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Thread: 2017 3A92 engine with roller cam.

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    2017 3A92 engine with roller cam.

    http://www.badasscars.com/index.cfm/...100/prd100.htm

    Are roller cams better? The answer is yes. Less friction, wear, faster lift rates. We know that 2017 has higher HP, but how about torque curve across the range?


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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


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    Moderator Eggman's Avatar
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    Quote Originally Posted by cyclopathic View Post
    ...faster lift rates.
    Could you explain how a roller cam has a faster lift rate?

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 50.0 mpg (US) ... 21.2 km/L ... 4.7 L/100 km ... 60.0 mpg (Imp)


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    Quote Originally Posted by Eggman View Post
    Could you explain how a roller cam has a faster lift rate?
    From what I understand due to lower friction they can push more aggressive cam profiles without wear concerns. This may be of benefit across the range not at the top only.

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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


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    Moderator inuvik's Avatar
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    I was impressed that Mitsu added a roller cam to this motor. The 2017 will have 4 more hp. People laugh when they hear that number but for a small motor that was rated at 74hp this is slightly more than a 5% increase in hp. Not bad at all.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.6 mpg (US) ... 17.3 km/L ... 5.8 L/100 km ... 48.7 mpg (Imp)


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    Senior Member Cobrajet's Avatar
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    There are also much lower frictional losses with roller cams. Easy way to make some HP without reworking the engine too much.

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    Moderator Eggman's Avatar
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    Quote Originally Posted by cyclopathic View Post
    From what I understand due to lower friction they can push more aggressive cam profiles without wear concerns. This may be of benefit across the range not at the top only.
    Wow. It already has MIVEC. I didn't know Mitsubishi changed the cam profile. Well, that's great news. I don't think I heard that in the press release.

    Go MIVEC! (And higher cam profiles!)

    Timing is continuously independently controlled to provide four optimized engine-operating modes:

    • Under most conditions, to ensure highest fuel efficiency, valve overlap is increased to reduce pumping losses. The exhaust valve opening timing is retarded for higher expansion ratio, enhancing fuel economy.
    • When maximum power is demanded (high engine speed and load), intake valve closing timing is retarded to synchronize the intake air pulsations for larger air volume.
    • Under low-speed, high load, MIVEC ensures optimal torque delivery with the intake valve closing timing advanced to ensure sufficient air volume. At the same time, the exhaust valve opening timing is retarded to provide a higher expansion ratio and improved efficiency.
    • At idle, valve overlap is eliminated to stabilize combustion.
    MITSUBISHI The Mechanism of the New MIVEC

    I like to watch the video in slow-motion.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 50.0 mpg (US) ... 21.2 km/L ... 4.7 L/100 km ... 60.0 mpg (Imp)


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    When I got behind the wheel I was fairly impressed fow flexible and usabi torque is on 3A92 especially under 2k.

    It is interesting to see how roller cam improve on it. HP ratings are great but most of the time engine is below 4k, so changes to that have more impact on drivability. Rollers allow faster valve opening/closing, so potentially better breathing, less overlap, higher effective compression ratio. That could also improve MPG.

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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


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    Moderator inuvik's Avatar
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    It's one of the things that sold me on the Mirage was the 3A92. It's a high quality engine that Mitsubishi has obviously put a fair amount of $$ into designing. Timing chain, MIVEC, multi-cam and high compression still able to run on regular octane fuel. Now with the addition of a roller cam and a more hp. Pretty darn impressive. Although the Mirage isn't perfect of course (suspension and rear axle alignment), I haven't read of ANYONE having any major mechanical issues with the engine. Go to any other forums on subcompacts and there are many tales of woe with engines.
    Last edited by inuvik; 11-30-2015 at 06:38 PM.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.6 mpg (US) ... 17.3 km/L ... 5.8 L/100 km ... 48.7 mpg (Imp)


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    To give a real world example of the positive effects of a roller cam, consider this;

    Roller cams, since they decrease friction, also increase longevity. A friend of mine had built a pretty crazy OHV pushrod V6 motor. He first went with a traditional cam, and after a single highway run of 160 miles, a couple of cam lobes had already worn down (300 lb/inch valve springs put a LOT of force on it). After a swap to roller lifters, he no longer had problems with the cam wearing down, even with 20 psi of boost, 300 lb/inch valve springs, and a rev limit of 8200 rpm that was touched quit often at the track.
    Certified holder of useless car knowledge.

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    Senior Member Rival Autosport's Avatar
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    Now my questions are if the current motor can be rebuilt to run roller cams? Will it require a full head swap? How about ECU mapping to accommodate the possible cam profile changes?



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