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Thread: Finally Got Boost to my 3A92!

  1. #11
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    Quote Originally Posted by Loren View Post
    That 16 could be advance over whatever the base timing is. (10?)

    And, also remember that there is VVT going on. They might be advancing cam timing via the VVT on top of the base ignition timing.

    Better to dyno tune, of course. But, if you're careful and tune CONSERVATIVELY, you can tune timing by ear. The dyno just lets you find "the ragged edge" for max performance a lot easier.
    .
    So my NA ignition table tops out at about 26degrees right now at full WOT, fuel cut come in about 7400rpm. I’ve tried running a couple more degrees but found zero improvements above the 25-26degree point. I have never tried to run as low at 16 but it’s something i’m going to have to try now.

    Good news is I can hear detonation easily with the head right over my my shoulder.

    It took me a little bit to figure out my VVT timing but I think i’ve got it dialed pretty good now (the MIVEC is intake cam advance only). VVT advance adds A LOT of torque in the 2-4k range on this engine which is when i’m advancing the most (45degrees) I have it setup to progressively return to under 5degrees at high RPM, which seems to work the best for reving out.

    I’m definitely going to take a closer look at this ignition table now given this possible new info, i’ll report back my findings



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    The timing would not be + base timing. That's an old distributor deal that isn't used anymore on distributorless systems. Plus it puts out 46 degrees advance at part throttle, which is realistic, 56 degrees would not be.

    It starts at around 8 degrees at 2000 rpm, plateaus at 16 degrees at peak torque in the 4-5k range, then goes all in and climbs to 18 degrees towards redline. These low numbers aren't very unrealistic. It's a sign of an efficient and fast burn. The goal of ignition timing is to reach peak cylinder pressure at around 31 degrees after top dead center for maximum power output. The reason we have ignition before top dead center is because that's how long it takes for the flame front to travel from the spark plug to the ends of the combustion chamber. An engine that requires more advance, has a slower burn and is also less efficient.


    Regarding tuning, you can do pretty well with a street tune. I've only ever dynoed one of my cars and it wouldn't make any gains over what I tuned on the street.
    I've also gained 1.2 seconds in the 1/4 mile simply by tuning at the track with no dyno.

    This is especially true with forced induction and pump gas. You're limited by the octane and getting fancy with tuning isnt really going to gain you much. An all out race engine with race gas is a completely different story.

  3. The Following User Says Thank You to Pimp_Daddy_Patty For This Useful Post:

    Loren (08-13-2020)

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    Obviously, if running a more power friendly 13.0-13.5:1 AFR and using premium gas, I'm sure you could push the ignition timing a fair bit higher than the teens. I'm talking WOT 0 psi boost of course.

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    Quote Originally Posted by Pimp_Daddy_Patty View Post
    Obviously, if running a more power friendly 13.0-13.5:1 AFR and using premium gas, I'm sure you could push the ignition timing a fair bit higher than the teens. I'm talking WOT 0 psi boost of course.
    This is so interesting to me because i’ve never felt I got the ignition right at the top. The 3A92 has seemed to have great torque down low but the top speed of this 1000lb buggy has always been low 70s. At WOT RPM just wouldn’t climb the way I thought it should.

    I mean isn’t the theoretical top speed of the Mirage like over 100mph? and im over 1000lbs less and I couldn’t top 80? Part of that is of course my much higher gearing and larger heavier tires but still.

    This project is far from done, i’m running the cast iron exhaust manifold currently but just ordered headers from Speedlab. Also making several changes to tune and charger. I think the 120hp i’m gunning for in a 1000lb buggy like this outa outrun just about any Rzr or Maverick I cross paths with out on the trails/tracks 😁

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    One more thing to consider: with modern detonation resistant engines, you can advance timing to the point of losing power before you actually get any detonation.

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    Quote Originally Posted by DirtGearTv View Post
    This is so interesting to me because i’ve never felt I got the ignition right at the top. The 3A92 has seemed to have great torque down low but the top speed of this 1000lb buggy has always been low 70s. At WOT RPM just wouldn’t climb the way I thought it should.

    I mean isn’t the theoretical top speed of the Mirage like over 100mph? and im over 1000lbs less and I couldn’t top 80? Part of that is of course my much higher gearing and larger heavier tires but still.
    Yeah the actual top speed of a mirage, atleast tested by me is 116mph, and your gearing could be a problem if it's a while's off from the stock gearing. I really hope to hear how this goes so I can boost mine one day

        __________________________________________

        click to view fuel log View my fuel log 2017 Mirage ES 1.2 manual: 37.4 mpg (US) ... 15.9 km/L ... 6.3 L/100 km ... 44.9 mpg (Imp)


  8. #17
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    Hello all,
    . . . . On my last drive which was during the first three weeks of June I covered 13K miles in 21 days. I was in some really fast traffic going from Dallas to Houston. The speed limit was 75 with the average traffic running at 80. There were 6 of us that were running at up to 115 in between the groups of 80 mph traffic. My G4 tops out at 115 on the flat with no wind!
    . . . . Could you please post pictures of how you did your installation?
    GOD Bless and Thanks,
    rich!

    Quote Originally Posted by DirtGearTv View Post
    This is so interesting to me because i’ve never felt I got the ignition right at the top. The 3A92 has seemed to have great torque down low but the top speed of this 1000lb buggy has always been low 70s. At WOT RPM just wouldn’t climb the way I thought it should.

    I mean isn’t the theoretical top speed of the Mirage like over 100mph? and im over 1000lbs less and I couldn’t top 80? Part of that is of course my much higher gearing and larger heavier tires but still.

    This project is far from done, i’m running the cast iron exhaust manifold currently but just ordered headers from Speedlab. Also making several changes to tune and charger. I think the 120hp i’m gunning for in a 1000lb buggy like this outa outrun just about any Rzr or Maverick I cross paths with out on the trails/tracks 😁
    2019 G4 Wine colored. 'Burgundy'
    130K miles, 37MPG average at 75-80 MPH with A/C and Lights
    I am on the second engine and trans! 4.5 months out of 18 in the shop!
    Not so happy any more!

  9. #18
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    Quote Originally Posted by Mechanic View Post
    Hello all,
    . . . . On my last drive which was during the first three weeks of June I covered 13K miles in 21 days. I was in some really fast traffic going from Dallas to Houston. The speed limit was 75 with the average traffic running at 80. There were 6 of us that were running at up to 115 in between the groups of 80 mph traffic. My G4 tops out at 115 on the flat with no wind!
    . . . . Could you please post pictures of how you did your installation?
    GOD Bless and Thanks,
    rich!
    I recently got my new clutch installed ls ItÂ’s a racing style with 6 ceramic pucks and the machine became way faster. It wasnÂ’t until the new clutch went in that I even realized how bad my other clutch had been slipping. I donÂ’t even want to know the top speed at this point because itÂ’s scary fast now. It will pull to 90+ mph in seconds and I have to back off it as itÂ’s just not designed for those speeds. IÂ’m currently running about 8psi with a new wastegate and going to put the thing on a dyno soon. I have a whole build series on the the turbo 3a92 on my channel DirtGearTv so go check it out. Just got back from racing rather b weldings 700lb cbr1000rr buggy (180hp) and I absolutely smoked him in every race. This thing is fast.

  10. #19
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    I watched several of your videos including replacing the 800cc with the 1.2L Mirage Engine. How did that automatic ECU work! I got a big kick out of you getting lost. I assume that you got back OK! Would you be willing to make an exhaust manifold to mount the BW KO3 Turbo? Lots of fun!
    GOD Bless and Thanks,
    rich!


    2019 G4 Wine colored. 'Burgundy'
    130K miles, 37MPG average at 75-80 MPH with A/C and Lights
    I am on the second engine and trans! 4.5 months out of 18 in the shop!
    Not so happy any more!

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