The following specifications are general guidelines offered to aide in
building an engine for street use. For more detailed specifications regarding your specific application or for "strip only" use, please consult a professional engine builder.



Pistons:
Forged pistons recommended for all applications. Cast and hypereutectic pistons can be used but should be limited to lower horsepower (approx 450-500 hp) applications.

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. Higher octane fuel will allow you to run higher boost levels, approximately 1 psi for every 2 whole octane number e.g. 12-14 psi = 95-97 octane

Heads:
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.

Cam:
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.

Exhaust:
Headers are recommended. The size of headers are dependent on whether you are wanting to create more low end torque or high rpm horsepower.

Intake manifold:
Dual planes are recommended to improve low end torque, however may require staggered jetting for good fuel distribution with carbureted applications.

Carburetor:
Holley double pumper w/ mechanical secondaries.
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 carburetor’s 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 applications):
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.

Example:
(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 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 1bs/hr. To convert to gallons per hour, divide this figure by 5.87.

Example:
(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).


http://www.procharger.com/bebs.shtml

 

should be a sticky

 

i dont agree with the carburetor specs for those horsepower levels..n/a wont have enough flow to support those figures

 

with a supercharger you will be using a "blow thru" style carb. I think Pro-charger knows what they are talking about. these HP levels are for boosted applications...

 

Well intercooled boost can see alot more psi with 9:1 comp, depending on heads and cam. Iron heads at 9:1 may not like too much more but aluminum heads that are kept cool with lower temp tstat could see 15-18 psi easily. I have had 2 aluminum head setups see that much boost on 9:1 comp on 93 gas. Not all will but intercooling helps alot when pushing pump gas limits

Piston ring gaps: na motors can run tighter gaps. Less pressure and heat in chamber with lower hp levels. Typically .0035-.0045 times bore diameter. Boosted apps should see atleast .0050-.0060 times bore diameter. High boost or more race abuse may want .0060-.0070. My personal turbo car making 750-800 hp was running .0055 times bore. Now i am at about .0063 for race high boost

 

Should be a sticky, I would however like to see the responses to this when it's put in the "Power Adder" section

 

This should only be considered the safe recommendation for an NA iron headed engine for a person new to SBC engines. Using decently designed aluminum heads, lower temp thermostats, richer fuel mixtures will easily allow you to run a compression ratio of 10:1, careful tuning and the right cylinder heads and a cam that bleeds enough pressure and you can run in the 11:1 range easily.