DONE: Supercharger / Turbocharger: Why supercharge or turbocharge your vehicle?

[IB Adrian]

I am doing a basic set of FAQ's for this forum:

Why supercharge or turbocharge your vehicle?
Quite bluntly, for more power. Doesn't matter at what rpm's power is required, the primary reason for supercharging or turbocharging is to increase the power of your engine.

What are the effects of supercharging or turbocharging?
The reasoning behind any form of forced induction is to "force" more air into the combustion chamber than the standard atmospheric 14.7psi pressure allows. The more air you can fit in there, the more fuel you can have, and the bigger the "bang" you can expect.
If you are going to supercharge or turbocharge, you should potentially expect:
Slightly greater fuel consumption (in gas engine applications)
More power
Slight reduction in throttle response (more notable with turbochargers)
Reduction in the expected life of some driveline components

What is the difference between supercharging and turbocharging?
Ok:
There are some large differences in the way in which they operate, but the most import thing to remember is that the idea of both a turbocharger or a supercharger is to force more air into the combustion chamber.
An engine is generally limited of the amount of air it can get into it. A supercharger and a turbocharger force more air into the engine.

Turbo
A turbo uses hot exhaust gases to compress intake air. Here is a good picture which describes the fundamentals of a turbocharger:

It compresses the air by the theory that air moving at speed will compress when it hits something - so the compression takes place in the intake manifold.

There are a few different types of superchargers, centrifugal, roots and twin-screw:

Centrifugal:
Works effectively the same as a turbocharger, except it is driven by the engine crank, and not by the hot exhaust gases. It has a turbine which spins at speed.

Compresses the air using the same theory that the turbo uses.

Roots:
The oldest type of superchager, dates back to the early nineteen hundredds. It is a positive displacement supercharger, because it moves a fixed amount of air per rotation.

Compresses the air within the supercharger. (as opposed to the intake manifold)

Twin Screw
Also a positive displacement supercharger.

Also comresses the air within the supercharger.
SHOULD I boost my vehicle?
Well for a start, you should weigh it all up. What do I want out of my vehicle. If performance is a necessity, there is no better route to creating a significant increase in performance than supercharging or turbocharging on a modern engine.
You need to weigh up the costs, warranties, be prepared for (generally) greater running expenses, and potentially having to pull over on a freezing cold rainy day because the engine warning light came on, and you need to diagnose it then and there. But if you choose to go ahead with it, I can almost guarantee that you won't be dissapointed with the performance.

Now you have decided to go ahead with putting a blower on your vehicle you need to decide which one is for you:

Supercharge or Turbocharge?
You need to decide what you want out of your vehicle, and choose from that:
Do you need low end grunt to get that 5'ver moving?
Are you after high rpm power to blow away everyone at the track?

Some of the general characteristics of each type:

Turbo:
Lack of wide availability of components and support for many current Ford trucks.
Generally provides more high rpm power (although with the right set up can provide good low rpm torque as well).
More efficient than supercharging.
Need to maintain exhaust gas temperatures below around 1400F to prevent the turbo blades warping.
Greatest reduction in throttle response.
Able to potentially provide the greatest amount of "boost" and therefore the most amount of power.
Easily able to "plumb" an intercooler into
Difficult to get to work with carburetters
The most complex of all the systems.

Centrifugal supercharging
Uses a turbine arrangement similar to a turbo, only it is driven by the engine crankshaft, and not the exhaust gases.
More based to higher rpm power.
Most efficient of the different types of superchargers.
Easily able to "plumb" an intercooler into
Roots style supercharging
Fantastic low end response.
Increases intake temperature significantly
Better suited for low boost situations.
Prehaps best solution with carburated engines.

Twinscrew supercharging
Better efficiency than Roots style
Provides significant low end boost as well.

What else do I need to change to my vehicle if I supercharge or turbocharge?
Here, the world is "your oyster", and you are usually only limited by your time and bank account (or the missus ). Most Ford engines have a large amount of aftermarket support.
Anyhow, here are some of the things you should look at if you are supercharging or turbocharging a modern Ford gas engine, remember, none of these are essential, you will see more power with just the supercharger or turbocharger, but these additional things will (in general) provide even more power (and improve drivability as well with your supercharger/turbocharger):

• Larger capacity Injectors - provides more fuel to the cylinders, with the more air that is now being forced into the engine
• Larger flow rate fuel pump - provides more fuel to your larger injectors
• Larger diameter exhaust - with the greater exhaust air flow with more air being forced through the engine, a less restrictive exhaust is important (especially with turbochargers)
• Greater capacity intake system - again, with the greater air being forced through the engine, a less restrictive intake system is good.
• Revised engine calibration - this can be provided through a custom chip/tuner etc. A revised calibration may be part of a supercharger/turbocharger package if you buy a kit.
• MAF - Mass AirFlow meter
• Intercooler - only really recommended with a centrifugal supercharger or a turbocharger, unless you are good at fabricating
• Water injection - works by reducing the temperature of the intake air, and effectively adds more boost.

Older Ford vehicles, and diesels:
Older Ford vehicles (read: carburetted) vary a lot, and are best dealt with on a case by case basis, so feel free to search the forum, or start a new thread if your question hasn't been asked before. Although, as mentioned previously it is quite difficult to get turbo's and carbureters to work well together, if you are working with a carburetted engine, the easiest option is to fit a basic efi system to it, or supercharge it.

Diesels fundamentally require similar modifications as to the ones mentioned above for newer gas engines (with the exception of the MAF).

Driveline components:
Each vehicle is different, but 2 things you may want to look into upgrading if you start piling on the power:
Auto transmission
Clutch if its a manual

My experience has been, if you aren't in the search of rediculous amounts of power, the rest of the driveline can cope (on modern Ford trucks) with some mechanical sympathy from the user. Although do remember that you are puting more force on the driveline components than the Ford engineers originally intended, so therefore you can expect greater failure rates.

Which brand should I choose?
I am not going to influence my personal opinion here, it is best to search the forum and make up your own mind, there have been some good and bad experiences with the larger manufactureres here.

Will Ford still warrant my vehicle?
Yes and no.
If the modifications you have made to the vehicle cause or provoke the issue or failure then no, that bit isn't warrantable. If you think about any component that can fail due to more torque, then those are the components that may get warranty denied. However they do need to be caused by your modifications.
If your door trim fails, then warranty should still cover it.


All of this above is purely what I wrote down one morning, and should be used as a guide, each specific project is different. Check some of the threads around here, odds on there is someone here that has tried (or at least thought about) a similar project to one you are attempting.


Feel free to contribute to this thread, by adding anything here that you feel may be worthwhile, or by PM'ing or e-mailing me. - You will recieve acknowledgement for it!!!

Thanks!

BigF350

[IB Adrian]

Ok,
Time for round 2.

Turbo's and carburetors
There are 2 ways in which a turbo can be set up with a turbocharger.
Draw through and Blow through.
With both set ups, the normal sized carb should be suitable.

Draw through
Far and away the easist of the 2 to set up, however there can be issues with it, and its performance isn't as great.
It, as the name suggests, draw air through the carburetor, to the turbo, which then compresses the air/fuel mixture.
Cars, such as the Corvair and the turbo Trans Am had such a system.

Benefits -
You don't need any form of adjustment for the carburetor to adjust fuel flow - as the carburetor is on the "atmosphere" side of the turbo, and therefore the pressure it sees is the same, therefore it is much easier to set up.

Detractors -
Poorer performance - The turbo now has to draw a much heavier fuel/air mixture, and therefore it isn't as efficient. Since fuel is much denser than air, it can seperate in the turbo, and pool, creating some turbo lag. The turbo can't be posistioned right on the exhaust side, and it requires longer headers - which will cause further turbo lag.
Also, given you are drawing air through the carburettor - which drops pressure, and then you are increasing the pressure with a turbo, means further inefficiency as you are compressing air from a lower pressure, and it will also increase your intake temp - and you can't run an intercooler (running fuel/air through one can be VERY dangerous (the fuel can condense inside the intercooler core and stay there if you then have an engine backfire the intercooler can explode), likewise a blow off valve shouldn't be used (it would eject a fuel/air mixture into the engine bay). Water Injection is the only way of cooling your intake charge.

If you are building the engine in the backyard cheaply, this most likely would be the preffered way to go, as long as you can live with the turbo lag, and don't want to run obscene boost pressures.

Blow through
More complex than the draw through arangement, but if set up correctly, has much improved performance.
It, as the name suggests again, means that the turbo is mounted before the carburetor, and it blows air through it.
To my knowledge this system has never been fitted to a production vehicle.

Benefits
Pretty much all of the detractors for the draw through set up are now reversed. You can use a blow off valve, an intercooler, turbo can be mounted on a set of real short exhaust headers, you aren't drawing air at a lower pressure etc.

Detractors
It is (as I mentioned previously) more difficult to set up. You have two major dilema's:
1. A carburetor can monitor air speed, and adjust fuel flow accordingly, but it can't measure an increase in pressure. Therefore, you may have a system making 15psi, and sending double the amount of air that a N/A engine would recieve, but the carburetor would only provide fuel for the N/A engine, meaning it will run super lean. As turbo's boost isn't linear, it can make it hard to tune.
2. You will now have a positive pressure, and it can cause headaches with your fuel flowing through your jets. The pressure will try to crush the fuel float, it's going to want to blow fuel mix out the throttle shaft, or back into the fuel line.
Also the carb must be sealed so it does not leak the pressurised air-fuel mix - it would be extremely dangerous. The best method I have heard of is placing the carb in an air tight box, and running a sealed throttle cable.

Because as the turbo increases boost that is more boost that the fuel pump must be able to overcome if it wants to push fuel into the carb. What you want is an electric fuel pump and a boost sensing fuel pressure regulator to increase fuel pressure as turbo boost pressure increases.
Fuel floats should be filled with something so they don't get crushed under the pressure.

For the black art of fuel enrichment (to adjust for the higher pressures that the carb can't monitor) I have heard some people overcome the first issue by just jetting the carburetor for when it is at maximum boost, however, when the turbo isn't at maximum boost (the majority or the time for a street driven vehicle) it will run horribly rich, and isn't really a suitible solution.
Another, better method is to have 4bbl carbs, the secondaries are jetted for the higher air pressures, and are operated by a vaccum system to open under sufficient turbo boost.
There are other more advanced methods, but if you want to attempt them, you (in my opinion) might as well run a basic EFI system, as most of them just attempt to mimic an EFI system.

So, what have you learnt after all this. Run EFI!!!

[IB_Tim]

Moderators please do not add nor subtract from this stickie at all, if you need to..... Contact me. No replies at all.

[pitch_black]

Hello,
I am about to install a svt supercharger on my stock 04 f-150. any advice or websites that might be helpful. looking for any diagrams on how to install or any pictures identifying all parts needed. thanks so much for any help

[rsalter66]

i have a 75 351w that i built for my 65 falcon street rod , its a stock motor with edelbrock performer cam,lifters , mani,carb ,150 shot nitro + aftermarket dist,gear to gear drive timing,+headers, i got an old mc,culloch supercharger( first paxton) that i made a hat for the carb + blow in down thru the carb. the only trick i had was i had to extend the bowl vents out thru the hat because i was pressurizing the bowls i have yet to really test it because i just bought a 78 bronco4+4 with a bad motor that i'm going to try to put the motor in insteadjust have to see if i can adapt the windsors c-6 to the broncos transfer case by changing the output shaft+nosecones?but i did have it running in the falcon and it seemed to run well!but im going to sell the falcon to help finance bronco proj,

[RABBITUSA]

Draw through - Detractors -you can't run an intercooler
ever seen a Gale Banks turo set up for a gasoline engines ?..........runs an intercooler
you can set a pressure / boost switch for your water injection system to come in as needed.....
as far as the fuel delivery problem...........need more fuel try 110 needle valves(holley)
sometimes less is more...... SAVINGS...no need for fancy head or intake work rough surfaces in the manifold and head chambers aid to elminate fuel pooling
THE BEST REASON FOR TURBO.....it's FREE HORSEPOWER it works only on exhaust gases not like blower or chargers (crank drive)...they cost horsepower ...when you hit the key they cost you whereas a turbo only comes in when needed......REMEMBER TIMING....TIMING......TIMING.........IT'S A TURBO KILLER.....only my thoughts.....

[RABBITUSA]

one other thing............... spend you money on good HIGH TEMP. valves.............