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28

tl;dr: They do. It's just harder to tell how much. The longer answer is that they do and that effective compression is failing you as an approximation for actual effects. Think about detonation (AKA premature ignition of the fuel-air mixture). Normally we consider two causes: compression (the change in the space enclosed by the cylinder as the piston ...


25

There are a few important factors at play here. Hot air rises, cold air sinks In physics-speak, hot air is less dense than cold air. This means that the volume occupied by 1 kg of hot air is greater than the volume occupied by 1 kg of cold air. The internal combustion engine is a volumetric device What this implies is that every time the engine turns ...


16

As has already been noted, anything rubber will have perished and will need replacing, as will all the fluids and any other normal perishable items (brakes, battery, filters etc). The brakes will have siezed on, and depending how dry the garage was, the interior may have mould and the bodyshell may have gone rusty... The biggest risk, however, is that the ...


15

Let me lead off with an excellent book on the topic: Corky Bell's Maximum Boost. There is a sound treatment of the basics of turbocharger operation in addition to some dated and esoteric applications that are still interesting. For example, I find the discussion of turbocharging different types of carburetor to be of intellectual if not practical interest. ...


12

Sounds to me like the car is suffering from a boost leak - either the plumbing has a leak somewhere or the wastegate doesn't hold pressure properly. Does the car have a boost gauge and if it does, can you see if you're losing boost at the same time you get the noise? Normally you'll have a hard time hearing the wastegate if it's an OEM one as they all ...


12

If you have a highly tuned performance car you are told, by the manufacturer, to idle for a few minutes before you roll up to the pump, otherwise you can destroy your turbo. Turbos get very hot - stopping them while hot means you don't have any way to transfer heat away from them - and so bearings die and cast components occasionally crack. I regularly see ...


12

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 ...


12

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 ...


11

The waste gate is designed (as you'll see in Bob's excellent answer to his linked question) to avoid spinning the turbo up unless needed. This saves fuel and wear. The blow off valve or dump valve is designed to stop a compression wave passing back into the turbo when you close the throttle, as this wave could stall the turbo completely, which can put high ...


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 ...


10

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 ...


8

You should whenever possible let the engine idle for a short period of time to allow the turbo to cool in big trucks and cars alike. It will definitely add life to your turbo. If you are keeping relatively low speeds and minimal boost in the last few minutes of your drive such as in your neighborhood or long driveway then the time needed to allow the ...


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

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 ...


7

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 ...


6

You pretty much guessed it, and if you didn't wikipedia is your friend. In summary, turbocharger operates by having two turbines connected to the same rotating axis. One turbine is spun by the exhaust gases, which cause the other turbine to spin. The second one is what forces the air into the intake of the engine. At idle rpm, there's barely any exhaust ...


6

You can't prevent the turbo from spooling up without physically removing it from the car. Depending on how the boost is controlled (ie, if there is a manual or electronic boost controller involved, too, or if it's just standard boost control by the ECU) you might be able to turn down the maximum boost to the pressure controlled by the spring in the wastegate ...


6

The letters are standard: Park Reverse Neutral Drive Sport (or possibly Snow - thanks @Brian) Braking (usually for going down hills) None of these have anything to do with 4WD or 2WD selection. If your Daihatsu is the 4WD version, it is permanently 4WD - there is no selector on that spec of car. It was a specific Japanese edition. You have stated ...


6

Turns out the previous owner of the car adjusted the wastegate actuator in an attempt to increase boost pressure. The sudden loss of boost came about because the ECU forced the wastegate open in an attempt to keep the manifold attached to the engine ;) Kudos to whomever wrote the software for the Bosch Motronics unit.


5

Two possibilities occur to me: a too-large turbo or a too-loose wastegate. when I press the accelerator there is no power until the rpm tachometer reaches 2500 This almost sounds like the replacement turbo is too large. when I press the accelerator there is no power until the rpm tachometer reaches 2500, then I need to release the accelerator ...


5

I wouldn't rule out a bad MAF so quickly - there was a generation of VW and AUDI MAFs that slowly went south without any indication from the ECU that they were doing so and IIRC the ECU managed to compensate for the dying MAF for a while. Also, if the ECU thinks you might be boosting at 15psi and using a conventional gauge suggests you're boost 7psi, you ...


5

Do you have any idea about potential power level of 132 kW (180 HP), 700 Nm MAN truck (TGL) 4.5 litre engine with damaged (not working) turbo? As a rule of thumb, for every atmosphere's worth of boost, you'll double the amount of power the amount the engine puts out naturally aspirated. For instance, if an engine puts out 100hp naturally aspirated, the ...


5

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, ...


5

As stated in the comments, it's a lot cheaper to remove excess weight. If you use this car as a daily drive it's best to keep stuff like a spare tire and jack in your car.. Start with the easy stuff: a lot of people have a lot of stuff in their car that they'll never need. If you want to make the car even more lighter, you could opt to remove the rear seat ...


5

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 ...


5

A few things to consider if you end up doing this: A longer shaft will reduce the speed that you can safely spin the turbos up to It's got to do with something engineers call rotordynamics, although I highly doubt you would need to spin something up to 125,000 RPM for a turbojet application :) You may also find that the existing journal bearings are not ...


5

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 ...


4

One of the reasons that a turbo setup with the equivalent effective compression is more forgiving of low octane gas than than a static compression setup is that you're not at that compression ratio all the time. Take that honda, for example. At 9:1 static ratio, you can run 87 octane all day as long as you don't push any boost at it. When you do start ...



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