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Answering "Why Are You Looking For A New Job?"

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This is one of those job interview questions that will be asked by the savviest of interviewers. Although it’s positively heart-stopping to be on the answering end of this question, if you were the employer, wouldn’t you want to know how this seemingly fabulous person ended up on the job market? It’s similar to meeting an interesting, attractive person of the opposite sex, or finding a used car that’s only got 1000 miles on it and is 3 years old. Just a little too good to be true, and you can’t believe that no one else has discovered this amazing find.

Basically they’re trying to figure out what is wrong with you, and suspect they will get a clue by looking at your relationship with your last job.

So your task is to not give them any ammunition to rule you out of the game.

1. Never, ever, ever speak ill of your current employer, or any former employers for that matter. Everyone knows that one reason for this is because your interviewer will envision you badmouthing them when you decide to leave, and nobody wants to think about bad rumors about themselves traveling through the industry. Another reason to avoid dissing your past employer is that in this very small world, they could be a friend, relative or even your potential client at this new job. No person works on an island and you must always be conscious of the seemingly invisible threads that connect so many people.

2. Another never is to speak ill of the tasks you were asked to perform at your past or current job. ANY tasks. You may think that this new job would provide a blissful escape from the tedium of your last one, and so gleefully explain to an interviewer all of the mind-numbing things you were asked to do. However, your interviewer is thinking about the similar (but different) mind-numbing tasks of this position, and decides that you would quit after the first month. There’s no reason to hire you if you’ve already given them a reason for you to quit.

3. Also, you don’t want to speak ill of your co-workers. Those were or are your teammates, and the same rule holds true as reason #1. This world is too small, and good jobs are too few to take the chance.

So what CAN you say?

1. You can say that you wanted a new opportunity. That you felt that you had taken your current or past position as far as you could within the company, you had achieved X, Y and Z, and now feel that it’s time for you to learn a different aspect of the business, or to work for a bigger (or smaller) company. The key here is to focus on the future. Focus on the opportunities you see in this new position, how it will help you grow and learn and not what was wrong with the last company you worked for.

2. If you are applying for a job that touts flexible hours, work from home or excellent benefits in the job posting, you can mention those qualities as a reason to look into this new position. Again you don’t want to speak ill of your current employer, but say that you understand why they need to run their business as they do, but if the working arrangements at this new company are better suited to your lifestyle at the moment then it might be a good fit. You are showing the employer that there is a natural fit between their needs and your needs.

In the cases where you were let go from a position, all of the above rules apply. If it’s the truth, you can say that you were laid off as a result of a company-wide restructuring or budgetary cuts. If it was due to a disciplinary action you can say that at the time you were having some time management issues (if you were fired for being consistently late), but you have learned your lesson, that you take an employer’s requirements a lot more seriously and have taken proactive measures (which you can briefly describe) to prevent yourself from getting in that situation again. Show that you have made your mistake with your past employer and have absolutely no intention of making the same mistake twice. Sincerity, an action plan and great references are necessary to counteract any remaining issues.

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Source by Melanie Szlucha

2015 Subaru WRX and STi Modifications to Increase Horsepower

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The Best 2015 Subaru WRX and STi Modifications

For the 2015 model year, Subaru has done what many never expected – split up the WRX and STi versions of its popular Impreza all-wheel drive Rally inspired four door. That’s right, the WRX and STi no longer share the same engine. While still featuring many of the same differences as prior generation, this is a big step for Subaru as they explore many new avenues and technologies with the 2015 WRX.

2015 STi vs 2015 WRX

Let’s start with the 2015 STi, as not much has changed with this model. It still retains many of the same old technology seen in prior generations. It makes sense for Subaru to hold back on any drastic changes where it matters the most, as the STi is one of the leading sellers in their current lineup. The engine remains an EJ257 using the same journal bearing turbocharger seen in past models, making an acceptable 305hp. Subaru did get into changing up the suspension a bit, making it stiffer and more refined for the road, but the AWD system remains the same as the last generation. In the end, the only big change for the 2015 STi is the exterior, taking up just a few more inches in parking spaces and giving it back to the interior occupants.

On the other hand, the 2015 WRX got major changes that affect every aspect from performance to handling. It also got a nice exterior makeover that many say makes it look better than the STi. New for the 2015 WRX is the engine, a shiny new FA20DET seen in the Forester XT and teasing it’s Subaru cousin’s N/A FA20. A twin scroll turbocharger helps propel it to an impressive 268hp, while direct injection helps rocket it to 16psi boost (from the factory!). The AWD system isn’t too terribly exciting as far as new-ness, but a 6-speed transmission helps push it down the road, while the refined suspension keeps it comfortable. The 2015 WRX cashes in at a few thousand cheaper than the 2015 STi, leaving it the more affordable option for AWD-turbo junkies!

Best 2015 Subaru STI Mods

2015 STi Intake: There are many brands that deliver great products at affordable, budget friendly prices. A quick search finds options from Mishimoto, Perrin, COBB Tuning, and AEM. From that list, AEM is one of the most recognizable names offering the most complete intake kit including air filter, heat shield, and intake pipe at the lowest cost. I imagine most companies will jump on board and start producing aftermarket 2015 STi intake systems, so keep an eye out for future offerings.

2015 STi Exhaust: For the exhaust, you really can’t go wrong with any choice you make. The 2015 STi exhaust is pretty restrictive from the factory, so utilizing a full turbo-back exhaust is recommended. If you’re on a budget, however, a plain jane 2015 STi catback will give adequate improvements in exhaust flow to increase power and torque. Many name brand exhaust systems are available for purchase from many online vendors, but ETS has become a reliable company producing quality parts for budget minded and cost indifferent owners alike.

2015 STi Tuning: Tuning has become much easier over the last 10 years. It has quickly become the fastest growing technology on the aftermarket today, earning the most power and torque in the process. There are only a few 2015 STi Tuning modules now on the market, making this decision easier than any other. COBB Tuning 2015 STi tuning module is one of the easiest modules to use- EVER! Its easy to read display and easy to understand layout make it the best option for not only the 2015 STi, but also many other cars on the market!

Best 2015 Impreza WRX Mods

2015 WRX Intake: Similar to the STi, chosing the best 2015 WRX intake system is a difficult decision. Many of the same kits are available for both platforms, with full kits from Perrin Performance, ETS, Injen, and AEM. COBB Tuning offers a complete kit including silicone intake pipe, air filter, and support bracket for the lowest price point compared to similar kits, while full kits from AEM and Injen are also available.

2015 WRX Exhaust: The best exhaust system for a 2015 WRX depends on what you want to do with the car. Catbacks are the best choice for daily driver vehicles, but full turboback systems are the definitive choice for racers and rally driven cars. Basic axle back exhausts do exist, but offer littler performance benefits and are more designed for changes in exhaust tone. Invidia has the largest selection of 2015 WRX exhausts, offering turboback, catback, and axleback exhausts at an affordable, budget friendly price while meeting high quality material requirements.

2015 WRX Tuning: Much like the 2015 STi, the only plug and play tuning device for the WRX comes from COBB Tuning. The same can be said about this unit as the STI, as it’s the same module just with different ECU tunes. Go with COBB Tuning, you won’t regret it.

Final Conclusion

Buy the aftermarket parts you can afford, but beware of bad materials used in the manufacturing process which can lower the life of the parts. Consider your power goals and the intended use of the car, and chose the best 2015 Subaru parts according to your budget and plans for the car. You’ll thank yourself in the end!

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Source by Alex Kollos

The Three Dimensions of Trust

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Webster offers numerous definitions for trust but the first one you would see if you were to look is: “total confidence in the integrity, ability and good character of another.”

That definition offers a fine starting point. At the same time something I read recently in the book, Crucial Conversations by Patterson, Grenny, McMillan and Switzler (McGraw-Hill, New York, NY, 2002) set me to thinking about all the nuances that contribute to or detract from our ability and willingness to place out trust in others.

According to those authors there are two key factors that enter into the degree of trust we place in an other person. One of those is the person’s ability (read: skill, knowledge and experience) as it relates to the performance of a task; i.e., can we trust them to perform in a competent fashion? By example, it’s the challenge for the parents of a newly-licensed teenage driver. The teen may be highly trustworthy as to their character but invariably they lack the experience required to handle the variety of risks they will face behind the wheel.

Actually, that facet of trust is what lies behind our ability to trust objects to perform as expected. I trust my truck to get me where I want to go. I trust the bridge I cross each day on my way to the office. I trust the roof over my head. Such trust can even extend to the performance and reliability of entities as in I trust my favorite Mexican restaurant to deliver a consistent quality meal.

When it comes to people, that sort of trust is a key determinant in our decision to delegate. Specifically, do they have the experience and technical ability needed to perform the task in a timely and effective fashion?

Many organizations spend small fortunes trying to convince you and me that we can trust them and their products. For instance I still remember from my childhood the tag line to Texaco’s commercials, “You can trust your car to the man who wears the star…” What about you? What advertisements can you recall where trust was (is) central to the message?

Yet when it comes to people (as well as some entities) there are two additional factors we must evaluate starting with motive or motivation. In that aspect of trust we are called upon to make a judgment about do we trust their commitment and integrity when they promise they will do something or behave in a certain manner. The authors of Crucial Conversations suggest this element of trust is (or should be) largely situational. That is, if their motive (motivation) is aligned with mine, then I should be able to trust them to fulfill their promise(s). Conversely, when the other party is operating with a different agenda it might not be so wise to place our trust in their pledge to perform.

Unfortunately, Patterson, Grenny, McMillan and Switzler stop there in their discussion. However I think there is a third, equally important element that almost always enters into the equation – that being our past experience with the individual (entity or object as the case maybe). Have they proven themselves to be dependable, reliable, a person of their word and therefore someone who is trustworthy? Or, have they violated the trust extended to them at some point in the past so that the evidence suggests a measure of risk? Having failed us in the past, can they be trusted now?

Personally, I believe this third dimension comes into play more frequently than does motive in a lot of settings and decisions if for no other reason than true motive can be difficult to judge or detect.

Of course past behaviors is a problem that could haunt just about all of us since who among us hasn’t managed to break trust with someone else at some point? Certainly I’ve been guilty more than I care to admit. And once that trust is violated or lost it is a very hard thing to re-establish.

Early on in this piece I stated that the decision to delegate a task to someone else involves placing one’s trust in their ability to perform as expected. In the workplace an act of delegation is most often thought of in the context of boss to subordinate. However, just as in the context of teams, family or the volunteer environment trust really must be a two-way street. For the employee to be effective he or she must have (earn) the trust of the supervisor. At the same time so too must the supervisor be worthy of the trust of those they would lead. Inconsistency on the part of the leader between walk and talk or talk and talk quickly calls into question the agenda (motive) not to mention the overall sense of integrity.

And though the road back from that place where trust has been lost may be long and arduous, I hope most would agree it is a road worth taking.

“Whoever can be trusted with very little can also be trusted with much, and whoever is dishonest with very little will also be dishonest with much. So if you have not been trustworthy in handling worldly wealth, who will trust you with true riches?” Luke 16:10-11

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Source by Keith Hughey

How To Make Your Car Masculine

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If your car looks a little on the girly side, there are a lot of modifications you can do to give it a more masculine touch. Making your car more masculine will make you confident when you pick up your date, and will make you enjoy it much more when you’re riding in it alone. Below are some ideas on how to make your car a male.

  • Change the Rims: Adding custom rims to your wheels will definitely give your car a manly personality. They not only make your car look really cool, but they also help your car’s traction and steering. Take a car with custom rims for a ride and you’ll definitely feel the difference. Most rims come in standard colors of silver, grey, chrome or black. But you can also get custom colors like white, gold or blue. If you really want to attract attention, get spinner wheels that rotate even after the car has stopped moving.

  • Get Custom Car Seat Covers: This is another great way to add the masculine personality to your car that you’re looking for. You can get solid colors like black, brown or tan in cloth fabric, or you can get nice leather covers if you can splurge a little more. You can also have your car seat covers customized by adding your initials or a design embroidered somewhere on the side of the cover. They also come in dual colors, like tan and black or red and black. An added bonus of having car seat covers is that they protect your seats from dirt, and other debris, making your car easier to clean. Since they keep food and drinks from getting trapped inside the cushions of your seats, seat covers keep your car smelling fresher longer. They also make an excellent gift for any male in your family or office.

  • Get a Steering Wheel Cover: A thick black or brown leather cover on your steering wheel will definitely add some masculinity to your automobile. There are many options when it comes to steering wheel covers. You can get them in leather, suede, polyester, or a soft fabric like sheepskin. The most popular colors amongst men are black and brown, but they also make custom steering wheel covers with different logos on them. You can get a cover with a logo of your favorite sports team on it. And you don’t have to stop there. You can also get floor mats to match. There is no way your car would be considered girly with all these accessories.

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Source by Ellen Langevitz

Causes Of Shortened Car Battery Life

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Taking care of your vehicle is a lifelong pursuit and an investment. In order to keep it functioning properly, you need to maintain a constant maintenance schedule for your car. If you neglect your vehicle, you will end up paying for it, literally, with costly repairs. The longer you have your car, the more likely you will need to start replacing essential parts.

There are many reasons that your car may not start up when you turn the key, but one of the most common problems is a dead battery. The average car battery lasts about 3 to 5 years, depending on several factors including consistency of use or harsh conditions. But there are a few specific things that are guaranteed to shorten the life of your battery. Battery corrosion is a common problem that can develop from battery overcharging. If left untouched, it can destroy battery terminals and connections. You can clean your battery terminals using a mixture of baking soda and water.

Another problem that can shorten the life of your battery is if your vehicle’s charging system is not charging the battery correctly. This can be caused by a few things including a worn drive belt that doesn’t turn the alternator fully, blown diodes, or faulty regulators. If you turn attempt to start your car with no results and you suspect it to be the battery, the best thing to do is to contact your local auto repair shop. They can check the charge of your battery and determine whether your problem is battery-related or something else entirely.

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Source by Cleo Gib

Supercharger Tuning Through Cam Selection and Cam Timing

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Camshaft tuning is an essential part of supercharger tuning. Camshafts orchestrate the valve opening and closing events in the engine and decide whether what comes out of our motor is beautiful high power music, or a mess of dysphonics.

The use of the proper supercharger optimized cam shaft can go a long way towards supercharger tuning and give considerable power gains for the money invested.

To understand camshaft timing and camshaft selection we have to understand first:

Relativity: Changing when the valves open or close (intake or exhaust) changes the the valve timing with respect to:

  • The piston position inside the cylinder. Depending on where the pistons is in the stroke, and where we are in the combustion cycle, then opening the valves will exploit the pressure difference between the cylinder and the intake and exhaust manifolds.For example it would make sense that the ideal time to open the intake valve is when there is peak vacuum inside the cylinder so that when the valve opens, the maximum amount of fresh air can be ingested. Similarly, it makes sense not to open the exhaust valve until peak cylinder pressures have been achieved inside the combustion chamber and the combustion is complete and all the power is extracted.
  • The high and low pressure pulses created by the design and runner lengths of the intake and exhaust manifolds.It would make sense to open the intake valve just as the reflected pressure waves in the intake manifold reach the intake valve as a high pressure portion of the wave, thus opening the valve at this high pressure point gives 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) portion of the exhaust wave (reflected back from the collector) reaches the back of the exhaust valve. At this point in time there is both peak pressure inside the cylinder, and vacuum in the exhaust which creates a higher pressure differencial and a faster evacuating exhaust gas.
  • With respect to the ignition timing event, for example a shorter duration or advanced exhaust cam, opens the exhaust valve sooner with respect to when the mixture was originally ignited, this means that although by advancing the exhaust cam we may have matched our header design and opened the valve with the lowest possible exhaust back pressure for best efficiency, at the same time, we have reduced the amount of time that the mixture is combusted and possibly opened the valve before reaching our peak cylinder pressures and thrown away some horsepower.
  • The intake valves with respect to the exhaust valves: and this is usually described in terms of lobe separation angles (the offset in degrees between the center of the exhaust cam and between the center of the intake cam), or in terms of how many degrees of overlap (the number of degrees that both intake and exhaust valves are open at the same time).

Since the combustion inside the cylinder occurs at a much higher pressure than atmospheric pressure, and since exhaust valves are usually smaller than intake valves (for this same high pressure reason) then exhaust gas velocity is much higher than intake gas velocity. So, in some engines it is beneficial to open the intake valve earlier than usual during the last part of the exhaust stroke, this is called overlap. During overlap – at the very end of the exhaust stroke – the amount of pressure left in the cylinder is low so it is possible to breathe in new air under atmospheric pressure, at the same time, the high velocity of the exhaust gasses exiting help draw in even more fresh air from the intake side in an effect much like ‘syphoning’ where the fluid (in our case air) flows as a continuous stream drawing in new intake air after the old exhaust gas leaves.

The other part of phenomenon that relates to timing intake valves with respect to exhaust valves is the duration of time where both valves are absolutely closed, which is your power stroke. This is the part of the combustion cycle where the mixture can be compressed and combusted. If either (or both) intake or exhaust valves are open you will not be able to neither compress nor combust the mixture, and the absolute duration of time (in degrees of rotation) that your mixture is combusted and allowed to reach peak cylinder pressures is affected by camshaft selection and cam timing. One thing to note is that the valve angle has a lot to do with exhaust scavenging, obviously you will get maximum scavanging if the exhaust and intake valves had ‘line of sight’ i.e. if the valves were separated by an angle of 180*. If so, the exhaust air can directly pull in new air. Conversely, you would have the least possible scavenging if you had valves that were at a narrow angle (zero degrees at the extreme) between each other, so that the air would essentially have to make a U turn to come in through the intake and get pulled out the exhaust.

So different motors respond differently to overlap depending on the exhaust back pressure and the valve angle.

Duration:

Cam duration is the number of degrees of the entire 360* rotation that the intake or exhaust valve is open. The longer the duration, the more air you can get into the motor, the more overlap you have (which helps more with higher rpm power performance), the shorter your power stroke is (which reduces your combustion duration and your peak cylinder pressures reducing low rpm fuel efficiencly and clean idle….etc

Increased duration (with it’s increased overlap and scavenging) also gives the opportunity for exhaust gasses to get to the intake, or intake gasses to leak to the exhaust, and so are more sensitive to proper timing events otherwise we can get some negative effects from being ‘overcammed’

Lift:

Lift is how far or how deep the valve opens into the cylinder. The more lift you have, the less the valve is a restriction to incoming air because it is farther away from the direct path of entering or exiting air. Adding lift in general adds power to all rpms, depending on how well the camshaft (and valve train) can accelerate the valve to a higher lift number in a short duration. It’s like a ramp, the shorter the duration and higher the lift, the steeper the ramp. So what happens here is that if your valve train isn’t light enough and well controlled (Through proper valve springs or hydraulic lifting and damping) to operate that rapidly then lift will give you improved performance at lower rpms (where there is a lot of time to move the valve to peak lift) but reduced performance at higher rpms, where there are more rounds per minute and so less time per round, and thus less time to go up the steep ramp and push the valve out to full extension.

Lift is good, but usually people don’t try to radically increase lift on their aftermarket cams because of a few considerations:

  1. Make sure that at this new lift, that there is still enough clearance between the valve (at full extension) and the cylinder (at top dead center) to prevent any catastrophic mechanical failure.
  2. Upgrade to lighter valve train, with stiffer springs or dual valve springs to have more control over the valve with this steeper cam profile.
  3. It does add power but it doesn’t shift the power curve up or down as radically as changing cam duration does, and so in most aftermarket applications we really want a cam to give us peak power at a certain rpm range and so we care much more about the best duration (and some added lift).

I know this is a somewhat complex topic, but I need to make sure we’re speaking the same language before we go into how this relates to superchargers. Before you decide which camshaft to use (or how to adjust the timing on your stock cams) you have to look at one very important thing:

Your exhaust system and exhaust back pressure:

If you have a stock log type exhaust manifold, with a close coupled cat, with a dual cat exhaust system, small exhaust tubing, and a couple of restrictive mufflers on your car then it is possible at peak power to have up to 10psi of back pressure.

If this is the case, my first recommendation would be to upgrade to a high flow, low pressure exhaust system because of the potential power gains; however, I do know that some of our readers have cars that they are setting up for their parents or for dual use where their partner or the laws in their location …etc are really strict when it comes to any added exhaust noise or any aftermarket exhaust. In this case, where exhaust upgrades are not an option, then you must select your camshafts, and tune your cam timing to where you have ABSOLUTELY the minimum possible amount of overlap. If you have significant overlap, then the more you rise above about 4500 rpms the more your supercharger will suffer and the more power you will waste. If the supercharger is geared to 7psi of boost for example, then during overlap, the cylinder sees 7psi of boost on the intake side, and 10psi of back pressure on the exhaust side, the net result is that air will flow from the high pressure zone (the exhaust) to the lower pressure zone (the intake) and so your cylinder will start to fill with exhaust gases. As the rotation continues, the exhaust valve will close and overlap will end, and the intake valve will stay open for the remainder of the intake stroke (for the rest of the duration of your intake cam), and the rest of the cylinder will fill with fresh air.

What happens here is that we get a cylinder that filled for 30* of overlap with exhaust air, and then filled for another 210* (of the original 240* of duration for a typical street cam) with fresh air. The result is a cylinder that is only 85% filled with fresh air or an engine that is literally 15% smaller in displacement! On the other hand, if our supercharger is geared for 18psi for example, then during overlap we will have 18psi on the intake side and our exhaust back pressure of 10psi on the exhaust side, the net result of this overlap is that our supercharger is effectively only producing 8psi worth of differential pressure between the intake and the cylinder and so we are only going to get a power boost of 8psi during overlap. So, during those 30* of overlap the supercharger is only effectively producing 8psi of boost, and after that once the exhaust valve closes, the supercharger will be able to go back to operating at full boost for the other 210*. The net result is something like 16psi of boost so 2psi (or about 12%) of our power was wasted.

Supercharger tuning through cam selection and cam timing

Intake cam:

Because of the negative effects of overlap on a supercharger car’s performance, and especially in the case of high exhaust back pressure as is the case with most factory supercharged cars, we find that the optimal cam duration for the intake cam is typically 30-40* of duration less than a normally aspirated camshaft for the same peak power RPM. The decision to reduce the intake cam duration rather than split the duration reduction between the intake and exhaust cams, is that the intake cam will flow air under pressurized conditions (due to the addition of the supercharger and the increase in intake manifold pressure) and so at a reduced intake cam duration the engine will still be able to get it’s full share of intake air. At the same time, the high rpm efficiency improvement from the reduction of overlap will also boost power production with a more conservative cam. Finally, if we would like to get more flow from the intake cam, there is still the option of using a higher lift camshaft (with a steeper profile due to the decreased duration) with supporting valve train modifications to make sure valve float doesn’t occur at higher rpms.

Intake cam timing:

The cam timing for the intake cam would ideally be retarded which would move the intake cam opening event farther away from the exhaust valve closing event so as to reduce or eliminate overlap, and as a side effect the power stroke duration will increase by retarding the intake cam which can also compensate for the lost power from the duration reduction.

Exhaust cam:

The exhaust cam duration and lift for a supercharged version of the motor should be similar to a nitrous camshaft, in the sense that the exhaust cams on nitrous specific builds have:

1- Very healthy cam duration & very healthy cam lift to allow a severely elevated amount of exhaust gases to be able to efficiently exit the motor when the nitrous is activated and the horsepower (and thus the exhaust gasses) have both doubled in quantity.

2- As little or no overlap if possible, as any overlap would mean that nitrous would be sprayed from the intake side and out the exhaust, which is wasteful of our limited supply of nitrous. Similarly the more overlap we have, the harder the supercharger will have to work because of what we explained earlier about either exhaust reversion into the intake, or the supercharger pressurizing the exhaust.

Exhaust cam timing:

Advancing the exhaust cam both opens and closes the exhaust valves sooner. Opening the exhaust valve sooner slightly reduces the power stroke, but at the same time it reduces overlap and makes better use of our supercharger. Typically an an advanced exhaust cam combined with retarded intake cam will provide the best results on a supercharged car, especially with a restrictive exhaust.

If we had a high flow exhaust system installed, then it may not be beneficial to advance the exhaust cam, a high flow exaust system that is optimized for our engine’s power requirements can clear the combustion chamber of all it’s gasses very efficiently. Having a high duration exhaust cam, a low back pressure exhaust system and a no overlap what so ever camshaft means that we are giving the exhaust gas plenty of time to exit they cylinder, the intake valve still hasn’t opened (because the we have decide to retard it, or use a conservative cam with less duration) and so the supercharger is not pushing any new fresh air in yet, now the cylinder is void and so some of the exhaust gas can revert back into the cylinder, then the exhaust valve will close, and then the intake valve will open only to find the cylinder already partially filled with exhaust gases.

This isn’t a problem with a restrictive exhaust because a restrictive exhaust will take some time to clear the cylinder at a lower velocity, however with a higher flow exhaust system we must be careful not to dial out ALL of the overlap in the cam timing, or to over-cam the exhaust cam (using too much duration).

So exhaust cam timing can be advanced or retarded, depending on the exhaust modifications and the intake cam selection and thus must be dyno-tuned.

It’s important to note that with all of these changes in cam selection , overlap, power stroke duration, and cam timing, that the power stroke duration is effected and if it is effectively shortened then we may need to retune the car’s timing advance on the dyno (for increased advance) to regain losses in duration of the power stroke (again this against popular thinking of never to advance timing on forced induction cars, if we have a shortened power stroke, or an application with significant overlap then it may be necessary to do so).

So we see here that the end result here a lop-sided camshaft with a conservative duration, high lift cam on the intake side, and a normal duration, high lift cam on the exhaust with minimal lobe separation angle and minimal (but not necessarily no) overlap.

The exception to the rule:

Sometimes people take a car that starts off with a 9000 rpm redline, has an 11.5:1 compression ratio, and a 280* duration camshaft, and an aggressive naturally aspirated-esque timing curve and decide to supercharge it for more power. One suck example is kleemann’s kompressor for the SLK55 AMG (which already makes 400 hp in normally aspirated form from an 11:1 compression ratio motor). In this type of application, if you use a more conservative cam, and dial out all the overlap, and increase the power stroke, in combination with an already high 11:1 compression ratio and a healthy amount of boost pressure (7psi or above) you will end up with a motor that produces extremely high peak cylinder pressures and those intense pressures and heat may easily start off a chain reaction of pre-ignition and detonation and you will find that no matter how much you retard the timing that the setup will end up both powerless and still not that safe.

In this case, I would consider RPM and compression my primary power adder, and my supercharger as my secondary power adder (that is unless I decided to change that and went ahead and lowered the compression ratio of the motor). In this case it is OK to sacrifice some supercharger high rpm efficiency for preventing high-load & low-rpm detonation. Furthermore, to overcome the overlap inherent in this kind of high rpm normally aspirated power-plant it would be very advisable to use a centrifugal supercharger that is capable of producing more boost and flow with increased rpm rather than a roots type charger that will easily run out of boost and flow capacity (CFM) when facing an aggressive camshaft ‘leaking’ boost away.

Here is a great example of how cam tuning can affect supercharged power:

The car is a 1.8 liter Honda motor equipped with:

  • Supercharger optimized big primaries and short runners Kamakazi header
  • A greddy 2.5? SP2 catback exhaust system.
  • An LHT ported “S” supercharger inlet tube
  • An LHT ported intake manifold ( Non intercooled)
  • A Carbon fibre intake
  • A Jackson racing eaton M62 supercharger geared for 7.5-8 psi.

The black line is the baseline run with all of these modifications before tuning with peak power coming in at: 223 wheel hp @ 7600 rpms.

The blue line is the power achieved after a full tine (camshaft timing redone for reduced overlap, ignition timing re-optimized, and air fuel ratio optimized for peak power), with peak power coming in at 248 hp @ 8400 rpms.

You can see on by the dyno results that by reducing overlap and properly tuning the car the power peak not only increased by 25 horsepower, but more importantly shifted up by 1000 RPM’s due to increased supercharger high rpm efficiency from reduced overlap.

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Source by Haitham Al Humsi

Snowmobile Power Valves – Polaris, Ski-Doo & Arctic Cat Variable Exhaust Valve System Basics

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They can be called “APV” by Arctic Cat, “RAVE” by Ski-Doo or “VES” by Polaris. If you own a 2-stroke snowmobile made in the last 15 years, the engine is likely equipped with “variable exhaust power valves”. If that is the case, you probably know that you have to be quite diligent about their cleanliness and operation. This is one engine component that has to be monitored regularly to maintain peak performance.

Variable exhaust power valves are moving devices located at the engine’s exhaust port. Every brand’s variation is there to provide the same essential service and that is to vary the height and width of the exhaust port according to engine RPM. This vastly broadens the power band. At low RPM, the valves are in a closed position which promotes more complete combustion. This improves low-end torque and minimizes unburned gases in the exhaust stream. At high RPM, the valves are wide open which allows for optimum exhaust flow. This enables the engine to rev freely and produce maximum top end horsepower. Older systems were actuated by a mechanical linkage which opened and closed the valves based on engine RPM. Modern systems are actuated by electronic servo motors which precisely position the valves throughout the RPM range. Before the advent of the power valve, engine builders had to determine one size and shape of the exhaust port and exhaust pipe. This predetermined whether the engine would provide its optimum power delivery at either the high, mid or low RPM range. The power valve allows the two-cycle engine to provide usable horsepower throughout its operating RPM range.

The modern power valve system has evolved from a number of different variations over the last 30 years. Yamaha was the first company to find success with this concept when they integrated a variable exhaust power valve system in their 2-stroke Grand Prix road-racing motorcycles in the late 1970’s. The technology then made its way to Yamaha’s production road and motocross bikes the early 1980’s. Other motorcycle manufacturers soon came up with their own systems. By the early 1990’s, virtually all high-performance two-cycle motorcycles, ATV’s, personal water-crafts and snowmobiles were equipped with variable exhaust power valve systems.

Keeping the power valve system clean is of paramount importance. As power valves are located directly in the stream of the exhaust flow, carbon deposits can accumulate on the valves over time. The deposit build-up can alter the shape of the valves and change the engine’s exhaust flow characteristics. In extreme cases, the exhaust port can become completely clogged and expensive damage can occur. Deposits can also can hinder the valve movement or leave them stuck in one spot. Any of these scenarios will drastically impair the power delivery and output of your engine.

The task of maintaining your snowmobile’s power valve system is not complicated. Your service or owner’s manual will give specific instructions on how to remove and clean the system. Be careful when cleaning the valves, as you do not want to scratch or roughen the surfaces. Your manual will also offer a specific service interval and it should be followed religiously.

Once your valves are clean, there are ways to prevent premature valve depositing. First and foremost is to make sure that your machine is tuned correctly. Overly rich carburetor jetting is a major contributor to this malady. Rich jetting will allow too much fuel into the combustion chamber and this promotes carbon formation. If your sled is fuel injected, make sure that the system is operating correctly. Also make sure that your oil injection system is delivering the proper amount of oil. Perform regular spark plug readings as described in your manual. If your plug readings are off and you cannot determine the cause, contact your dealer.

Another major contributor to power valve depositing is the use of poor quality 2-cycle oil. The cheaper base stocks and additives used in lower grade oils can be cooked into carbon deposits very quickly. High quality synthetic two-cycle oil is notorious for its clean burning characteristics and will dramatically lower the rate of deposit formation. Good quality synthetic oils use sophisticated base stocks and high temperature additives which are engineered to avoid power valve depositing. They also have an effective detergent/dispersant package which will allow for much cleaner operation. When it comes to two-stroke injector oil, you definitely get what you pay for. Spending a little more on an oil that is specifically engineered to provide clean power valve operation will not only improve your engine’s performance, it will save the headaches and expense that come with premature power valve depositing.

Snowmobiles operated at low speed and steady RPM over extended periods can also promote deposit build up. During this type of operation, the valves maintain a stationary position and this allows deposits to form. If the valves are constantly changing positions, there is less chance of deposits forming and increasing in size.

Variable exhaust power valves have revolutionized the capabilities of 2-cycle engines. With a little bit of maintenance and care, they will offer trouble-free performance.

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Source by Marc Roden

Nine Driving Practice Maneuvers

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When you have become familiar with the car and the sequences required for starting and stopping, practice the following maneuvers, moving from Exercise One to Nine. During the exercises, good driving habits will be formed by remembering to use the proper signaling and shoulder checking techniques at all times.

Use a parking lot or an off street area to practice in, if possible, and if pylons or some other kind of markers are available, they will also prove very helpful.

When you are driving, remember to make all your movements gently, using light pressure on the accelerator or the brake pedal, and easy movements of the steering wheel. A good driver is a smooth driver.

When you are ready, start the car and move away slowly.

Exercise One: Driving Forward In A Straight Line

• Make sure the parking brake is on.

• With your right foot on the brake, place the gear selector in Drive.

• Keep your hands on the steering wheel at the ten and two position.

• Check the traffic.

• Signal.

• Place your right foot on the accelerator.

• Release the parking brake.

• Press gently on the accelerator, so that you move ahead slowly.

• Remove your right foot from the accelerator and apply the brake easing up slightly just before the car comes to a stop.

• Move the gear selector to Park.

Exercise Two: Backing in a Straight Line

• With your right foot on the brake, move the gear selector to the Reverse position.

• Assume the proper backing position. Many drivers find the best procedure is to place their left hand on the steering wheel at the 12 o’clock position, shift their position in the seat, and look backwards over their right shoulder.

• Check the traffic.

• Place your right foot on the brake, and bring the car to a gentle stop.

• Move the gear selector to Park.

Exercise Three: Steering Left and Right

Turning Left

• Place your hands at the ten and two position on the steering wheel.

• Turn the wheel counter clockwise with the right hand.

• Cross your left hand over your right, and, grasping the wheel at the top, pull it downwards to the left.

• Replace your right hand at the two o’clock position, and turn counter clockwise again.

• Straighten your wheels as you complete your turn by letting the steering wheel slide through your hands. Be prepared to correct as needed.

Turning Right

• Place your hands at the ten and two position.

• Turn the wheel clockwise with your left hand.

• Cross your right hand over your left, and, grasping the wheel at the top, pull it downwards to the right.

• Replace your left hand at the ten o’clock position, and turn clockwise again. Straighten your wheels as when turning left.

When you practice these maneuvers, be sure the car is moving before you begin to turn the steering wheel; otherwise, excessive wear to the tires and the steering mechanism will result.

When straightening out from a curve, return the steering wheel to its original position in a hand over hand motion.

Exercise Four: Turning A Corner To The Right

• Drive slowly forward.

• Signal a right turn.

• Check your mirrors, and over your right shoulder.

• Adjust your speed before starting the turn (braking in the turn can cause a skid).

• Take your foot off the brake and return it to the accelerator. Maintain speed, but do not accelerate.

• Turn the steering wheel to the right, using the techniques from Exercise Three. Be careful not to over steer.

• Straighten your wheels as you complete your turn by letting the steering wheel slide through your hands. Be prepared to correct as needed.

• Accelerate lightly coming out of the turn. Caution: harsh acceleration in the turn may cause a skid.

Exercise Five: Turning A Corner To The Left

• Drive slowly forward.

• Signal a left turn.

• Check your mirrors, and over your left shoulder.

• Adjust your speed before starting the turn.

• Take your foot off the brake and return it to the accelerator. Maintain speed but do not accelerate.

• Turn the steering wheel to the left.

• Straighten your wheels as you complete your turn by letting the steering wheel slide through your hands. Be prepared to correct as needed.

• Accelerate lightly coming out of the turn.

Exercise Six: Making a Figure 8 Turn

The purpose of a figure 8 turn is to combine right and left turns in the same exercise. Figure 8 turns may be made either starting to the left or to the right – both should be practiced. Caution: this maneuver should be practiced only in a vacant parking lot or other open space.

• Drive slowly forward.

• Signal a right turn.

• Check your mirrors, and over your right shoulder.

• Turn the steering wheel to the right. Complete a 360 degree turn before straightening out.

• Signal a left turn.

• Check your mirrors, and over your right shoulder.

• Turn the steering wheel to the left. Complete a 360 degree turn before straightening out.

• Repeat the procedure several times. Try varying the sharpness of your turns, so as to make large 8’s and small 8’s.

Exercise Seven: Backing To The Right

• Place the gear selector in Reverse.

• Assume the proper backing position. Many drivers find the best procedure is to place their left hand on the steering wheel at the 12 o’clock position, shift their position in the seat, and look backwards over their right shoulder.

• Back the car very slowly.

• Turn the wheel clockwise to the right (the rear of the car will turn right).

• Just before the car has reached a 90 degree turn, straighten the car by steering to the left.

• Apply the brake to stop the car gently.

• Return the gear selector to the Park position. Caution: since vision is restricted when backing, a good rule to follow is never to back unless necessary, and never back farther than necessary.

Exercise Eight: Backing To The Left

• Place the gear selector in Reverse.

• Back the car very slowly

• Place hands at the ten and two position on the steering wheel. Turn the wheel counter clockwise to the left (the rear of the car will turn left).

• Just before the car has completed a 90 degree turn, straighten the car by steering to the right.

• Apply the brakes to stop the car gently.

• Return the gear selector to the Park position.

Exercise Nine: Backing The Car Through A Figure 8 Turn

• Place the gear selector in Reverse.

• Back the car very slowly.

• Place both hands at the ten and two position on the steering wheel. Turn to the right. After the car has completed a 360 degree turn, turn the wheel to the left and straighten the car.

• Turn to the left. After the car has completed a 360 degree turn, turn right and straighten the car.

• Apply the brakes to stop the car gently.

• Return the gear selector to the Park position.

By now, you have made a good deal of progress in becoming a safe, skillful driver. If you have mastered the essential controls of your car, and can effortlessly perform the practice maneuvers in the exercises above, you are ready for the next step – driving in actual traffic conditions. If you are relaxed and careful, it will be a pleasant experience – but don’t forget to take learner’s permit with you when you get behind the wheel!

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Source by Kris Kolanko