I have heard a lot of talk about changing the stock injectors to a Ford piece. Will it improve performance if I do this? I have done gears and was wondering what I should expect from my Renix 4.0. FYI 4.88s and 33' tires. If some of these mods will net me some performance, be it fuel economy or power, I would be interested in doing them! Any Renix Gurus out there that can point me in the right direction?? Thanks much guys!!

 

As far as I know yes you would. The Ford injectors are a higher PSI...

 

It isn't the higher PSI that is what the injector is set at. It is the spray pattern but the biggest savings is in the wallet b/c they are cheaper and more available to everyone at any parts house anywhere.
Performance advantages..........yes, but you would need a dyno to see them, they are so small.
Injectors have a spring inside them that has to be overcome for them to spray. That spring shuts the injector off after the electrical power is removed and the increased spring pressure make for a crisper shutoff after it has finished it's cycle. This means no dribbling as injectors with a weak or incompetent spring will do. Why inject after the compression stroke starts which wastes fuel, b/c the computer has determined the correct duration of injection for optimal fuel usage.
Just from my reading of the Renix F.I. manual. This is solely my interpretation of the manual. The use of Ford 5.0L injectors I have found to be cheaper and more available.

 

http://offroadjeepers.com/showthread.php?t=383
Some useful info about this..

4.0L Engine revisions *********

'87-'90: 177hp at 4500rpm, 224lbft at 2400rpm, redline 5000rpm
The '87-'90 engines had Renix electronic multipoint fuel injection, electronic ignition, a 52mm throttle body, and an inefficient "low port" cylinder head similar to the old 4.2L/258. They have a water temp port in the back of the head. (Use a '91-'95 HO head for a head swap to replace these most easily.)

'91-'95: 190hp at 4750rpm, 225lbft at 3950rpm, redline 5250rpm
In 1991 engines received Chrysler sequential MPFI, a larger 60mm throttle body, revised intake and exhaust manifolds, and a more efficient high port cylinder head. As a result, these engines produced 13hp more than their predecessors and gained the "High Output" designation.

'96-'99: 190hp at 4600rpm, 225lbft at 3000rpm, redline 5300rpm
In 1996 engines received noise, vibration, and harshness fixes. The blocks were stiffened with extra ribbing, a main bearing brace was added, and lighter cast aluminium pistons were introduced to improve efficiency and reduce cold start piston slap. Engines also received revised camshaft timing for more low rev torque. Heads are similar except that they have no water temp port. (The OBD II system drives the guages and, only requires one port, these can be drilled and tapped for the sender used in earlier models if you're doing a head swap.)

'99.5-'01: 193hp at 4600rpm, 231lbft at 3000rpm, redline 5300rpm
In 2000 a distributorless coil-on-plug ignition system was installed, intake and exhaust manifolds were revised, and a more efficient water pump was included. These heads are quite different. They have smaller exhaust ports and, mounting bosses for the coil pack used with the distributorless ignition. There are different accessory mounting hole locations on these as well.

Injectors *********

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, ...Dark Tan, ...39psi, .................18.6lb/hr
'91-'93, ........33007127, ...Brown, .......39psi, .................21.0lb/hr
'94-'95, ........53030343, ...Tan, ...........39psi, .................21.0lb/hr
'96-'99, ........53030778, ...Grey, .........49psi, .................23.2lb/hr
'99-'01, ........04854181, ...Blue tip, .....49psi, .................22.5lb/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 19lb/hr @ 43.5psi (ACC-150819)
Accel 24lb/hr @ 43.5psi (ACC-150824)
Accel 26lb/hr @ 43.5psi (ACC-150826)
Accel 30lb/hr @ 43.5psi (ACC-150830)

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)


Cylinder head *********

The stock cylinder head is cast iron. The valve head diameter is 1.91" intake, 1.50" exhaust.

Cylinder head flow figures (cfm) at 25inH2O pressure drop are:

Non-HO head
Valve lift (in)..... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 122.0 168.0 186.0 189.0 192.0
Exhaust flow....88.0 114.0 130.0 134.0 138.0

HO head
Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 66.0 128.0 179.0 206.0 209.0 209.0
Exhaust flow. 55.0 100.0 120.0 136.0 141.0 141.2

Ported HO head with 2.02/1.60 valves
Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5
Intake flow.... 73.9 142.4 197.8 229.8 247.0
Exhaust flow. 65.3 114.0 135.9 146.3 157.1


Head gaskets *********

The compressed thicknesses of the following gaskets for the 4.0 engine are:

Stock 4.0 '87-'90 #33004447, '91-'93 #33007143, '94-'95 #53020219, '96-'99 #53020754----0.052"
Mopar Performance #P4529242----0.041"
Victor-Reinz (Dana) #5713----0.045"
Detroit Gasket #67-1045----0.050"
SCE Pro-Copper #67-9035----0.050", #67-9034----0.043", #67-9033----0.032"
Fel-Pro #9076PT----0.052"


Pistons *********

The pin heights and dish volumes of pistons available for the 4.0 engine are:

Stock 4.0 cast aluminium '87-'93 #83500251, '94-'95 #4773157, '96-'01 #4798329----1.601" 13.3cc
Keith-Black Silvolite hypereutectic #2228----1.581" 11.5cc
Sealed Power hypereutectic H802CP----1.592" ~16cc


Stock Cam Specs *********

The stock Jeep 4.0 camshaft is a dual pattern cam with an advertised duration of 253.3/259.0 degrees intake/exhaust. Here are all the cam specs:

Duration: 253.3/259.0 degrees
Cam lobe lift: 0.265"
Rocker arm ratio: 1.6
Valve lift: 0.424"
Lobe separation angle: 107.3 degrees
Intake centerline angle: 114.3 degrees
Valve overlap: 41.6 degrees
IVO: 12.4 degrees BTDC
IVC: 60.9 degrees ABDC
EVO: 49.8 degrees BBDC
EVC: 29.2 degrees ATDC


Aftermarket camshafts *********

Crane Cams http://www.cranecams.com
Crower Cams http://www.crower.com
CompCams http://www.compcams.com
Isky Cams http://www.iskycams.com
Clifford Performance http://www.cliffordperformance.com
Mopar Performance http://www.buymopar.com
Erson Cams http://www.mrgasket.com
Hesco
http://hescosc.com

 

nick... thanks for posting that... I am starting a E-85 conversions for my wheeling Jeep... I needed to find the specific flow rates for the injectors...

 

WE SHOULD MAKE THIS A STICKY

 

Ford Motorsport 19.0lb/hr @ 39psi (Part no. FMS-M9593-C302)
This is great! Now I know what injectors to buy. Can someone please tell me if these fit just like the stockers,ei. plug & play? Please explain. Thanks much!!

 

Every thing I've read says it's plug and play no mods needed...

 

Yes COS any of the FoMoCo part numbers ending in 302 should be plug n play for your 4.0L. They are even complete with o rings too if you buy them through the Ford dealer. They are in a kit of 8 from there as well. At least they were two years ago when I got mine. I just dumped the two extras in my spare parts box.

 

Got a question for you guys, would the 302 fuel injectors make a worth wile difference? Educate me please.

 

They are just cheaper when you need new injectors. They have a better spray pattern but that would need a dyno to be able to appreciate the improvement. They do not seem to change the fuel mileage, so overall I would say that other than initial cost savings over Jeep ones you see no benefit.
Blue JMHO

 

If you had a way to properly burn the additional fuel, then you could go up a size and gain some HP... But there lies the second problem... getting a powerful enough spark to properly burn the additional fuel....

 

Or thedisplacement required to combust that fuel. Remember it has to be a combinmation of fuel and air. If you introduce additional fuel you need the additional air as well. This can be provided by a supercharger or a turbocharger but if that is not in the cards for you then displacement will suffice in the form of a stroker. From my point of view those are your choices when trying to squeeze more ponies out of our beloved 4.0L.

 

I've noticed my Renix runs a touch to the lean side to begin with. IIRC, I read somewhere that they do to assist in meeting emissions standards. The 19 lb. Ford Injector may just be enough additional fuel to offset that factory lean condition...

But yes... to go up 5lbs/hr in flow rate you would need additional oxygen in the mixture. A super or turbo would do the job, so would stroking the engine. But that wouldn't be a budget mod then....