Stock Fuel Rails, why they don’t keep up

[Speedy!]

I always keep the AFR gauge on display in my dash. When off throttle it'll show 18 which means it's in DFCO. Basically the engine is free spinning and injectors are shut off while you coast. There are various limits in the tune when this can occur, like speed, MAP, etc.

 

[Doublewide]

But managed a decent 1/4 run, the 315 555R2’s didn’t due to bad on 30F pavement. This is the 1/4 Run in the log video. HEMI therapy was much needed and I enjoyed it and miraculously my car stayed clean
I mapped out a clean path earlier in my 4Runner and it paid off.
Now on to blower rebuild, leak down test, clutch replacement, Fore filter installation and fuel line restriction investigation and maybe some motor upgrades before spring depending on leak down test results. Got to stay busy.
View attachment 34087 View attachment 34088

You happen to know what your 1/8th mile time was for that run?

 

[Speedy!]

I was thinking the same thing about the filter but I’ll be running pump E85 most of the time and it’s highly recommended by Rick to use it when doing such. What would be your reason(s) for not installing it?

Factory flex fuel vehicles don't run additional filters as far I know and every sample I've looked at on E85 locally has been clear as water.

 

[16GoManGoHC2]

You happen to know what your 1/8th mile time was for that run?

Here is the whole run including G’s per gear. You can see from the G force graphs where I was peddling it on the edge of losing traction I love the G tech meter, with its 50 Hz milatary grade GPS unit it’s just as accurate as track timer, I’ve checked it many times against such, always within +/-.005 seconds of track marker times. And you can graphs runs side by side to one another and watch them play out in real time.

 

[16GoManGoHC2]

New data today shows modification was of help. Temp here today 36F, only 2 degrees warmer then last test pulls at 34F but today fuel pressure stayed above 84psi and injector duty cycle low to mid 80’s not exceeding 90% which triggers the bypass to open and bleed boost. A 1-2-3-4 1/4 is pull definitely more taxing on fuel system then just a 3-4 pull. Look at these 2 data logs, a 3-4 pull Pump Commanded % actually had some headroom left verse a full 1/4 pull. 1-2-3-4 137 mph 11.6 second 1/4 pulls ( I did 4) fuel pressure never went under 82 psi, previously before the modification I saw it dip as low as 77 psi to which injector DC would exceed 90%. DA here today around -800. My Gtech had a memory crash on my last pass and lost all my data from today’s runs, PISSED me off, here’s car data on one of the 1/4 runs.

Here is the 3 and 4 gear pull, much improved, pump not maxed out and pressure stayed above 85 psi.

Excuse background noise, other half watching tv.

 

[16GoManGoHC2]

Dogs are the greatest creatures on earth imo. Sorry to hear about yours

Looking forward to seeing the results.

Check out today’s results, I think this modification was a success. There’s still another restriction some where. I can email you this logs if you would like to check them out in more detail. Did 4 or 5 1/4 pulls over and over hot lapping, didn’t run out of injector today and 36F today verse 34F during the last test. I wonder if there was air pockets caught in the rails during the first test run as today they kept up much better. DA today and the other day really not that much different when I look at the screen shots of airport data which is only about 15 miles away from me and same elevation, I can see the airport from where I run.

 

[fubar569]

Sounds like you might have a new side business.

 

[Speedy!]

That's good data @16GoManGoHC2. Your fuel system is at its limits, but this shows factory rails are actually fine and money better spent elsewhere. What you'll have to decide is if you're going to continue to run it this hard in these kind of conditions and go from there. Larger injectors would take the pressure off the system for sure, but means spending more coin.

You need to remove 2deg of timing. I'd not keep leaning on it like that with knock in the logs.

 

[16GoManGoHC2]

That's good data @16GoManGoHC2. Your fuel system is at its limits, but this shows factory rails are actually fine and money better spent elsewhere. What you'll have to decide is if you're going to continue to run it this hard in these kind of conditions and go from there. Larger injectors would take the pressure off the system for sure, but means spending more coin.

You need to remove 2deg of timing. I'd not keep leaning on it like that with knock in the logs.

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I did such last night, removed 1.5 degrees of timing above 1800 air charge and ran it again today, -1700 DA, aircharge hitting 2000, It reduced STKR, take a look at screen shot attached. My knock sensors are set up stock yet which is making them overly sensitive, their the next thing to work on come spring. But your right, I’m out of fuel system even with the modded rails. In 25 F today it ran out of injector top of 4th and bypass opened. I did these runs mainly to test the fuel rail mods, I won’t be running in this kind of cold weather often enough to justify the expense or worse the retuning flex on new injectors. The mod definitely helped capacity and more importantly fuel trim evenness from side to side.

 

[Speedy!]

I believe you're logging knock sensor volts. Graph them like you have the rest of the data and look for patterns. The upper RPM area seems to want to show a bit of STKR on your logs. Previous logs were showing 1-2 deg STKR, but if you removed 1.5 and still see 1-2 then it's likely false knock. To test I'd remove 2 more deg, retest, and compare knock sensor volts and STKR readings.

I found patterns in mine and had to tweak the knock sensors just a tick to get rid of it. Doesn't take much usually. I started by setting my knock window to match that of a 2019 Redeye factory calibration at 42.

On my car it'd get knock at 2,000 rpm and 4,000 rpm no matter what. I could set it to 0 deg of timing and it wouldn't matter. Josh from Flatout gave me the tip on putting knock sensor volts in the graph to look for patterns and sure enough. I'd see 1.5V on the knock sensors right at 2,000 and 4,000 for a blip every time. In the end it was the increased noise from the pulley on the supercharger and I just had to adjust things accordingly. When you get to that point lemme know and I can give you some tips on how I did it very conservatively.

 

[16GoManGoHC2]

I believe you're logging knock sensor volts. Graph them like you have the rest of the data and look for patterns. The upper RPM area seems to want to show a bit of STKR on your logs. Previous logs were showing 1-2 deg STKR, but if you removed 1.5 and still see 1-2 then it's likely false knock. To test I'd remove 2 more deg, retest, and compare knock sensor volts and STKR readings.

I found patterns in mine and had to tweak the knock sensors just a tick to get rid of it. Doesn't take much usually. I started by setting my knock window to match that of a 2019 Redeye factory calibration at 42.

On my car it'd get knock at 2,000 rpm and 4,000 rpm no matter what. I could set it to 0 deg of timing and it wouldn't matter. Josh from Flatout gave me the tip on putting knock sensor volts in the graph to look for patterns and sure enough. I'd see 1.5V on the knock sensors right at 2,000 and 4,000 for a blip every time. In the end it was the increased noise from the pulley on the supercharger and I just had to adjust things accordingly. When you get to that point lemme know and I can give you some tips on how I did it very conservatively.

COOL!! I’ll try all!! GREAT TIPS!! THANK YOU!! My supercharger front bearings are noisy, different SC going on soon, been waiting to change it and see if it effects the Knock I’m seeing before tweaking with the sensor settings. I’ve run 90% E and the knock pattern hasn’t changed much, I find I hard to believe knock could be occurring at 15-16 degrees of timing on that high of alcohol content or doesn’t that matter? I have 98% ethanol on hand, I could load it up with that and see if it changes knock?

 

[Speedy!]

If it's known E90 from a can and tested to confirm then no I'd not expect any stkr. Just watch the fuel system, E90+ is likely gonna put it over the limit in the good air.

 

[16GoManGoHC2]

If it's known E90 from a can and tested to confirm then no I'd not expect any stkr. Just watch the fuel system, E90+ is likely gonna put it over the limit in the good air.

I have a 55 gallon drum of E98, it tests 99.5%. I mixed E77 and E98 this morning to a electronically digitally tested mix of 86.5%, that’s what was in the car for today’s test on reduced timing settings. The car sensed it as 83.5%, it probably didn’t help with the fuel system keeping up today in 26F -1700 DA
Here a picture of the WOT alcohol spark table running today. Reduce more?

 

[16GoManGoHC2]

If it's known E90 from a can and tested to confirm then no I'd not expect any stkr. Just watch the fuel system, E90+ is likely gonna put it over the limit in the good air.

I reduced timing in lower right corner by .5 to 1 degree in about 6-7 blocks.
Hopefully get to test again this week sometime. Freezing rain here now


To hopefully get rid of the last of the STKR peaks above 6250 rpm

 

[yellow_hellcat]

Perfectly timed thread for me. Following!

I am running the 2.5" pulley with FIC 1200 injectors and dual TI285 drop-in pumps and having the same fuel issues on e98 at the top end of my pulls.

I find myself stuck between two, what I would consider, experts in Mr. Dusterhoff and Mr. Tapped as they are recommending different solutions. One wants me to use a boost-a-pump to get more pump and the other says I need the Fore fuel rails to fix the issue. Very interested to see how this thread plays out as it appears the fuel rails may be the limited factor based on what you are finding with these modified versions.

Thanks!

 

[16GoManGoHC2]

Unfortunately no more testing for me until some heavy rains come, the roads are white with calcium and salt and cinders every where. But I do plan on looking near the fuel pump and line from it to the rail inlet for other choke points in the mean time. I’ll post what I find. My opinion on my setup, my 1050’s are running out of time at high rpm to get the amount of fuel needed out of them in the milliseconds they have to do such in at high r’s. I may gain some DC back if I get fuel pressure back up in the rails by getting rid of any other choke points but even if I get 85-88 psi back in the rails my injectors are on the small side if I step it up any more then I already am. Your FIC 1200’s will carry you futher for sure. I’m not a boost a pump fan, I’d go bigger injectors first. The rails, the Fores are nice, but I think modded stock rails will flow just as much unless the Fore rails are configured with a rear center T’d feed to the back of each rail not a feed through set up as the entry level setup is supplied. Ideally a rear center T’d feed to the back of the rails, connect the front of the rails together then a return line to the tank with a regulator in it

 

[yellow_hellcat]

I hear ya on the roads! Nebraska likes their brine solutions and full salt on occasion also.

I looked into getting a second set of stock rails to try to modify, like you did, but the cost is nearly the same as the Fore rails! I only have hand tools and a bench vice for the modifications so I am a little hesitant to try on my stock set!

Here is one of the 4th gear pulls I made while trying to dial it in. You can see the Fuel Pump Commanded DC at 89% with the injectors at 71% duty cycle but the pressure has fallen to 78.3 psi.

 

[Speedy!]

@yellow_hellcat - 71% inj DC wouldn't worry me with your inj pw and commanded EQ looking good. I'm surprised to see a pressure ratio of 2.25 and an aircharge of less than 1700mg though. What did that aircharge look like earlier in the pull? I'm assuming this is an E85 tune based on the timing advance.

I'd suggest adding actual fuel pressure to the log, that way you can compare commanded to actual.

Finally, fuel pressure can be increased a bit in the tune to a little over 90psi at WOT. Curt I'm sure knows how to set that up, pretty easy.

 

[16GoManGoHC2]

You still have a good deal of injector left yet, 12 milliseconds at that rpm is not bad. What is the desired fuel pressure? Yes, pump commanded at 89% is max but just curious what desired verse actual fuel pressure is? You look like you would benefit greatly with the modded rails. Why buy another set just mod yours? I’d do them for you if you want to send me them. It’s very time consuming how I do them as I only take out about .010” at a time which means changing drill bits a couple hundred times before all 10 holes are done and then deburred by hand with a dremel and a ball end cutter to get to the back sides of the holes all while pumping air in them and eating the chips that come out LOL. Then after blowing them out with even more air I take them to the gas station and put a hose on the pump nozzle and into the rail feeds and blow about a gallon of gas through them. No doubt their clean when done LOL. Don’t smoke around the pump after I leave it though, it’s done late at night lol.

 

[yellow_hellcat]

I was able to find another recording of a full eighth mile pass. Hope this has some more info for you guys.

@Speedy! - This is my e98 race only tune with some launch tricks in it. I was running e85 for this pull that tested at 87%.

@16GoManGoHC2 - I may take you up on that offer! I just don't have the setup to modify myself and feel confident that I wouldn't budge it all up...

One other question for you both... how are you getting the alcohol % to log in your scans? Am I just logging the wrong PID or did you add something to get the cars to read the %?