Forced induction occurs when the engine is supplied with strongly compressed air. This is usually accomplished with the help of a supercharger or turbocharger.
How to install a turbo on your car
Contrary to common opinion, this is not a simple bolt-on replacement item.
As you can see from this article, there are also plenty of other requirements to make it function.
Because installing a turbo or supercharger is a pretty difficult modification that frequently comes up in our forums, we'll go through the basics in this post.
Why add forced induction?
The primary goal of forced induction (turbo or supercharger) is not to raise the compression or maximum pressure in each cylinder of the engine.
The fundamental reason is to improve the volumetric efficiency of the engines (the efficiency of the engine at drawing in air and converting this to power by adding fuel and burning it).
In video games like GranTurismo and Forza, we just check a box, and our car is completely turbocharged and significantly quicker in seconds.
Things are significantly different in the actual world.
Put a turbo on a 10:1 compression ratio engine and watch it blow out!
Higher compression engines employ direct injection (fuel is injected into the cylinder at the last possible minute) to avoid premature ignition concerns, and this technology has been successfully implemented on current petrol engines, which they acquired from diesels.
You could also utilise water injection to soften the intake charge and delay the timing, but this is getting into rocket science area, and if you don't know what you're doing, you're going to have difficulties.
When it comes to installing a turbo to a NASP engine, there are a number of factors to consider.
How to install a Turbo on a NASP engine
Things to consider when installing a turbo to a non-turbo vehicle (NASP or naturally aspirated engine).
When a naturally aspirated engine draws air in, the intake valve closes and seals the cylinder after a certain amount of time.
As a result, the average N/A engine only pulls in around 60% of its full capacity and is just 60% volumetrically efficient.
This is why NASP automobiles seldom produce more than 100 horsepower per litre.
The higher the engine's tuning, the more efficient it will be.
When employing Natural Aspiration, a typical Modified Rides member will have already spent a significant amount of time and effort tweaking their NASP engines, but will still struggle to achieve anything close to 85 percent efficiency.
The efficiency of the engine and drivetrain is continually increasing with updated ECUs and engine control as pollution rules tighten.
Manufacturers are increasingly employing tiny capacity engines with turbochargers, with a current 1.4 turbo putting out as much power as an early 2.0 turbo or 3.0 NASP engine, while also providing superior fuel efficiency and weighing far less.
The most effective approach to boost power is to force more air and, as a result, more fuel into the cylinders (forced induction).
The typical forced induction engine has a volumetric efficiency of 110 to 150 percent (the incoming air is compressed).
Here are some examples to help put the benefits of installing a turbo into perspective.
A 2 litre NASP motor would normally utilise roughly 1200-1300cc of its capacity and produce up to 200bhp at its peak (based on 100bhp per 1000cc).
Because it can now burn more gasoline, a turbocharged or supercharged 2.0 litre engine will utilise significantly more of its capacity, providing higher power.
(Some OEM 2.0 engines are pushing out 300bhp!) This offers a turbo engine an ideal power figure much in excess of 100bhp per cylinder!
Take, for example, a turbocharged 1.6 engine that delivers over 1500 horsepower in early Formula 1 racing.
We routinely see modified 2.0 litre turbo cars putting out 600bhp or more with moderate ease, allowing them to be used on a daily basis while remaining reliable.
The trick is to start with a solid foundation and components.
The more boost you run, the more efficient the engine becomes, which is why we now have 1.4 litre turbo engines that can provide as much power as massive V6 engines.
Having a compact but strong engine also provides you a weight advantage, which improves handling and makes the power increase even more noticeable when driving.
However, the major advantage of raising boost is that it raises the final compression ratio, which means you get more bang for your buck from a higher air/fuel charge mix in your cylinders (the actual engines compression ratio stays the same but as there is more air coming into the engine it will become more compressed).
If you increase the amount of air/fuel in the cylinders, the compression will rise as well, which might be excessive.
To compensate for the loss of initial compression (without boost), the ultimate running compression must be reduced.
With more air, there will be more oxygen available for burning, and with more fuel, the engine will produce more power.
Turbocharging is the most efficient approach to boost an engine's efficiency.
There are several significant problems to consider when installing a turbo to an engine that was not built for one.
When installing an aftermarket turbocharger, there are a number of issues to consider.
Pre-ignition, often known as knock, occurs when the gasoline ignites under pressure before the spark.
If a piston has not reached top dead centre, it will travel in the opposite direction, which will have severe effects for the engine.
You'll need to decrease the engine's compression ratio and/or limit the turbo to a lower boost level to avoid detonation (premature ignition).
(Low-compression engines with turbochargers also avoid some of the turbo lag issues that plague typical turbo applications.)
Small turbos with low boost levels are the ideal turbos to add to a non turbo NASP (naturally aspirated) engine.
Remote turbo kits are becoming more popular as a result of the low boost they offer and the fact that they don't take up any engine compartment space.
Installing a water injection kit to attenuate the air charge and avoid explosion is another alternative.
You can use a re-bore and lower compression pistons to reduce the compression ratio, or you can use a stroker kit to change the compression ratio by modifying the compression stroke length.
You may purchase a bigger head and thicker head gasket for minimal changes, increasing the combustion chamber capacity and lowering the compression ratio.
If you're installing a turbo, you should aim for a compression ratio of roughly 7:1; anything higher than 9:1 will cause difficulties.
Compression ratios in modern direct injection engines are substantially greater.
In all situations, use the highest octane gasoline available, as the greater the octane, the less likely the gasoline is to cause engine knock.
We've seen folks run 25psi of boost on a 10:1 compression ratio with the correct fueling, but we should point out that the aftermarket ECU and fueling mods on this application were of extremely high quality.
You should be possible to run a turbo on a regular engine with roughly a 9:1 compression ratio if you limit the boost pressure to 5-7psi (as opposed to 25-35psi) and use higher octane fuels (e.g. Shell Optimax).
Direct injection, which was first used in diesel engines, is now being used in petrol engines. Because the fuel is injected later into the intake charge, the temperature of the charge is reduced, which helps to prevent premature ignition.
Because of this, FSi and Di turbo engines may achieve extremely high compression ratios.
Modifications to improve dependability and power
Because there will be a significantly higher amount of air going through the engine when installing a turbo, you should also get the head flowed, increase the port size, fit bigger valves, and go with a larger exhaust header and system for optimal performance improvements.
Installing an adjustable boost controller will allow you to test boost pressure and timing advance on a rolling road while connected to diagnostic equipment.
Fueling should be given special care.
More air necessitates more fuel, or you risk burning too lean.
You should also avoid overfueling when the turbo's boost lowers, since this might damage the engine.
Because the car's present fuel delivery system is unlikely to give enough fuel in most aftermarket turbo installations, you'll need to upgrade the fuel pressure with a new pump and fuel pressure regulator, as well as the injectors.
The car computer will also have to account for the turbo's unique fueling requirements, particularly in terms of throttle position and wastegate management, as well as quickly shifting fuel requirements between on and off boost settings.
The air intake will also need to be upgraded, since only a few OEM air intakes can handle the increased air demands of a 40 percent power increase.
A solid aftermarket ECU will allow you to develop a custom map for your new turbocharged engine, which we strongly suggest.
Most turbo kits simply include the pieces needed to physically instal the turbo, such as an exhaust header and the appropriate intake tubing to the air filter.
Turbos are costly, but they provide the most power for the money.
Fitting should take approximately 40 hours; you'll need to know what you're doing and be able to develop an unique ECU map.
In general, however, it will be easier to locate a turbocharged engine and perform an engine transplant to this than it will be to instal a turbo to a NASP engine.
Video: How To: Install a Turbo Kit
Most manufacturers now offer turbocharged engines, which might serve as a good donor for your project.