Thinking about injectors

[Knoxes]

So I'm very close to re-installing the rebuilt engine and I need to start thinking about what kind of injectors that I should use. It's a 2003 WJ, slightly stroked to 4.2, stock cam, stock throttle body and exhaust system. SCR should be about 9, DCR should be about 7.6 and the quench should be about 0.040. What say you?

[SilverXJ]

Refresh my memory, what is the fuel pressure on the 2003?

On my 2000 with 49 psi I've ran the Neon/Bosch 0-280-155-784 injector and the Jeep/ Delphi 53032704AB injectors with good results.

[Knoxes]

The FSM says it's 49. Stock flow with the 04854181 is 22.5. Seems like I should be targeting something slightly higher than that, correct?

[SilverXJ]

Those two flow ~24#

[Alexia]

The FSM says it's 49. Stock flow with the 04854181 is 22.5. Seems like I should be targeting something slightly higher than that, correct?

What horsepower are you expecting to make or calculated with this engine setup? Around 225 horsepower and the stock injectors are still fine running at 49.2PSI. Past the 225 horsepower target pushes the injectors past 80% duty cycle. The stock 4.0L injectors are over sized for their original application and were also used on the ZJ's 5.2L V8 and 5.9L V8 until 1998. This changed on the WJ though and use a different part number, 53032145AA, for the 4.7L V8 that are larger injectors.

[SilverXJ]

1) While the stock injectors may be "oversized" (as you say) the PCM will not have the capacity to correct the AFR correctly when pushed far enough out of its bounds. Yes, a stroker will do that.

2) Comparing the injector used in the V8s should show the injectors are oversized for the V8s, not as you are saying. They have two extra cylinders. Hp/cylinder on the 4.0L= 31.67 hp, HP/cylinder for 5.2L = 27.5 hp, 5.9L = 30.62 HP, similar results for HP/L. Comparing what is used in V8s has no bearing on what fits for a 4.0L or stroker.

[Knoxes]

The FSM says it's 49. Stock flow with the 04854181 is 22.5. Seems like I should be targeting something slightly higher than that, correct?

What horsepower are you expecting to make or calculated with this engine setup? Around 225 horsepower and the stock injectors are still fine running at 49.2PSI. Past the 225 horsepower target pushes the injectors past 80% duty cycle. The stock 4.0L injectors are over sized for their original application and were also used on the ZJ's 5.2L V8 and 5.9L V8 until 1998. This changed on the WJ though and use a different part number, 53032145AA, for the 4.7L V8 that are larger injectors.

I've looked around for a HP calculator and haven't found anything that I feel is accurate. Dino's recipe says 241 for this build. I've varied a couple of things, some positive and some negative, so I'm not sure where I'll land. But let's call it 230.

[CobraMarty]

Throwing out injector numbers and flow rates always leads to confusion when the flow rates are not given with PSI.
Also not mentioning what year vehicle is also confusing due to the PSI differences, different connectors and tune differences.

Found this on another forum, maybe helpful.
http://www.cherokeeforum.com/f2/lets-ta ... post333966

[QUOTE=VAXJCOUNTRY;333966]I have read that thread many times. Thanks for pointing it out though. Neon injectors are not drop it though right? Different plugs.

80's chrysler turbo injectors will fit, here is info on them. but I'm not sure if any of these would work.

http://www.thedodgegarage.com/turbo_fuel.html

Found this data..
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[/QUOTE]

[SilverXJ]

Throwing out injector numbers and flow rates always leads to confusion when the flow rates are not given with PSI.
Also not mentioning what year vehicle is also confusing due to the PSI differences, different connectors and tune differences.

He mentioned what years his vehicle is along with the fuel pressure. 2003 WJ, 49psi. The ones I recommend flow ~24# @ 49 psi.

Found this data..
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

Those might work. For a stock engine.

[CandyCaneXj]

How accurate are those fuel injector calculators online? They seem pretty close to your current injector size if you put in specs of a bone stock vehicle so i guess they are pretty good to go by?

[Knoxes]

Refresh my memory, what is the fuel pressure on the 2003?

On my 2000 with 49 psi I've ran the Neon/Bosch 0-280-155-784 injector and the Jeep/ Delphi 53032704AB injectors with good results.

About to order the Delphi - but are these the same connector that I currently have? Can't seem to find confirmation of that anywhere.

[SilverXJ]

Yes, they are the same connector.