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Thread: Turbo Mirage - le mons project race car

  1. #11
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    I have been running turbo front wheel drive race cars for years now with welded diffs, they are an absolute pig in the pits or parking but on track they make for a real easy car to set up and drive,I have tried all the regular types of lsd,torsen,plate,helical ect and nothing comes even close to the welded diff,mind you this is in cars with 300hp and the mighty lemon may not have enough power to even worry about wheelspin out of corners, its one of the last jobs on my to do list atm.



  2. #12
    Senior Member MightyMirageMpg's Avatar
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    Then by all means sir, weld the differential. But you'll never convince me by giving up half of all available front traction on every turn, you'll go faster around a track due too handling characteristics.

    Doax has an interesting thread about the rear chassis
    http://mirageforum.com/forum/showthr...ar-alternative

  3. #13
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    Heres a few more pics of progress.
    Oil feed to turbo simply tapped into port on engine where oil pressure gauge is.
    The map sensor overboost bleed, so I tapped the manifold and fitted this dash4 set up, the restrictor to the map sensor and one way valve bleed is a nitrous jet so this can easily be swapped size wise if the restrictor hole is too large .
    simple steam pipe manifold.Name:  20170308_134509.jpg
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    Administrator Daox's Avatar
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    Very nice work. That manifold looks great!

    What is the turbo you're planning on using?

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    Administrator MetroMPG's Avatar
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    Great project!

    Added to the featured threads on the home page.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


  7. #16
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    A simple way to stop that MAP sensor from freaking out electrically due to the presence of boost pressure is to install a MAP clamp. This is a Zener diode which when installed right, will prevent voltage above a set amount from being seen by the computer. What you need to do to find out what value you need is to turn the key on but do not start the motor. Then probe the MAP sensor wires. There should be 3 wires.

    1. ground
    2. 5 volt reference
    3. the third wire is the one the computer uses to determine the pressure in the intake. At full throttle (or the key on but the engine not running) this will typically be somewhere around 3.9 volts to about 4.7 volts.

    After you get your reading, go buy a Zener diode closest to the value that you measured.

    It has been years since I have used a Zener diode for this purpose so quit frankly I do not remember how to wire it. But it should not cost more than $1.



    As far as the extra fuel needed, I have seen one setup almost 20 years ago that was effective. The guy had a 4 cylinder car and he took a fuel rail from another 4 cylinder car, welded 4 bungs into the intake pipe right before the throttle body, and hooked the injectors into the fuel rail like they normally would. Each injector was activated via an adjustable Hobbs pressure switch. Since most economy cars are programmed to run rich at full throttle from the factory, he had the first extra injector triggered to turn on at 3 psi of boost of I remember right. Each extra injector was then activated in 2 or 3 psi intervals. I'm this way, he was able to safely double the rated horsepower.
    Last edited by 91cavgt; 03-23-2017 at 10:13 AM.
    Certified holder of useless car knowledge.

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    Senior Member MightyMirageMpg's Avatar
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    A zener diode doesn't work the way you described i think your mistaking the name (there's a LOT of different diodes!) A zener works like a regular diode until it's transverse (avalanche) voltage is reached then it allows it both ways.

    I dig the pressure switch idea tho simple and effective. Exactly How people ran blow thru carbs in the 80s! (NOS plate under carb for extra fuel)
    Last edited by MightyMirageMpg; 03-23-2017 at 06:33 PM.

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    Quote Originally Posted by MightyMirageMpg View Post
    A zener diode doesn't work the way you described i think your mistaking the name (there's a LOT of different diodes!) A zener works like a regular diode until it's transverse (avalanche) voltage is reached then it allows it both ways.
    I think some biasing resistors are needed to finish this.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.6 mpg (Imp)


  11. #19
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    Quote Originally Posted by MightyMirageMpg View Post
    A zener diode doesn't work the way you described i think your mistaking the name (there's a LOT of different diodes!) A zener works like a regular diode until it's transverse (avalanche) voltage is reached then it allows it both ways.

    I dig the pressure switch idea tho simple and effective. Exactly How people ran blow thru carbs in the 80s! (NOS plate under carb for extra fuel)
    I just looked it up to make sure my memory was right. Yes, it was a zener diode that was used. However, it is not wired the traditional way a diode is wired. I used a zener diode, a relay, and a Hobbs pressure switch back in the day on my old SRT4 to fool the computer into thinking I was at full throttle anytime boost pressure was over 7 psi. On this car, I used a zener diode to send voltage to the ECM from the TPS with the pressure switch sending signal to the relay to switch from the normal TPS signal to my altered signal. This has to be done because from the factory, the ECM limited boost at part throttle to only 5 psi. When you added a boost controller, it defeated this factory programming on how much boost to run. And on the original SRT4, unless you were at full throttle the ECM commanded stoich air/fuel ratios. So needless to say, it was dangerous to be feathering the throttle while at 13 to 19 psi which happened frequently with the tiny turbo it had. So by filling the computer that you were in fact at full throttle when you weren't it improves driveability greatly. All with a zener diode.
    Certified holder of useless car knowledge.

  12. #20
    Senior Member MightyMirageMpg's Avatar
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    Thank you for the longer explanation.

    I don't understand how the zener is necessary whatsoever because it doesn't effectively "clamp" or alter the number of volts. But regardless i believe you that you did it, and the fact it worked.

    With the mirage being drive by wire however I'm not sure this could happen, because it's comparing a to b with 2 potentiometers one on the pedal and one on the throttle body.
    If they don't match it kills the fun.

    OP: have you considered pulling the back seatremoving the fuel pressure regulator (its connected to the fuel pump) and installing an adjustable rising rate regulator and slightly bigger injectors? It's cheap easily tuned and you could probably use the previously mentioned hobs/relay trick with another map signal



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