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tl;dr To combat detonation (in SI engines) To increase power/efficiency Details There are a few important factors at play here. Engine detonation is a real concern for SI engines A spark-ignition engine is more likely to experience premature ignition (aka knocking or detonation) with hotter air. In fact, the calculations in the example below can show ...


20

The "take some of the output force to reuse it as input" can be interpreted as regenerative braking, but the big differences are: Regenerative braking takes power back from the wheels while turbo take power from the engine itself, that would be otherwise wasted. The power of the turbo adds to the normal power of the engine while the power of regenerative ...


19

tl;dr: Overboost is too much air, usually at too high a temperature. Detonation is likely to follow. Remember, the engine is just an air pump. All the turbo is doing is making it easier for air molecules to get into the intake side of the engine. Of course, the turbo has finite efficiency: it is pushing in more air molecules but it's also increasing ...


17

regenerative braking This question and answer regarding the subject matter has some very good information in it as well the answer reveals a mathematical paradox with regenerative braking What is regenerative braking and why don't we use it? This Q&A is a bit off your topic but has breadcrumbs regarding recapturing lost energy through a turbo to ...


17

No, there isn't any equivalent. A turbo is used because combustion engines are inherently inefficient: they convert chemical energy into mechanical energy, using an awkward detour via heat. Unfortunately, heat is pretty much the worst possible way to store energy: by the laws of thermodynamics, you can only convert it to other forms of energy if you also ...


15

In bold, I'm answering the questions at face value, specific answers for your scenario are below each bold answer. 1: I would be a bit concerned about driving this car until diagnosed by a mechanic. From the sounds of it, the high pressure oil feed for the turbo came off. Which meant you were running the turbo with no oil running through it, depending on ...


15

The power of an engine is not determined by the difference in pressure between the combustion chamber and the exhaust. Power is determined by how much energy one can put into the combustion chamber and the efficiency of how that energy is applied. When one is compressing the intake air, additional oxygen is being included in the "mix" allowing for ...


14

I thought it could work more like a supercharger, except it will be powered by battery instead of engine. This isn't the first time someone has thought of "electric" supercharging. There's nothing wrong with having electrical power source per se (the leaf-blower Monza comes to mind), but you're going to need way more than 10 W worth of power (which is what ...


13

The A/R ratio is the ratio of the cross-sectional area of the area where gasses flow and the radius of that spot from the center of the turbocharger. Usually the A/R ratio is constant along the channels where gasses flow. In simpler terms The letters A/R refer to Area and Radius. If the radius of the turbocharger is greater at a given point, the cross-...


12

OP's question states: It should follow that turbocharging should be equally effective pumping air out the exhaust, than in the inlet. No, it is not as effective. You can't reduce the pressure to less than 0 psi. So the maximum "suck" you can get is 1 bar. The boost pressure on high performance engines can be 2 to 3 bar. But working from the ...


11

Most of my knowledge comes from turbo engines. Detonation or preignition is caused by the air/fuel mixture igniting before the spark plug fires. The mixture is typically ignited by a hot spot either in the head, or on some carbon deposits. Turbo and superchargers are more likely to detonate, because of the higher pressure. There is more volume of air/...


11

Using that kind of blowers as turbochargers is generally proved worthless. The main drawback is these devices are not capable of creating any significant pressure, especially considering internal combustion engine's air flow rate. As @HandyHowie already mentioned one could even experience air flow restriction. Some quick maths: consider 1 cylinder 2 stroke ...


10

They Exist I was unable to find any manufacturers that have rolled out this technology into production vehicles but there are several manufacturers that have the baseline technology in R&D Formula 1 Formula 1 has always been a playground for engineers and with the new rules implemented in 2012 the current platforms are running this technology and ...


9

It is quite likely the work performed has introduced a subtle air leak that only manifests itself under high boost. Pressurizing the intake tract with the car off will help you identify the source of the leak. A hose fitting that isn't honked down all the way will exhibit this kind of behavior under boost. I like how Jafro figured out the source of his car'...


9

IMO this is not a stupid idea, however it doesn't actually make sense for multiple reasons: A naturally-aspirated Otto or Diesel engine by itself doesn't expand the gas even to atmospheric pressure. When opening the exhaust valve, there's an overpressure escaping – thus wasting energy – before the exhaus stroke itself starts. (This is the concrete reason ...


8

Non-turbo diesels lose less power in the Rockies At least according to the SAE J1349 standard. (Calculations shown below). Assumptions Dry air pressure in the Rockies = 90 kPa ( at 3000 ft) Absolute Temperature = 277.15 K ( 4 °C ) This allows us to compute the two quantities, A & B, that are used to determine the correction factors for ...


8

What does the term A/R ratio mean? In almost all automotive applications that you are likely to see, turbos are a radial flow, snail shaped turbine section attached to a similar compressor section. As we see in this illustration from the Turbocharger Fundamentals article: How is it computed? The cross-sectional Area to Radius ratio is a consequence of ...


8

Preamble What does forced induction buy? In a word, density. Remember: For compressible fluids, pressure alone doesn't tell the full story But pressure and temperature together do. The old physics adage "hot air rises, cold air sinks" is a great example of this. Air at the same pressure but different densities at different temperatures. The internal ...


8

I suspect a 96bhp 1.4 engine would struggle to provide enough power to spin up a supercharger and two turbochargers. I also suspect that the charging units you have chosen would not be well matched to your engine. Might I suggest obtaining something like an IHI from a Lancia Y10 Turbo, a G40 G-ladder from a VW Polo 1.3 G40 or a Garret from an MG Metro ...


7

Yes, you have to do that. Your turbo heats up to around 900 degrees Celsius under hard driving conditions. When you shut off the car, You suddenly take away the heat source and the ambient temperature falls to around 95 degrees Celsius (the normal operating temperature for a Subaru that has been driven hard). This causes the turbine housing to experience ...


7

You've understood how they work, now you must think about "when" they work to understand why they're there. A turbo utilizes the exhaust gas to spin a turbine which which is mechanically coupled to another impeller on the intake side which forces air into the engine. As the engine produces more exhaust, the turbo spins faster and produces more boost until ...


7

Both turbochargers and superchargers perform the same function: compress air that will be fed into the engine. In other words, they are glorified air compressors. As with any compressor, both need energy in order to compress the air, which is where the difference between the two devices becomes relevant. Superchargers are belt-driven or chain-driven, so ...


7

Several reasons: First: Diesels have a very simple operation which is basically more air, more fuel = more power. On gasoline engines you have to worry more about running too lean, too hot, having incorrect timing. And, you generally already have enough air. You run at higher RPMs and suck in more air. Gasoline is much more volatile than Diesel. It burns ...


7

I Believe It's a Hose Connection Point Unmetered air whether it's a negative pressure or positive pressure is bad. That being said, I find it interesting that losing some of the boost isn't detected and triggering a CEL. So that maps to your idea of a smaller leak along with the not subtle high pitched sound. You said If it were a bad gasket, I'd ...


7

tl;dr: no, a 1:1 ratio is only possible in imaginary perfect laboratory conditions. Or is the relationship more complicated? It's a bit more complicated but for perfectly understandable reasons. NOTE: I'm intentionally leaving intercoolers and bags of ice out of the discussion below. They are germane to boost discussions but should be covered under a ...


6

Actually running rich is less dangerous than running lean. I don't know specifically about Subaru, but in general, running lean can cause detonation more easily. And yes, while 14.7:1 is the stoichiometric ratio deemed as perfect for an air fuel mixture, running rich has the big advantage of reducing the chances of pre-ignition or pinging. In a turbo car, ...


6

Having spent a few years in a shop I completely understand LKQ not honoring a warranty for this engine. In their warranty document it's pretty clear that almost nothing is covered. The way the manufacturer looks at the aftermarket turbo is this. If you are increasing the volumetric efficiency beyond what the engine was intended to handle regarding power ...


6

Dodge installed VNT Turbochargers on cars in 89 and 90. The most well known of which is the 1989 Shelby CSX-VNT. The vanes were controlled by a dual port vacuum actuator. There was nothing electronic on the turbo itself, but there were vacuum solenoids (for boost control) on the lines going to the actuator. The VNT Turbo has movable vanes on the exhaust ...


6

Too long for comment, but I suspect wastegate linkage or door not closing fully due to distortion from heat (it's really hot around there). You could try and get it hot enough to duplicate the problem, park, and attempt operate the wastegate manually with pliers or gloves... but it's tricky to get to without removing the turbo heatshield. Also make sure ...


6

The process is just the same. The turbo on every engine that I've worked on gets its oil supply from the same system as the rest of the engine.


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