# Fuel Injectors



## Poncho Dan (Jun 30, 2009)

Question: At what point do bigger or higher flow fuel injectors become necessary? For instance, after installing a cam, and then doing something to aid induction, like porting (or different) heads? I'm just curious when that would come into play, because I didn't think about it until after I put together a lengthy wishlist...


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## jpalamar (Jul 22, 2008)

I'm using my stock injectors with my cam. NO issues. That is a good question, but I'm sure I won't hit the HP level to ever need to repalce.


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## Rukee (Feb 8, 2007)

I think your alright untill you go to FI then you need bigger injectors and bigger fuel pump.


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## Poncho Dan (Jun 30, 2009)

I probably won't have to worry about it either (my pockets aren't that deep :lol, but I wasn't sure how much room there was for modification with stock injectors, I've seen very little discussion about fuel delivery.


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## 740tank (Mar 23, 2009)

I talked to my budy lee howie he told me to take the lbs per injecter and times by 16. On the 04 ls1 we have 26 lbs injecters good for 416 hp so I also just realized I need bigger ones to thanks for making me look that question up hope this helps


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## jpalamar (Jul 22, 2008)

Dyno Testing The Texas Speed & Performance LS1 Cylinder Head Upgrade - High Performance Pontiac

Search for injector info and found this build. Very good info for everyone.


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## GM4life (Mar 18, 2007)

Poncho Dan said:


> Question: At what point do bigger or higher flow fuel injectors become necessary? For instance, after installing a cam, and then doing something to aid induction, like porting (or different) heads? I'm just curious when that would come into play, because I didn't think about it until after I put together a lengthy wishlist...


There are equasions out there to figure out what size injectors you need. I have them somewhere in one of my books, you can probley find it on the internet. Also during a dyno session you can see what the duty cycle is of the injectors are at WOT. From what I've read in the past you don't want to be above 80-85% injector duty cycle for long periods of time. You can damage the injector and cause the car to run rough.

I _think_, not sure that the 04 GTO came with 28lb injectors and the LS2's came with 32lbs injectors. I've read in certain places the the 28lb'ers are good for 430-450bhp. I think alot of that depends on the engine. When you get anytype of FI they usally come with 42lbs injectors.


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## RLTjock05 (Mar 13, 2010)

Does anyone know where I can find a aftermarket fuel pump kit for my 2005 gto? I am pushing around 530 hp right now and my check engine light is coming on at high rpm's saying the system is lean. I popped out 4 plugs and they are all tan indicating not enough fuel. I hooked up a fuel pressure gauge today and it dropped down to 51 lbs of pressure at 5000 rpm which to my understanding it should never go below 55? I really hope someone has upgraded their fuel pump because I want to drag race this beast soon and am having no luck finding one thats specifically for the car.


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## 740tank (Mar 23, 2009)

Jegs!!!!!! AEROMOTIVE A1000


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## dustyminpin (Jun 19, 2006)

I talked to a rep from FAST/Comp cams and told him the heads/cam setup that I was putting in. As mentioned above, there is a formula they use which tells you roughly how big of an injector you need. With the specs on my cam, and the CNC ported LS3 heads flowing 349 CFM, they told me I needed 46 lbs. injectors. So, 400 bucks later, I have FAST 46 lbs. injectors. I was going to get a bigger fuel pump but they said that wasn't necessary unless I was going with forced induction.


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## GM4life (Mar 18, 2007)

RLTjock05 said:


> Does anyone know where I can find a aftermarket fuel pump kit for my 2005 gto? I am pushing around 530 hp right now and my check engine light is coming on at high rpm's saying the system is lean. I popped out 4 plugs and they are all tan indicating not enough fuel. I hooked up a fuel pressure gauge today and it dropped down to 51 lbs of pressure at 5000 rpm which to my understanding it should never go below 55? I really hope someone has upgraded their fuel pump because I want to drag race this beast soon and am having no luck finding one thats specifically for the car.


Lingenfelter Performance Engineering: Fuel Pumps & Filters


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## Rukee (Feb 8, 2007)

GM4life said:


> Lingenfelter Performance Engineering: Fuel Pumps & Filters


Those Kenne Bell Boost-A-Pump units look cool. Wonder if it burns out the pump quicker?


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## 87GN06GTO07IRL (Aug 10, 2009)

GM4life said:


> From what I've read in the past you don't want to be above 80-85% injector duty cycle for long periods of time. You can damage the injector and cause the car to run rough.


Thats a good rule of thumb. Once you hit 100% idc the injector goes static meaning it stays open and can't control fuel or worse flow enough. At that point you'll be worried about running lean and blowing an engine not about damaging an injector. 

O.p. what are your idc's now? If your in the upper 80's it be a good time to change. Bigger injectors won't give you rough running like people say if you know how to tune. I'm running 60's in my four banger now and will have to switch to 80's soon when i convert to e. Still idles like stock and i'm sure it will too with the 80's


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