LT1 injectors Q

[POLAR_JEEP_04]

I got a set of injectors from a 1993 Fire bird with a 5.7L to swap into my jeep. my question is are they direct swap or is there something i need to modify for them to fit. my jeep is a 1997 I6 and ill be swapping a 99 intake manifold on at the same time. TIA

 

[Hellbent]

you should be ok. i got mine out of a '95 lt1 caprice. was a direct swap, worked out great. this is in my '96(same as '97 set up).

 

[bigdaddyjlove]

I put a set from a '96 Caprice in my '98tj stroker. direct swap and work great

 

[POLAR_JEEP_04]

ok thanks guys I just thought the plugs might be different

 

[Blaine B.]

What is the benefit to these injectors versus running the 19lb Ford injectors?

 

[Hellbent]

they flow closer to what the later o.e. xj injectors flow(23lb/hr?). the ford 5.0's caused my '96 to lean out/ping like a b*itch @ wot. swapped 'em out, ran much stronger, no more leaning out at the top end.

 

[Blaine B.]

Interesting, I know the older XJ's (pre 97) use something like 14lb injectors which is why the Ford 19lb are a good upgrade.

I wasn't aware of the newer XJ's switching to a different injector.

I suppose for that you could also use a Ford 24lb injector.

 

[bigdaddyjlove]

The LT-1s are about 23-24 lbs at 49 psi. Also, they are 6hole sparyers where the ford are 4hole. Better spray pattern and throttle response

 

[RedChuck]

just wondering do you need to modify the map or any sensors when you switch injectors?

 

[bigdaddyjlove]

I didn't have to. Now, I've never run mine on a dyno either. Just pulled some spark plugs to "read" them. It runs fine, its 4.6 stroker, with a moderate Crane cam. It can get as much as 23-24 mpg hwy or 3-4 across town (foot on the floor )

 

[RedChuck]

what else is done to your jeep to get you those kinda nums

 

[Slip Kid]

Pressure and flow being the important part...

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-'99, ........53030778, ...Grey, .........49psi, .................23.2lb/hr
'00-'01, ........04854181, ...Blue tip, .....49psi, .................22.5lb/hr

 

[bigdaddyjlove]

what else is done to your jeep to get you those kinda nums

Nothing really. Its a '98 TJ 4.0 manual that I built for my daughter. The rear axle was toast when I got it and the engine was knocking pretty bad. I built a Renix era block, short-nose 4.2 crank .30 over Silvolite 822hp pistons (maybe, working off memory here) and a mild Crane cam. Static compression ratio is about 9.01 - 1.

No knock on 91 or better octane.

The rear end, I re-built with an Auburn Ected, but i stuck with the 3.07s that came in it.

its got 29" tires on it and on the highway its turning about 1800 at 70ish, which is plenty fast in a ragtop TJ.

I've regreted the 3.07s ocasionally, but it'll burn both tires into second and cruises on the highway, so its plenty for a 16 year old girl:laugh:

 

[bigdaddyjlove]

Pressure and flow being the important part...

Thanks, I knew the ones I had were between 23 and 24, but this is a great list to carry to the junkyard.

 

[Hellbent]

i didn't mess with the map either. '99-up intake, k&n fipk, apn header, 2.5 ex front to back w/ a drony-ass flowmaster, and 62mm bored tb. pulls like crazy at all speeds. and just passed smog today with flying colors.

 

[stoneattic]

Does any one know how the flows at different psi relate? For example, I have a 95 with the 99+ intake that I put my original fuel rail and injectors on. Would the newer injectors (I have to check the color) flow more or less? Are the 23.2 or 22.5 lb/hr @ 49psi rated injectors going to flow more or less than my 21 lb/hr @ 39psi rated if they are both feed at the same psi from my 95 fuel pump/system?

 

[Hellbent]

here's the formula for that.
http://www.csgnetwork.com/fiflowcalc.html

 

[stoneattic]

here's the formula for that.
http://www.csgnetwork.com/fiflowcalc.html

Excellent, thanks! :thumbup:

 

[Hellbent]

you're welcome.

 

[Slip Kid]

Does any one know how the flows at different psi relate? For example, I have a 95 with the 99+ intake that I put my original fuel rail and injectors on. Would the newer injectors (I have to check the color) flow more or less? Are the 23.2 or 22.5 lb/hr @ 49psi rated injectors going to flow more or less than my 21 lb/hr @ 39psi rated if they are both feed at the same psi from my 95 fuel pump/system?

The pressure of the system should be controlled by the regulator, which should have come with the fuel rail. So If I'm understanding what you did correctly, your fuel pressure should be 39psi, no matter what pump is used.
Now I need to go study some more fluid dynamics because I still don't understand it all.