Stock Fuel Pump Limits
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Tuned
Joined: Apr 2003
Posts: 351
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From: Davis County, UT
Stock Fuel Pump Limits
Any one with knowledge on a 460 EFI setup know with the stock fuel pump(s) what max horsepower they are capable of?
I am contemplating upgrading to 30 or 32 lb injectors. I have added a few external mods and am getting close to being ready to take it to my local dyno tuner to have the ECM reflashed and calibrated. I have a MAF system. I don't have the luxury of having any cheap tuners around me, they charge $400+ for each dyno/calibration appointment. So I want to make the first one count.
I really don't want to upgrade the fuel pumps, so if the stock pumps can supply 30 or 32 lb injectors I will do it. If any one know's please respond - thanks!
I am contemplating upgrading to 30 or 32 lb injectors. I have added a few external mods and am getting close to being ready to take it to my local dyno tuner to have the ECM reflashed and calibrated. I have a MAF system. I don't have the luxury of having any cheap tuners around me, they charge $400+ for each dyno/calibration appointment. So I want to make the first one count.
I really don't want to upgrade the fuel pumps, so if the stock pumps can supply 30 or 32 lb injectors I will do it. If any one know's please respond - thanks!
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Unless the motor moves a lot more air than stock you're wasting your time and money with bigger injectors, the stock 24/s will support 300hp at 80% duty cycle, 325hp at 85%, etc. If your motor is up past that mark I sugget you simply get a MAF meter that is "calibrated" for 30lb injectors, there's a pretty good chance the dyno tuner will do the exact same thing as what the meter does... i.e. tweak the MAF curve.
As for the fuel pumps they won't support the full capacity of 30lb injectors, that will require at least 155l/hr pumps. Stock is around 110l/hr.
As for the fuel pumps they won't support the full capacity of 30lb injectors, that will require at least 155l/hr pumps. Stock is around 110l/hr.
Thread Starter
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Tuned
Joined: Apr 2003
Posts: 351
Likes: 1
From: Davis County, UT
Unless the motor moves a lot more air than stock you're wasting your time and money with bigger injectors, the stock 24/s will support 300hp at 80% duty cycle, 325hp at 85%, etc. If your motor is up past that mark I sugget you simply get a MAF meter that is "calibrated" for 30lb injectors, there's a pretty good chance the dyno tuner will do the exact same thing as what the meter does... i.e. tweak the MAF curve.
As for the fuel pumps they won't support the full capacity of 30lb injectors, that will require at least 155l/hr pumps. Stock is around 110l/hr.
As for the fuel pumps they won't support the full capacity of 30lb injectors, that will require at least 155l/hr pumps. Stock is around 110l/hr.
I just don't want to get to the tuner and he says after the dyno, something like "now all you need is 30-32 lb injectors and we can get you X-more horespower". I don't want to hear that after forking out $400 bones. So to hear that my stock fuel pump won't support any bigger injectors is frustrating but reality.
Thread Starter
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Tuned
Joined: Apr 2003
Posts: 351
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From: Davis County, UT
Anyone seen any vendors offering hi-performance fuel pumps? I would like to upsize my injectors and will need to reflash the ECM upon completion. Checked around and only finding stockers for F-series.
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
I suggest you invest your money in an electric fuel pressure gauge and a wideband O2 sensor. With those things you will be able to determine with certainty if you have enough fuel pump and injector capacity. The diagnosos is simple..
If fuel pressure drops at rpms you don't have enough pump.
If pressure stays solid and A/F ratio goes lean at rpm you need bigger injectors.
If pressure stays solid and A/F stays rich(12.5-13.5:1) then you don't need either.
If fuel pressure drops at rpms you don't have enough pump.
If pressure stays solid and A/F ratio goes lean at rpm you need bigger injectors.
If pressure stays solid and A/F stays rich(12.5-13.5:1) then you don't need either.
Posting Guru
Joined: Dec 2008
Posts: 1,226
Likes: 5
From: Rusty, Maine
I suggest you invest your money in an electric fuel pressure gauge and a wideband O2 sensor. With those things you will be able to determine with certainty if you have enough fuel pump and injector capacity. The diagnosos is simple..
If fuel pressure drops at rpms you don't have enough pump.
If pressure stays solid and A/F ratio goes lean at rpm you need bigger injectors.
If pressure stays solid and A/F stays rich(12.5-13.5:1) then you don't need either.
If fuel pressure drops at rpms you don't have enough pump.
If pressure stays solid and A/F ratio goes lean at rpm you need bigger injectors.
If pressure stays solid and A/F stays rich(12.5-13.5:1) then you don't need either.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Here's a calculator for fuel pump and injector sizing... Autolounge.net | Calculators | Fuel Injector and Pump Sizing
All the default values are good so just insert the HP number you want and you'll see what it requires. I think it will take more than a free flowing intake and exhaust to exceed 300hp with an otherwise stock 460, and the computer will push the injectors all the way to 100% if it needs to so the pump will be the first limitation you run into. You can also extend the capacity of the injectors by increasing the fuel pressure.
All the default values are good so just insert the HP number you want and you'll see what it requires. I think it will take more than a free flowing intake and exhaust to exceed 300hp with an otherwise stock 460, and the computer will push the injectors all the way to 100% if it needs to so the pump will be the first limitation you run into. You can also extend the capacity of the injectors by increasing the fuel pressure.
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Postmaster
Joined: Jan 2009
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X 2 on the fuel pressure gauge & wideband , its not how big the injectors are its how much air & fuel your pushing thru the motor...Lew
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From: Longview Tx
You definetly need a O2 wide band and to moniter your fuel pressure. I didn't see that you had any internal engine work done that would require more fuel. I'm not sure exactly what the stock fuel pumps can support or what they flow exactly. But with my mods i am running the stock fuel pumps and 36# injectors they are a tad to much but they where free and i just toned them down with my programmer. I would say your are pretty safe still with the 24# injectors they are probably working at about 80-85% duty a WOT. Lets see those dyno #'s
Thread Starter
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Tuned
Joined: Apr 2003
Posts: 351
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From: Davis County, UT
That Autolounge Calculator is awesome - thanks for sharing.
I would be satisfied at 350 horse. Would like to get to 375 though. I have an adjustable fuel pressure regulator now. I only have it set at 34psi. Not sure how much I can really turn it up without having issues. If the stock pumps flow 110 gph then it will support up to the horsepower goal with a tweek of the fuel pressure reg. It will support 350 horse at 34 psi on 24lb injectors per the calculator at 80% duty cycle.
With the necessary internal engine mods, 375 horse looks like it is doable at 35 psi but would require bigger injectors. No chance of ever pushing more horse without bigger fuel pumps.
Still need a good dyno/calibration re-flash. Have not done that investment yet because not sure what to do long term with this powertrain. Getting really tired of watching the diesels pass me up on 6-7% grades. Thinking about overhaulling the 460 with some good internal upgrades or doing a 12-Valve 6BT Cummins Conversion. Not sure where to go, I can buy a lot of gas for the price of the Cummins swap.
I would be satisfied at 350 horse. Would like to get to 375 though. I have an adjustable fuel pressure regulator now. I only have it set at 34psi. Not sure how much I can really turn it up without having issues. If the stock pumps flow 110 gph then it will support up to the horsepower goal with a tweek of the fuel pressure reg. It will support 350 horse at 34 psi on 24lb injectors per the calculator at 80% duty cycle.
With the necessary internal engine mods, 375 horse looks like it is doable at 35 psi but would require bigger injectors. No chance of ever pushing more horse without bigger fuel pumps.
Still need a good dyno/calibration re-flash. Have not done that investment yet because not sure what to do long term with this powertrain. Getting really tired of watching the diesels pass me up on 6-7% grades. Thinking about overhaulling the 460 with some good internal upgrades or doing a 12-Valve 6BT Cummins Conversion. Not sure where to go, I can buy a lot of gas for the price of the Cummins swap.
Thread Starter
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Tuned
Joined: Apr 2003
Posts: 351
Likes: 1
From: Davis County, UT
"TRUCK ENGINES Engine Mode Engine Application
All Applications
ENGINE RUNNING 30—45 PSI
210—310 kPa
KEY ON, ENGINE OFF 35—45 PSI
240—310 kPa
Note: Maximum fuel pressure is obtainable at WOT or the vacuum hose removed from the fuel pressure regulator".
Conanski, I know I don't completely understand EFI - but my limited understanding led me to believe more pressure = more horsepower, but also worse fuel economy. Thus my conservative pressure at 34 psi engine running. Am I wrong in this thinking? Are you making that adjustment at Engine Off or On?
