Forged pistons recommended for all
applications. Cast and hypereutectic pistons can be used but
should be limited to lower horsepower (approx 450-500 hp)
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. Higher octane fuel will allow you to run
higher boost levels, approximately 1 psi for every 2 points
of octane. To determine the maximum boost level for your
compression ratio (using pump gas), refer to the enclosed
compression ratio chart.
The same rules for normally aspirated
engines apply to supercharged motors. Higher flowing heads
will help generate more horsepower than stock heads.
Supercharging produces a percentage gain in horsepower; by
starting with more base horsepower a modified motor will
receive a larger total hp gain (from the same percentage
gain). Porting, especially on the exhaust side is
recommended. Aluminum heads will allow you to run
approximately 1 psi more boost than cast iron heads due to
their ability to dissipate heat.
Lobe separation: 112 to 116 degrees
Split pattern: Exhaust duration and lift approximately 10
degrees and .010, respectively, greater than intake. Install
cam straight up. Contact a cam manufacturer for lifts and
durations that best suit your application.
Crankshaft and rods:
Cast up to 450 horsepower, forged for
higher horsepower or for rpm levels above 6,000 rpm.
Headers are recommended. The size of
headers are dependent on whether you are wanting to create
more low end torque or high rpm horsepower.
Dual planes are recommended to improve
low end torque, however may require staggered jetting for
good fuel distribution with carbureted applications.
Holley double pumper w/ mechanical
600 cfm (#4776) for up to 500 hp
650 cfm (#4777) for up to 650 hp
700 cfm (#4778) for up to 750 hp
750 cfm (#4779) for up to 900 hp
All carburetorís will require removal of the choke assembly
and choke horn, replacement of the floats with the solid
nitrophyl floats and jetted to suit your motor.
Fuel pump (carbureted
Your fuel pump must be capable of
supplying the proper amount of fuel flow at the maximum
operating pressure. To determine maximum operating fuel
pressure requirement, add your maximum boost pressure to
your initial idle fuel pressure.
(8 psi idle fuel press.) + (10 psi boost
press.) = 18 psi max. fuel press.
multiplying this figure by 1.2 (20% safety factor) gives us
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 1bs/hr. To convert to gallons per hour,
divide this figure by 5.87.
(500 boosted hp) x (.65 lbs/hr/hp bsfc) =
325 lbs/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 pressure of 21.6 psi is required.
This can be accomplished by an all electric high
pressure-high flow fuel pump (i.e. SX #18201, B.G. 400,
Magna-Flow 250 or similar type fuel pump) and a return
style, boost sensitive fuel pressure regulator (Mallory
#4309 or similar). Or by using a boost referenced mechanical
fuel pump only (up to 500 hp) or a boost referenced
mechanical fuel pump in conjunction with a low pressure
electric pump (i.e. Holley blue, Comp 140 or similar).