Originally Posted by bigmuddyford
I have a 92 f250 with an efi 460. Im wanting a lot more power cause the 240 it has stock just isnt enough. What all do i have to do to put a turbo on?
There are two ways of approaching this project. The correct way, where you figure out the RPM range you want to run the engine in, how much boost that new engine will handle based on the parts you choose, what compression ratio, what size turbos etc, then fabricate/buy/have made the parts necessary to put that together for a reliable, powerful system. The monkey way is to slap on a turbo (or two if you use smaller, junkyardish ones) and see what happens and hope the rings stay on the pistons.
The latter method is by far cheaper, initially, assuming the engine holds together.
Where most people run into trouble is tuning the EFI system. Your 92 is speed density based which by itself isn't problem except that there is very little tuning software that supports it well enough that you'd be able to achieve a forced induction engine with the EEC that's in there now.
What most people do is convert their truck to mass air, i.e. the 95+ F-series EEC or the 89-93 mustang EFI mass air system, the latter being supported by many more tuning softwares and some of the hardware dongle type tuners.
Regardless what EFI system you use, you must be able to tune it because in factory/stock form none of these EEC's are going to understand there's a 460 with forced induction. You'll have to scale many parameters differently, adjust the fuel table settings depending on how large of injectors you will end up with, and so on.
Stock injectors aren't useful for such projects. For example, on my 500cid (460 based) twin turbo stroker project, I'll be using 160lb bosch injectors, which are just a "hair" bigger than the stock 42lb injectors.
The subaru turbo you references is grotesquely too small, and will overspeed at very low engine RPMs and basically commit suicide in short order. It's sized for a 2-something liter engine, not an almost 8 liter engine.
Fabrication isn't very difficult if you can weld:
First you will have to decide whether you want one larger turbo, or two smaller ones, and how the plumbing will have to be as well as fabricate or pay a shop to fabricate all the necessary parts. There aren't any 460 turbocharger kits for the F-series that I'm aware of. But if you can weld, you can make your own turbo manifolds out of ordinary materials. Here is what I did:
How To: http://frederic.midimonkey.com/f350-...manifolds.html
I made two of those, one for each side of the engine. The manifolds in the above picture/link started out as a 10' piece of black pipe sectioned and welded to get the basic curves, welded to 3/8" thick plate which is the header flange.
Then, because my math determined that the stock dual-inlet throttle body was too small, I chose to make a "adapter" and use two much larger, 4.6L throttle bodies.
How To: http://frederic.midimonkey.com/f350-superplenum.html
Mechanically, making a turbocharger system isn't a big deal, it's just time consuming and requires a fair amount of planning so everything fits together.
Hopefully that gets you started. Before you throw cash into this, think about the approach you want to think, and start digging through the internet for math that will help you, and calculate it all out just to be safe.
Here are some of my older posts that may (or not) help you:
And here is some math that might get you started...
Calculating Airflor Requirements
cfm = (cid x rpm x VE) / 3456
cfm = (302 x 6000 x 0.85) / 3456
cfm = 445.66
Calculating Pressure Ratio
pressure ratio = (boost psi + 14.7) / 14.7
If you want 10psi of boost, the pressure ratio is:
= (10 + 14.7) / 14.7
A compressor will raise the temperature of air as it compresses it. As temperature increases, the volume of air also increases. There is an ideal
temperature rise, which is a temperature rise equivalent to the amount of work that it takes to compress the air. The formula to figure the ideal
outlet temperature is:
T2 = T1(p2/p1)^0.283
T2 = outlet temp degrees R
T1 = inlet temp degrees R
degrees R = degrees F + 460
P1 = inlet pressure absolute
P2 = outlet pressure absolute
If the inlet temperature is 75 degrees F, and we want 10psi of boost, to figure out T1 in degrees R:
T1 = 75 + 460 = 535 degrees R
The P1 inlet pressure will be atmospheric in our case and the P2 outlet pressure will be 10 psi above atmospheric. Atmospheric pressure is 14.7
psi, so the inlet pressure will be 14.7 psi, to figure the outlet pressure add the boost pressure to the inlet pressure.
P2 = 14.7 + 10 = 24.7psi
Now we have all the variables and we can figure out the idea outlet temperature.
T2 = 535(24.7 / 14.7)^0.283 = 620 degrees R
the convert back to degrees F
620 - 460 = 160 degrees F
The above formula assumes a 100% adiabatic efficiency (AE), no loss or gain of heat. The actual temperature rise will certainly be higher than that. How much higher will depend on the adiabatic efficiency of the compressor, usually 60-75%. To figure the actual outlet temperature, you need this formula:
IOTR ÷ AE = AOTR
IOTR = Ideal Outlet Temperature Rise
AE = Adiabatic Efficiency
AOTR = Actual Outlet Temperature Rise
Lets assume the compressor we are looking at has a 70% adiabatic efficiency at the pressure ratio and flow range we're dealing with. The outlet temperature will then be 30% higher than ideal. So at 70% it using our example, we'd need to do this:
85 ÷ 0.7 = 121 degrees F Actual Outlet Temperature Rise
Now we must add the temperature rise to
the inlet temperature:
75 + 121 = 196 degrees F Actual Outlet Temperature
As air is heated it expands and becomes less dense. This makes an increase in volume and flow. To compare the inlet to outlet airflow, you must know the density ratio. To figure out this ratio, use this formula:
(Inlet deg R ÷ Outlet deg R) × (Outlet Pressure ÷ Inlet Pressure) = Density Ratio
We have everything we need to figure this out. For our 302 example the formula will look like this:
(535 ÷ 656) × (24.7 ÷ 14.7) = 1.37 Density Ratio
Using all the above information, you can figure out what the actual inlet flow in CFM. To do this, use this formula:
Outlet CFM × Density Ratio = Actual Inlet CFM
For the 302...
445.66 CFM × 1.37 = 610.55 CFM Inlet Air Flow
That is about a 37% increase in airflow and the potential for 37% more horsepower. When comparing to a compressor flow map that is in Pounds per Minute (lbs/min), multiply CFM by 0.069 to convert CFM to lbs/min.
610.55 CFM × 0.069 = 42.12795 lbs/min
Now you can compare these results with compressor maps of turbos you are considering and determine how suitable they are, or aren;t. Play with sevearl adiabatic efficiency numbers and pressure ratios until you have good results. Twin turbo systems would require each turbo to do half the work, whereas a single turbo system would be required to do all the work.