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Thread: Increase MPG

  1. #1

    Default Increase MPG

    I'd like to get more MPG out of my stock LQ4. I'm getting about 14 MPG, Stock 6.0L LQ4, 4L60E, 3.55, 3200 +/- lbs.

    I'm reading the Holley help file and it says "If searching for maximum fuel economy at one point, you can monitor the Fuel Flow variable at a steady state point. Keep leaning the Target A/F value until either the Fuel Flow increases or the engine operation becomes unsatisfactory."

    Right now my idle is at the preset 13.8 and cruise is 14.7. Any recommendations on a good idle AFR? Manual says: “Cruise area” is tuned to maximize fuel economy and driveability. This area is typically 13.5 to 15.0:1 for gasoline engines. Should I touch timing or leave it be for now?

  2. #2
    Join Date
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    Connecticut
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    Originally Posted by Danny Cabral
    Holley's base calibrations are not designed for good fuel economy.
    Good fuel economy is a direct result of the fine-tuning performed on the EFI system.
    NOTE - I've found the following EFI tables to be the most significant areas for improving fuel economy:
    Target Air/Fuel Ratio Table (too rich in cruising area).
    Ignition Timing Table (not enough advance in cruising area & light acceleration area).
    Acceleration Enrichment Tables (way too rich once Fuel Table is self-tuned).
    Coolant Temperature Enrichment & A/F Ratio Offset Tables (base calibrations too rich).
    https://forums.holley.com/showthread...8640#post88640 (AFR & Timing Information)
    Unfortunately, self-tuning/Learning alone, will not produce good fuel economy. The EFI system (Global File) must be tuned for it. See above quote.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  3. #3

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    Thanks, I especially like these two articles:
    http://www.autospeed.com/cms/A_1595/article.html
    http://www.autospeed.com/cms/A_109132/article.html
    Looks like I could lean out both the idle & cruise pretty good while monitoring Fuel Flow.
    Also with my lower compression LQ4 9.4:1, I can advance the timing in idle & cruise to 15°/40°.
    Does that sound right? Thanks.

  4. #4
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    Quote Originally Posted by SixPointOh View Post
    Does that sound right? Thanks.
    Research the factory ignition timing for your particular engine.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  5. #5

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    I have the stock LQ4 HPTuners file, but it's written in cylinder airmass rather than MAP.
    Click image for larger version. 

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  6. #6
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    Remember, the only thing this EFI system self-tunes, is the Base Fuel Table, via the Learn Table.
    You're responsible for everything else, especially the Target A/F Ratio Table & the Base Timing Table.
    A dynamometer is the only real way to determine the optimum ignition timing for your performance engine.
    Most people research it, or just "know" what their engine needs or likes. Especially if it's a popular engine.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  7. #7

    Default

    Quote Originally Posted by Danny Cabral View Post
    Remember, the only thing this EFI system self-tunes, is the Base Fuel Table, via the Learn Table.
    You're responsible for everything else, especially the Target A/F Ratio Table & the Base Timing Table.
    A dynamometer is the only real way to determine the optimum ignition timing for your performance engine.
    Most people research it, or just "know" what their engine needs or likes. Especially if it's a popular engine.
    Thanks for the help, I've read a lot of threads so I know that's the standard reply. I understand that the system only self-tunes so much, that's why I'm adjusting the AFR tables as well as the spark table.
    I'm trying to do some due diligence here and see if anyone with a similar setup has any tips they could share. I plan on doing what the manual says for AFR. Watch the fuel flow and lean it out until it increases flow or causes the engine to run poorly. A little trickier for cruise, but I'll find a flat road and a steady RPM to watch. Timing is more difficult, as you said, the only way to know for sure is with a dyno. I don't have one and I'm trying to research, but it's hard to find conclusive data.

  8. #8
    Join Date
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    This is what I did. I created an Advanced Table that would lean the engine and another one that would advance the timing in my cruise area. I used an input to activate these table when I wanted to. I then found a nice flat piece of highway. I then created a Target AFR table and ignition table that would be considered normal for my engine (SBC). Then as I was cruising at a steady state I flipped the switch and leaned the engine from 14.7 AFR to 16 AFR and datalogged the difference. I could feel the loss of power and you could see the change in RPM, MPH, MAP, MPG, etc. So then I change the Target AFR table so the engine ran at 16 AFR. Then for the next test I added timing. At a steady state I flipped the switch and added 5° of timing, and I could feel the difference in the way the engine ran. It increased in power and again I could see the difference in the datalog. So I changed my timing table and gave it the extra 5° of timing. Then I went out again and repeated the same test. This time, when I added the 5° of timing, there was no difference in the way the engine ran, and no difference in the datalogs. I ended up at 16 AFR, 28° of timing at 2000 RPM. Nowhere near the 40° of timing everyone tells you to go to. At 65 MPH steady state cruise I can get upwards of 25 MPG. The reason I did it this way was because I also fell into that trap and followed everyone's advice and turned the timing up to 40° at cruise. All that did for me was to pound out the tops of the rod bearings and the bottom of the mains. Too much cylinder pressure at TDC. It was trying to push the crank out of the bottom of the engine. From everything I hear and read about LSx engines, you're going to need less timing than me. I will be putting a LSx in this winter, so I'll have to do this all over again.
    Last edited by 81 TransAm; 11-13-2019 at 10:22 AM.

  9. #9
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    Quote Originally Posted by 81 TransAm View Post
    I ended up at 16 AFR, 27° of timing at 2000 RPM. Nowhere near the 40° of timing everyone tells you to go to. At 65 MPH steady state cruise I can get upwards of 25 MPG. The reason I did it this way was because I also fell into that trap and followed everyone's advice and turned the timing up to 40° at cruise. All that did for me was to pound out the tops of the rod bearings and the bottom of the mains. Too much cylinder pressure at TDC. It was trying to push the crank out of the bottom of the engine.
    Which cylinder heads, pistons & compression ratio does your SBC have? Yes, 40° at only 2000 RPM is too much, especially if the engine has aftermarket cylinder heads, high compression ratio & dome pistons.
    https://forums.holley.com/showthread...824#post218824 (Related Forum Thread)

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Size:  27.4 KB
    https://www.jcna.com/ignition-advanc...requirements-0 (Ignition Advance Curve Factors)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  10. #10
    Join Date
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    383 ci, 10:1 compression, flat top pistons with older design 190cc AFR heads. The newer LS heads are a much better design than any SBC head. Yes, Danny, good point about the timing vs RPM. Most times people forget about that. I will admit, I made that mistake and it cost me $2000 to rebuild my engine. Danny, I don't use a key board a lot, where is that degree symbol?
    Last edited by 81 TransAm; 11-13-2019 at 10:31 AM.

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