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Thread: 2.1 m10

  1. #1
    Join Date
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    2.1 m10

    I am planning to build my m10 this summer. I will be shooting for 400whp on e85

    I have two options.

    Option 1 using 92x82 vw type 1 pistons and s14 rods

    Bore:92mm
    Stroke:80mm
    S14 Rods: 144mm
    Deck height:217.5mm
    Compression height:35mm
    Headgasket thickness:1.5 or 1.8mm
    Combustion chamber volume:63 cc
    Compression ratio: 9.25:1

    With this setup pistons will be sticking out approximately 1.5mm out of hole. With the 1.8mm gasket i should have 0.3mm clarance.


    Or I could mill 1.5mm from top of the piston and zero deck it which will result in 8.25:1 compression ratio

    Option 2 using 92x69 vw type 1 pistons and m10 rods



    Bore:92mm
    Stroke:80mm
    M10 Rods: 135mm
    Deck height:217.5mm- 2.7mm= 214.8
    Compression height:39.8mm
    Headgasket thickness:1.5 or 1.8mm
    Combustion chamber volume:63 cc
    Compression ratio: 8.25:1

    I would have to deck the block 2.5-2.7mm to get it "zero decked"


    What would you rather do? Deck the block and use shorter rods or mill the pistons and use longer rods?

    Or maybe let the pistons stick out the holes and use 1.8mm gasket but it will give me only 0.3mm clearance.




    Thanks




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  2. #2
    Join Date
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    IMO i'd see if enough meat on the piston and go that route.

    Your other two issues are the quench of .3mm that's only 12 thou clearance and pretty tight. Would make at least .028-.035". Far as the block decking 2.5mm route no way man forget it that's decking 0.100 thou I was looked at sideways for doing mine .018" lol

    400hp reliable; just buy real forged custom pistons to start with for the application. 144mm rods either S14 or aftermarket. Would last a lot longer.
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  3. #3
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    Quote Originally Posted by autox320 View Post
    just buy real forged custom pistons to start with for the application.
    This is what I told him on facebook.

    The stock deck height is 217.3, not 217.5.

    Should probably be using an MLS headgasket anyway, and they come in at least .080 and .120 inch (approx 2 and 3 mm). Don't know if there's any thicknesses between those. This still alters your cam timing, but I think advanced is better than retarded. Might need an adjustable gear either way.

    Longer rods are always better, but used S14 ones are costly and aftermarket ones are stratospheric. I'd rather spend that money on the correct pistons and keep the stock rods. They are VERY strong. An old forum member called Good-n-tight (or something like that) managed to bend them by turboing a stock E30 M10 to like 550hp.

  4. #4
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    Quote Originally Posted by Layne View Post
    This is what I told him on facebook.

    The stock deck height is 217.3, not 217.5.

    Should probably be using an MLS headgasket anyway, and they come in at least .080 and .120 inch (approx 2 and 3 mm). Don't know if there's any thicknesses between those. This still alters your cam timing, but I think advanced is better than retarded. Might need an adjustable gear either way.

    Longer rods are always better, but used S14 ones are costly and aftermarket ones are stratospheric. I'd rather spend that money on the correct pistons and keep the stock rods. They are VERY strong. An old forum member called Good-n-tight (or something like that) managed to bend them by turboing a stock E30 M10 to like 550hp.

    yup pay once cry once

    I actually messaged Otis (Good N Tight) about his motor before it blew. I was curious about the rods and my memory was foggy from early 2000's. Stock rods 365rwhp and 333rwtq but he S'd a rod badly when it went.

    Not a MLS fan, but some have success. Needs fine RA finish and then still can leak between layers. I thought aftermarket Hbeam rods were cheaper than S14 parts. No idea what the chinese eagle ones will hold I like arrow rods, but can say the price is high. Cheaper than titanium rods though.
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  5. #5
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    Quote Originally Posted by autox320 View Post
    yup pay once cry once

    I actually messaged Otis (Good N Tight) about his motor before it blew. I was curious about the rods and my memory was foggy from early 2000's. Stock rods 365rwhp and 333rwtq but he S'd a rod badly when it went.

    Not a MLS fan, but some have success. Needs fine RA finish and then still can leak between layers. I thought aftermarket Hbeam rods were cheaper than S14 parts. No idea what the chinese eagle ones will hold I like arrow rods, but can say the price is high. Cheaper than titanium rods though.
    Yep otis popped his m10 at around 360whp.

    Maybe you're right. It will be probably better to get proper pistons.

    I am not a big fan of mls either. I would rather oring the block.


    Yes i was thinking cheap cx racing s14 rods. Couple of my friend push them to 500whp in the volvo 5 cylinder motors without any issues.

    I am still tempted to try the vw pistons just to see if it will hold.


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  6. #6
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    Quote Originally Posted by Retoropak View Post
    Yep otis popped his m10 at around 360whp.

    Maybe you're right. It will be probably better to get proper pistons.

    I am not a big fan of mls either. I would rather oring the block.


    Yes i was thinking cheap cx racing s14 rods. Couple of my friend push them to 500whp in the volvo 5 cylinder motors without any issues.

    I am still tempted to try the vw pistons just to see if it will hold.


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    If going the first route still. I've not seen the tops, but if try it stick together and see for yourself then measure will be the only way. Then machine off what you need. Just a guess but I'd imagine take about .020" off them which is nothing if lots of meat above top ring. Maybe cut valve reliefs depending on cam used. Actually i've heard cx/eagle/rsi (and many others) (chinesium) have been fair also. Double check sizing mic them once have them in your hands. If someone hasn't done it yet would be interesting to see FEA on those.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  7. #7
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    You know second thought maybe ask IE about their rods. Get real ARP bolts at least. I have heard horror stories of chinese copy ARP letting go.

    This comes to mind. S14power forum member that didn't realize he bought chinese copy ARP rod bolts
    when you gamble on chinese rod bolts (they'll even be stamped arp2000 but not the real thing)


    https://www.youtube.com/watch?v=m0uHM6lrUSM
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  8. #8
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    If I was going to do it, I would only machine down the piston below the quench pads and around the edges. It's hard to get high enough compression with flat tops and a 1.8 head, even for a turbo application. Might as well keep the small amount of extra compression available there.

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