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8

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. ...


7

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 ...


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 ...


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

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

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 ...


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

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

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 ...


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

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 ...


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

For what ever reason, if Chevrolet, or thier subsideries say they need to investigate the problem with your vehicle then you should allow this to take place. Chevrolet will know the vehicle better then anyone else, and if the addition of the CNG equipment is at fault they will easily home in on it.


1

That particular engine (single cam) commonly has an intake gasket leak with high idle as a symptom. There are other common issues with the same behavior such as the throttle position sensor, idle air controller, and engine coolant temperature sensor. Some googling into saturn forums will provide more troubleshooting and info than I could in a ...


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

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 ...


1

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 ...


1

Probably the most critical part for higher RPM's is the valvetrain. So you want better valve springs and retainers and a custom ground cam that is designed for the RPM you are trying to acheive. This is all to ensure that you don't encounter a situation where the valves cannot close fast enough and the piston head crashes into the valve. The higher the RPM ...


1

You don't need to worry about the RPM, just what the engine is capable of putting out. Engine 2 has more power, but together with differences in gearing and everything else, the fact that it does more RPM doesn't mean much. It could just be that the engine puts out about the same force as car 1 (Torque) but turns slightly faster therefore it has slightly ...


1

The deciding factor of an engines output is BMEP. Brake mean effective pressure. The dimensions of the engine components such as crankshaft throw, cylinder bore diameter and stroke will decide the BMEP. Further consideration would be volumetric effciency, ignition timing and the number of cylinders. An engine may be designed for economy, or power, or simply ...


1

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


1

If your RPM shoots up when you downshift it should cause your engine brake to or slow down. (Unless you still have your foot on the gas). I would say TMN was probably thinking about over revving the engine when downshifting If you are at 4000RPM in 4th then you downshift to 3rd and your RPM goes up to 6000+ or anywhere close to the redline you could ...


1

I did some research and on automatic-transmission models, the most common cause of this problem seems to be a broken or dirty IAC (idle air control) valve. So the first thing I tried was removing the hose from the air intake into the IAC, and spraying Seafoam into it with the engine running. In order to get the engine to run with the hose off, I had to ...


1

It takes a specific amount of energy to accelerate a specific amount of mass to a specific speed. So just looking at those factors, you'd be right to assume that it matters little how quickly you accelerate said mass. But that's not how the real world works. The problem here is that combustion engines and the many things we connect them to are astoundingly ...


1

Very much engine specific. One of my cars has a replacement engine block that came from a car that only had a cam angle sensor (and mine requires cam AND crank angle sensors). Even though it's technically the same block other than the one sensor hole missing it was still a bit of an ordeal. A hole had to be drilled and tapped (very carefully), seals ...



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