LT4 Fuel Injector Compatibility

Tdola · June 17

Does anyone know if these fuel injectors will fit my 2020 Chevy Silverado 1500 with a 5.3 Liter motor?

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Nominal-Flow Multiport Fuel Injector

GM Part # 19420334

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I’m adding a Magnuson 2650 Supercharger (stock bottom end) and want to ensure that I have no fuel issues. The stock injectors are rated at about 24 lbs and these LT4 injectors are rated at about 28 lbs and good for around 800 hp. It’s really just for insurance and probably not needed but I don’t want to leave anything to chance and limit the Tuners options for more “SAFE” power. Also, the dealer said that they didn’t know whether or not they will fit but I’m pretty sure they will fit in the existing OEM injector location as per a few mechanics I spoke to. Thanks in advance.

Edited June 17 by Tdola
More info

silveradosid · June 18

that number is for the 6.2 , 2015 -2023. i would say they would fit. the stock injector is 12720120 which was used in the 5.3 and 6.2 in 2021

newdude · June 18

Yes but I'd be getting the LT4's high pressure fuel pump to match those as well.

Edited June 18 by newdude

Tdola · June 18

1 minute ago, newdude said:

Yes but I'd be getting the LT4's high pressure fuel pump to match those.

What about getting a Boost-a-Pump instead?

newdude · June 18

4 minutes ago, Tdola said:

6 minutes ago, newdude said:

Yes but I'd be getting the LT4's high pressure fuel pump to match those.

What about getting a Boost-a-Pump instead?

That's not gonna help the high pressure pump make more PSI. That looks like it helps the low pressure pump in the tank.

I'm talking the high pressure pump at the engine. If you are running a stock cam, I'm saying switch to the LT4's high pressure fuel pump to match what the injectors put out. LT4 makes much more pressure than the stock pump.

If you are swapping cams, many cams have a more aggressive fuel pump lobe to deliver more fueling that way.

Edited June 18 by newdude

Tdola · June 18

1 minute ago, newdude said:

That's not gonna help the high pressure pump. That looks like it helps the low pressure pump in the tank.

I'm talking the high pressure pump at the engine. If you are running a stock cam, I'm saying switch to the LT4's high pressure fuel pump to match what the injectors put out. LT4 makes much more pressure than the stock pump.

If you are swapping cams, many cams have a more aggressive fuel pump lobe to deliver more fueling that way.

Keeping stock Cam

Gangly · June 18

If you are changing injectors, then you are changing your fuel feed volume, whether you have adjusted your tune or not. Larger injectors will spray more fuel given equal pulse lengths. I would want to make sure that the HPFP feeding those injectors was providing adequate pressure and volume to maintain consistent fuel feeding. If you are going with larger injectors, install the larger fuel pump. Its a relatively easy install, just pull the intake and swap out the pump and stainless steel fuel lines.

Tdola · June 18

2 minutes ago, Gangly said:

If you are changing injectors, then you are changing your fuel feed volume, whether you have adjusted your tune or not. Larger injectors will spray more fuel given equal pulse lengths. I would want to make sure that the HPFP feeding those injectors was providing adequate pressure and volume to maintain consistent fuel feeding. If you are going with larger injectors, install the larger fuel pump. Its a relatively easy install, just pull the intake and swap out the pump and stainless steel fuel lines.

When you say change the Fuel Pump you are referring to the High Pressure Fuel Pump? If so, where is it located? Under the hood? “Pull the Intake” meaning the Intake Manifold?

Gangly · June 18

The HPFP(High Pressure Fuel Pump) is located beneath the intake manifold. You will have to remove the intake manifold to swap out the injectors, so you might as well do the HPFP at the same time since its right there and only 2 bolts.

The HPFP is circled in the image below.

Note: The heads DO NOT have to be removed to access the injectors and the high pressure fuel system, only the intake manifold.

Edited June 18 by Gangly

Tdola · June 18

3 minutes ago, Gangly said:

The HPFP(High Pressure Fuel Pump) is located beneath the intake manifold. You will have to remove the intake manifold to swap out the injectors, so you might as well do the HPFP at the same time.

Ahhh I see. Well the Intake manifold is also coming off for the Magnuson Supercharger too so like you said, now’s the time to do it. Thanks for the advice.

Edited June 18 by Tdola

Gangly · June 18

2 minutes ago, Tdola said:

Ahhh I see. Well the Intake manifold is also coming off for the Magnuson Supercharger too so like you said, now’s the time to do it. Thanks for the advice.

When you are removing the fuel pump, you need to make sure you back out the bolts evenly, meaning do a turn on one bolt, then the other bolt, and so-on and so-on until the pump is free. The same goes for the install as well, one turn on each bolt, then go to the other bolt, and continue until it is properly fastened. Also, you should check the lash on the fuel pump to make sure things don't bind or slap.

Tdola · June 18

7 minutes ago, Gangly said:

When you are removing the fuel pump, you need to make sure you back out the bolts evenly, meaning do a turn on one bolt, then the other bolt, and so-on and so-on until the pump is free. The same goes for the install as well, one turn on each bolt, then go to the other bolt, and continue until it is properly fastened. Also, you should check the lash on the fuel pump to make sure things don't bind or slap.

Did you have a bad experience with the screws and that’s why I need to remove/install it this way?

Gangly · June 18

1 hour ago, Tdola said:

Did you have a bad experience with the screws and that’s why I need to remove/install it this way?

No, that's just the proper procedure according the factory manual....

"Caution: Alternately loosen the fuel pump bolts one turn at a time until the pump is fully disengaged from fuel pump lifter follower. Trying to remove the pump bolts without even side-to-side loosening may result in pump plunger damage."

Tdola · June 18

15 minutes ago, Gangly said:

No, that's just the proper procedure according the factory manual....

"Caution: Alternately loosen the fuel pump bolts one turn at a time until the pump is fully disengaged from fuel pump lifter follower. Trying to remove the pump bolts without even side-to-side loosening may result in pump plunger damage."

Ahhh, ok Great Info. Thank you for that!

Tdola · June 18

Just now, Tdola said:

Ahhh, ok Great Info. Thank you for that!

So all in all, I need to tell the Chevy Dealer Parts Guy, that I need a High Pressure Fuel Pump and a set of eight LT4 Fuel Injectors for a 6.2 Liter Chevy Silverado…correct?