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24

What does the power at different rpm mean? Does it mean Car 1 has better power than Car 2 because it is at lower rpm? It depends. Or does the rpm not affect the power comparison? tl;dr: The rpm of the power peak affects the engine's usability for different applications. The "peak power" number is just one point on the power band of the engine. ...


22

Ok, let's start from the same picture so we're on the same page: These engines are four stroke engines, which means the piston goes up and down a total of 4 times, twice up, and twice down for each cycle. So to answer your questions: Of course I do realize it stands for revolutions per minute, but revolutions of what? As you stated later, it's ...


17

While i'm not sure if there are mechanical tachometers like speedometers electronic tachometers are quite simple. An electronic tachometer works like an old analog volt meter. The speed of the engine is converted to a voltage. The voltage is fed to the moving coil. The coil creates a magnetic field. That field of the coil tries to align itself with the ...


16

In Short its based on low burn rate of diesel plus the longer stroke of the diesel engine. First you must understand the difference between these engines, the diesel works on purely compression of fuel , heating and generating bang to produce power, the gasoline on the other hand is natively twitchy and needs a spark to explode and produce power on its own. ...


13

Traditional rev limiters work by controlling the ignition and/or fuel. Ignition Control Retarding the spark (smoother) Completely cutting the spark (more aggressive) Fuel Control - Amount of fuel thrown in is controlled. This is used very carefully as effects of running lean at such high RPM can be detrimental to the engine health. In fact, lot ...


10

I am presuming this is a gasoline engine. If so, the symptoms sound very much like the throttle internals are dirty. If gunge builds up on the butterfly valve, it can restrict the air required for a smooth idle when the butterfly is closed, so the engine ECU needs to open the Idle Air Valve more that it thinks it should have to and you get into a cycle of ...


9

To answer your question, no it isn't bad for your car to keep it in as high a gear as you can while still maintaining speed. As long as you are above idle in RPM and your engine isn't lugging, you aren't doing any damage. See this link for more information about lugging. You mentioned that you might do this to be quieter and for fuel efficiency. Your car ...


9

Background I would be primarily concerned with the i-VTEC cam related mechanisms. I do not see that this engine is an interference engine. If it were an interference engine and you floated your valves, you would have more than likely had valve to piston contact and that would have immediate effect on your motor as well as your driving experience, you would ...


9

You have a few options out there. There are meters that clip onto the ignition system that show the engine RPMs that are quite simple and cheap: Tach meter at Amazon for example... You can also pick up a "timing light" that has a tachometer function. Either of these tools have other purposes for a shade tree mechanic, so find one that you think you will ...


8

Idle speed is limited by the weight of the flywheel. A heavier flywheel allows for lower RPM idling and vice versa. If the flywheel is too light, it doesn't have enough inertia to keep the engine turning when you're not using the accelerator pedal. But if the flywheel is too heavy, the car won't accelerate fast enough. At 540 to 1000RPM idle speeds, you can ...


8

It is in fact true that driving at slightly (key word) higher rpms is much better (for both fuel efficiency and engine life. The rpm range for the two can be different). Part 1. Engine life: Every engine has a least resonant rpm. This is when your engine vibrates the least (Think of this as the opposite of that point when your entire car begins to shake ...


7

Your engine was designed in such a way that it is most efficient between 3500RPM and 5000RPM. That means that the valve timing and camshaft profiles were made in such a way that your engine "breathes" best between those speeds. That's why you have the most torque in that region. Another thing is that as the RPM increases, it gets harder and harder to get the ...


7

It depends what you're trying to optimize. If you're looking for optimal acceleration, more RPMs are better. Most engines today produce peak power at redline. As for optimal efficiency, there's two parts to that as well: Turning fuel into mechanical energy as efficiently as possible, and using the least amount of fuel to cover a distance. The engine ...


7

This is a math-only question, and no one has explained the formulas. Also I like the idea of this simple question having multiple answers so... RPM is Revolutions Per Minute, but we want a time in seconds. When you hear that word "per" it means division. So, what we have is 4000 revolutions / 1 minute (where / is the division symbol). This easily ...


6

I'm working on developing an automatic bicycle (mostly microcontroller based) and I'd presume I'd be shifting in a similar way to a car. Well, you're in for a shock: it's going to be pretty different. So my question is, what factors does the transmission take into consideration when shifting? ... So is it concerned more with speed, rpm, some ...


6

To expand on Anarach's excellent answer; the burn rate of diesel is slower than petrol and at higher RPM you would risk the exhaust valve opening whist the mixture in the cylinder was still burning. Increase the RPM higher, especially on engines designed with some overlap so that inlet and exhaust valves are open at the same time and if you still have a ...


6

tl dr - Yes to mileage; no to wear. Would you get better gas mileage? The general rule of thumb would be to run your vehicle in the highest gear possible without lugging the engine. This means if you can drive down the road at 1000rpm at 20mph, you will get better gas mileage than you will driving 20mph at 1500rpm. When you try to accelerate in the ...


6

It's very hard to say what damage, if any, will have occurred. All I can tell you is from my own personal experience. I once went from the red line in 3rd gear with a wide open throttle to 4th at approximately 90mph on a 1983 Golf and accidentally selected 2nd (and managed to get the clutch up). The instantaneous effect was that all of the dials gave ...


6

The rev limit of a petrol (gasoline) engine is generally set to protect the internals of the engine. Less sporty engines are designed to a cost and their components may not have the strength or manufacturing tolerances to cope with the higher forces experienced at higher engine speeds. Diesel engines, as you say, are more often limited by the speed of ...


6

To get us on the same footing, I'm going to assume by saying "clutch pressed halfway" you are suggesting the clutch be halfway engaged (meaning, you are still getting power from the engine, but it's not fully engaged). What you are talking about is called slipping the clutch. It is a process whereby you can get the engine within the power/torque ...


6

In addition to what JPhi1618 said... You can set any standard tach up with clips. I did this with a cheap tach when tuning my truck. They have 4 wires - positive, ground, signal, light. Positive and light go to the positive side of the battery with a fuse. Ground goes to the negative side of the battery or an unpainted part of the engine/body. Signal ...


6

One important factor is the mass of the components. Smaller, lighter components and shorter strokes allow higher RPMs. Given equal RPMs, an engine with a bigger stroke will put higher stresses on the components, which means they need to be stronger, which means they need to be heavier, which increases the stress even more. Motorcycle engines tend to have ...


5

The issue with low idle is more significant when viewed from the perspective of oil pressure. Reducing the idle, albeit a noble cause of saving the planet, reduces overall emissions insignificantly when compared to the implosion of an engine. The carbon footprint related to throwing a rod and having processed oil spill out over an open uncontrolled surface ...


5

Paulster2 is right, varying the injection timing with respect to the engine crank angle timing is the main way to control the combustion process in a diesel engine. In a conventional gasoline engine (PFI or SIDI) fuel and air are largely pre-mixed before the spark event (which controls the start of the combustion process) which then leads to a fast ...


5

Engines are designed to withstand a certain amount of stress. When you exceed that threshold, longevity will start to deteriorate. I stated something to that effect in this answer. The engine has a redline where you shouldn't take its speed past. This redline is not the maximum speed which the engine can run, but more correctly the threshold which you ...


5

Doesn't it suck up only as much as engine speed and throttle position allows? No, throttle position and engine load determine the quantity of air consumed. It can be quite hard to understand at first how a naturally-aspirated engine can ingest different quantities of air at the same RPM. Here's what the Engine Management Fundamentals chapter of the Bosch ...


5

The P1506 code is an idle air control overspeed error. From autocodes.com: The P1506 code means that the engine idle is out of factory specification. Sometimes the Idle Air Control (IAC) may have carbon built up. Disconnect the car battery, remove the valve, clean, re-install valve, and drive the vehicle for about 5 minutes with the headlights and A/C ON to ...


5

Yes, I'd take it back to the shop to see if there is something they missed. While 300 rpm at 60mph is not a huge difference, to me this is about the difference of when a lock up torque converter isn't locking up. This could be a programming issue which wasn't taken into account with the new CEM. While it isn't a huge issue, it will cause greater wear of ...


5

yes, that's correct. Now, rotating a flywheel at 2000 rpm is not a big deal: it's well within the capabilities of the material, as long as the flywheel is well-balanced. Other elements in the engine undergo much higher loads. The pistons, for instance, also go through a full stroke (up+down) 33 times per second at that engine speed, going from 0 to 100 km/...


4

Sounds like a transmission related issue. I would take it back to the immediately if it wasn't doing that before they serviced it. I doubt anything they did caused the problem, but if it did the quicker you take it back the better. A slipping torque converter clutch would cause similar symptoms, which could be caused by a bad solenoid, bad torque converter, ...


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