Tag Info

Hot answers tagged

11

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. ...


8

It all depends on your definition of high. In my car, the red line is at 7500 rpm, and that indicates that driving with the revs over this line for anything other than brief periods is expected to cause damage, either through overheating, increased wear, increased loading on bearings, lack of sufficient oil/fluid flow etc. When driving I have to keep my ...


6

There are 3 key factors to work on when uprating for higher revs: Moving parts Spinning a rod, cam or flywheel faster than it is rated for will result in it destroying itself, often spectacularly, as the stresses become too much. Moving linkages and pistons back and forth also takes a lot of energy - Kinetic energy = 1/2 m v squared, and it is that ...


6

Although automated manuals are becoming more popular, the 2012 Civic (from my 2 seconds of searching) appears to be a normal automatic. Even still, I'm guessing your vehicle may have the sensors and programming necessary to determine that it's descending an incline and is employing engine braking to help you slow down. What it sounds like it's doing is ...


5

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 ...


4

Within a certain range, of course more RPMs mean more wear. Especially if your maintenance is based on time or miles. Consider a bearing that has a lifetime of 1,000,000 revolutions. If you drive at 5,000 RPM, that bearing is going to use up its lifetime twice as fast as if you were driving at 2,500 RPM. On the other hand, "lugging" an engine at too low an ...


4

Alternators aren't built for one engine so the manufacturer can't possibly know the gearing / ratio between the alternator and the engine. Therefore the RPM listed in the spec will be the RPM for the alternator. To calculate the alternators RPM you will need to find the diameter of the alternator pully [a] and the one connected to (presumably) the ...


4

It's just another word for Rev limiter. It means that when you reach 4,400 RPM, the ECU starts to limit the amount of injected fuel and air, in order not to let the engine rev any further, because revving it any further may cause severe damage to it.


4

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 ...


4

A tachometer typically has 4 inputs - +12v, ground, signal and light. +12v goes to switched power, you can tap into the power for the radio or cig lighter. Ground goes to any good body ground. Light get tapped into the power for your dash lights (or headlights, fog, light signal to the radio, etc.) Signal typically goes to the negative side of the ...


4

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. ...


4

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 car run, but more correctly the threshold which you ...


3

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, ...


3

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 ...


3

This sounds like a clutch problem. If it is nearing end of life opening the throttle can break its friction, which is why the speed drops and revs increase. Get it along to the garage before it finally gives up the ghost.


3

The rev limiter would have to be removed. This would be involved in a custom DME. With the limiter removed then you'd be able to blow it up if you wanted to. To support the higher revs, the vehicle would need the engine internals worked on. Stronger camshaft(s), valves, valve springs. (Head work). Depending on the strength of the rotating assembly at the ...


3

As you said the crux of the issue has to do with getting every last amount of energy out of a unit of fuel. You can consider this your total fuel efficiency. Accelerating your vehicle from rest to 60mph or 100km/h will require a fixed amount of energy based on the weight of the vehicle. (excluding wind, friction and rolling resistance). So you need to ...


3

You would need a heavier flywheel. If you idle too low, your flywheel doesn't have enough momentum to keep the engine running smoothly. A heavier flywheel will remedy that.


3

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 ...


2

You don't mention the type of engine you've got or the age. Older engines that are fitted with distributors and mechanical ignition systems typically drive their tachometers off the coil trigger wire, as this pulses each time a spark plug is fired. If that is the case, you simply need to connect a suitable tacho to the -ve terminal of the coil (i.e. the ...


2

If it is analogue the cable could be snagging, this could cause the tacho to read 0 or jump about. Alternatively, it is plausible that it's simply damaged internally.


2

Does accelerating faster worsen fuel efficiency? Yes. Now obviously when you accelerate harder, more fuel is being pumped into your engine, but you'll sooner get to that cruising sweet spot where fuel consumption is a lot less. So is the payoff worth it or not? No. This is easily measured via the OBD II port. For example, my Accessport ...


2

As Cinelli said, you'll have to do extensive work to the header and possibly the rods,pistons and bolts too. But here's a little secret: manufacturers always leave a wide and comfortable margin of error in their mass-produced engines to make them more durable. In the case of your 320i, it is entirely within safe limits to increase almost any ...


2

Suzuki garage found the issue. Broken hose going to the engine was the problem, nothing major.


2

While a manual transmission in the Subarus seem to run high at highway speeds (according to this website, 3200 @ 70mph is normal ... this to me who runs a vehicle which maintains ~1800-2000rpm at 70mph seems high, but nothing like what you are experiencing), running over 3500rpm at 50mph seems quite a bit excessive. This could be the cause of your heating ...


2

"When using cruise control and pulling the lever for acceleration RPM goes all the way up giving a sudden push to reach the desired speed." That's an important characteristic. That means one of two things: Either (a) your accelerator cable is running into an obstruction that prevents it from opening the throttle further or else (b) (if that car happens to ...


1

Have you checked your transmission oil level? Low oil level could cause your symptoms. Whilst checking your oil level is there any water contamination? Coolant can get into trans fluid from the trans-oil cooler. You need to let your vehicle repairer carry out an examination of its transmission.


1

The most likely cause is that your clutch is slipping. Either because the mechanism isn't working properly (rare but possible) or the clutch is worn (very likely).


1

I believe the @bobcross answer is pretty good, but wanted to add some more information which I believe is pertinent to the question, yet does not negate what Bob has written: You asked about the logic behind how an automatic transmission shifts and why it shifts when it does. To answer part of this, we need to look at what actually controls the ...


1

I am from Norway so I am sorry if I use wrong words or misspell. It is normal that the starting rpm is dropping when it's cold. The battery is struggling a bit to deliver power needed to turn the starter. When it's cold the engine shrinks a little and makes is harder to start. I will recommend you to start the engine and then let it run for a couple of ...



Only top voted, non community-wiki answers of a minimum length are eligible