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Thread: Turbo pistons available!

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    Turbo pistons available!

    The new 4b40 engine in the eclipse cross has a 75mms bore and the pistons are forged! Semi floating wrist pin, press fit into the connecting rod while the piston floats. .8mms offset wrist in set towards the thrust side of the engine. Unfortunately I don't have any other measurements yet and I can't remember how the wrist pins are set on our 3a92, either way I'm excited.



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    That's interesting. Where did you get this information? I would like to read more.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 50.1 mpg (US) ... 21.3 km/L ... 4.7 L/100 km ... 60.2 mpg (Imp)


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    Mitsubishi academy. From my parts guy I got prices around $75 for one piston and wrist pin and around $130 per rod. I don't think we'll be able to use the rods though as the stroke on the 4b40 is only 84mms compared to our 90mm. I wasn't able to get deck height but it does look like a taller block, probably has a decent rod ratio.

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    Cheers for giving this information, I had a suspicion this was the case as the launch information about the 4b40t was that it was based on the 4a91, which is what the 3a92 is based on.

    I'm tempted to purchase the pistons for my build, I'm looking to purchase a crank so I can measure piston crank journals so i can figure out a H beam rod that might work, in the first few years of production there were suppliers on Alibaba listing H beams for the 3a92 but that has all dissapeared.

    I can only imagine what a 180-200bhp mirage would be like to drive.

    link to the wiki with some info on the 4b40 https://en.wikipedia.org/wiki/Mitsubishi_4B1_engine

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    Quote Originally Posted by wilbur View Post
    Mitsubishi academy.
    Mitsubishi Academy is password protected.
    Is there any other way for others to access this information?

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 50.1 mpg (US) ... 21.3 km/L ... 4.7 L/100 km ... 60.2 mpg (Imp)


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    No it's for Mitsubishi employees. I think I remember them saying something like the trans used in the eclipse cross is the same one used in the mirage. I'm not sure though I'll have to look through my book again today. If that's the case I think we might have a decent swap, the 4b40 only appears to be an inch maybe two longer than the 3a92

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    Quote Originally Posted by wilbur View Post
    No it's for Mitsubishi employees. I think I remember them saying something like the trans used in the eclipse cross is the same one used in the mirage. I'm not sure though I'll have to look through my book again today. If that's the case I think we might have a decent swap, the 4b40 only appears to be an inch maybe two longer than the 3a92
    Only drama with the 4b40 swap is that it seems to be CVT only

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    There was a version of the 4a engine that was turboed in a Chinese application. I posted it on here a while back. Can't remember if it was the 4a91 or 2 though. The 4a92, I think, would be direct replacement as its just the 4 cyl version of our engine. Seemed like a pretty obscure engine though and the parts might be all stock to the non turbo.

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    The 4a engines were available in Mitsubishi Colts available in Europe Japan Australia maybe Canada. I think some did come with turbos.

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    I don't know that it matters what it is normally bolted to. If you're going through the work of a swap nobody's done yet I'm sure you'd put it on a manual trans and get it tuned accordingly.



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