[parbreak]

Are the crossover (S shaped) line that feeds the 2 injector rails and the high pressure pipe coming out of the HPFP that feeds the crossover, ONE time use lines? I am installing a LT4 HPFP and LT4 injectors soon and have been hearing some conflicting info. If I need to replace those, that's fine, but if not needed I really don't want to.


Also, if needed does anyone have the part #'s for those two lines that would be needed when upgrading to LT4 fuel system?

[TJay74]

Originally Posted by parbreak

Are the crossover (S shaped) line that feeds the 2 injector rails and the high pressure pipe coming out of the HPFP that feeds the crossover, ONE time use lines? I am installing a LT4 HPFP and LT4 injectors soon and have been hearing some conflicting info. If I need to replace those, that's fine, but if not needed I really don't want to.


Also, if needed does anyone have the part #'s for those two lines that would be needed when upgrading to LT4 fuel system?

Do they have to be replaced, not really. The GM tech document states to replace them but many have re-used them with no issues including myself.

If I was putting the LT4 HPFP and injectors in I would go ahead and replace the LT1 lines with the LT4 lines. The LT1 low side line that goes into the HPFP has a restriction orifice built into it, the LT4 version does not. Also both of the cross over lines that go from the HPFP to the fuel rail distribution block have very tight bends in them, GM revised the LT4 versions to reduce the radius on the bends to help with flow.

So if it was me I would replace all 3 of the lines with the LT4 versions.

[KingLT1]

We tried re-using them and ended up having a leak and had to replace them. That is how my luck works.

[Eldi Z]

Originally Posted by TJay74

Do they have to be replaced, not really. The GM tech document states to replace them but many have re-used them with no issues including myself.

If I was putting the LT4 HPFP and injectors in I would go ahead and replace the LT1 lines with the LT4 lines. The LT1 low side line that goes into the HPFP has a restriction orifice built into it, the LT4 version does not. Also both of the cross over lines that go from the HPFP to the fuel rail distribution block have very tight bends in them, GM revised the LT4 versions to reduce the radius on the bends to help with flow.

So if it was me I would replace all 3 of the lines with the LT4 versions.

Can you post the Part#s of the 3 LT4 lines?

[Shocker91]

parbreak here are the two part numbers for the LT4 HPFP feed line and HPFP to rail pipes.
#12677005
#12663577

[TJay74]

Originally Posted by Eldi Z

Can you post the Part#s of the 3 LT4 lines?

Sorry, I dont have them. I just walked into my dealer and told them what I wanted.

[parbreak]

Originally Posted by Shocker91

parbreak here are the two part numbers for the LT4 HPFP feed line and HPFP to rail pipes.
#12677005
#12663577

Thanks!

[cmitchell17]

When I took my fuel injectors out, I took the rails, injectors, pipes, and pump all attached as one together. It came out fine it was just a little tight since the injectors were trying to bend outwards.

So now I don't have to worry about buying news lines, I haven't finished putting everything back together yet so we will see if taking it all out as one causes any problems. I don't see how it could.

[TJay74]

Originally Posted by cmitchell17

When I took my fuel injectors out, I took the rails, injectors, pipes, and pump all attached as one together. It came out fine it was just a little tight since the injectors were trying to bend outwards.

So now I don't have to worry about buying news lines, I haven't finished putting everything back together yet so we will see if taking it all out as one causes any problems. I don't see how it could.

What are you doing that makes for the need of the LT4 HPFP and injectors? If it is anything the need as much fuel as possible then you need to replace the LT1 fuel lines with the LT4.

I mean unless you are purposely wanting to restrict flow and only get part of the power potential from the $1500 of LT4 you just put on the engine.

[parbreak]

I decided to replace all 3 pipes: low pressure inlet, high pressure outlet and crossover. For a few $ it's worth the peace of mind. Not just for the extra flow, but to reduce any chance of leaks from reusing these "one time use" fittings.

[cmitchell17]

Originally Posted by TJay74

What are you doing that makes for the need of the LT4 HPFP and injectors? If it is anything the need as much fuel as possible then you need to replace the LT1 fuel lines with the LT4.

I mean unless you are purposely wanting to restrict flow and only get part of the power potential from the $1500 of LT4 you just put on the engine.

I'm not upgrading to the LT4 pump, I am just putting in a cam with a 33% fuel lobe, DOD and VVT delete, lifters, pushrods, and springs.

I am just hoping I didn't unknowingly damage anything by pulling everything together, I don't see how it would damage anything, its just a little tight when you go to pull the injectors out the tips rub against the head a little but nothing major. Although I haven't put everything back together yet so they may not go back in as one piece and I may end up having to take the lines apart anyway.

[adnan92]

Originally Posted by cmitchell17

When I took my fuel injectors out, I took the rails, injectors, pipes, and pump all attached as one together. It came out fine it was just a little tight since the injectors were trying to bend outwards.

So now I don't have to worry about buying news lines, I haven't finished putting everything back together yet so we will see if taking it all out as one causes any problems. I don't see how it could.

For how much the S pipe and HP line cost you?

[Choda]

i reused mine

[Ajs16400]

Isnt 12663577 the line that comes with all the supercharger kits?