On Fuel Rail Pressure...

stripSHO

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So I originally wrote this out in the above thread but unbeknownst to me it got locked. Spent too much time to let it vanish, and I think it is important set the record straight and show precisely why listening to anything @DadMobile says is damaging to your brain cells. I personally don't care what tuner anybody chooses. They all have their individual quirks, and people should share their own experiences to help others know what to expect. Trolling around the internet hyperbolically bashing products you've never used, based on incomplete information, shows a complete lack of character. Doing it for personal gain via youtube views takes an extra slimy type of turd. Maybe I'm alone in thinking this, but I feel like the SHO community and the internet in general would be a much better place if such people would just shut up and crawl back into the septic tanks they were born in. Anyway, we now return to our originally scheduled post...

I don’t know what guys do with fuel pressure but how are you making these mistakes after tuning SHO’s for a few years now??
I highlighted the key fact of the above sentence. This guy seriously doesn't even know how to read a log and yet he's out there trying to play tuner expert. In his video he pointed out a fuel pressure dip to 1400 psi [9.92 MPa]. But then a guy mistakenly commented that it was the lpfp and he agreed, saying that "the lpfp shouldn't get that low WOT." Fuel Rear Pressure in Livelink is rail pressure. Has this clown ever even opened his own datalog before??? I doubt it.
1650985520143
Really??? lift pump pressure shouldn't be so low as 9.92 MPa?! Wow, that's news to me! Didn't know there was such a capable in-tank pump on the market! What kind of fuel line do I need to install to handle that kind of pressure?? LMAO This just goes to show that he has zero actual interest or understanding of tuning but is just clambering for anything he can sensationalize for clickbait without the slightest idea of what it means.

Now I'm going to waste a shit ton of time trying to educate him. Maybe if I can open his eyes to just how ignorant he really is, it might encourage him to do some self reflection and stop being such an insufferable dou.chenozzle at the expense of peoples' livelihoods. If not, I may at least be able to help others see what an unreliable and irrelevant source of information he is and stop watching him.

Fuel pressure, by itself, means absolutely nothing in comparing tunes. It's really not that effective indicator of a problem on its own, either. If Ortiz runs a flat 0.81 lambda (which he does) and experiences a slight FRP drop, but GH runs more lean with a tapered target of .85 to .82 lambda (which he does) and there is no decline in rail pressure, which one is safer assuming identical airflow? ORTIZ. The richer tune wins. Ortiz runs 3.6% richer for cooler combustion charge temperatures, which puts more load on the HPFP, hence the higher potential for rail pressure dips. But mechanically nothing changes. The capacity of you HPFP is what it is, and pumping greater fuel via lower AFR's does not create a more dangerous situation IN ANY WAY WHATSOEVER.

Gearhead lambda targets:
1650985989090

Ortiz lambda target:
1650986008954

Both of the above logs are from the same owner/vehicle and same mods. Does this imply that Gearhead is tuning around a problem? I'm sure some will think that, but that is not true either. The reality is that the amount of fuel required to maintain cylinder temperatures is dependent on the amount of heat generated. Lower RPM = less horsepower = less heat generated -> less charge cooling necessary.

"But Stripsho, if my fuel rail pressure dips below setpoint, won't my engine lean out and blow up?!" Well, no, very unlikely.
-First of all, the PCM has built-in protection and will automatically close the throttle if the injector duty cycle approaches maximum.

-Second, rail pressure loss is most common to occur at low to mid RPMs due to HPFP capacity being proportional to engine speed. See my comments in the previous paragraph regarding RPM and effective cooling requirements.

-Third, and corollary to the previous point, max injector pulsewidth (window of injection) is inversely proportional to engine speed. At lower RPM there is more time available to inject fuel, so you do not need as much pressure to meet fuel demands. Look at this log below, 5th chart. You can see me plummet all the way to 900 psi rail pressure yet I'm still only using 82% injector duty cycle at that point. Shortly thereafter, I hit max pulsewidth and stay near max pulsewidth even though rail pressure is increasing AND air load is decreasing. By 5600 RPM I've nearly doubled my rail pressure, load has dropped 15%, but I'm still 95% inj. duty cycle. It's due to the injection window shrinking as well as my progressively lower lambda targets.
1650986501768

Oh btw this is from expirimental testing specifically seeking out these limits. I'm swinging for 20 psi and .78 lambda on a stock fuel system. Spare me any criticisms of what you may see.

Now let's dive into some meat and potatoes about the fuel system. Below are some specs and volumetric efficiency table of a stock HPFP.
1650986543673
Source: HPTuners Tune Repository, 2013 Taurus SHO stock calibration

WARNING: MATH INCOMING!
The HPFP has a displacement of 0.0171 cubic inches, or 0.0683 cubic inches per cam revolution. Using the provided fuel density 46.82 lb/ft^3, we arrive at a theoretical pump capacity of (0.0683 cu.in/cam rev) * (1 cu.ft/1728 cu.in) * (1 cam rev/2 engine rev) * (46.82 lb/cu.ft) = 0.0009259 lb fuel per engine revolution at 100% volumetric efficiency. V.E. of the pump is inversely proportional to rail pressure, and also varies with RPM as the table and 3d chart illustrate.

Let's use this data to expound on various tuners' lambda target decisions and how this impacts rail pressure. As an illustrative example, let's take an engine operating at 4000 rpm and 1.90 Load, running E10 pump gas with a stoichiometric AFR of 14.1:1. A 3.5L engine displaces 0.00157 lb of standard air per cylinder, per intake stroke. This represents 1.00 Load. So let's multiply this out: (.00157 lb per cylinder load) * (6 cylinders) * (4000 RPM / 2 RPM per intake stroke) * 1.90 Load = 35.80 lb/min mass air flow.

Consider first the GH tune running 0.84 lambda at 4000 rpm. That's 14.1 Stoich * .84 = 11.844 AFR. The required fuel mass flow rate is: (35.80 lb/min airmass) / (11.844 AFR) = 3.02 lb/min fuel flow requirement. Now, we can actually look at the pump data and figure out what rail pressure it is able to sustain at this flow. We need (3.02 lb/min req) / (3.70 lb/min [100% VE]) = .816 or 82% V.E. At 4000 RPM this interpolates to the 2176 psi row of our pump's VE table.

Now let's do the same thing for an Ortiz tune. 0.81 lambda at 4000 rpm = 11.421 AFR. The required fuel mass flow rate is: (35.80 lb/min airmass) / (11.421 AFR) = 3.13 lb/min fuel flow requirement. 3.13/3.70 = .846 or 85% minimum pump VE to sustain flow. This interpolates to a rail pressure capability of 1631 psi.

There you have it. 545 psi difference in rail pressure just by having a 3.6% richer (and therefore safer) fuel target. Not because of running too much boost or any other "mistake". Additionally, the richer lambda setpoint would trigger Insufficient Fuel Flow mode faster in the event of a problem. It is completely illogical and bass ackwards to say an Ortiz tune is dangerous or flawed because of a dip in rail pressure. IT MEANS NOTHING.

Now, since the log in question within his video is an e30 log, I could dive into all the factors with the latent cooling properties of ethanol and the over-the-top margin of safety inherent to the physics of it. But I'm afraid this is where the free lesson ends. Hopefully this has been sufficient to open the eyes of some of you to the intricacies and mechanics of tuning a car and encourages you to not be influenced by irreverent and incompetent attenion wh.ores.
 

SM105K

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Good information. Being on E30 for the majority of my SHO ownership experience I have learned a couple things with our set ups and have backed them up with data logs, dyno runs, and track runs within my own ownership thread.

1. Pushing the limits on a stock HPFP. I have logs where my HPFP pressured dipped to 1400 psi. Brad told me to watch for it. It was cold, and I was on E30. My car has never stuttered, or missed a beat. However, I was not comfortable, and Brad turned the tune back down. Putting the FS (rolls my eyes) HPFP in my car was the best bolt on mod in my book sans the AD TQ mounts. It put my fuel pressure problems to bed.

2. Tuners. Do your research. Look over multiple forums and FB groups. My car was tuned by Brad almost immediately after I purchased it. I did my research and from what I saw on the net, Brad has fulfilled every tuning box I needed checked and diligently explained every question I have asked. I have had tuners reach out in the past, however I am extremely happy with my results. Each tuner has weaknesses and strengths. Do their weaknesses bother you more than the strengths?

3. @stripSHO is an idiot savant. He knows his $h1t (and has $h1t on me with facts in the past) however he doesn't always convey his message in the most elegant manner (which personally I dig), but that can also turn people off from reading what he actually is saying.

Anyways back to Youtube land.
 

stripSHO

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Good information. Being on E30 for the majority of my SHO ownership experience I have learned a couple things with our set ups and have backed them up with data logs, dyno runs, and track runs within my own ownership thread.

1. Pushing the limits on a stock HPFP. I have logs where my HPFP pressured dipped to 1400 psi. Brad told me to watch for it. It was cold, and I was on E30. My car has never stuttered, or missed a beat. However, I was not comfortable, and Brad turned the tune back down. Putting the FS (rolls my eyes) HPFP in my car was the best bolt on mod in my book sans the AD TQ mounts. It put my fuel pressure problems to bed.

2. Tuners. Do your research. Look over multiple forums and FB groups. My car was tuned by Brad almost immediately after I purchased it. I did my research and from what I saw on the net, Brad has fulfilled every tuning box I needed checked and diligently explained every question I have asked. I have had tuners reach out in the past, however I am extremely happy with my results. Each tuner has weaknesses and strengths. Do their weaknesses bother you more than the strengths?

3. @stripSHO is an idiot savant. He knows his $h1t (and has $h1t on me with facts in the past) however he doesn't always convey his message in the most elegant manner (which personally I dig), but that can also turn people off from reading what he actually is saying.

Anyways back to Youtube land.
I like that moniker. I'm keeping it. Thank you!
 

SHOthyme

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#3, yes he comes off as I'm-the-smartest-guy-in-the-room-know-it-all-a-hole sometimes, but this post that he added from the "education" down is the reason I come to this forum. I was trying to find the words, and @SM105K put it so great I'm not going to change it, let the idiot savant stick! (I'm somewhat of an idiot myself, so it is more of a term of endearment)

@stripSHO - I know you couldn't care less about what I have to say on it and we dig that about you, but I find it odd you will try to "put some tuners in their place" yet scold others for doing the same thing. Bashing others, whether warranted or not, has always been a big turn off for me. I do love seeing the facts though so thanks for that part.

With that being said, I would love to see more of the above posts, as a matter of fact could you do one on fuel trims or torque source I would definitely read it. I get what the fuel trims are supposed to do, but how high is too high and shouldn't they get higher as you roll into the throttle, if they are off what are common causes... inquiring minds want to know. Maybe you could start something like SM's maintenance thread but call it something else? StripSHO's corner?

I digress...
 

stripSHO

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#3, yes he comes off as I'm-the-smartest-guy-in-the-room-know-it-all-a-hole sometimes, but this post that he added from the "education" down is the reason I come to this forum. I was trying to find the words, and @SM105K put it so great I'm not going to change it, let the idiot savant stick! (I'm somewhat of an idiot myself, so it is more of a term of endearment)

@stripSHO - I know you couldn't care less about what I have to say on it and we dig that about you, but I find it odd you will try to "put some tuners in their place" yet scold others for doing the same thing. Bashing others, whether warranted or not, has always been a big turn off for me. I do love seeing the facts though so thanks for that part.

With that being said, I would love to see more of the above posts, as a matter of fact could you do one on fuel trims or torque source I would definitely read it. I get what the fuel trims are supposed to do, but how high is too high and shouldn't they get higher as you roll into the throttle, if they are off what are common causes... inquiring minds want to know. Maybe you could start something like SM's maintenance thread but call it something else? StripSHO's corner?

I digress...
Your point is reasonable, though in response I honestly don't recall trying to put any tuner in "their place" besides the one I have first hand experience with. And in those instances it was always a case of me saying something he didn't like in passing within a troubleshooting thread or general conversation about knock, OAR, or whatever. His ego shatters at the site of objective criticism and he comes unglued at me. He was always the one pulling out personal attacks, accusing me of weird sh.it like trolling him under multiple accounts, mocking me, etc. like it's my fault that he has dozens if not hundreds of customers brainwashed into believing it's normal to have to add e85 to quell KR on a pump gas tune. I've never gone out of my way to spread hate or set on a campaign to ruin his reputation.

And as far as content goes, there's been many occasions where I've invested appreciable time into making detail oriented "techie" type posts or comments. They seldom get much attention and sometimes not so much as a Like. Maybe that's on me and my pompous writing style. Ever hear the saying "you've got a face for radio"? Well, I guess maybe I just have a voice for [silent] meditation.
 

yaycandy

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Good information. Being on E30 for the majority of my SHO ownership experience I have learned a couple things with our set ups and have backed them up with data logs, dyno runs, and track runs within my own ownership thread.

1. Pushing the limits on a stock HPFP. I have logs where my HPFP pressured dipped to 1400 psi. Brad told me to watch for it. It was cold, and I was on E30. My car has never stuttered, or missed a beat. However, I was not comfortable, and Brad turned the tune back down. Putting the FS (rolls my eyes) HPFP in my car was the best bolt on mod in my book sans the AD TQ mounts. It put my fuel pressure problems to bed.

2. Tuners. Do your research. Look over multiple forums and FB groups. My car was tuned by Brad almost immediately after I purchased it. I did my research and from what I saw on the net, Brad has fulfilled every tuning box I needed checked and diligently explained every question I have asked. I have had tuners reach out in the past, however I am extremely happy with my results. Each tuner has weaknesses and strengths. Do their weaknesses bother you more than the strengths?

3. @stripSHO is an idiot savant. He knows his $h1t (and has $h1t on me with facts in the past) however he doesn't always convey his message in the most elegant manner (which personally I dig), but that can also turn people off from reading what he actually is saying.

Anyways back to Youtube land.

Tune ive had for over a year from Brad, i have dips to 1300psi. He thought i would be ok. No issues at all. I drive like a nut and track the car. I really should get the pump maybe. I asked stripsho about it right away last year. Not distrusting Brad but to get a another TRUSTED opinion and he said he wouldnt bat an eye at it. All has been good

D51A1CB4 C848 4468 86D9 A7607778B8CC
 

76FoMoCo

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Tune ive had for over a year from Brad, i have dips to 1300psi. He thought i would be ok. No issues at all. I drive like a nut and track the car. I really should get the pump maybe. I asked stripsho about it right away last year. Not distrusting Brad but to get a another TRUSTED opinion and he said he wouldnt bat an eye at it. All has been good

View attachment 83922
Get the pump.
 

yaycandy

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I agree, get the pump. My car picked up 25 hp and almost 60 ft of tq.
Oh wow. I was trying to figure the math on hp per lb of boost and figured a lb or so wouldnt be much of a difference more than adding a few more stickers but I never looked into torque increase. That most definitely makes me want to buy one from Brad now. Screw hp, tork where its at. Im a redlight to redlight guy.
Makin me spend money will ya. Ill just buy a tesla 3 performance. More free. Tear out interior, quick enuf. Only upgrades are brakes, tires and suspension. Thats a dream
 

SHOthyme

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Your point is reasonable, though in response I honestly don't recall trying to put any tuner in "their place" besides the one I have first hand experience with. And in those instances it was always a case of me saying something he didn't like in passing within a troubleshooting thread or general conversation about knock, OAR, or whatever. His ego shatters at the site of objective criticism and he comes unglued at me. He was always the one pulling out personal attacks, accusing me of weird sh.it like trolling him under multiple accounts, mocking me, etc. like it's my fault that he has dozens if not hundreds of customers brainwashed into believing it's normal to have to add e85 to quell KR on a pump gas tune. I've never gone out of my way to spread hate or set on a campaign to ruin his reputation.

And as far as content goes, there's been many occasions where I've invested appreciable time into making detail oriented "techie" type posts or comments. They seldom get much attention and sometimes not so much as a Like. Maybe that's on me and my pompous writing style. Ever hear the saying "you've got a face for radio"? Well, I guess maybe I just have a voice for [silent] meditation.

Ha, that last part almost made me spit out my coffee.

I do read your stuff and the parts I understand seem well thought out, I'll make sure to throw a like on it, so you know we are reading it because like I said that kind of content is the reason I come to this forum.
 

SHOthyme

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Idk, if my return to the sho world was a good idea. Yall still can't drop a subject after the conversation is dead. Someone always gotta have the last say lmao

Ha, just because someone closed it, doesn't make it dead.
 

stripSHO

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I dunno. For me personally I just can't wrap my head around upgrading my pump as a solitary upgrade. The car is happy with e40 as is. And yes I do technically have a small amount of boost left on the table, but you SCT guys don't get to log turbo speed. 220,000 RPM inferred speed is fairly common to see, and I don't know if I'm comfortable pushing the stock snails any harder than that. I imagine a dual intake kit would help a lot in that regard. The other part of it is that when I have the timing set to YES, PLEASE! I actually lose enough exhaust energy to have a reduction in boost potential. My car makes more boost on a hot summer day with pump gas than it can make on a cold october night with C40.
 

DadMobile

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First you tried to discredit me over the 8k shift. Remember when you called ******** then like 3 posts later Lee and owner of log confirmed it to be true. I’m not going to share anything that won’t hold up in court just in case Ortiz thinks they have a case. I have been truthful about everything I have done in the community.

The log with fuel pressure issues was from a car that would stutter then take awhile to recover WOT due to fuel pressure. That’s a nice long post about how I’m wrong but that car had fuel pressure issues ‍♂️. Why did it stutter then take about 4 seconds to recover? If it was running fine.

These are logs are from real people 802SHO and others. He went on to break the record after switching off the Ortiz sauce, remember that? I’ll be the first to admit I’m no tuner but that doesn’t mean I can’t open up a log and go whoa that’s **** up.

Your educating the wrong guy, I’m not the one selling tunes with fuel pressure issues. It seems like Ortiz they could use someone with your skills collaborating with them.

Are we going to race this year?!?
 

SM105K

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Oh wow. I was trying to figure the math on hp per lb of boost and figured a lb or so wouldnt be much of a difference more than adding a few more stickers but I never looked into torque increase. That most definitely makes me want to buy one from Brad now. Screw hp, tork where its at. Im a redlight to redlight guy.
Makin me spend money will ya. Ill just buy a tesla 3 performance. More free. Tear out interior, quick enuf. Only upgrades are brakes, tires and suspension. Thats a dream
On E30 with the stock HPFP I was pretty much tapped out on boost because my turbos are worn out however there was still some left. Also this was with the GH IC. Car made 391 hp and 494 tq to the tire. Dyno Graph below.

20220427 085325


With the FS HPFP Brad was able to turn the turbos all the way up WITH THE STOCK IC, and the car made 411 hp and 546 tq to the tire. If you look at my Dyno sheet. Just look at 3100 rpms. Stock HPFP 260 hp and 450 tq. FS HPFP 325 hp and 546 tq. So up 65 hp and up 96 tq @ 3100. Also the 546 tq is misleading. The dyno tech started the recording late, so I would venture to say the car probably makes 555 to 560 tq. So long story short, the HPFP just didn't add power, it completely shifted the power band in the car.

411 dyno
 
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