Engine speed or how to choose a camshaft. Optimal engine speed during car operation How many revolutions does

19.06.2019

Setting up a chainsaw carburetor with your own hands

For an independent carburetor option, you need to familiarize yourself with its device and understand the procedure for the work that is carried out to adjust the parts responsible for the correct functioning constituent parts device and parts close to it.

It is necessary to carefully handle the items for the system option, and also determine the compliance of the set characteristics with very acceptable values.

About the carburetor device

The carburetor serves to mix the combustible mixture with air, subject to predetermined proportions. If clear doses are not observed, the correct operation of the motor is at risk. When a huge amount of air enters during mixing, and there is not enough fuel, then such a mixture is considered "poor".

Oversaturation should not be allowed, because with a large amount of fuel compared to air, malfunctions or engine wear are also likely. Carburetor adjustment is needed not only before the initial implementation, but also when any differences in its operation are detected. Before you start working with a chainsaw, do not forget to break it in.

Components of a carburetor

The design of the carburetor contains standard set parts, but may vary slightly depending on the manufacturer. Components:

The basis. This is a special tube that visually resembles an aerodynamic design. Air passes through it. A damper is located in the transverse direction in the middle of the pipe. Its position can be changed. The more it is extended into the passage, the less air enters the engine.
Diffuser. This is the narrowed part of the tube. With its help, the air supply speed is increased precisely in the segment where the fuel comes from.
Channels for fuel supply. The fuel mixture is contained in the float chamber, then passes into the jet, from which it flows into the atomizer.
float chamber. It is a separate structural element, reminiscent of the shape of the tank. Designed to constantly maintain optimal levels fuel fluid before entering the channel from where air enters.

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Looking for cheaper models, but reliable and time-tested? Pay attention to Russian-made chainsaws.

Or study foreign manufacturers chainsaws such as Stihl.

What you need to have to set up

Every carburetor owner should have necessary tools to adjust this system. There are three adjustment screws that are located on the body of the device. They have their own markings:

L - screw for correcting low speed.
H - screw for adjusting high speed.
T - regulates idle move, in most cases used for experiments.

Chainsaw air filter

Before adjusting the carburetor, you need to prepare the device:

The engine warms up, that is, it starts up about 10 minutes before repair, and turns off at the start of work (see how to start a chainsaw).
Check and clean the air filter.
The chain is stopped by turning screw T as far as it will go (see chain oil).

To carry out a safe repair, you need to prepare a flat surface where you can carefully position the device, and turn the chain in the opposite direction. You need a tachometer. It determines the presence of a violation in the operation of the carburetor. When turning the screws, the sound should be perfect and absolutely even. If squealing notes are noticed, then the mixture is oversaturated.

Setting instructions

Carburetor adjustment is divided into two main stages. The first is called basic. It is done with the engine running. The second is performed when the engine is warm.

To complete the carburetor tuning procedure successfully, You need to read the instruction manual beforehand. specific model to identify additional features device settings.

First stage

The adjustment screws for the highest and lowest speeds should be turned clockwise until the highest resistance is met. When the screws reach the stop, you need to transfer them to reverse side and leave at the passage of 1.5 turns.

main stage

Chainsaw STIHL 180 check how many revolutions it turns

In this video we will answer the question of how to tune or adjust the carburetor chainsaws do it yourself

Chainsaw STIHL 230 check how many revolutions it turns

Carburetor adjustment chainsaws Champion 254 DIY. Initial carburetor adjustment shown

The engine turns on at medium speed and it warms up for about 10 minutes. The screw responsible for adjusting the idle speed must move clockwise. It is released only when the engine enters the stable operation mode. It is necessary to check that the chain does not move during this process.

In idle mode, the engine may stall (the reason is here). In this case, you must immediately bring the adjusting screw clockwise to the stop. Sometimes the chain starts to move. In this case, turn the adjusting screw in the opposite direction.

Checking the operation of acceleration

You need to do a little research. Device acceleration is initiated. It is necessary to evaluate the serviceability of the engine during the maximum speed. When the engine is running correctly, when you press the accelerator, the speed quickly increases to 15,000 rpm.

If this does not happen or the increase in speed is too slow, the screw marked L must be used. It turns counterclockwise. Moderate movements must be observed, since the turn cannot be more than 1/8 of a full circle.

Max RPM

To limit this figure, you need to use a screw marked H. To increase the number of revolutions, turn it clockwise, and to reduce them in the opposite direction. The maximum frequency should not exceed 15000 rpm.

If this indicator is made larger, the engine of the device will wear out, which will lead to problems in the ignition system. When rotating this screw, the ignition processes of the device must be taken into account. If the slightest failures appear, then the maximum speed value must be reduced.

Final check at idle

Before this procedure, it is necessary to perform a full adjustment of the carburetor components when operating at maximum speed. Next, you should check the operation of the device in idle cold mode. When the correct parameters are reached when adjusting, you can see the exact correspondence of the carburetor design to the following criteria:

When the idle cold mode is connected, the chain does not move.

Chainsaw Accelerator

When even a slight pressure on the accelerator is carried out, the engine is gaining momentum at an accelerated pace. With a gradual deepening of the pressure, you can notice that the engine speed increases commensurately, reaching the maximum allowable values.
When the engine is running, you can compare its sound with a four-stroke device.

If there are violations in the given parameters or the device was not fully adjusted, you need to perform the main setup step again. Sometimes actions are performed incorrectly. In this case, the device may fail due to the loss correct settings node. In this case, you will have to contact a specialist.

Dismantling the carburetor if necessary to check or repair components

Device different models carburetors are almost the same, so when working with them, you can use the standard scheme. All elements must be removed carefully, and then post in the order below so that you can successfully arrange items in place at the end of the repair work.

Read:

Removing the Top Cover

Filmed top cover. To do this, unscrew the 3 bolts holding it in a circle.
The foam rubber is also removed, as it is the top integral part air filter.
The fuel hose is removed.
The drive thrust is displayed immediately on it.
The end of the cable is disconnected.
The petrol hose can be completely removed by systematically pulling it off the fitting.

To finally prepare the carburetor for a major overhaul or replacement of the smallest parts, you need to carefully disconnect it from the main system. Sometimes further disassembly is required. Should be unscrewed constituent elements carefully and fold the fasteners in groups, as these small parts are easily lost.

Instruction for Chinese

To properly set up the carburetor of a Chinese chainsaw, you must first remember the factory settings of the device, then turn on the engine. Subsequently, you will have to leave it running for several hours in order to accurately set your own parameters. Sometimes work is performed once after ten minutes of engine operation, however, many models Chinese made require special handling.

Chinese chainsaw model

Adjustment procedure:

Activities start in idle mode. With the help of adjusting screws, you need to achieve a systematic increase in engine speed, so you should first let it work at low speeds. The deviation from the norm is the movement of the chain along the tire. In this case, you need to adjust the outer screws to the optimal position so that the chain remains stationary.
Turnover is in progress average speed . Sometimes the engine will smoke. This defect can be eliminated by tightening the screw to supply a leaner fuel mixture.

In this case, the smoke will disappear, but the engine speed will increase. It is necessary to adjust the settings until it reaches a level where, when you press the throttle, the engine smoothly picks up speed, you can’t hear sharp jerks or interruptions.

Checking the engine of the device. The chainsaw is transferred to the minimum speed, and then the lever is pressed rapidly. At the maximum pressing it is maintained for 3 seconds. If there is a malfunction in the engine, you need to gradually loosen the screw until the optimum position is reached.

The chainsaw should work for several hours in real conditions. It is necessary to engage in sawing wood, and then inspect all the elements involved in this event. If there are deviations, they must be corrected using adjusting devices. When all defects are eliminated and the optimal settings for supplying correctly concentrated fuel are set, the process of setting up the device can be considered completed.

Almost every driver is well aware that the resource of the engine and other components of the car directly depends on the individual driving style. For this reason, many car owners, especially beginners, often think about what speed is best to drive. Next, we will consider what engine speeds you need to keep, taking into account different road conditions during vehicle operation.

Read in this article

Engine life and revs while driving

Let's begin with competent operation and constant maintenance of optimal engine speed allows you to increase engine life. In other words, there are operating modes when the motor wears out the least. As already mentioned, the service life depends on the driving style, that is, the driver himself can conditionally "regulate" given parameter. Note that this topic is the subject of discussions and disputes. More specifically, drivers are divided into three main groups:

the former include those who operate the engine on low revs, constantly moving "retracted".
the second should include such drivers who only periodically spin up their motor to above-average speeds;
the third group are car owners who constantly support power unit in a mode above medium and high engine speeds, often driving the tachometer needle into the red zone.

Let's understand in more detail. Let's start with driving on the "bottom". This mode means that the driver does not raise the speed above 2.5 thousand rpm. on gasoline engines and holds about 1100-1200 rpm. on diesel. This style of driving has been imposed on many since the days of driving school. Instructors authoritatively state that it is necessary to drive at the lowest speeds, since in this mode biggest savings fuel, the engine is least loaded, etc.

Note that in driving courses it is advised not to turn the unit, since one of the main tasks is maximum safety. It is quite logical that low speed in this case is inextricably linked with driving at low speeds. There is logic in this, since slow and measured movement allows you to quickly learn how to drive without jerks when shifting gears on cars with manual transmission, teaches a novice driver to move in a calm and smooth mode, provides more confident control over the car, etc.

Obviously, after receiving driving license this driving style is further actively practiced on own car turning into a habit. Drivers of this type they begin to get nervous when the sound of a hyped motor begins to be heard in the cabin. It seems to them that the increase in noise means a significant increase in the load on the internal combustion engine.

As for the engine itself and its resource, too “sparing” operation does not add to its service life. Moreover, everything happens exactly the opposite. Imagine a situation when a car is moving at a speed of 60 km / h in 4th gear on even asphalt, the speed is, say, about 2 thousand. In this mode, the engine is almost inaudible even at budget cars fuel consumption is minimal. At the same time, there are two main disadvantages in such a ride:

it is almost completely impossible to accelerate sharply without switching to downshift, especially on "".
after changes in the road surface, for example, on slopes, the driver does not downshift. Instead of shifting, he simply presses harder on the gas pedal.

In the first case, the motor is often outside the “shelf”, which does not allow you to quickly disperse the car if necessary. As a result, this driving style affects general security movement. The second point directly affects the engine. First of all, driving at low revs under load with a strongly depressed gas pedal leads to detonation of the motor. The specified detonation literally breaks the power unit from the inside.

In terms of consumption, the savings are almost completely absent, since a stronger pressure on the gas pedal on overdrive under load causes enrichment fuel-air mixture. As a result, fuel consumption increases.

Also, “pull-in” driving increases engine wear even in the absence of detonation. The fact is that at low speeds, the loaded rubbing parts of the motor are not sufficiently lubricated. The reason is the dependence of the performance of the oil pump and the pressure it creates. engine oil in from all the same engine speeds. In other words, plain bearings are designed to operate under hydrodynamic lubrication conditions. This mode involves the supply of oil under pressure into the gaps between the liners and the shaft. This creates the desired oil film, which prevents wear of the mating elements. The effectiveness of hydrodynamic lubrication is directly dependent on engine speed, that is, more revs the higher the oil pressure. It turns out that with a heavy load on the engine, taking into account the low speed, there is a high risk of severe wear and breakage of the liners.

Another argument against driving at low speeds is a reinforced engine. In simple words, with a set of revolutions, the load on the internal combustion engine increases and the temperature in the cylinders rises significantly. As a result, part of the soot simply burns out, which does not happen when permanent operation on the "bottom".

High engine speed

Well, you say, the answer is obvious. The engine needs to be revved more strongly, as the car will respond confidently to the gas pedal, it will be easy to overtake, the engine will be cleaned, fuel consumption will not increase so much, etc. This is true, but only in part. The fact is that constant driving at high speeds also has its drawbacks.

High speeds can be considered those that exceed the approximate figure of about 70% of the total number available for a gasoline engine. With the situation is slightly different, since units of this type are initially less revving, but have a higher torque. It turns out, high speed for engines of this type, one can consider those that are behind the "shelf" of the diesel torque.

Now about the engine resource with this driving style. Strong spinning of the engine means that the load on all its parts and the lubrication system increases significantly. The temperature indicator also increases, additionally loading. As a result, engine wear increases and the risk of engine overheating increases.

It should also be borne in mind that at high speed modes, the requirements for the quality of engine oil increase. Lubricant should provide reliable protection, that is, meet the declared characteristics for viscosity, oil film stability, etc.

Ignoring this statement leads to the fact that the channels of the lubrication system when constant driving at high RPMs, they can clog up. This happens especially often when using cheap semi-synthetics or mineral oil. The fact is that many drivers change the oil not earlier, but strictly according to the regulations or even later than this period. As a result, the liners are destroyed, disrupting the operation of the crankshaft and other loaded elements.

What speed is considered optimal for the motor

To save engine life, it is best to drive at such speeds, which can conditionally be considered average and slightly above average. For example, if the “green” zone on the tachometer suggests 6 thousand rpm, then it is most rational to keep from 2.5 to 4.5 thousand rpm.

In the case of atmospheric internal combustion engines, designers try to fit the torque shelf in this range. Modern turbocharged units provide confident traction at lower engine speeds (the torque shelf is wider), but it is still better to spin the engine a little.

Experts say that the optimal operating modes for most motors are from 30 to 70% of maximum number rpm while driving. Under such conditions, minimal damage is caused to the power unit.

Finally, we add that it is periodically desirable to spin up a well-heated and serviceable motor with quality oil by 80-90% when driving on flat road. In this mode, it will be enough to drive 10-15 km. Note that this action do not need to be repeated often.

Experienced motorists recommend spinning the engine almost to the maximum once every 4-5 thousand kilometers traveled. This is necessary for different reasons, for example, so that the cylinder walls wear out more evenly, since with constant driving only at medium speeds, a so-called step can form.

Low speed driving with early shifting

Often, driving school instructors and old drivers recommend that beginners drive “in tightness” - switch to top gear upon reaching 1500–2000 rpm crankshaft. The first give advice for safety reasons, the second - out of habit, because before the cars had low-speed engines. Now this mode is only suitable for a diesel engine, whose maximum torque is in a wider rev range than a gasoline engine.

Not all cars are equipped with tachometers, so inexperienced drivers with this style of driving should be guided by speed. The early shift mode looks like this: 1st gear - moving from a standstill, shifting to II - 10 km / h, to III - 30 km / h, IV - 40 km / h, V - 50 km / h.

Such a shifting algorithm is a sign of a very relaxed driving style, which gives an undoubted advantage in safety. The downside is an increase in the wear rate of parts of the power unit, and here's why:

The oil pump reaches its nominal capacity from 2500 rpm. Loading at 1500–1800 rpm causes oil starvation, especially suffer connecting rod bearings sliding (liners) and compression piston rings.
Burning conditions air-fuel mixture far from favorable. In the chambers, on the valve plates and piston bottoms, carbon deposits are heavily deposited. During operation, this soot is heated and ignites the fuel without a spark at the spark plug (detonation effect).
If you need to rev the engine sharply when driving downhill, you press the accelerator, but acceleration remains sluggish until the engine reaches its torque. But as soon as this happens, you shift into a higher gear and the crankshaft speed drops again. The load is large, there is not enough lubrication, the pump poorly pumps antifreeze, hence overheating occurs.
Contrary to popular belief, there is no fuel economy in this mode. When you press the gas pedal fuel mixture is enriched, but not completely burned, which means it is wasted.

Owners of vehicles equipped with on-board computer, it is easy to be convinced of the uneconomical movement "in tightness". It is enough to turn on the display of the instantaneous fuel consumption.

Such a driving style wears out the power unit intensively when the car is operated in difficult conditions- on ground and country roads, fully loaded or trailer. Do not relax and car owners with powerful motors with a volume of 3 liters or more, capable of accelerating sharply from the bottom. After all, for intensive lubrication of rubbing engine parts, you need to keep at least 2000 rpm of the crankshaft.

Why is high crankshaft speed harmful?

The driving style “sneaker on the floor” implies constant crankshaft spinning up to 5–8 thousand revolutions per minute and late gear shifting, when engine noise literally rings in the ears. What is fraught with this driving style, in addition to creating emergencies on road:

all components and assemblies of the car, and not just the engine, are tested maximum loads during the service life, which reduces the total resource by 15–20%;
due to the intense heating of the engine, the slightest failure of the cooling system leads to a major overhaul due to overheating;
exhaust pipes burn out much faster, and with them an expensive catalyst;
transmission elements wear out rapidly;
since the crankshaft speed exceeds the normal speed by almost twice, the fuel consumption also increases by 2 times.

The operation of the car "at break" has an additional negative effect associated with the quality pavement. Movement on high speed on rough roads literally kills the suspension elements, and in the shortest possible time. It is enough to fly the wheel into a deep pothole - and the front strut will bend or crack.

How to ride?

If you are not a race car driver and not an adherent of tight driving, who finds it difficult to retrain and change driving style, then to save the power unit and the car as a whole, try to keep the engine operating speed in the range of 2000-4500 rpm. What bonuses will you receive:

Mileage up to overhaul the motor will increase (full resource depends on the brand of car and engine power).
Thanks to the combustion of the air-fuel mixture in the optimal mode, you can save fuel.
Fast acceleration is available at any time, you just need to press the accelerator pedal. If there is not enough speed, immediately switch to a lower gear. Repeat the same steps when moving uphill.
The cooling system will function in operating mode and protect the power unit from overheating.
Accordingly, suspension and transmission elements will last longer.

Recommendation. On most modern cars equipped with high speed gasoline engines, it is better to shift gears when the threshold of 3000 ± 200 rpm is reached. This also applies to the transition from higher to lower speed.

As stated above, dashboards cars don't always have tachometers. For drivers with little driving experience, this is a problem, since the crankshaft speed is unknown, and the beginner does not know how to navigate by sound. There are 2 options for resolving the issue: buy and install on a dashboard electronic tachometer or use the table, which shows the optimal engine speed in relation to the speed in different gears.

Position of the 5-speed gearbox	1	2	3	4	5
Optimum crankshaft speed, rpm	3200–4000	3500–4000	at least 3000	> 2700	> 2500
Approximate vehicle speed, km/h	0–20	20–40	40–70	70–90	over 90

Note. Considering that various brands and modifications of machines, there is a different correspondence between the speed of movement and the number of revolutions, the table shows the average indicators.

A few words about coasting from a mountain or after acceleration. In any fuel supply system, a forced idle mode is provided, which is activated under certain conditions: the car is coasting, one of the gears is engaged, and the crankshaft speed does not fall below 1700 rpm. When the mode is activated, the supply of gasoline to the cylinders is blocked. So you can safely brake the engine at top speed without fear of wasting fuel.

In materials about cars, the expressions “high speed”, “high torque” are often used. As it turned out, these expressions (as well as the relationship between these parameters) are not clear to everyone. So let's talk about them in more detail.

Let's start with the fact that the engine internal combustion is a device in which the chemical energy of a fuel that burns in working area, is converted into mechanical work.

Schematically, it looks like this:

The combustion of fuel in the cylinder (6) causes the piston (7) to move, which in turn causes the crankshaft to rotate.

That is, the expansion and contraction cycles in the cylinders actuate crank mechanism, which in turn converts the reciprocating motion of the piston into rotational motion of the crankshaft:

What the engine consists of and how it works, see here:

So, the most important characteristics engine are its power, torque and speed at which this power and torque are achieved.

Engine speed

The commonly used term "engine revolutions" refers to the number of revolutions of the crankshaft per unit time (per minute).

Both power and torque are not constant values, they have a complex dependence on engine speed. This relationship for each engine is expressed by graphs similar to the following:

Engine manufacturers are struggling to ensure that the maximum torque of the engine develops in the widest possible speed range (“torque shelf was wider”), and maximum power achieved at speeds as close as possible to this shelf.

Engine power

The higher the power, the great speed develops auto

Power is the ratio of the work performed in a certain period of time to this period of time. In rotary motion, power is defined as the product of torque and angular velocity rotation.

Engine power has recently been increasingly indicated in kW, and earlier it was traditionally indicated in Horse power Oh.

As you can see in the graph above, maximum power and maximum torque are achieved at different crankshaft speeds. The maximum power for gasoline engines is usually achieved at 5-6 thousand revolutions per minute, for diesel engines - at 3-4 thousand revolutions per minute.

Power curve for diesel engine:

In practical terms, power affects speed characteristics auto: the higher the power, the more speed the car can develop.

Torque

Torque characterizes the ability to accelerate and overcome obstacles

Torque (moment of force) is the product of the force on the arm of the lever. In the case of a crank mechanism, this force is the force transmitted through the connecting rod, and the lever is the crank of the crankshaft. The unit of measure is Newton meter.

In other words, torque characterizes the force with which the crankshaft will rotate, and how successfully it will overcome rotational resistance.

In practice, the high torque of the engine will be especially noticeable during acceleration and when driving off-road: at speed, the car accelerates more easily, and off-road, the engine withstands loads and does not stall.

More examples

For a more practical understanding of the importance of torque, let's give a few examples on a hypothetical engine.

Even without taking into account the maximum power, some conclusions can be drawn from the graph reflecting the torque. We divide the number of revolutions of the crankshaft into three parts - these will be low revolutions, medium and high.

The graph on the left shows a variant of the engine that has high torque at low speeds (which is equivalent to high torque at low speeds) - with such an engine it is good to drive off-road - it will "pull" out of any quagmire. The graph on the right shows an engine that has high torque at medium speeds (medium speeds) - this engine is designed for use in the city - it allows you to accelerate quite quickly from traffic light to traffic light.

The following graph characterizes an engine that provides good acceleration even at high speeds - with such an engine it is comfortable on the track. Closes charts universal motor- with a wide shelf - such an engine will pull it out of the swamp, and in the city it allows you to accelerate well, and on the highway.

For example 4.7 liter Gas engine develops a maximum power of 288 hp. at 5400 rpm, and a maximum torque of 445 Nm at 3400 rpm. And the diesel 4.5-liter engine installed on the same car develops a maximum power of 286 hp. at 3600 rpm, and the maximum torque is 650 Nm at a "shelf" of 1600-2800 rpm.

The 1.6-liter X engine develops a maximum output of 117 hp. at 6100 rpm, and the maximum torque of 154 Nm is reached at 4000 rpm.

The 2.0-liter engine delivers a maximum output of 240 hp. at 8300 rpm, and a maximum torque of 208 Nm at 7500 rpm, being an example of "sportiness".

Outcome

So, as we have already seen, the relationship between power, torque and engine speed is quite complex. Summing up, we can say the following:

torque responsible for the ability to accelerate and overcome obstacles,
power responsible for top speed car,
A engine speed everything complicates, since each value of revolutions corresponds to its own value of power and torque.

And in general, everything looks like this:

high torque at low rpm gives the car traction for off-road driving (such a distribution of forces can boast diesel engines). At the same time, power can already become a secondary parameter - remember, for example, the T25 tractor with its 25 hp;
high torque(or better - “torque shelf) at medium and high speeds makes it possible to accelerate sharply in city traffic or on the highway;
high power engine provides high top speed;
low torque(even when high power) will not allow to realize the potential of the engine: being able to accelerate to high speed, the car will take an incredibly long time to reach this speed.

The choice of the required camshaft should begin with two important decisions:

determining the main operating range of engine power;

how long the camshaft should run.

First, let's check how we determine the operating rpm range, and how the choice of camshaft is determined by this choice. Maximum engine speeds are usually easy to isolate, as they directly affect reliability, particularly when the main parts of the block are conventional.

Maximum engine speed and reliability for most engines

Maximum engine speed	Estimated working conditions	Expected service life with related parts
4500/5000	Normal movement	Over 160,000 km
5500/6000	"Soft" forcing	Over 160,000 km
6000/6500		Approximately 120,000-160,000 km
6200/7000	Forcing for everyday driving/ "soft" racing	About 80,000 km
6500/7500	Very "hard" street riding or "soft" to "hard" racing	Less than 80,000 km in street driving
7000/8000	Only "hard" races	Approximately 50-100 runs

Keep in mind that these recommendations are general. One engine can hold up much better than another in any category. How often the engine is accelerated to maximum speed is also very important. However, as general rule you need to be guided by the following: the maximum engine speed should be below 6500 rpm if you are building a boosted engine for everyday driving, and it is required reliable performance. These engine speeds are normal for most part limits and can be obtained with medium force valve springs. So if reliability is the primary goal, then a top speed of 6000/6500 rpm would be a practical limit. Although the decision on the maximum RPM required may be relative simple process based in principle on reliability (and maybe cost), the inexperienced engine designer may find determining the engine's operating speed range a much more difficult and dangerous task. Valve lift, stroke duration and cam profile camshaft will determine the powerband, and some inexperienced mechanics may be tempted to choose the "largest" possible camshaft in an attempt to increase the engine's maximum power. However, it is important to know that maximum power is only needed for a short time when the engine is at maximum speed. The power required from most uprated engines is far below the maximum power and RPM; in fact, a typical boosted engine can "see" a full opening throttle valve only a few minutes or seconds for a whole day of work. However, some inexperienced engine builders ignore this obvious fact and choose camshafts more by intuition than by guidance? If you suppress your desires and make a careful choice based on real facts and possibilities, then you can create an engine capable of delivering impressive power. Always keep in mind that the camshaft is pretty much a compromise part. After a certain point, all gains come at the cost of low-end power, loss of throttle response, economy, etc. If your goal is to increase horsepower, then first make modifications that add maximum power by improving intake efficiency, as these changes have less effect on power at low rpm. For example, optimize the flow in the cylinder head and in the exhaust system, reduce the flow resistance in the intake manifold and in the carburetor, then install a camshaft in addition to all the above "set". If you use these techniques judiciously, the engine will produce the wider power curve possible for your investment of time and money.

In conclusion - if you have a car with automatic transmission, then you need to be conservative when choosing the valve timing of your camshaft. Too long valve opening will limit engine power and torque at low rpm, which are essential elements in ensuring good acceleration and starting the car from a standstill. If your car's torque converter stops at 1500 rpm (typical for many standard transmissions), then a camshaft that puts out good torque, though not necessarily maximum power, at 1500 rpm will provide good acceleration. You may be tempted to use a high stop torque converter and long valve timing in an attempt to achieve best result. However, if you are using one of these torque converters with normal traffic then their efficiency at low speeds will be very low. Fuel efficiency will suffer quite a lot. For an everyday car, there are more efficient ways to improve low rpm acceleration.

Let's summarize the main elements of choosing a camshaft. First, for everyday driving, the maximum engine speed must be maintained at a level not exceeding 6500 rpm. RPMs above this limit will noticeably shorten the life of the engine and increase the cost of parts. While a "normal" engine can benefit from as much valve lift as possible, too much valve lift will reduce engine reliability. For all high lift camshafts, bronze valve guides are a necessary item to ensure long term bushing service life, but for valve lifts of 14.0 mm or more, even bronze guide bushings cannot reduce wear to a level acceptable for normal applications.

The longer the valves are held open, especially inlet valve, the more maximum power the engine will produce. However, due to the variable nature of camshaft timing, if valve timing or valve overlap goes beyond a certain point, all the extra maximum power will come at the cost of low-end performance. Camshafts with intake strokes up to 2700 measured at zero valve lift are good replacements for standard camshafts. For high-powered engines, the upper limit of the duration of the intake stroke of more than 2950 is the property of a purely racing engine.

Valve overlap causes some torque loss at low rpm, however, these losses are reduced when valve overlap is carefully selected for the application - from about 400 for camshafts standard engines up to 750 or more for special applications.

Valve timing, valve overlap, valve timing and cam center angles are all related. It is not possible to adjust each of these characteristics independently on single cam engines.

Fortunately, most camshaft specialists have spent many years creating cam profiles for power and reliability, so they can offer a camshaft that suits your needs well. However, do not blindly accept what the masters offer you; you now have the information you need to competently discuss camshaft specifications with camshaft manufacturers.

After all, the camshaft is one of the parts of the intake system. It must match with the cylinder head, intake manifold and exhaust system. Volume intake manifold and the size of the exhaust manifold pipes must be matched to match the power curve of the engine. In addition to this, the air flow rate in the carburetor, the number of chambers, the type of activation of the secondary chamber, etc. also have a noticeable effect on power.