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Thread: tuning virtual volumetric efficentcy table

  1. #1
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    tuning virtual volumetric efficentcy table

    Currently learning to tune gen 5 vehicles, maf calipbration is done. no sweat. Following the tuning schools printed course on gen 5. Uploaded a no maf tune which is shown below. Made a ve vs ltft table in vcm scanner. Here is the issue, in editor under edit-virtual volumetric efficiency, the row axis is MAP/BARO (PRESSURE RATIO) column axis is RPM. When creating a graph in scanner what row axis do i choose, map (frequency) is already chosen but the row in editor is a PRESSURE RATIO. Looked high and low in scanner for MAP/BARO (PRESSURE RATIO) and cant find it. i know it must be simple but im trying to learn. Maybe a custom math? The tuning book is very clear in everything. Except this. did a support ticket on their site but its already the weekend for them.

    TIA
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  2. #2
    Senior Tuner Ben Charles's Avatar
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    It’s there!! We use to have to make custom maths for it through

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    Okay thanks for the info. What math is used. The truck only has an intake so I know it?s not a must. Just want to learn how it works.

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    Senior Tuner Higgs Boson's Avatar
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    It's under Maths - Predefined -- Pressure

    you need to have MAP Hi Res and Baro logging in the channels

  5. #5
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    Quote Originally Posted by Higgs Boson View Post
    It's under Maths - Predefined -- Pressure

    you need to have MAP Hi Res and Baro logging in the channels
    you are the man! i got it figured out. the course didnt explain this. now i know!

  6. #6
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    What are the values in the VVE horizontal axis ( the map/baro) represent? g/s?

  7. #7
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by HNK View Post
    What are the values in the VVE horizontal axis ( the map/baro) represent? g/s?
    they represent manifold pressure divided by barometric pressure

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    Thx HB, realized after logging. A question, do you run your car in SD mode or both? Why is it important to get the VVE dialed in if I will be MAF only? Would bumping the flow axis in the fuel pump leading edge angle help fuel starvation in non cammed cars??

  9. #9
    So there’s a tuner than does not and will not Taylor VVE specifically for each car. The cars seem to be the faster cars around. Can anyone explain this?

  10. #10
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by HNK View Post
    Thx HB, realized after logging. A question, do you run your car in SD mode or both? Why is it important to get the VVE dialed in if I will be MAF only? Would bumping the flow axis in the fuel pump leading edge angle help fuel starvation in non cammed cars??
    my car, i like to run both or one or the other since I am perpetually tuning my own cars, lol. in fact, I have been known to buy cars only so I can tune them....it's an undiagnosed disease.

    tuning VVE is important because the calibration references it for torque produced and compares it against the torque model even if you are only using the maf to dictate fueling needs. torque representation accuracy is important because it is a baseline for all other controls between the crankshaft and the halfshaft.

    remember, typically fuel tables need to accurately represent the hardware, injector tables, fuel pump info, etc. more or less fueling comes from calibrating the airflow tables so the ecm known how much fuel it needs to match. i would not hack fueling to try to compensate for hardware, that will just bake errors into your airflow models which then also bakes them into your torque references and then the car doesn't run right.

  11. #11
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by nicul15 View Post
    So there’s a tuner than does not and will not Taylor VVE specifically for each car. The cars seem to be the faster cars around. Can anyone explain this?
    correlation is not causation. never forget that.

    "faster cars around...." lol, around WHERE? no one knows who or what is out there running what. WORLD RECORD!!! (of the people reading this). Come on with that....

    there are more people who DON'T want you to know what they have than people who need to brag about what they have.

    tuning VVE is 99% about driveability, shifting, idling, smoothness, etc and tuning it properly certainly doesn't make your car slower....

    typically when a tuner doesn't address the VVE this is a choice of time and money. if you get charged the same price (due to competition) for a tune where Tuner A spends 30 minutes loading his base tune and making a few dyno pulls to get the MAF in line and tells you "It runs like that cause of the big cam, you got a real man's car" vs Calibrator A telling you "I tuned the VVE for you for a couple hours so it drives just like stock and won't die when youre coasting or idling" and they both are going to put down similar numbers within margin of error, the VVE tuned car possibly putting down more depending on knock retard problems, who are you going to use?

    The Hype Man or the Calibrator?

  12. #12
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    Quote Originally Posted by HNK View Post
    Thx HB, realized after logging. A question, do you run your car in SD mode or both? Why is it important to get the VVE dialed in if I will be MAF only? Would bumping the flow axis in the fuel pump leading edge angle help fuel starvation in non cammed cars??
    VE is used for trans shifting parameters along with a handful of other items. You could see how much more air is moving now than before (I log cars before taking them apart for real world data) and scale the VE to match for an easy option or get you close to then dial it in. There are other ways as well to get to the same result - personal preference that's all.
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  13. #13
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    Quote Originally Posted by nicul15 View Post
    So there?s a tuner than does not and will not Taylor VVE specifically for each car. The cars seem to be the faster cars around. Can anyone explain this?
    Without mentioning the tuner because I'm not calling him out especially if it's who I think it might be, I'll say the following with due respect to him. I'll take the information challenge on. If anyone in Chicago has a vehicle that was tuned by this person you mention where the VE was not tuned or altered for the mods, I will retune it for free (no credits purchased), then make dyno pulls for comparison numbers and report back if VE actually matters. I will do this for one person only. I already know it does matter on the drive ability side since I fix alot of tunes remotely for this problem and log data supports it for power as well. I will not touch their spark table, fueling, nothing but VE and clean up the rpm hiccup in the high rpm with one alteration to the tune. Then I will actually tune it for power. Owner can be present the entire time for verification, orig known tuner, doesn't matter to me.

    I just did a CTS-V that was tuned locally, owner was unhappy with drive quality, it gained 44rwtq/30rwhp (with other shops timing, fuel, etc), the power comes on much sooner than before, and no drive issues. Pulls were all done on the same day. This was a VE situation. I then actually tuned it and the owner was in shock looking at the dyno screen. He called later and said the car drives so nice now, its smooth like a sewing machine, but shifts firm and gets down with the throttle pressed. These are the results I see all the time.

    I'm confident because I just worked an extremely known persons tune (person you might be speaking about) with very good prelim results and fixed driveability issues the owner was having. The person who you mention, might do other things as well and those mods are on point. Honestly, the best I have ever seen. I was amazed at the results thinking I was doing something wrong with my numbers, saying no way to myself, but it was a holy crap it's correct............ I told the owner the same, he isn't upset with the orig tuner either, so lets get that out of the way. Driveability is how it started with the owner since he felt it was just tuned for balls out, then I found out who tuned it and it struck my interest into overload. (17 1LE, M6) Waiting on the owner to dyno it at a third party facility for actual comparison numbers since he is not local to me:-) Driveability is pristine now and balls out power appears to be higher than before from log data and hangs the HP steady out to redline vs drop off :-) Owner is extremely ecstatic and says it's a pulling machine now!!!!!

    I'm here for the informational dyno session, but my 6gen is too modded for this test. Again, full respect to the other tuner you mention/don't mention. Higgs is correct with his posts on VE correlation to other items. Higgs, ever rent a vehicle just to pull the tune, dyno it for numbers, and gains? Create good tune for base setups and build from there, lol... I might have done that once, twice, heck who's counting....
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  14. #14
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    By the way, why does delivered torque max out at 640 while logging

  15. #15
    What preferred method of logging are you guys using to graph VVE? Are you just driving around trying to populate as many cells as possible? Or disabling PE and other items, etc and doing the 2000rpm hold 5 secs, 2500rpm hold 5secs up to 4000rpm etc etc pulls? I did the later but when I calculated the coefficients I had the same issue Ghost was having with some cells being WAY off from the surrounding ones. I assume i can just interpolate manually in those cells? Or is HPtuners having an issue with the coefficient calculations?

  16. #16
    Senior Tuner Higgs Boson's Avatar
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    you have to pay attention to the Zones and boundaries.

  17. #17
    Quote Originally Posted by Higgs Boson View Post
    you have to pay attention to the Zones and boundaries.
    I am definitely still learning the Virtual torque and VVE side of it. I ordered Greg's Gen5 DVD. Can't wait to watch it adn get some more learnings in my brain.

  18. #18
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by Poppacapp View Post
    I am definitely still learning the Virtual torque and VVE side of it. I ordered Greg's Gen5 DVD. Can't wait to watch it adn get some more learnings in my brain.
    read up in GenIV forums about VVE also since that's when it came out.

  19. #19
    Quote Originally Posted by Higgs Boson View Post
    read up in GenIV forums about VVE also since that's when it came out.
    So is everyone smoothing a bit manually before hitting calc coefficients? Then how do you apply the same changes to closed and dod?

    Excel?

  20. #20
    Senior Tuner Higgs Boson's Avatar
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    i don't smooth but if there are and cells that are obviously not in line with the group then I will smooth that individual cell.

    you can copy the whole table and paste it into the other ones.

    on a side note, on my C7Z I've been experimenting with the VVE Editor and set everything from 500 to 7000 RPM and 1.0 PR to 2.4 PR (boost) to one value (2300 for example) so it's all one plane and my fueling showed zero errors at WOT. that's a little concerning. I asked Howard at Redline if he ever experienced this, he told me he has thought for a while now that the VVE Editor is not calculating the coefficients properly....not sure if HPT is aware of this or not.