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6.0 LS Swap

yossarian19 said:
Do you think you could get the Vortec mechanical fan in between the radiator & motor?
Also -
Consider cutting & "stretching" your gauge wires so you can run the Jeep PCM under the dash somewhere, using one of the factory wiring passages. Use solder for the splices and you won't mess up your signals. Might not be worth the effort but it would get the Jeep PCM & some of the wiring out of the engine bay.
I'm jealous of this thing already. Someday, someday...
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Definitely not enough room to use the GM fan. I'm in the proses of trying to remove the Jeep PCM completely from the harness then make it a remote stand-alone with only the VSS, tach, oil, water, power, fuel level and ground inputs.
 
Get a late model (04 and newer I think) fuel rail. Its reyurnless. You can then just hook the factory jeep fuel line up to the LS engine. You DO NOT need to gut the stock regulator. That can be fixed in the tune. Actually I would highly recommend you dont gut the regulator. It keeps the fuel pressure steady even when voltage changes (turn on fans, lights, a winch, etc). The PCM can't adjust based on fuel pressure effected by voltage. It can only adjust injector pulse width to compensate for voltage change. But it will want a constant pressure no matter what.
 
Team Willys said:
Get a late model (04 and newer I think) fuel rail. Its reyurnless. You can then just hook the factory jeep fuel line up to the LS engine. You DO NOT need to gut the stock regulator. That can be fixed in the tune. Actually I would highly recommend you dont gut the regulator. It keeps the fuel pressure steady even when voltage changes (turn on fans, lights, a winch, etc). The PCM can't adjust based on fuel pressure effected by voltage. It can only adjust injector pulse width to compensate for voltage change. But it will want a constant pressure no matter what.
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Wait, are you talking about the 6.0's stock regulator or the XJ's? The XJ regulator keeps pressure to, give or take, 49 PSI. The 6.0, from the factory, takes 58-59 PSI. You may be able to run the 6.0 with 49 psi at the rail but that does not mean you should do so.
 
Keep the XJ regulator. Swap the fuel rail on the 6.0 to a late model non return style. 49 psi is fine as long as its compensated for in the tune. The only issue I could see is maybe not enough fuel injector to compensate. In which case you could swap to 8.1 marine injectors. I really dont see that being an issue though IMHO. I didn't have to change anything on the LS2 XJ other than the tuning in the computer and it was fine... And it makes a lot more power than your LQ4.

No matter what you do you have to have some type of regulator, whether its the stock XJ one on the tank, the stock truck one on the fuel rail, or a corvette fuel filter. But in either of those last 2 cases you'll need to add a fuel return to the tank. The return needs to go almost all the way to the bottom of the fuel bowl. Do not let it free fall as this will airiate the fuel and cause the engine to run lean when the tank is low.

If you run the XJ regulator or the corvette regulator you'll need to swap fuel rails & change it in the engine's tune. If you run the LQ4's regulator you only need to add the return line. But dont let it free fall into the tank.
 
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Team Willys said:
Keep the XJ regulator. Swap the fuel rail on the 6.0 to a late model non return style. 49 psi is fine as long as its compensated for in the tune. The only issue I could see is maybe not enough fuel injector to compensate. In which case you could swap to 8.1 marine injectors. I really dont see that being an issue though IMHO. I didn't have to change anything on the LS2 XJ other than the tuning in the computer and it was fine... And it makes a lot more power than your LQ4.

No matter what you do you have to have some type of regulator, whether its the stock XJ one on the tank, the stock truck one on the fuel rail, or a corvette fuel filter. But in either of those last 2 cases you'll need to add a fuel return to the tank. The return needs to go almost all the way to the bottom of the fuel bowl. Do not let it free fall as this will airiate the fuel and cause the engine to run lean when the tank is low.

If you run the XJ regulator or the corvette regulator you'll need to swap fuel rails & change it in the engine's tune. If you run the LQ4's regulator you only need to add the return line. But dont let it free fall into the tank.
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Thank you for the info. I definitely don't want to replace the fuel rail and injectors. It would cost me more than I'm trying to save. Plus I don't feel comfortable running 49 psi. I know the LS2 makes 400hp/400'lbs, and the LQ4 is 300/360, I think the best way to do this is to bypass the Jeep regulator, use the LQ4 regulator and run a return line. Good info on running the return to the lower part of the tank! I don't think I would have thought about that.
 
Interesting to know that you can compensate for a decreased rail pressure in the tune. Myself I'd stick with higher pressure.
Also - interesting point about not aerating the fuel as it drops through the tank. I'd think a 90' 5/16 brass elbow would do it. Drill 9/32 hole in the top of the fuel pump, apply heat gun, shove barbed elbow through until you can get a fuel hose onto the bottom.
It's modifying stock parts to fit, which I like to avoid when possible to make future service easier, but in my view it's preferable to tuning, swapping rails, or swapping injectors. I mean, if it was my Jeep...
 
The Jeep harness is complete! I know it doesn't look like much but this was a huge job. The only part of the harness that shows in the bay is where the harness splits to go to the fender and up to the wiper motor. The Jeep PCM and fuse box is mounted under the rear seat. The battery will be in a battery box in the back. I also installed the Jeep oil presser and water temp sensors.







 
Cool! I bet that's really clean.

I'm not trying to say any one way is better than another. There's always a number of ways to skin a cat & often times more than one way is the "correct way". I'm simply just stating the options & pros & con's of each. I have a ton of experience with LS swaps, their tuning requirements, & their capabilities. I wouldnt let a tuning issue keep you from doing something you want to do because realistically you're gonna need a custom tune anyway.
 
Team Willys said:
Cool! I bet that's really clean.

I'm not trying to say any one way is better than another. There's always a number of ways to skin a cat & often times more than one way is the "correct way". I'm simply just stating the options & pros & con's of each. I have a ton of experience with LS swaps, their tuning requirements, & their capabilities. I wouldnt let a tuning issue keep you from doing something you want to do because realistically you're gonna need a custom tune anyway.
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I totally understand and appreciate your input. This is my first LS swap and need the help from the veterans of the swaps like yourself. I may not use everyone's input, but I will use the info everyone gives me to make my own mistakes/successes.
 
Doing it again, I would bolt the engine / trans together & get all my sensors, coils, injectors etc in place. Put it on the ground or wherever works so you can reach everything.
Attach the harness - plug everything in - and drape the wiring how you want it.
One pin (or if you must, one circuit) at a time, delete the wires you don't need.
I chopped a GM harness down on the living room floor of a tiny apartment in Berkeley over the course of 4 or 5 evening sessions. At times I'd get lost, put a wire back in a different bundle than it started, forget which pin was which, etc. That is pretty much the opposite of what you want to do.
it's like track driving. If it looks slow, it's probably fast. Taking your time will get it done faster.
I promise I'll stop preaching about the virtues of patience now. Just eager to save somebody else my mistakes is all.
 
John D said:
I laid out a piece of cardboard and drew the engine/trans including sensor locations in the engine bay. Then I followed the instructions on lt1swap.com. Everything fit perfect and no mistakes. It's a pretty easy part of the swap.
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Thats a great idea. Thank you.
 
yossarian19 said:
The Cherokee fuel pump, once you gut it's internal regulator, should support the 6.0. Probably not if you add heads or a cam, but IIRC it does have the pressure / volume capacity for a stock Vortec motor.
So now your main problem is how to get return fuel to the tank.
You can use a 2002 Silverado fuel filter or a 2002 Camaro LS1 fuel filter, either one works, and use your engine's fuel pressure regulator that came on the rail.
If you can make the return line happen, I think you are good to go.
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Team Willys said:
Get a late model (04 and newer I think) fuel rail. Its reyurnless. You can then just hook the factory jeep fuel line up to the LS engine. You DO NOT need to gut the stock regulator. That can be fixed in the tune. Actually I would highly recommend you dont gut the regulator. It keeps the fuel pressure steady even when voltage changes (turn on fans, lights, a winch, etc). The PCM can't adjust based on fuel pressure effected by voltage. It can only adjust injector pulse width to compensate for voltage change. But it will want a constant pressure no matter what.
Click to expand...

IIRC the fuel pressure regulator on a 97-01 is part of the check valve assembly on the top of the pump assembly. If it'll run fine at 49psi with a tune, which I completely believe Team Willys on, you should be fine. Also, I'm 99.9% sure (can check the parts catalog if anyone wants, but I'm not bothering unless I am asked) that the same exact pump assembly, or at least a very very closely related one with different assembly heights and the same pump/regulator/electronics, is used in the 97-01 XJ, as well as the TJ, Dakota, Durango, and Ram series trucks. I have the tank out of a 94 Ram 2500 I tore apart for its 5.9/nv4500 in my basement and the fuel pump assembly on it also looks exactly the same. If it'll feed 5.9s in workhorse pickups towing trailers, it'll feed a 6.0 in a jeep.
 
I got the GM harness all striped and removed all of the unnecessary wires. Now I'm rerouting all of the wires and trimming or extending every wire.









 
Looking good.
I just started doing the same thing on my '57. Fun, isn't it?
 
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