Fuel Starvation
Thread Starter
Racer
Joined: Sep 2006
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From: Houston TX
Fuel Starvation
I think my engine is starving for fuel when hammering down on the gas pedal. I'm still using stock injectors, but have a LSX455 (535rwhp/567rwtq) under the hood. What size are the 07' C6 stock injectors? What size should I be using? My understanding is the fuel pump produces roughly 58lbs of pressure so going with 42lb injectors would make them equal to 51lb injectors. I'm confused and I haven't found the answers via search feature included on the forum.
Pro
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From: LZ IL
Thread Starter
Racer
Joined: Sep 2006
Posts: 309
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From: Houston TX
Thread Starter
Racer
Joined: Sep 2006
Posts: 309
Likes: 0
From: Houston TX
I'm not looking for someone to post up links of those sites where you put in approx hp and it shoots out a basic fuel injector size. From my understanding, our fuel pumps have x amount of constant pressure, so we have to compensate for that in order to get the correct injector. With that in mind, it seems like we might be able to get away with smaller injectors based on the constant fuel pressure from the pump.
I hope I'm making sense (lol) because I'm on the brink of confusing the hell out of my own self - ssshhhhh.
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
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First, I believe that 58PSI for the fuel pressure is the stock amount.
I don't think we have rising rate fuel regulators in the cars so the fuel pressure will fall as you go higher in RPMs while at WOT.
Putting higher fuel injectors would be helpful if you had more pressure to sustain them. That would mean that you would need a higher volume pump. Something like a Walbro 255 or the like.
Even with higher FIs, you need to keep the pressure level and that would take a different fuel pressure regulator or a boosta pump to run the pump at a higher volume.
What I'm trying to say is with your HP, you need a fuel system not just larger fuel injectors.
My $.02
Elmer
I don't think we have rising rate fuel regulators in the cars so the fuel pressure will fall as you go higher in RPMs while at WOT.
Putting higher fuel injectors would be helpful if you had more pressure to sustain them. That would mean that you would need a higher volume pump. Something like a Walbro 255 or the like.
Even with higher FIs, you need to keep the pressure level and that would take a different fuel pressure regulator or a boosta pump to run the pump at a higher volume.
What I'm trying to say is with your HP, you need a fuel system not just larger fuel injectors.
My $.02
Elmer
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
Scroll down on this and plug in your numbers to determine Injector size:
http://www.rceng.com/technical.aspx#...Injector_Size_
Remember it asking for BHP, not RWHP. I believe that BHP would be higher than your 535 RWHP. I used 600 as the number and 42 Pounds would work. I'd personally just get the 60s and allow for growth in the future.
Elmer
http://www.rceng.com/technical.aspx#...Injector_Size_
Remember it asking for BHP, not RWHP. I believe that BHP would be higher than your 535 RWHP. I used 600 as the number and 42 Pounds would work. I'd personally just get the 60s and allow for growth in the future.
Elmer
Last edited by eboggs_jkvl; May 23, 2009 at 05:40 PM.
Melting Slicks
Joined: Jul 2008
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St. Jude Donor '09-'10
First, I believe that 58PSI for the fuel pressure is the stock amount.
I don't think we have rising rate fuel regulators in the cars so the fuel pressure will fall as you go higher in RPMs while at WOT.
Putting higher fuel injectors would be helpful if you had more pressure to sustain them. That would mean that you would need a higher volume pump. Something like a Walbro 255 or the like.
Even with higher FIs, you need to keep the pressure level and that would take a different fuel pressure regulator or a boosta pump to run the pump at a higher volume.
What I'm trying to say is with your HP, you need a fuel system not just larger fuel injectors.
My $.02
Elmer
I don't think we have rising rate fuel regulators in the cars so the fuel pressure will fall as you go higher in RPMs while at WOT.
Putting higher fuel injectors would be helpful if you had more pressure to sustain them. That would mean that you would need a higher volume pump. Something like a Walbro 255 or the like.
Even with higher FIs, you need to keep the pressure level and that would take a different fuel pressure regulator or a boosta pump to run the pump at a higher volume.
What I'm trying to say is with your HP, you need a fuel system not just larger fuel injectors.
My $.02
Elmer
I agree as most would with FI. I run 700hp and look for 60-65 psi at ALL times. Be Careful! You may want to consult with a reputable shop on this one - you will need a boostapump.
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Thread Starter
Racer
Joined: Sep 2006
Posts: 309
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From: Houston TX
Scroll down on this and plug in your numbers to determine Injector size:
http://www.rceng.com/technical.aspx#...Injector_Size_
Remember it asking for BHP, not RWHP. I believe that BHP would be higher than your 535 RWHP. I used 600 as the number and 42 Pounds would work. I'd personally just get the 60s and allow for growth in the future.
Elmer
http://www.rceng.com/technical.aspx#...Injector_Size_
Remember it asking for BHP, not RWHP. I believe that BHP would be higher than your 535 RWHP. I used 600 as the number and 42 Pounds would work. I'd personally just get the 60s and allow for growth in the future.
Elmer
Am I getting close or on the right track? System fuel pressure seems to be a key factor to ensure correct injector size. Any thoughts?
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
I used 58 PSI at the fuel rail, 600 BHP, .50 for NA, not .65 Forced Induction, 8 injectors, and 80% injector limit. The OP doesn't mention SC or turbo. Nothing but a big cam.
Those numbers give 40.59 for injector size.
I show 52.77 injectors when I go to turbo "needs" and .65 in the brake specific fuel consumption box.
You should enter your fuel rail pressure. You surely don't run 43.5 do you?
My old Camaro had 550 to the wheels. I ran an Aeromotive 1000 pump, a rising rate fuel pressure regulator that raised the fuel pressure 1 PSI for each pound of boost. I started at 58 and topped out at 70 PSI fuel pressure at full boost of 12 on the car. My fuel injectors were 60 pounders and I had -10 AN fuel lines to the rail with -8 lines on the return. I had a jump switch on the fuel pump that raised the pump voltage under boost and gave the higher volume to the engine. If you're blown, do it right or pray often!
Elmer
Those numbers give 40.59 for injector size.
I show 52.77 injectors when I go to turbo "needs" and .65 in the brake specific fuel consumption box.
You should enter your fuel rail pressure. You surely don't run 43.5 do you?
My old Camaro had 550 to the wheels. I ran an Aeromotive 1000 pump, a rising rate fuel pressure regulator that raised the fuel pressure 1 PSI for each pound of boost. I started at 58 and topped out at 70 PSI fuel pressure at full boost of 12 on the car. My fuel injectors were 60 pounders and I had -10 AN fuel lines to the rail with -8 lines on the return. I had a jump switch on the fuel pump that raised the pump voltage under boost and gave the higher volume to the engine. If you're blown, do it right or pray often!
Elmer
Last edited by eboggs_jkvl; May 23, 2009 at 06:51 PM.
Thread Starter
Racer
Joined: Sep 2006
Posts: 309
Likes: 0
From: Houston TX
I used 58 PSI at the fuel rail, 600 BHP, .50 for NA, not .65 Forced Induction, 8 injectors, and 80% injector limit. The OP doesn't mention SC or turbo. Nothing but a big cam.
Those numbers give 40.59 for injector size.
I show 52.77 injectors when I go to turbo "needs" and .65 in the brake specific fuel consumption box.
You should enter your fuel rail pressure. You surely don't run 43.5 do you?
My old Camaro had 550 to the wheels. I ran an Aeromotive 1000 pump, a rising rate fuel pressure regulator that raised the fuel pressure 1 PSI for each pound of boost. I started at 58 and topped out at 70 PSI fuel pressure at full boost of 12 on the car. My fuel injectors were 60 pounders and I had -10 AN fuel lines to the rail with -8 lines on the return. I had a jump switch on the fuel pump that raised the pump voltage under boost and gave the higher volume to the engine. If you're blown, do it right or pray often!
Elmer
Those numbers give 40.59 for injector size.
I show 52.77 injectors when I go to turbo "needs" and .65 in the brake specific fuel consumption box.
You should enter your fuel rail pressure. You surely don't run 43.5 do you?
My old Camaro had 550 to the wheels. I ran an Aeromotive 1000 pump, a rising rate fuel pressure regulator that raised the fuel pressure 1 PSI for each pound of boost. I started at 58 and topped out at 70 PSI fuel pressure at full boost of 12 on the car. My fuel injectors were 60 pounders and I had -10 AN fuel lines to the rail with -8 lines on the return. I had a jump switch on the fuel pump that raised the pump voltage under boost and gave the higher volume to the engine. If you're blown, do it right or pray often!
Elmer
At any rate, I entered my fuel pressure as both 43.5 and 58. While I'm still green with the idea of how system pressures work, 58 seems to be the comfortable variable for me. 58 is only based on what I've been told. BTW, is 58 what you typically would use for your vehicle prior to FI? Honestly, I'm not even sure 58 is my system fuel pressure. I'm only taking it for granted because I know no different, nor found anything which says otherwise. Presently, I'm under the assumption all stock C6 LS2 fuel systems should have the same pressure. Since mine hasn't been altered, I can only assume I'm still under stock pressure.
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
Yes 58 is what you get out of the box. The only reason my rig was complicated was the Forced Induction. You're cam is giving you a lot of HP and you need more gas. Do you have the ability to get the car hooked up to a wide band O2 sensor and some tuning software? Do you know how bad your fuel starvation is? I'd guess that you are having issues with fuel injector size and fuel pressure both. You can't work on this by just getting bigger injectors. The bigger injectors will require you to have a tuner reset your injector flow rate in the ECM to reflect the bigger injectors. This is not as easy as adding big injectors and saying, fixed.
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
Here is a film of the fuel system on the Camaro.
http://www.ls2.com/boggs/98tank/ETANK.wmv
It is a large file so be patient. Windows Media Player will play it.
http://www.ls2.com/boggs/98tank/ETANK.wmv
It is a large file so be patient. Windows Media Player will play it.
Thread Starter
Racer
Joined: Sep 2006
Posts: 309
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From: Houston TX
At the moment, I'm not certain as to how bad the starvation is. Right now, I'm assuming max duty cycle on the injectors has been reached based on the power output from the motor. The only symptoms I've seen have been a lag in response from when I mash the petal to when the car actually catches up with whats happening. Once it does catch up, then I can feel the loss of traction - two very distinct feelings. So in essence, I have two issues I'm working to resolve. Fuel & traction.
After running the numbers through the formula you had given, what I noticed was with a bigger fuel pump (assuming system pressure goes up with the bigger pump), you can get a way with smaller injectors. Just as bigger injectors can compensate for a smaller pump - up to a certain point of course. This is only based on raising and lowering the fuel pressure within the forumla.
It doesn't seem like the whole fuel system needs a revamp. I'm wondering if slightly bigger injectors (44lbs) and a fresh retune will solve the problem. What do you think?
Thread Starter
Racer
Joined: Sep 2006
Posts: 309
Likes: 0
From: Houston TX
Here is a film of the fuel system on the Camaro.
http://www.ls2.com/boggs/98tank/ETANK.wmv
It is a large file so be patient. Windows Media Player will play it.
http://www.ls2.com/boggs/98tank/ETANK.wmv
It is a large file so be patient. Windows Media Player will play it.
I like the setup on your Camaro. If only the fuel pump was as accessible on the C6 as you have there. From the looks of it, you had a custom made tank, no?
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
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Yes, the tank is a "Rick's" custom stainless tank. It has the Aeromotive 1000 pump submerged in it. The C6 pump in the tank tank is seriously nasty to get at. Usually the Forced Induction forum has more "fuel" related information. They will explode if they lose fuel so they take extra precautions to "hold" pressure in the fuel and often, as in the Camaro, actually raise fuel pressure. I'd fumble around in that forum and talk fuel stuff with them.
Elmer
