Quote Originally Posted by sev View Post
Can anyone tell me what 2004 4.0L injectors are rated at? They are the bosch style, the thin black ones. I put these on and I have a feeling theyre not flowing enough.... Any ideas?
http://www.jeep4.0performance.4mg.com/tech_specs.html
Injectors
Some of those specs that are hard to find in any workshop manual.

The following is a list of the injectors used on the 4.0L since 1987 along with their rated static flow:

Model Year, ...Part #, ...........Colour, .....Fuel Pressure, ...Static Flow,
'87-'90, ........53003956, .........Black, ...........39psi, .................18.6lb/hr
'91-'93, ........33007127, .........Brown, ..........39psi, .................21.0lb/hr
'94-'95, ........53030343, .........Tan, ...............39psi, .................21.0lb/hr
'96-'98, ........53030778, .........Grey, .............49psi, .................23.3lb/hr
'99-'04, ........04854181, .........Blue tip, ........49psi, .................22.5lb/hr
'05-'06, ........53013690AA, ...Brown tip, .....49psi?, ...............23.3lb/hr?

The injector flow rate varies as the square root of the pressure drop across the injector. The stock '91-'95 4.0 injectors are rated at 22lb/hr @ 43psi fuel pressure, so at 39psi they flow ( sq. rt.(39/43) x 22.0 = 21.0 ).
For stock/modified 4.0 engines or stroker build-ups the following injectors can be installed. The flow rates are:

Ford Motorsport 19.0lb/hr @ 39psi (Part no. FMS-M9593-C302)
Ford Motorsport 24.0lb/hr @ 39psi (Part no. FMS-M9593-A302)
Ford Motorsport 30.0lb/hr @ 39psi (Part no. FMS-M9593-B302)
Chevy LT1 24.0lb/hr @ 43.5psi (Part no. 17124248)
Chevy LT4 28.0lb/hr @ 43.5psi (Part no. 17124251)
'98 Chevy LS1 25.2lb/hr @ 58.0psi (Part no. 12533952)
'99-'00 Chevy LS1 26.2lb/hr @ 58.0psi (Part no. 12456154)
'01-'02 Chevy LS1/LS6 28.6lb/hr @ 58.0psi (Part no. 12482704)
Accel 19.2lb/hr @ 44.1psi (ACC-150119)
Accel 21.1lb/hr @ 44.1psi (ACC-150121)
Accel 24.4lb/hr @ 44.1psi (ACC-150124)
Accel 25.6lb/hr @ 44.1psi (ACC-150126)
Accel 29.4lb/hr @ 44.1psi (ACC-150130)

The '95 Jeep 5.2 ZJ/Dodge 5.9 injectors (Part no. 53030262) are rated to flow 24.6lb/hr at 39psi.

The selection of injector size will depend on the estimated horsepower output, brake specific fuel consumption BSFC (assume 0.5), no. of cylinders, and the injector duty cycle (assume 80% or 0.8). The formula is:

Injector size (lb/hr) = (horsepower x 0.5)/(no.of cylinders x 0.8)