Twin Turbo Diagram 101?

[drsnapper55]

I was wondering if anyone might have any model instructions or pics that show all the connections for a twin turbo setup?  I have researched online, but it seems like a lot of the photos are missing all connections that I need to see from all angles (ex. top and underneath, waste gates, radiator, exhaust, etc.).  I have one set of model instructions for a twin turbo (Chevelle 454), but the model parts themselves aren't detailed enough to know what I am looking at.  I know some of it has to do with an art of where you can position and fit them in the engine compartment and that there are different kinds of turbos too, which has also been a little confusing to someone like me that is new and trying to understand it.  If I do this in a model kit, I want it to be correct with the connections.  Thanks for any help.

[Ace-Garageguy]

Turbo setups all work the same way, and aren't as complicated as they may look initially.

Once you understand the functions of the various parts, you'll be able to put them in any model engine bay so that they would be correct on a real car.

Every turbocharger has two main parts...an exhaust-driven turbine section, and a compressor section that's driven from the turbine via a short shaft.

Exhaust gas exits the engine through the exhaust ports on the head, flows through the turbine, turning it very fast as it passes, and exits out the side of the turbine into a relatively normal exhaust system.

The turbine spins the compressor side via the short shaft connecting the two, and air is drawn in from an air filter, through the compressor, and then (usually) through an intercooler (that removes some of the heat air picks up as it's compressed), from there through the intake manifolding into the intake ports on the cylinder head.

This somewhat simplified drawing is valid for EVERY turbocharger setup known to man. They ALL function exactly the same way...whether in cars, big diesel trucks, aircraft or locomotives,

There can be additional detail parts, like popoff valves (also known sometimes as waste-gates) that dump exhaust gas ahead of or after the turbine under some conditions, and there can be pressure dump valves in the inlet tract as well in some applications (also known as blow-off-valves).

The drawing above doesn't show where fuel is taken in, and that is where several major variations occur.

A modern electronically fuel-injected engine will usually have injector nozzles in the intake ports, like a normally-aspirated (non-turbo) engine.

Suck-through carbureted systems will have the carb positioned between the air filter and the compressor inlet.

Blow-through carb systems will have the carb AFTER the compressor, but living inside a sealed box (old school) or specially modified for blow-through installation; blow-through systems are considered somewhat obsolete, so you won't encounter them very often these days (they can also be a real PITA to set up and tune).

A twin-turbo system will essentially just have two of everything, unless it's a staggered system with a little turbo and a bigger turbo that provide boost progressively.

Edited February 13, 2017 by Ace-Garageguy

[Len Woodruff]

Good info Bill.

[MeatMan]

Bill mentioned the wastegate, which would have plumbing to the actuator to read the boost signal, i.e. when to leak exhaust. Google "turbo wastegate plumbing" and look at the pics. Plenty of stuff showed up for me.

Additional plumbing would be the oil lines to the turbo where the diagram shows "oil inlet" and "oil outlet". Nothing special there, just run a couple of lines to an adapter where the oil filter used to be, or research your engine to see if there are other places to use. If you're using a dry sump system you can plumb to that.

Beyond that I don't think there's anything else. I'm not an expert though so someone else may have something to add.

Take it a system at a time instead of trying to get the whole picture at once, then put it all together.

I too have done a lot of research for a twin turbo C-7 I'm planning, good luck

[Ace-Garageguy]

Bill mentioned the wastegate, which would have plumbing to the actuator to read the boost signal, i.e. when to leak exhaust. Google "turbo wastegate plumbing" and look at the pics. Plenty of stuff showed up for me.

Additional plumbing would be the oil lines to the turbo where the diagram shows "oil inlet" and "oil outlet". Nothing special there, just run a couple of lines to an adapter where the oil filter used to be, or research your engine to see if there are other places to use. If you're using a dry sump system you can plumb to that.

Beyond that I don't think there's anything else. I'm not an expert though so someone else may have something to add.

Take it a system at a time instead of trying to get the whole picture at once, then put it all together.

I too have done a lot of research for a twin turbo C-7 I'm planning, good luck

Dennis makes good points. The waste-gate may also sometimes dump into the muffled part of the exhaust system or it may vent directly to the atmosphere.

Far as oil lines to a turbo, the supply line is generally quite small. It's usually taken directly out of the main oil gallery, at the base of the oil filter adapter (as Dennis suggests) or at a T-fitting under the oil-pressure-gauge sending unit. The return line is usually located as low as possible on the bearing housing, and is relatively large in diameter to promote free draining. The return line is very often plumbed directly into the side of the oil pan. 

If good drainage isn't provided to the turbine bearing, early seizure may result due to "coking up", which is simply residual oil inside the bearing burning and solidifying after engine shut-down, due to the very high temperature of the turbine housing. This was a common failure mode for early turbo installations.

The photo below shows a small oil line in going at the top, and a large drain line out at the bottom.

Photo below shows an oil return line going directly into the side of the oil pan under the engine.

Edited February 14, 2017 by Ace-Garageguy

[drsnapper55]

Good info, and thank you for all the replies.  This helps me to kind of put it all together and understand it a lot more with explanation.  Thanks again,

[1930fordpickup]

Thanks for the explanation of the Turbo systems. 

Bill I was wondering if this part of your statement is why I have been told that turbo cars and trucks that have been ran hard should not just be shut down right away. 

(If good drainage isn't provided to the turbine bearing, early seizure may result due to "coking up", which is simply residual oil inside the bearing burning and solidifying after engine shut-down, due to the very high temperature of the turbine housing. This was a common failure mode for early turbo installations.)

I have been told about this just did not know if it was an urban legend or bad info passed along.  

[High octane]

A Twin- turbocharged intercooled 2.7 V-6 can be had on some Ford trucks also.

[Ace-Garageguy]

Bill I was wondering if this part of your statement is why I have been told that turbo cars and trucks that have been ran hard should not just be shut down right away. 

I have been told about this just did not know if it was an urban legend or bad info passed along.  

To the best of my knowledge, either allowing the engine to idle for a couple of minutes, or just driving easily for a couple of miles prior to engine-shutdown makes a lot of sense as far as allowing the turbine housing to cool. If you've ever seen a turbo run hard at night, you've probably noticed they will glow red-hot, and lubrication oils can't really withstand that kind of sustained heat. This, again, is why very free drainage of the turbo oil system is imperative, but since the beginning of time, turbo-car-builders and engineers have been recommending a cool-down period before shutting-down the engine after hard driving.

I haven't personally done the research, but I've seen a fair number of seized turbos.

And it can't possibly HURT anything to be a little kind and considerate towards your machine.   

EDIT: Here's an experiment. Put a pan on the stove, on high. Let it get HOT. I mean crackling-smoking-turning blue HOT. Throw in some engine oil and watch what happens to it.

          Now take a clean pan, heat it just as hot, then shut off the flame and throw in some oil after it's cooled down for a minute or so.

         See any difference?   

Edited February 16, 2017 by Ace-Garageguy

[signguy2108]

When I was in the trucking business, i was always told not to shut the engine down without a cooldown period for the turbo