Upgrade pump or nozzles

[Yngdmax92]

Here we go guys.

Big tune on my truck is dropping rail off to 25000 when commanding for 27-28k.
Lbz with 3794 stg2, the fuel system is stock. Should I upgrade the pump or do some injectors first and if so what size?

 

[JoshH]

I would do injectors before I did a CP3 unless your CP3 is bad. Size depends on horsepower goal.

 

[Chevy1925]

how much pulse width?

im with josh

 

[ZeroGravity58]

When I had my big tune on my lb7 it would drain the rail with stock injectors. I upgraded to 50 overs with the same cp3 and the truck picked up 4 tenths in the quarter. So unless the cp3 was bad I'd do injectors first.

 

[Yngdmax92]

3150us

I was leaning that way too. I'd like to keep this lbz alive as long as possible, we will see. So go with 45 or 60 overs??

 

[Dozerboy]

Injector would be your wise choice. Do you want more power or just take some stress off the engine? Is 3150us your daily tune? Bigger cp3 could do both if your not holding rail on your daily tune. That way you could run less PW and make same/more power because you have more pressure.

Size injectors depends on you end HP goal. 60 overs are going to limit you if you twin your truck down the road, but I don’t know you can do 100overs with a stock cp3.


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[gmduramax]

80% injectors at minimum before pump.

 

[Yngdmax92]

3150 is my race tune. I'm looking to take less stress off the engine. I figure staying with a stock cp3 will keep my engine alive the longest as well.

I thought if I got larger nozzles, I could cut the duration a bit and on the back side of things bring back up the psi in the rail.

 

[Yngdmax92]

What size can you go up to, before you have to send them out and get them balanced and flow rated?

Could you just buy some 60 overs and swap them out for stock ?

 

[Brent@LDS]

What size can you go up to, before you have to send them out and get them balanced and flow rated?

Could you just buy some 60 overs and swap them out for stock ?

It's a good idea to have any oversized injector tested/balanced. We test, calibrate, and balance all our injectors here within less than 4%. Let me know if I can help you out or get you pricing.

 

[Yngdmax92]

It's a good idea to have any oversized injector tested/balanced. We test, calibrate, and balance all our injectors here within less than 4%. Let me know if I can help you out or get you pricing.

Pm me a price for 45% overs and 60% overs plz

 

[Yngdmax92]

Just thinking fellas,

You think I should try a rail plug before I go ahead and buy a pump, it'll hold 2800us, once you command for more it dies off to 24-25k psi. It's completely stock fuel system lbz with airdog 165.

 

[clrussell]

Just thinking fellas,

You think I should try a rail plug before I go ahead and buy a pump, it'll hold 2800us, once you command for more it dies off to 24-25k psi. It's completely stock fuel system lbz with airdog 165.

Yeah it’s worth $40 and I think everyone needs one to prevent issues later on. I’ve replaced a lot of failed plugs

 

[Yngdmax92]

I'm on It! Any preferred brand?

 

[onebaddmaxxx]

if your rail plug was popping open youd be in the 11-13k psi range though until you let off the throttle.

 

[clrussell]

if your rail plug was popping open youd be in the 11-13k psi range though until you let off the throttle.

I always wondered if there was a better range for them when they open.

 

[Chevy1925]

Do the bottle test. Pull the little hoop rubber hose in front of the fprv, put a longer hose on the rail side and plug the return side. Put the long hose in a gal jug and tuck under the hood somewhere. Go drive it hard on the big tune and see if there is any fuel in that jug afterward. If there is, put a plug in or shim the fprv. If there isn’t any, that’s not your issue

 

[gmduramax]

Just throw a plug in and make sure it isn’t leaking. I would hate to lose a race because the FPRV decides to pop open. You also want to keep your pulse width close to stock.

 

[paint94979]

Ah depends on your goals and location. I ran and still do run stock injectors with a modded pump. 3300pw, 75mm turbo and Modified LLY pump. 700hp and 11.8 1/4 mile ET. Plenty of ways to get it done.

 

[Yngdmax92]

Do the bottle test. Pull the little hoop rubber hose in front of the fprv, put a longer hose on the rail side and plug the return side. Put the long hose in a gal jug and tuck under the hood somewhere. Go drive it hard on the big tune and see if there is any fuel in that jug afterward. If there is, put a plug in or shim the fprv. If there isn’t any, that’s not your issue

Good thinking, I'll report back when I get it done.