HP Tuners Fuel Tuning Tutorial
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- Опубликовано: 13 июл 2024
- This tuning tutorial explains how to gain extra headroom for free horsepower above and beyond what your stock fuel system would normally allow. This HP Tuners fuel pressure hack circumvents the programmed limitations of the fuel system, allowing you to achieve as much fuel flow as the hardware will allow, usually netting you up to 10% extra capacity that you don't need to pay for.
Works great for turbo setups with programmable waste gates or superchargers with smaller pulleys and of course jets mean you can add as much HP as you want with nitrous so the fuel pump is more often than not, the limiting factor forcing you to buy upgraded parts. If you just want to nudge the power a bit higher than your current setup but have been holding off because the car can't handle it, this guide might be the answer you've been waiting for. 
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If deliveeing same amount of fuel pressure will decrease if flow is increased. It may seem counter intuative, however, fuel delivered can increase as pressure decreases so long as flow increases. Actually makes perfect since. As the injector opens more (duty cycle increases) flow increases so less pressure is needed for a given amount of fuel.
Thanks for sharing this info!
I’m new to hptuner although I’ve not purchased it yet. I have a 5.3 gen 3 factory stock setup in a suv. I’m looking to increase the horsepower to at least something over 325hp. It’s a 2003 suv so I’m not sure what’s still in good shape or needs replaced. I’ve beaten the snot out of it and the engine seems to be solid yet except the exhaust system. Rusty exhaust manifolds with broken bolts. That’s being fixed soon to long tube headers and 3” exhaust. Been watching anything about power increase to the ls engines based on Hptuner tuning. I’m learning slowly but I’m still a bit lost yet. Some people here seems to think extreme changes gives them a hot rod but I’m not looking to blow mine up yet. Hopefully never. I need help is my point. I guess keep watching and reading about this. So much has changed with gm motors. It’s no longer a big cam and a double pumper Holley and a timing issue setup anymore to get a decent amount horsepower. LOL . Maybe some starter points to help me out. Note. My 5.3 sputters or bogs out at a quick attempt to wot at a low speed and rpm. Why?? Heard to raise the afr at cruising but not sure what’s real and what’s a gizmoetric fix. Thanks. You got a sub.
I'm st 842 hp ls3 with a supercharger. I am running a little lean due to injector size. I will be installing 1200 or 1300cc injectors, and running e85. You video is great,for small things that I missed. Thank you. Great video BTW.
those are big ones. Let me know if you have any trouble tuning them
@@ChrisCamaro I put some new ID 1300 injectors in my twin turbo Camaro 5th gen. I’m running rich at 4K rpm at 7lbs of boost. Afr says 8’s I should be in the 11’s how do I make that adjustment in Hp tuner ?
@@Louie88 8 is super rich. Have you already entered the new injector data into HPTuners? You wouldn't want to fiddle with fuel trims if you hadn't already accounted for the new injector size. Because, when you size up, the old duty cycles were longer to give you more fuel from a smaller orifice. Now with a larger orifice, if you don't reduce the duty cycle, you'll get proportionally more fuel for the same duty, which means rich. So you need to enter the manufacturer's data into the injector tables first and then tune your AFRs. Check out my fuel injector swap video for details on how to do that.
@@ChrisCamaro thank you for your reply. Tuner says they need to be scaled. Not sure how to do that. I need a tuner that can do the job frim a-z and not make me wait for E tunes months at end. Any recommendations on a dyno tuner would be so very much appreciated. Thank you from Connecticut
@@Louie88 So basically, it's what I was saying about the duties. Suppose your new injectors are 80 lbs and the old ones were 40 lbs. 80lbs are twice as big as 40lbs so the scale factor is 2x. That means your injector data needs to be cut in half, else you'll be 2x richer. So you just need to determine how much larger your new ones are than your old ones and at least then you have the scale factor to apply to your injector tables. Now in practice it's not that simple, as there are non-linear functions that are unique to each manufacturer. However your car obviously starts and runs so it can't be that far off. Scaling the main tables will at least get you a lot closer to stoich and then you can fine tune from there. Really though the manufacturer should give you all the tables you need. Pretty lame if they don't. HPTuners will give you access to those tables so you don't need anything fancy to do the actual programming.
Thanks Chris. Interestingly, the 2014 ZL1 stock table shows 12.0 up to 32, then goes to 14.5 volts from there on out. Looks like GM had this in mind.
Haha maybe that's Rev 2.0 of the computer eh?
ChrisCamaro Not sure, but I’m glad I saw the adjustment. It means they were looking at other things too. Less for me to worry about.
@@fasnuf Exactly. If I had to guess, with the stock ZL1 pump, I'm thinking you could get up to 750 HP safely on your ZL1. Since the LSA has stronger internals, it'll take it and you can give Dodge a run for its money ;) My SS can't reach those power levels without forged components but I'm happy with a target of 650 anyway.
@@ChrisCamaro I'm running a little over 600 whp and gearing up to add a few more. I think my pump is good for the task. I wonder sometimes about GM. They put cast HE pistons in the LSA to try and keep the engine quieter. I'de rather have forged and not have to work the bottom end when I start to push 800 whp.
@@fasnuf ZL1 has hypereutectic? I assumed the whole rotating assy was forged but must just be the CRs. As long as you maintain a smooth compression profile free of pressure spikes, I think the pistons will last but having the extra insurance with forged is better because you can make mistakes and get away with it.
Fuel pumps are centrifugal pumps. If you look at typical centrifugal pump curve you will see that as flow rate increases pressure goes down. I’m sure gm did this to help get that extra desired flow rate while staying on curve.
I think you are referring to Bernoulli's theory, which, in a closed system, demonstrates the correlation between flow speed, pressure and cross section to conserve mass in an incompressible fluid. However the table in question has to do with commanded pressure or pressure head. I see no reason why reducing the commanded pressure would increase flow. The pump may be more efficient at higher speeds, requiring proportionally less head for a given flow but still, more head means more flow. My hypothesis is that the opposite is true. With compressible flows, such as in turbos, the compressor work goes up exponentially with rpm. While we're not talking about compressible flow, there are viscous losses that go up with speed so if it takes more work to push the fluid at higher speeds, then the tables are telling me that GM doesn't want to blow their pump and to back off the power going to the pump if the flow gets too high, to prevent damage to the pump.
I've read that because the FPCM only goes to 15volts, that adding a JMS boost a pump wont be allowed to go past the 15volts even though the JMS is putting out say 17v. What have you found on this?
Thanks
Well theoretically, the BAP is supposed to bypass the computer altogether and act pretty much as an amplifier, feeding off the car battery so the pump should only see the BAP. In practice it appears not to work 100% of the time but I couldn't tell you why. Maybe some cars have a feedback circuit coming from the pump if it's in an over-volt condition. Best advice (what I would do) is if you decide to go the BAP route, to simply ask the company to verify support for your particular car or better still, upgrade the pump, as then the voltage is a moot point. Both will cost a couple hundred and are really the only options if the stock cheat from this video doesn't get you enough headroom. In my case I have an extra special advantage because electric boost doesn't leech power from the engine so I could get even more HP on stock internals without extra fuel but this is a niche case so for 99% of people you're going to run out of pump around 700 without hardware upgrades.
Thanks for the vid. Would this little trick work on a tiny 2.2l s10? I have an upgraded 340lph fuel pump. TIA
It depends on the car's OS and what menus are exposed by HPT. If they give you access to the same tables as I've shown, and if the pressure doesn't sustain at high RPMs, you can apply the same logic to your car as well. Unfortunately the support for this hack depends on the car and its OS.
@@ChrisCamaro I just got the tuner, I'll have to check again once I get home. I know the parameters seem to be limited. Thanks anyway!
I have 2013 caprice with a supercharger, 80lb injects and zl1 fuel pump. My pressure keeps dropping at high rpm to 45 when I am commanding for 65. I have a zl1 FPCM tune but I don’t know what to insert in to make the Calibration correct
If the tune is stock then it's probably dropping pressure at the high end just as I've shown in the video. Also consider that flow is a product of injector duration x pressure. So with 80 lb injectors you have way more bore than you need and the injectors only need to be on a very short time. If they are open for too long the only way to prevent a rich condition is to have a low fuel pressure so your injector tables may already be doing this compensation. Check the FPCM pressure table though to see if it drops off first. If you are able to write to it with HPT, you can max the entire table out and tune the IPW and VE tables instead to get the fuel you want.
@@ChrisCamaro I am really inexperienced with tuning. I did your method with upping the voltage for the fuel pump and upping maxing pressure tables for the pump.I still had the same result of loss of pressure at high RPMs. I completely understand what you’re saying but I have no idea how to tune it and see what is dropping Off first 😂
@@ChrisCamaro I did do this and made the tables maxed and for some reason it still wants to go down in pressure
@@GoYoteSlaya I see. So these table changes are academic in the sense that they are the "due-diligence" approach to protecting your car. However the proof is in the pudding as they say and what you really need to be careful of is the fuel ratio. Since you're running boost, can I assume you have a wideband O2 gauge? If you have different pulleys then you should revert back to one you know withe certainty has no issues. Do a WOT pull with HPT scanner and check the wideband, IPW and fuel pressure. You may see the pressure drop but so long as your IPW doesn't go static and your wideband isn't lean, you're ok. If you have some headroom with that pulley (say 20%, go down a size and try again. Using this more empirical method, you can interpolate the data to figure out how high you can go on the boost without issues. You will want to stop when either your IPW exceeds 90% duty, your fuel pressure collapses to 0 or your AFR goes up past say 14 (and that this has nothing to do with your VE tune, so you're commanding fuel and not getting it). Just creep up on it and you'll be ok.
@@ChrisCamaro I am good on AFRS now. My wideband goes low 11s at WOT which is what my tuner wants. I understand that it’s a calibration with the computer for pressure to go down as RPMs go up, I’ve tried everything to adjust and keep them from dropping but still keeps going down. I guess I will have to stick with my 5 pounds of boost!
All I have is a diablo i3 and was curious if I add fule pressure will it help. Its a 05 GMC Sierra 1500 5.3 and its a dog down low and SCREAMS up about 4 to 5500 RPM. Or more timing down low? I need help man haha.
If you lack low-end torque but have good power at the top end, it's unlikely that fuel pressure is the problem. Fuel pressure will always drop at max HP, which is usually top end. Down low it won't do anything for you. You'd be better off adding spark, tuning cam phasers (assuming you have them) and adjusting P/E ratio.
@@ChrisCamaro I took the added fule pressure out and added timing but haven't tested it yet. Sorry but what is PE ratio? My truck is a 05 so I don't know if I have that.
@@ChrisCamaro The highest octane in my area is 92 so I use octane boost with about 12 to 15 gallons in my tank. It was my dads truck and is priceless to me and I drive it daily. I just want to wake up the 5.3 LM7. It is weird though because if the streets are wet I can roll at 30 mph, floor it and it will shift exactly how I want and then when im WELL into 3rd at about 4500 to 5000 the tires will break loose. I would expect them to break loose when it shifts but it doesn't, the power comes on so strong at that rpm and they break loose. The truck isn't fast by any means but its odd to me that the top end has enough power to break the tires loose at 45 to 5500 RPM at 70 MPH or more. I would like that same pull on the bottom end. But alas im no tuner and need advice.
@@DM-qp7do Power Enrichment is a factor you define that says how much additional fuel is added under full load or wide open throttle conditions. It is typically a factor like 1.2 or the reciprocal of that 1/1.2 and adjusts the fuel to be rich when you stomp on the gas. There's a whole tab for it in HPTuners. Also covered in my video.
@@DM-qp7do Tuning can only get you so far. Fueling is more of a prerequisite but most power comes from advancing the spark. Most stock cars without physical mods can only tolerate a couple, maybe a few degrees of extra timing and then you're maxed out and getting KR. If you want to reshape your power curve more than a few % points in any area you have to make a physical change. Tuning won't work on a car that's already dialed in for its physical setup.
When the pressure goes up the ammount the pump can flow goes down... i dont fully understand it myself but its facts.. gm lowers the pressure to be able to flow more actual fuel.
You mean like they're trying to keep the Reynold's number of the fuel below the turbulent point or something?
Yep you’re right. If you look at a typical centrifugal pumps curve you’ll see that as pressure decreases that flow rate increases. Gm did this reduction in pressure at high flow rates to help keep the pump on curve.
@@ChrisCamaro Hi Chris This is pretty old now but just found it looking for HPT Fuel Pump info...Did you ever look to see what the pump Duty Cycle was doing? Curious if this Camaro went into a limp mode on injector duty cycle?
@@jcasey460 It's an ongoing investigation. Right now I'm on the brink of getting my electric supercharger working... I mean it's already working but it's not wound correctly so once that's fixed and I'm actually getting 5-6 psi of boost I'll be able to let you know if I hit a ceiling in injector pulse time or fuel pressure.
@@ChrisCamaro Thanks...electric supercharger...wow you must be the first or at least you're the first one I have heard of. That alternator pulls a lot less HP than a supercharger. Keep an eye on the fuel pump duty cycle. I suspect that is the reason for the pump pressures used by Chevy.
BAP put out 17 to 20V at the BAP and to keep it you need bigger wire to the fuel pump. If you raise the voltage to 15V with hp tuner you need to raise the alternator voltage output also.I use the BAP with 52 lbs injector for 2 year now without problem i paid $75 for use one
BAPs are great if you decide to invest in one. I just didn't want to pour into that at the time so I looked into other options. I tried fiddling with the alternator tables as you mentioned but after a certain point the computer ignores the values so that's why I just max that table out and then rely on the fuel control module to do the rest. It won't compete with a BAP but it stretches the pump a little bit if you're just looking for 50HP extra headroom
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