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Thread: Anyone gone turbo?

  1. #11
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    Quote Originally Posted by live4redline View Post
    I'm willing to bet a small fortune that the Mirage motor has at the very least forged rods. Everything Mitsubishi has put out in the past twenty years has forged rods. Not to mention forged components weight less and would have been the number one choice for use in Mirage. The pistons are a toss up. Cast pistons are better then forged pistons in a lot of ways. Not to mention Mitsubishi engineers a strong cast piston unlike for example Nissan SR-20 pistons which have weak ring lands. Although forged pistons do make a great deal more noise and the little three cylinder is indeed noisy, so there's a chance but it may just be a coincidence.

    Plus I disagree with the 7psi limitation theory. The old school thinking was don't push it past half a bar (roughly 7psi) but that is derived from poor tuning options being limited by stock MAP sensors that only have half a bar left in their reach. It's never been the limit or any motor and failures at such a low boost level are 100% the fault of the builder or lack of tuning. A high pressure storm has more pressure per square inch then 7psi. My hand can hold more pressure then 7psi. These are horrible examples but so is the thought that a motor engineered this century can't hold more then 7psi. My 2.4L 10:1 compression originally NA motor is running 27psi with stock forged rods and stock cast pistons without a hickup. Stock 2.0L has run 38psi but it's tracked tuned to 32psi. The Lancer guys still say 7psi is the limit for an 02 Lancer OZ spite me running 20psi on the stock motor for years. I guess what I'm saying is that I've seen far too many NA Stock motors run more then that assumed 7psi limit that was proposed 30 years ago.

    Honestly if your gonna set a limit for your self you have to shoot higher, don't gimp your self before you even start. I've set a bunch of HP records in the past cause I shoot higher then everyone else and have yet to blow a motor. I honestly think 20psi should be easy to do with proper tuning, key word proper tuning. When it come time to find out I'll progress the tune a few psi at a time and a legitimate tuner will be able to see when the motor starts to struggle and long before a failure. So in the end, it really is not going to hurt anything for me to push for 20psi. If however your tuning it your self and don't know what your doing or how to identify the limits of a motor, then that may be a diffrent story.

    Sorry for the rant, but it's disappointing to see the bar being set so low when I know it should be higher. The 7psi strategy is a really safe strategy, but I wouldn't call it a limit by no means.

    Hopefully I'll get the opportunity in the future to show what this little three cylinder can do. If not in my own then in some other brave souls Mirage. That will be the real moment of truth.
    I'm just speaking from experience. The 6g motors from Mitsubishi blown themselves apart running more than 7ish psi.
    Sure, you can pump 10psi for a while. It's not built for that and inturn destroys the engine. It's why the supercharging kit for our car only runs 7psi.
    Maybe these engines can handle more. I have heard the opposite. And have seen many 6g engines(3.5 and 3.8) blow up from too much boost.

    Might as well go forged anyway. I wouldn't go turbo without it.



  2. #12
    Senior Member MightyMirageMpg's Avatar
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    Forged / cast / hyperpnuteptic pistons at this power level is absolutely insignificant

    The ONLY advantages of any of them would be during initial tuning. Forged and cast pistons will absorb (minimal) detonation. Hyperpnuteptic are harder and brittle in comparison. People shy away from cast pistons for no good reason.

    Once the engine is tuned the only difference would be weight of the piston.

    You guys are arguing about PSI numbers... what turbo did you find? Post up them flow charts....

    The only limit of boost is the detonation threshold. You could run 90psi of boost thru an ice chest, retard the timing to TDC and make 80hp. What's the point? To say you ran 90psi? Or to make power?

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  4. #13
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    Quote Originally Posted by MightyMirageMpg View Post
    Hyperpnuteptic are harder and brittle in comparison.
    Cool - I love new words! What does this mean?

    Hyperpnuteptic from various search engines:
    Google
    DuckDuckGo
    Dogpile

        __________________________________________

        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 ... 59.5 mpg (Imp)


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    Senior Member MightyMirageMpg's Avatar
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    Quote Originally Posted by Eggman View Post
    Cool - I love new words! What does this mean?

    Hyperpnuteptic from various search engines:
    Google
    DuckDuckGo
    Dogpile
    Sorry I probably spelled it wrong. I can't say it right either here's what I'm talking about https://en.m.wikipedia.org/wiki/Hypereutectic_piston

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  8. #15
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    As a turbo lsx guy, you guys are getting wrapped up too much a gauge reading (psi) and not pressure volume. PSI is used for a tuning reference.

    12psi on a lq4 with a 78mm makes nearly 600 at the wheel. 12psi on a 88mm makes nearly 700 at the wheel through a t56. The guys running the Mirage supercharged @ x amount of psi means squat. You don't know how much the supercharger displaces. A factory GM LSA supercharger at 12psi would get wrecked by a 2.9l whipple supercharger on the same engine at the same psi.

    STOP saying PSI like it matters. What matters is what size turbo/supercharger on what engine THEN the amount of boost.

    Pressure ratio is the measurement you want to focus on. I could stick a 35mm on my 6.0 lq4 and make a **** ton of psi and not as much power AND higher incoming air temps.

    The 1.2 in my Mirage doesn't rev high nor does it make a lot of power stock. Those two factors mean it's not going to displace much in terms of heat and exhaust pressure. So more than likely to maintain a driveable car you'd have to use a VERY small turbo. Sport bike turbos for bikes that are similar in displacement would likely be too large. In my very quick research I found the gt-15 as a probable candidate for a turbo charger. Maybe even a gt-12. More research would be needed in choosing the housing specs etc...

    Even so you'll notice the Mirage's engine does not make the recommended power for the gt-15 turbo (85). More than likely this turbo size would still work but would shift the powerband farther up. To run more cylinder pressure and rpm the valvesprings will more than likely need to be upgraded. Does anyone make valvesprings for these cars? I haven't a clue. You could run the turbo until you encounter valve float on the stock springs. CVT cars? I wouldn't risk adding the hp.

    As far a tuning.....I'd be willing to bet a megasquirt ecu could be made to work. I have seen them on other 3 cylinder engines. If someone wants to turbo one of these things they need to get engine management going FIRST.

    In the lsx world you can literally slap in a $300 cam and -$100 valve springs on stock engines and rev to about 6800 and throw a turbo, fueling, and tuning on it and make 7 or 8 hundred at the wheel with a 3 or $400 junkyard engine. That's why they are popular. You don't need forged anything to make stupid power. Gen3 factory rods are good for 700 wheel and gen4 (05+) at least 2 or 300 more. Factory pistons are fine just take them out and gap the rings .028.

    MightyMirageMpg sounds like he knows his stuff.

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    Last edited by Wubbalubbadubdub; 10-02-2016 at 01:40 AM.

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  10. #16
    Senior Member ahausheer's Avatar
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    http://turbochargerspecs.blogspot.co...30-hp.html?m=1

    Some info in the gt12 turbo. Looks promising but I know nothing about turbos.
    Last edited by ahausheer; 10-13-2016 at 05:04 AM.

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    I really wouldn't trust these stock blocks with a turbo. The rods look pretty wimpy, the pistons do have a decent ring land thickness but the iron cylinder wall is only like 1mm thick.

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    Yeah, seeing that torn down Mirage engine, installing a turbo is quite scary.

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    Senior Member ahausheer's Avatar
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    Quote Originally Posted by Gerami View Post
    Yeah, seeing that torn down Mirage engine, installing a turbo is quite scary.

    Why is that?

    Does the all aluminum and open deck come into play?

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    I guess so and how wilbur himself described his observation. On the other hand, in this supersonic age, anything can be imagined, I wonder how the alloy of the Mirage engine would compare to that of a modern jet fighter.



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