S & M Kustomz Forum

Throttle Bodies

• Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm

• Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm

• TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm

• TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm

• Stock 98 Camaro 3800 II Throttle Body -- 554.3 cfm

• Stock 4.3/5.0/5.7 2bbl TBI complete -- 574.1 cfm (dry)

• Stock 4.3/5.0/5.7 2bbl TBI w/o injectors -- 584.7 cfm

• Stock 3800 vin L throttle body w/ screen -- 419.1 cfm

• Stock 3800 vin L throttle body w/o screen -- 444.8 cfm

• 4bbl MPFI Holley Throttle Body -- 1287.6 cfm

Mass Air Flow Sensors

• Stock TPI Bosch MAF sensor w/ screens -- 517.8 cfm

• Stock TPI Bosch MAF sensor w/o screens -- 658.4 cfm

• Stock 87 GN 3.8L Turbo AC MAF sensor w/ screen -- 584.2 cfm

• Stock 86 2.8L AC 5-wire MAF sensor w/ screen -- 576.2 cfm

• Stock 96-up AC 3100 V6 MAF sensor w/ screen -- 616.4 cfm

• Stock 96-up AC 3100 V6 MAF sensor w/o screen -- 670.7 cfm

• Stock 94-up LT1 MAF Sensor w/o screen -- 719.0 cfm

Other Air Induction Pieces

• Stock 85-87 Firebird TPI airbox mid piece -- 499.3 cfm

• Stock 88-92 Firebird TPI intake bellows w/ integral 90 degree bend -- 693.0 cfm

In-Tank Fuel Pump Flow Rates

92 Buick Ultra 3800 Supercharged High Volume AC Delco EP311

• 36.6 Gallons Per Hour @ 43.5 PSI

• 25.8 Gallons Per Hour @ 60.0 PSI

Walbro 307 In-tank (86-92 GM high-performance replacement)

• 255 liters per hour (67.3 gal/hr) @ 70.0 PSI

Injector Flow Rates (@ 43.5 psi)

• 3800 vin C injectors -- 19.0 lb/hr

• 3800 vin L injectors -- 21.2 lb/hr

• 3800 SC vin 1 injectors -- 29.0 lb/hr

• 3800 Series 2 (non SC) Rochester 17103146 injectors -- 21.2 lb/hr

• 3800 Series 2 (non SC) Bosch 0280150973 injectors -- 21.2 lb/hr

• 86 Vette RP 5235211 TPI injectors -- 21.6 lb/hr (Bosch design with plastic tip)

• 87-88 Vette RP 5235302 5.7L TPI injectors -- 21.6 lb/hr (Bosch design with aluminum tip)

• 85 5.0L RP 5235047 TPI injectors -- 19.3 lb/hr (Bosch design with plastic tip)

• 97-up LS1 Bosch 12554271 grey plastic injectors -- 25.2 lb/hr

• 2001 GM C/K Truck 6.0L V8 P/N 25317628 (Delphi EV6 short style injector) -- 22.1 lb/hr (2.78 gm/sec)

• 1996-up 3800 Series II Supercharged (white LS1-style) -- 36 lb/hr

Here are some simple formulas you can use to determine what your injectors would flow at different pressures. To double the flow through a jet or nozzle would take 4 times the pressure:

New Pressure = Old Pressure x (new flow / old flow)²

If you know the flow of a jet or nozzle at a certain pressure, you can figure the flow at a new pressure:

New Flow = Old Flow x √ (new pressure / old pressure)


Here are some formulas you can use to determine how much horsepower a particular injector flow rate will support or how big of injectors you need to support your engine's HP number:

HP / Number of Injectors x BSFC / Duty Cycle = Injector size required

Injector Size x Duty Cycle / BSFC x Number of Injectors = HP supported

BSFC = Brake Specific Fuel Consumption. Most naturally asperated engines have a BSFC factor of 0.50. Most Supercharged or Turbocharged engines have a BSFC factor of 0.65.

Duty Cycle = The maximum sustained "ON-TIME" of the Injector. The typical maximum injector ON-TIME sustainable in a modern EFI engine is 80%. For the above formulas, use 0.80 for the duty cycle.