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  1. #21
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    Sean, what do these pistons put the compression number at in the 15f?

    https://store.schnitzracing.com/woss...ki-zx12-00-05/


  2. #22
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by TMiller View Post
    Sean, what do these pistons put the compression number at in the 15f?

    https://store.schnitzracing.com/woss...ki-zx12-00-05/

    Nice, those are the same compression ratio as the JE's I ran for a while. Its right at 12:1 if my math was right 8ish years ago...

    They fit nicely between the 10.6:1 stock 15f and the 14:1 12f pistons in a 15f motor.

    I ran it on 93 octane and never saw any evidence of deto.

    Sean

  3. #23
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    I thought MTC had a piston to give the 15f 9.5/1 that means it would be listed at like 8/1 for the zx12

  4. #24
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by TMiller View Post
    I thought MTC had a piston to give the 15f 9.5/1 that means it would be listed at like 8/1 for the zx12
    Rough guess with no math but that sounds right. I have the 9.6:1 mtc's going into my motor if uschrome can get their stuff together and replate my cylinders properly.

    Sean

  5. #25
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    I cant remember what james said exactly but I recall him saying they were mtc 9.5/1 in the turbo motor, I dont see a listing on their site for that.
    What are you building that the 9.8 pistons are going in?

  6. #26
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by TMiller View Post
    I cant remember what james said exactly but I recall him saying they were mtc 9.5/1 in the turbo motor, I dont see a listing on their site for that.
    What are you building that the 9.8 pistons are going in?
    They may be 9.5s, I don't remember specifics. They are dished further than the ither mtcs I have. MTC doesn't make the 15f pistons anymore but they have been helpful in getting pins and clips for them since thats a stocked part.

    Its a vortech v5 h trim sc'd motor. Getting rods, pistons, cam gears, retainers, new valve seals, and the ported head I did for the na 15f.

    Sean

  7. #27
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    So MTC actually made pistons specifically for the 15f? I thought they were just zx12 pistons being used

  8. #28
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by TMiller View Post
    So MTC actually made pistons specifically for the 15f? I thought they were just zx12 pistons being used
    Yep, these were actually 15f pistons. They came in the old riva boats. Kawi factory ran them as far as I know. They were available in stock compression and lowered. I have one set of each.

    They use heavier wrist pins which when added to the lighter pistons means they weight the same as stock. They also use kawi stock rings unlike JE who used a differebt ring pack.

    The 9.6:1 set I have are currently getting coated. The 10.5:1 set is for sale if anyone wants them.i didn't want to mess with race gas on my setup so I went lower static compression.

    Sean

  9. #29
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    Ok so the pistons MTC made back in the day specifically for the 15f had compression ratio numbers listed for our motors not the zx12 ? I sent him an email and he stated my motor has 9.5 pistons with a 1mm spacer plate which he thought should be 8.5/1

    Now that I think of it I remember speaking with MTC a few years ago and I think they said they could do a run of pistons but need a minimum order.

  10. #30
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by TMiller View Post
    Ok so the pistons MTC made back in the day specifically for the 15f had compression ratio numbers listed for our motors not the zx12 ? I sent him an email and he stated my motor has 9.5 pistons with a 1mm spacer plate which he thought should be 8.5/1

    Now that I think of it I remember speaking with MTC a few years ago and I think they said they could do a run of pistons but need a minimum order.
    Correct

    They were specific to the 15f and came in 2 variants from what I have been able to find.

    When mine get back from being coated I will take measurements. I am planning on ditching the spacer when I put mine together.

    Sean

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