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Thread: Race Gas Tune?

  1. #1
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    Race Gas Tune?

    Sooooooooo....I have had a thought. I know it is a dangerous practice but here me out. The knock octane modifier is used to limit power for lower octane fuel and take advantage of higher octane when used. Well, what stops us from setting the low setting for 87 octane, the mid level setting for 91-93 octane and the high level tuned on race gas... It should be as simple as increasing the timing up to a point so that the modifier stops climbing on 93 after midway. Then transferring the LSPI from high to Nominal. The low setting would stay the same. Then when running higher octane or race gas, the KOM should climb higher and allow for a higher LSPI as well. May be that the multiplier tables need to be adjusted as well but I'm just spit balling an idea. Thoughts?

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    Don't see any reason that couldn't work, but you'll also have to change the knock octane tables under the spark/retard tab, so it knows how to map the levels of learned knock to an OAR value.
    But just remember, you will also need a higher flow HPFP, I'm already maxed out on 93 and the stock turbo as it is.
    Fuel injection quantity is the problem at these loads, not knock resistance, though at those loads more knock resistance wouldn't be a bad thing.

    My goal is a bigger HPFP and run e85 as my race gas, but I plan on hopefully leveraging flex fuel for that, since HP added those parameters.

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    yea im waiting to get that eb mustang i been working on for a year on the flex tune and try it after redoing my torque tables hoping to finish dialing in on 93 then hit it on e30.wish the hpfp werent so expensive lol

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    See, that is what I am not sure about. I am not sure, at least in my case, that knock resistance is not a problem. I have trouble running anything over 22lbs before knock becomes an issue. MAT is controlled so unless I am sucking in lots of oil vapors, I need some extra help. About 315-325 hp is all I can eek out and sure this might be the top of turbo flow but I imagine there will be a bit left in the timing table. If nothing else it would be peace of mind. Also I am not having any fuel flow problems just yet so I must still have some room left. Not much maybe but some.

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    No kidding.

    I may have a lead on a cheaper HPFP solution though...
    I wasn't going to post about it until I had more information, but I think a pump off a 2018+ 5.0 F150 will work, the high pressure hard line will need some bending though, as the inlet/outlets aren't exactly the same, but quite a bit closer than others I've considered.
    The 5.0 F150's DI pump flows the same as the XDI 35, if I'm not mistaken.

    I've been trying to find a super cheap used one, but I haven't been able to get one cheap enough to be worth while taking a chance on.

    Edit:
    Actually, not just the F150, the 5.0 Mustang with DI also uses the same pump, just the F150 is easier to find used parts for.

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    Rock auto has some 5.0 pumps in stock I believe

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    They do, but I don't want to spend that much on a hunch

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    Thats a good idea as those can run full e85 with out a issue and can put our more psi

  9. #9
    Quote Originally Posted by Seishuku View Post
    No kidding.

    I may have a lead on a cheaper HPFP solution though...
    I wasn't going to post about it until I had more information, but I think a pump off a 2018+ 5.0 F150 will work, the high pressure hard line will need some bending though, as the inlet/outlets aren't exactly the same, but quite a bit closer than others I've considered.
    The 5.0 F150's DI pump flows the same as the XDI 35, if I'm not mistaken.

    I've been trying to find a super cheap used one, but I haven't been able to get one cheap enough to be worth while taking a chance on.

    Edit:
    Actually, not just the F150, the 5.0 Mustang with DI also uses the same pump, just the F150 is easier to find used parts for.
    That's pretty interesting... I'll check pricing on one with my local Ford guy. I would love to switch my 2013 over to straight E85.
    Owner/Tuner@Evolution Automotive Performance
    Lincoln, Ne

  10. #10
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    KOM Test.hpl
    Confirmed that the KOM will continue to climb on 93 octane. Im thinking, see how far this will continue to climb and go from there. Any dangers that come to anyone's mind so far?

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    It shouldn't hurt anything, octane modifier clip (unless changes) is 1.0, so the computer shouldn't do anything with it beyond that.
    It doesn't affect timing, so as long as the knock sensors are doing their thing (and LSPI limit is resonable), it should stay safe.

    Edit:
    Actually, it's possible that the KOM could get high enough to add way more timing than it should via borderline correction octane map, but even then, the knock control should keep it in check.
    Last edited by Seishuku; 02-01-2023 at 08:20 PM.

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    Right. That and cylinder pressure limit. Continued testing show a KOM peak of 1.49 so far. But I think that that may be a false reading. It climbed that high using the old "Hold 3lbs of boost through a tall gear(7th in this case)until I'm going entirely too fast" technique. I'm not entirely sure that that methods reflects normal driving or how the KOM was intended to react or react too. I would think that it would be designed to operate at all possible driving scenarios but who knows what is in the mind of a Ford engineer/calibrator. What worries me is this. To add timing on race fuel, the cylinder pressure limiter will have to be raised and timing added to see the peak hp and tq on a loaded dyno without knock. Or at least the best average power. The question is, how quickly, and far down, will the KOM shrink back to 1 once the race gas has been used up? I was secretly hoping that the KOM would not have shot up this high with the cap removed. 93 on race gas level timing is relying heavily on the knock sensors to keep things safe and I think that is a recipe for disaster. Or maybe they are fast enough and sensitive enough to reduce the timing safely. I could be over thinking things.

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    That's how the system is intended to run, it's generally sensitive enough to pick up on small minor knock and correct for it.
    Not much different than how it relies on the wideband o2 for fueling.

    But yeah, getting to a higher KOM isn't big deal, coming back down is. In the case of switching from high octane to low, I would prefer to reset adaptation/KAM, force to relearn KOM.

    Too bad there isn't a way to reset just the KOM without messing up long term fuel trims and other adaptations.

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    This does not work or at least i do not know enough about it for it to work. I tried adding some octane booster in the proper mix for just around 98 octane. Just wanted a little extra protection at wot to get rid of the tiny amount of knock I had. Now it seems I have way more knock and way less timing. I set the cyl pressure limit back to stock which is really close to 0* timing and had audible tip in knock. So loud in fact that I cannot keep my foot in it. Full pull at this point is impossible. This is the only time that I have actually heard the knock when it occurs. The after 2 log was an attempt to run almost no timing to see if the knock disappeared. It didn't. I couldn't hear it on this one but it was way down on power so I abandoned the run.
    Before.hpl
    After 1.hpl
    After 2.hpl

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    Can't view the logs right now, that'll have to wait until I get home.
    After those pulls, did you happen to pull spark plugs, might give some insight that the logs don't.

    Might not be a bad idea to check out the cylinders/combustion chambers with a borescope while you're at it...

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    Quote Originally Posted by Seishuku View Post
    Can't view the logs right now, that'll have to wait until I get home.
    After those pulls, did you happen to pull spark plugs, might give some insight that the logs don't.

    Might not be a bad idea to check out the cylinders/combustion chambers with a borescope while you're at it...
    Might not. Are you thinking carbon deposits? These were supposed to be one step colder plugs but that may or may not matter. I do know I am really disappointed lol. A week ago I was making fine power. Seems I lose power and increase knock any time I try to chase anymore boost. I would love to have a tune that was stable where your power level is at but I just can't seem to get there. Sad really. I don't have any sustainable fuel alternatives. This octane booster was supposed to be my way into 400ftlb territory which I have seen done. At least it has been claimed to have been done on pump gas. I dunno guys I'm kinda depressed about this one.

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    Gotta be something... I wouldn't think carbon buildup, being it's not that old of a car and I assume you don't have many miles.

    Then again, I have seen vw/audi engines get pretty gross after even just 30k miles... So who knows.

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    Just rolled over to 37k...... Wish there was a way for me to test this gas that is in my tank. Like an at home octane rating test.

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    Looking at the logs... Oof, "after 1" is hard to look at.
    The only thing I can think of is that having KOM over 1.0 is having some hidden undesired effects on timing that aren't reflected in the timing advance PID.

    Maybe revert the changes you made for the KOM stuff and take another log? If it's still knocking bad like that, then it's gotta be a mechanical issue...

  20. #20
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    Quote Originally Posted by Seishuku View Post
    Looking at the logs... Oof, "after 1" is hard to look at.
    The only thing I can think of is that having KOM over 1.0 is having some hidden undesired effects on timing that aren't reflected in the timing advance PID.

    Maybe revert the changes you made for the KOM stuff and take another log? If it's still knocking bad like that, then it's gotta be a mechanical issue...
    That is the same reaction that I had! I also was wondering what hidden effect the KOM might have been having. Unfortunately I do not see a way to experiment with that. I decided to go back to a tune that gave me good results and decent timing and probably stick with that for now and refine my fuel trims. Maybe that will have a positive effect I should be able to get a datalog this morning.