SUPERCHARGING

Building Your Own Super Charger System

I have been interested in super charging my carbureted motor for quite some time now. I have searched many manufactures sites trying to find as much info as I can on this modification. Several companies are making blower kits for carberated motors now so you can pick and choose which one you want for your needs. It is however possible to use any SuperCharger  unit if the proper fuel and timing requirements are met. Many blower companies such as ATI, Paxton, Kenny Bell, Vortech and Powerdyne sell accessory parts for carbureted motors. It is possible to build your own system and install it on a carbureted motor with excellent results. Below I have listed several parts that are needed to build a complete system for an 85 Stang. Parts may be added or substituted for your specific needs.

• Super Charger! You will only need the Blower and it's mounting hardware so a full kit is not required. Choose the blower that is best suits your application. Also if the kit is lubricated by the engine oil you will need to get the oil line kit with the blower.

• Air Filter! I suggest using a conical K&N filter!

• Air Tubing! Many blower companies carry a air tubing kits for this purpose. The kits usually include tubing and an assortment of elbows.

• Carburetor Hat! This can be purchased from serveral supercharger companies. This will connect the blower tubing to the carb. Note: The choke assembly and air horn on the carburetor will have to be removed and nitrophy floats will have to be installed. Some aftermarket carbs like the Demon line of carberators and holleys HP series carbs do not have the choke horn on them and may be a good carb to start with.

• Fuel System! There are several electric fuel pumps avalible on the market. You can pick the right one out if you follow the instructions here (Fuel Pump) for figuring out the fuel ratio needed. You will need a high flowing,  high pressure fuel pump, a boost controlled fuel pressure regulator, and proper fuel line to handle your fuel pressure and to bring the fuel from the tank up to the motor.

• Boost/Fuel Pressure Guages! Many companies sell boost and fuel gauges.

The rest of the system will take a creative mind and good mechanical knowledge. I have added a small section at the bottom of this page to help tune your system and ensure you have the proper parts.

Pistons:

Forged Pistons should be used. The stock 85 5.0 motor already has forged pistons. Cast or Hypereutectic pistons can be used but are prone to burn out quiker than the forged pistons will unless tuned correctly.

Compression Ratio:

For pump gas (91-93 octane) applications, a compression ratio of 8.5:1 to 9:1 is recommended for boost levels of 8-10 psi. (Non-Intercooled). Higher octane fuel will allow you to run higher boost levels, approximately 1psi to every 2 points of octane.

Heads:

The stock 85 heads will work fine with most blowers and do not have to be replaced. Higher flowing heads will help generate more horsepower. Porting on the exhaust side is recommended. Aluminum heads will allow you to run more boost than cast iron heads due to their ability to dissipate heat.

Camshaft:

. The stock 85 cam works well with most blowers and should not need to be changed. Contact your cam manufacturer for lifts and duration that best suit you application if you choose to upgrade it.

Crankshaft and Rods:

Cast 5.0 cranks can safely handle 450 horsepower although many Mustang owners push this with no problems. Forged steel cranks are recommended for higher horsepower or rpm levels above 6,000 rpm.

Exhaust:

Headers are recommended. The stock 85 short tube headers should be fine. 87 and up Mustang 5.0 headers have a larger outlet and can be used in place of the 85 stock headers if the exhaust is upgraded too.

Intake Manifold:

Dual planes are recommended to improve low end torque, however may require staggered jetting for good fuel distribution. The stock manifold is very restrictive and I suggest changing this to a better flowing high rise manifold.

Carburator:

Holley double pumpers w/mechanical secondary's recommended. Do not use the 85's stock carb for this unless it has been worked over.

All carburetors will require the removal of the choke assembly and choke horn, replacement of the floats with nitrophy floats and jetted to suit your motor.

Fuel Pump:

Your fuel pump must be capable of supplying the proper amount of fuel flow at the maximum operating pressure requirement, add your maximum boost pressure to your initial idle fuel pressure.

Formula:

(8psi idle fuel pressure) + (10psi of boost) =18 psi. max. fuel pressure. Multiply this figure by 1.2 (20% safety factor) gives us 21.6 psi.

To determine required fuel flow multiply your total expected horsepower by a BSFC (brake specific fuel consumption) of .65. This will give your fuel flow requirement in 1lbs/hr. To convert to gallons per hour divide this figure by 5.87.

Example:

(500 boosted HP) x (.65 lbs./hr/hp BSFC) = 325lbs/hr fuel flow

325 lbs./hr /5.87 lbs./gal = 55.4 gals/hr fuel flow

Therefore, a fuel pump capable of providing a minimum fuel flow of 55.4 gals/hr at a max pressure of 21.6 psi. is required.