output of the engine if the nitrogen is activated, allows the power (and therefore the gas discharge), both in abundance.
2 - How do you little or no overlap, if possible, would mean that any overlap with respect to nitrogenwas sprayed on the suction side and the exhaust gas, is the waste of our limited nitrous oxide. In addition, we have to overlap more, plus the compressor must be, since what we have already explained on both back exhaust intake, or to work under pressure of the exhaust of the compressor.
Timing of discharge:
Advancing vent it opens and closes the exhaust valves before. By opening the exhaust valve before reducing slightly the power stroke,But at the same time reduce duplication and better use of our compressor. Usually, an extended drain is combined with the intake camshaft late, the best results on a supercharged car, especially with a restrictive exhaust.
If we had installed an exhaust system high, then it can not be of benefit to the exhaust cam, exhaust gas at high speed, engine performance is optimized for our needs, the combustion chamber of all gases, is a huge improvementefficiently. With a high continuous discharge, low-pressure exhaust system back and do not overlap, which means that each camshaft exhaust that give enough time to leave the cylinder, not the intake valve opens (because we have decided to delay it, or use a cam with less conservative duration) and then the compressor does not matter, or the new fresh air, now is the empty cylinder and then be able to draw a part of the exhaust gas in the cylinder, the exhaust gasTo close the valve and the intake valve opens only on the cylinder is partly filled with exhaust gas to be found.
This is not a problem with an exhaust restriction, because a little restrictive exhaust 'time will take the cylinder to a lower speed is significantly longer, but with a higher exhaust system, we must be careful not to make outgoing calls to ALL overlap in time or over-the exhaust cam (too long).
Sun exhaust cam timing is advanced ordelay, depending on the change and the choice of the exhaust camshaft intake and, therefore, must be coordinated test.
It 'important to note that in all these changes in the selection cam overlap, power stroke duration and timing, and duration of power stroke is made and whether it will be reduced effective then we may need to change your mind to the test vehicle ahead ( for increased pre-) for losses in the duration of power stroke (also against the ever popular thoughtPre-ignition on the car when we charge a reduced power stroke or an application with considerable overlap, then it may be necessary to do so).
So here we see that the end result here is a camshaft with a duration of one-sided conservative, high-cam on the intake side and a normal duration, high-cam on the exhaust lobe minimum angle of separation and minimal (but need not) overlap .
The exception to this rule:
Some people take a car that startswith a 9000 rpm redline, has a compression ratio of 11.5:1 and a 280 * duration cam and a naturally aspirated engine-esque aggressive over time, and decided to update it to improve performance. An example is sucking SLK55 AMG Kleemann compressor for (which is already naturally aspirated 400 horsepower in the form of a compression ratio of 11:1 motor). In this type of application, if you use a cam to increase rather conservative, and select all overlap, and the power stroke, in combination with acompression ratio of 11:1 is already high and a good dose of pressure (7 psi or higher) you will end up generated by an engine, the pressure peaks and extremely high cylinder pressures and heat that can just start a chain reaction Pre-ignition and detonation, and find that no matter how much time that will end the installation is powerless and still do not want to delay safe.
In this case, I would like my primary compression and power adders RPM, and myCompressor as my secondary power adder (that is, when I decided to change and that he went ahead and lowered the engine compression ratio). In this case goes well, some high-speed compressor to sacrifice efficiency in order to avoid the stress of high and low velocity of detonation. In addition to overcoming the overlap in this type of high-speed power plant should be aspired to have a centrifugal compressor which is able to apply more pressure and flow with the increased userpm instead of a root type charger that will run easily cut and flow (CFM), where a camshaft aggressive push "leaky" way.
Here's a great example of how cam supercharged performance optimization can involve:
The car is a 1.8-liter Honda engine, equipped with:
Overfeeding optimized large primary runners and short header Kamakazi A GReddy 2.5? SP2 exhaust exhaust system. A feed port LHT "S" magazine tube LHT brought an inlet manifold (No intercooler) A carbon fiber intake A race Jackson Eaton M62 supercharger for 7.5 to 8 bar aligned.
The black line is the bottom line with all these changes before running setup to get maximum performance at 223 hp @ 7600 RPM wheel.
The blue line is the power achieved after a complete tooth (variable valve timing for reduced overlap renovated, re-optimized and power optimized air-fuel ratio for maximum performance), reaching a peak power of 248 hp @ 8400 RPM.
You cansee the results table that correctly, reducing duplication and increasing the development of the car not only top performance by 25 horsepower, but more important is to shift around 1000 rpm at high speed through a more efficient compressor, avoiding the twice.
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