Hot answers tagged

37

cc is the size of the engine, in cubic centimeters - literally the volume of the cylinders. A larger cylinder can ingest more air (and more fuel), thus converting more energy per cycle than a smaller one, so making more power - assuming all other factors are the same, and there are many factors that affect power output. You can measure it by a simple volume ...


29

All electric motors consume more current at startup compared to steady state. Check out the label on your fridge for example (or look at this one): the max current on the label is 2-3 times higher than the value you'd obtain from power to voltage ratio. The reason behind this lies in the properties of electric motors. Approximately, such motors have torque ...


23

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. ...


19

Does this mod ever give a measurable increase in power? tl;dr: yes, sometimes it works well. But... Your picture is a good illustration of some of the problems with just saying "cold air intake" and expecting that to mean the same thing to all people. Let's break down the pieces of the puzzle and talk about how those might help or hurt: Filter: notice ...


18

That is a great question. I believe the true answer here is "it depends". Like so many other things you can do with your vehicle, if your vehicle cannot use the higher octane fuel, it won't benefit from it. Something to remember about octane ratings is, the higher number does not mean it is more energy dense. The higher number indicates the fuel is actually ...


16

This article has further details: To keep the reciprocating weight as low as possible, which enables this engine to scream to 10,400 rpm, the forged Wiseco pistons weigh just 260 grams and are supported by a set of 340 gram aluminum GRP “Pro Stock” connecting rods — producing some serious cylinder pressure with a 16:1 compression ratio. So: the engine ...


16

It takes a LOT of power to get the rotating assembly - crank, pistons (or rotors), etc. - moving. For reference, try turning your engine over with a breaker bar on the crank. It's not super-easy (though some of that is due compression). All the parts in the rotating assembly - crankshaft, connecting rods, pistons, valves, camshafts, timing chain - add up ...


13

The answer is no because you mention being limited by your redline. Regardless of power, a certain RPM will result in a certain speed for a given gearing. Chances are the gear ratios were chosen based on the factory output of the engine. However, for other cars this may not be the case. Because of wind resistance (in many cases) a vehicle may not have ...


12

Some things to check in order of likelihood- Check the battery connections are tight. A loose connection may prevent your car from starting, even when the lights, radio, etc., may seem to be working fine. The battery may not be fine. Lights are not high load,so having the lights work is not an indicator of how healthy your battery is Starter motor. Some ...


12

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 ...


12

Intake manifold runner length is the linear distance from the inlet port (the face of the head) to a common point shared by all cylinders. Depending on the throttle position this could be the open atmosphere (if each cylinder has its own throttle butterfly) or a plenum (if they share a throttle body). The intake runner volume is the volume of that section ...


11

tl;dr: Cold dry air has a substantial effect on horsepower. This can be confirmed through experimentation on any modern car. I can think of two scientific reasons as to why this may be: Increased air density Decreased humidity Yes and yes. You're already most of the way there. Let's take a quick trip to simplified theoretical model land:...


11

It says right on the webpage: Conventional all-wheel drive cars employ complex mechanical linkages to distribute power from a single engine to all four wheels. This sacrifices efficiency in favor of all weather traction. In contrast, each Model S motor is lighter, smaller and more efficient than its rear wheel drive counterpart, providing both improved ...


11

The power losses in a MT are primarily do to friction. Everything in a MT is positively locked together, meaning there is no slip anywhere. Beyond friction at least one of the rotating assemblies is partially submerged in the gear lube to provide splash lube for everything else. Stirring the fluid looses power. In an automatic everything I just mentioned ...


11

Summarized Answer No, HP does not determine MPH in a gear, the gear ratio does. Although there are hypothetical ways that HP can seem to make the vehicle go faster in the same gear, it doesn't actually change the speed capacity of that gear as long as the engine RPM is limited. Expanded Answer As noted, the answer is no... or at least not really. In ...


10

There's an app for that! Basically if you can constantly measure the acceleration of your car, you can calculate horsepower and torque. I know I have seen advertisements in car magazines in the past for devices you would sick to the windshield, but since smartphones are so widespread and have such advanced accelerometers, Apps have taken over. I don't ...


10

Horsepower is how much power the engine can produce (how much work is done in a given time), wheras torque is the amount of turning force it can make (how much work is done). The two are quite intricately linked, so you can't have one without the other. You'll need to think of a few physics equations: Force = Mass x Acceleration Power = Work Done (Torque)...


10

Torque is work, horsepower is work rate In the context of engines: Torque indicates how much load an engine can carry for a certain distance in a certain amount of time. Power indicates how fast the engine can move that load over that distance. Some other things that may help to explain the difference between the two: Torque is what accelerates a vehicle ...


9

The "swept volume" of one cylinder is given by : pi * r^2 * L r = cylinder radius (bore / 2 ) in centimetres L = stroke in centimetres Then multiply by the number of cylinders (they will all be the same bore and stroke) Example : Bullet 350 bore and stroke given as 70 mm ( 7.0 cm) bore and 90 mm (9.0 cm) stroke So : r = (7.0 / 2) 3.5 cm L = 9.0 cm Then :...


9

The point is to feel like you've done something cool to your car and freed it from the shackles of The Man/the OEM intake. The primary benefit of Cold Air Intakes is to the bank account of the kit manufacturer, the secondary benefit is your car making a nicer noise, if you like the sound of an aftermarket intake. There's been a few debunkings of CAIs over ...


9

The link @cory posted is the description from the service manual. Just a repaste and I'll add some images and additional information. Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. The deactivation lifters contain spring loaded locking pins that ...


8

There are advantages, but also disadvantages to using a smaller turbocharged engine with a higher power output. The pro's of smaller, turbocharged engines: When not on boost (below e.g. 3000RPM) the engine uses much less fuel. turbocharged engines have a flatter torque curve, meaning they're working closer to optimal level throughout a larger portion of ...


8

Torque is the amount of force exerted by your engine at a particular RPM. In two cars with equal gearing and in the same gear, a car making twice as much torque will accelerate exactly twice as fast. Horsepower is calculated from torque and RPM. A given amount of torque at a low RPM equals less horsepower than the same amount of torque at a higher RPM. ...


8

A characteristic of electric motors is that they produce the highest torque when stationary, coupled to this is a very high initial current 400 to 600A for cars and commercial starter motors can exceed 1000A. Once they start to rotate the current demand goes down - remember that the pinion / flywheel ratio is 10 to 1 or more so when the engine is being ...


8

Well the simple answer is (as you suspect)... No. With fixed gearing, you are going to be doing the exact same speed at any given engine RPM with 100bhp or 600bhp.


7

Not sure what it "should" be pulling, but anywhere near a whole amp is way too much and will drain the battery in no time. Are you sure you tested right? Often the pull when you first connect the battery can be a lot higher than the steady pull since you might be charging some capacitors, etc. If it stays that high you definitely have a problem, possibly a ...


7

How old is the battery? If it's the original one, it's probably just in need of replacement. 5-7 years is a typical battery lifetime. At the end of life, they will sometimes appear to charge, but die rapidly if not used for a few days.


7

It depends. Just because an intake can flow more air mass doesn't guarantee that the engine will utilize it. The intake is part of a system of components. The engine produces power by managing air flow into and out of the combustion chamber. There are usually other actors involved: Intake side. Carburetors, throttle bodies, intake manifolds, intake valves,...


7

Power <-> torque relation In general, the relation between power an torque is a simple formula: Power[kW] = Torque[Nm] * RPM * π / 30,000 which means that you can always calculate the one curve from the other in torque/power diagrams (That's also what the dynamometer does) So, why are always both curves plotted, if they are more or less the same? ...


7

This looks like your first posting with Motor Vehicle maintenance and repair site. It looks like you are an engineering student, looking at a possible school project. Is that right? Welcome to the stackexchange! You have a whole lot of decisions to make. First Choice: Type of engine? I'm going to assume you want an internal combustion engine. Choices ...


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