35 votes
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Why do we need to cool air after it leaves a turbocharger?

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 ...
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20 votes
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Turbo equivalent on electric motors

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 ...
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19 votes
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What is overboost?

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 ...
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17 votes

Turbo equivalent on electric motors

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 ...
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17 votes

Turbo equivalent on electric motors

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. ...
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15 votes

Oil draining out shortly after turbo hose detached/broke

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. ...
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15 votes

Why is it that when supercharging, it's preferred to compress the input, rather than pull a vacuum on the exhaust?

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 ...
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14 votes
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Can I attach a DC blower to intake manifold of my 150CC Yamaha FZS FI engine?

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 ...
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13 votes

What is an A/R ratio?

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 ...
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  • 261
12 votes

Why is it that when supercharging, it's preferred to compress the input, rather than pull a vacuum on the exhaust?

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 ...
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  • 1,479
11 votes
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What are the various causes of preignition / detonation?

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 ...
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  • 8,413
11 votes

Can I attach a DC blower to intake manifold of my 150CC Yamaha FZS FI engine?

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 ...
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  • 336
10 votes

Why no exhaust gas turbine generator in hybrid vehicles?

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 ...
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9 votes

Minor boost leak and shrill tone at peak boost: hose clamp, gasket or blow off valve?

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 ...
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9 votes
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Why is it that when supercharging, it's preferred to compress the input, rather than pull a vacuum on the exhaust?

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. ...
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8 votes
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Would a non-turbo diesel perform better in high altitudes than a comparable gasoline engine?

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) ...
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8 votes
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What is an A/R ratio?

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. ...
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8 votes
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Is there a 1:1 relationship between boost pressure and power increase?

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 ...
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8 votes

How do I install a turbocharger and a supercharger on a 2008 Hyundai Accent?

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 ...
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7 votes
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Do you really need to cool down your turbo after hard driving?

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 ...
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7 votes
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How does a supercharger differ from a turbocharger?

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 ...
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7 votes

What is the function of a blow-off valve vs a wastegate?

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 ...
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7 votes

Petrol vehicles, what are the advantages and disadvantages of a turbo charger?

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 ...
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  • 541
7 votes

Minor boost leak and shrill tone at peak boost: hose clamp, gasket or blow off valve?

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 ...
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  • 32.8k
7 votes

Is there a 1:1 relationship between boost pressure and power increase?

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. ...
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6 votes

Why do Subarus run so rich under boost

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 ...
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6 votes
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Shop replaced engine, blew about six weeks later

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 ...
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6 votes

what sensors and formula are used to control VGT/VNT turbos?

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 ...
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  • 8,413
6 votes

1997 Subaru WRX STI Type R - Strange and occasional turbo lag

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 ...
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6 votes
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Is the procedure for an oil change different for a turbocharged engine?

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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