Not quite getting the MPG's that I expected. - Page 5
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Thread: Not quite getting the MPG's that I expected.

  1. #41
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    Quote Originally Posted by MetallicaMatt View Post
    I jumped over to the "how-to".


    I want 0.028", not 0.035", correct?
    I didn't see anything mentioned about torque specs, so I'm assuming the calibrated hand is good enough?
    The original GM Spec for this engine was 0.033" to 0.037". The response XR got when GM Powertrain finally looked into this was 0.025" to 0.0275".

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  3. #42
    Off-Road Champion ErikBEggs's Avatar
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    Quote Originally Posted by titan2782 View Post
    Um, or you can increase it by 12mph. I achieved 41mpg doing 80 MPH. Sorry but I cannot stand to drive 60-70. Considering no one else (at least on my route) drives < 75, 68 would be hazardous to my health.
    I wish I could drive that fast here.... wait? The New York State Troopers give people **** for going 65 mph in the 55 mph.

    But seriously.. unless you are driving further than 30 miles (which most people aren't) you know only you save like 3-4 minutes by going that fast vs. the speed limit right? You are probably burning a good 20% more gas too.

  4. #43
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    Quote Originally Posted by ErikBEggs View Post
    I wish I could drive that fast here.... wait? The New York State Troopers give people **** for going 65 mph in the 55 mph.

    But seriously.. unless you are driving further than 30 miles (which most people aren't) you know only you save like 3-4 minutes by going that fast vs. the speed limit right? You are probably burning a good 20% more gas too.
    I just stated that I was getting 41 mpg commuting 102 miles per day @ 80mph. And I saved about 26 minutes of travel time which to me is a long freaking time when you're in the car for that much time per day. That's almost 30 minutes of driving time per day saved and not using fuel. And yes, I lived AND worked literally right off the freeway so no surface streets to deal with.

    At 30 miles one way you save 7 minutes which is 14 round trip. Significant IMO. Then again, I have little patients and I have driving.
    Last edited by titan2782; 12-05-2012 at 06:13 PM.
    Back to stock. Bored.

  5. #44
    Off-Road Champion ErikBEggs's Avatar
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    Quote Originally Posted by titan2782 View Post
    I just stated that I was getting 41 mpg commuting 102 miles per day @ 80mph. And I saved about 26 minutes of travel time which to me is a long freaking time when you're in the car for that much time per day. That's almost 30 minutes of driving time per day saved and not using fuel. And yes, I lived AND worked literally right off the freeway so no surface streets to deal with.

    At 30 miles one way you save 7 minutes which is 14 round trip. Significant IMO. Then again, I have little patients and I have driving.

    If you can do it then by all means. 102 miles is a lot of traveling!!! As many others have said as well, you have a manual transmission which responds better to higher speed than the automatics.

    However, for the average person the math just doesn't check out.

    Assuming you travel 30 miles on the highway at 65 mph speed limit. This is how constant speed equates to time:

    60 mph - 30 minutes, 0 seconds.
    65 mph - 27 minutes, 36 seconds.
    70 mph - 25 minutes, 43 seconds.
    75 mph - 24 minutes, 0 seconds.
    80 mph - 22 minutes, 30 seconds.
    85 mph - 21 minutes, 11 seconds.

    So yeah, how much is your time worth? Since most people actually only drive 15-20 miles per day the actual timed saved by driving like a madman vs. obeying the speed limit is at most 2-3 minutes. It is up to you to determine if it is worth it.

  6. #45
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    Quote Originally Posted by George Carlin
    Ever notice that people driving slower that you are idiots, and the people driving faster than you are freaking crazy!
    Your post reminded me of this. I love this quote.
    ErikBEggs, obermd and beeztee like this.
    Back to stock. Bored.

  7. #46
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    9.2L/100KM (like ~25mpg?) 99% city driving on my 2012 LT 1.4L. It seems normal but I swear my gas just disappears over the weekend :s
    2012 Cruze LT 1.4L - 9000KM

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  8. #47
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    Intelligence was finally shown when the spark gap was specified at 0.028 inches, when some engineer specified a 0.060" gap, he didn't know the difference between voltage nor current, thinking a higher voltage would produce a hotter spark. When in fact its current that produces a far greater reliable spark. This greatly reduces the tension on the plug wires, prevents combustion chamber swirls that can literally blow the spark out, and in particular with a turbo engine.

    In the typical distributorless ignition system, to save cost, one coil is used to fire two plugs, doubling the effective gap. Least the 1.4 L turbo has its own coil for each plug. If a plug does misfire, all the energy is absorbed by a zener diode located in the ignition module.

    I installed Autolite double plantinum APP3923 spark plugs in my Cruze, gapped to 28 mils. Put a very thin coat of anti-seize on the the threads and torqued to 18 ft-lbs. Removed the boots from the coil pack and stretched out those spring contacts, they can bind on the inside of the boots leaving a very large gap. Coated the inside of those boots with dielectric grease so you can remove them down the road. Otherwise the bake on as hard as a rock and you will break them off.

    What a huge difference that made in my Cruze in terms of engine load power and fuel economy. I don't go by myth, have been designing ignition systems for over 30 years. The size of the coil core its losses determine the energy of the spark in joules, the larger the better, but had budget considerations. Second most important factor is the fall time of that gated bipolar transistor so that little bit of energy stays in the coil and not dissipated by that transistor. Then getting that energy across the gap of that plug and not the interconnecting wires.

    Really seen an improvement in the Cruze ignition system. Surprised they don't have a TSB on those springs, too short from the factory.

    Still burning that filthy carbon gas that builds up on the center electrode, I blast mine with walnut shells every 20K miles and check the gap, that carbon is conductive and shunts out your spark. Spark plugs and gasoline is over a hundred years old now, but still have the same problems.

    In theory, can't really increase the performance of an ignition system if you are getting good hot spark at the correct time. Carbon is one of the largest enemies.
    titan2782 and obermd like this.

  9. #48
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    Quote Originally Posted by NickD View Post
    What a huge difference that made in my Cruze in terms of engine load power and fuel economy.
    What exactly was your setup before? Stock? What were your gaps? Why did you choose those plugs?
    Back to stock. Bored.

  10. #49
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    I've run Autolite Double Plats in a turbo car before - my experience is that they're unhappy with them after about 5K and start blowing out at high RPM at stock gaps. It misfired so bad on a hard 1-2 shift (though the car didn't show it was misfiring) that I thought the auto transmission was lurching and in its death throes. This is not just Autolites, but pretty much ALL platinum plugs.

    Platinum plugs don't produce as strong of a spark - it always ran fine on regular copper plugs, which is a standard practice in most boosted applications. Iridium plugs have the advantage that they conduct a spark better (while also resisting erosion WAY better than copper), but they're also much more expensive than either platinum or copper plugs.
    2012 Cruze 1LT 6M


  11. #50
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    Quote Originally Posted by jblackburn View Post
    I've run Autolite Double Plats in a turbo car before - my experience is that they're unhappy with them after about 5K and start blowing out at high RPM at stock gaps. It misfired so bad on a hard 1-2 shift (though the car didn't show it was misfiring) that I thought the auto transmission was lurching and in its death throes. This is not just Autolites, but pretty much ALL platinum plugs.

    Platinum plugs don't produce as strong of a spark - it always ran fine on regular copper plugs, which is a standard practice in most boosted applications. Iridium plugs have the advantage that they conduct a spark better (while also resisting erosion WAY better than copper), but they're also much more expensive than either platinum or copper plugs.
    What turbo cars and what were their application? (DD, x-cross, etc?) Have you tried them in your Cruze?
    Back to stock. Bored.

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