Rebuilding advice?

Discussion in 'Mazdaspeed 3/6 Engine' started by jsilva, Sep 24, 2020.

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  1. jsilva

    jsilva Silver Member

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    I recently bought a used block/head with the intention of rebuilding it. I’m looking for some advice.

    My goal: I’m looking mainly for reliability, but I am also interested in eventually boosting the power a bit, maybe to the 300-320 range (I don’t need advice on boosting, just saying so you know what I’m planning). As I understand it, the OEM rods/pistons may not provide great reliability with higher power. Although maybe 300-320 is still in range?

    The engine’s condition: The person I got it from said it had rod knock (he also shared a video of it). The block and head are still together along with the oil pan, timing and valve covers. Looks to be in good external condition, and I can transfer parts (such as manifolds, turbo, etc.) from my existing broken motor.

    I’ve never rebuilt an engine and while I don’t want to be overly particular I do want to do what is needed. I’m sure there are many things I need to learn and I want to have a good idea as I’m approaching this.

    Thanks.
     
    jsilva, via an iPhone, Sep 24, 2020
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  2. StreetSpeed6

    StreetSpeed6 Diesel Slayer Gold Member

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    Are you planning to use this as a daily driver or just an every few days/weekend car? That will determine a couple decisions you will need to make imo. A little more ring gap will keep you safer for higher power im sure even with stock pistons and rings but might burn a bit of oil. The stock motor, if tuned properly, can safely support that power goal for s good while I would say. Some people make high hp on stock motors they just keep the TQ under a close watch and not above 350 or 380 being max for sure.
     
    StreetSpeed6, via a mobile device, Sep 24, 2020
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  3. jsilva

    jsilva Silver Member

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    This would be a daily driver kind of car. I mean I don’t actually go out everyday (3-5 days a week), but I want to see this as my goto car for when I do things.
     
    jsilva, via an iPhone, Sep 24, 2020
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  4. StreetSpeed6

    StreetSpeed6 Diesel Slayer Gold Member

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    Most reliable will obviously be your power goal with better internals but from what I gather 300-320 is a safe dd goal for a stock motor. I would only say if you are planning to want it to last a long time to consider better pistons and rods just so you know for sure it isn't going to throw a rod after 30-40k miles. I have wesico 88mm 2628 pistons and manley h beam rods and have had zero issues. I'm at your power goal now basically and thst is half of what they are rated for so it all depends what you can spend. Stock head is also probably more reliable than modifying it and guys make plenty of power with stock heads and cams.
     
    StreetSpeed6, via a mobile device, Sep 24, 2020
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  5. StreetSpeed6

    StreetSpeed6 Diesel Slayer Gold Member

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    Oh and im at like 13k miles already. Absolutely zero piston slap with the 2628 pistons even in zero degree weather on cold start. I just haven't had the funds to get to the higher power yet but this setup has been a dd as well
     
    StreetSpeed6, via a mobile device, Sep 24, 2020
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  6. jsilva

    jsilva Silver Member

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    Thanks StreetSpeed6, I appreciate the info. One thing I’m unsure about right now is how to know what size rings to get. Should I base it entirely on a measurement once the cylinders are accessible or can I assume the proper size according to original design? I know if the walls have some damage that I’ll need to get that sorted out, but in that case would it be better to get different size rings or would I definitely need to get it sleeved?

    There are many things I don’t know... :)
     
    jsilva, via an iPhone, Sep 24, 2020
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  7. StreetSpeed6

    StreetSpeed6 Diesel Slayer Gold Member

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    Well first off I am calling a bit of back up on thst one lol
    @JohnnyTightlips
    @Sho
    Next is my attempt to answer this... My assumption would be to first decided whether it is just needing honed or actually needs to be bored out to get it back within tolerances. If bored I would expect it to be easier to just go with an aftermarket piston.(88mm instead of stock 87.5) ring gap if you are expecting to run only 320-350hp could probably be tighter since you aren't going for major boost. Most guys go around 0.0020 on ring gap but wesico recommended like .0017 for a 2.3l boost application I personally would go bigger pistons before sleeving a motor unless it was a lot cheaper and was still supposed to be reliable
     
    StreetSpeed6, via a mobile device, Sep 24, 2020
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  8. Chris' Garage

    Chris' Garage Greenie Member

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    if you are breaking down the motor... especially with a rod knock, you might as well have the entire block machined. there are way too many tools needed to check yourself. in the machining process you will know if you need bigger pistons or not.
     
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  9. jsilva

    jsilva Silver Member

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    I really appreciate the input, thanks! I am planning on having it machined. Do you think I should have the cylinders honed regardless?

    Lots to learn, but I’ve got a better idea of where to go from here.

    Does anyone have recommendations for a good machine shop in the Philly area?
     
    jsilva, via an iPhone, Sep 24, 2020
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  10. Chris' Garage

    Chris' Garage Greenie Member

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    the machinist will know what's best. if the bores are round and not damaged you can hone, otherwise over bore.
     
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  11. StreetSpeed6

    StreetSpeed6 Diesel Slayer Gold Member

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    When I built my motor it was at 200k miles and the bore looked great and could've been ball honed but I already had the oversized pistons and wanted to bore it anyway. Are you wanting to do assembly of the motor and just have someone else do the machining? If so just invest in very reliable 1/2" drive and 3/8" torque wrenches. Aside from that look at @JohnnyTightlips Mazdaspeed 3 build thread as he has tons of great info on doing your own build. Pretty sure he made a bunch of how to threads as well so read up on all of it
     
    StreetSpeed6, via a mobile device, Sep 25, 2020
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  12. JohnnyTightlips

    JohnnyTightlips Platinum Member

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    Do this.
    1. Take bare head and block to machine shop
    2. Have them check block for round and see if you can keep 87.5mm or need to go 88mm bore. DO NOT have them bore it until you have the pistons and they can measure it with them. DO NOT buy pistons until you know what you can use. When in doubt 88 is fine for your goals and only can become and issue at 600+hp with wall strength of the block.
    3. Have them check the block and head surface to see if they need decked.
    4. Read my entire build thread. HERE
    5. Check your crank and make sure it is in good shape, have the machine shop polish it.
    6. After they do all that and say it is worth using you can buy your pistons and rods and flywheel and have them do a balance of the rotating assembly Or just have them balance the pistons and rods to the crank.
    7. I would recommend paying the shop to install the wrist pins to the pistons if it is cheap as that sucks.
    8. Manley Platinum pistons and rods will be perfect for your DD life and 550+ hp
    9. You will not need the trimetal bearings for your goals.
    10. You can use OEM head studs but they will lift around 500 so if you plan to do more than that get the freek h11
    11. I am sure there is more I am forgetting. If you read my thread carefully it should really help you on your journey. It's a lot of fun , enjoy.
     
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  13. Easter Bunny

    Easter Bunny Professional Engineer Platinum Member

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    You also don't need a deck plate to machine the block even if the machine shop says they do.
     
    Easter Bunny, via a mobile device, Sep 25, 2020
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  14. JohnnyTightlips

    JohnnyTightlips Platinum Member

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    My machine shop did not use a tq plate and everything is working well. I don't think it is the end of the world but more of a nice to have.
     
  15. Easter Bunny

    Easter Bunny Professional Engineer Platinum Member

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    It literally doesn't do anything. The head bolts/ studs are really long and extend below the Piston area of the cylinder. Someone on the old forum did a shitload of measuring a block with and without a deck plate and the difference was miniscule as in well below the precision of the measuring tools.
     
    Easter Bunny, via a mobile device, Sep 25, 2020
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  16. jsilva

    jsilva Silver Member

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    Thanks for the replies everyone! Very helpful.
     
    jsilva, via an iPhone, Sep 25, 2020
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  17. jsilva

    jsilva Silver Member

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    I was just reading about flywheel balancing and I’m not sure I fully understand and wanted to clarify.

    The motor I bought didn’t have the flywheel. Is balancing another flywheel a big ordeal given that there isn’t an existing flywheel? Or is having it balanced like Johnny says meant to cover this scenario?
     
    jsilva, via an iPhone, Sep 28, 2020
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  18. Easter Bunny

    Easter Bunny Professional Engineer Platinum Member

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    Flywheel should be self balanced
     
    Easter Bunny, via a mobile device, Sep 28, 2020
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  19. StreetSpeed6

    StreetSpeed6 Diesel Slayer Gold Member

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    When I had my motor built I balanced the crank and pistons together only and deleted the balance shaft. I bought a new fidanza flywheel but didn't balance it with everything else and it is just fine man so don't sweat it if you only balance the crank and pistons and rods together!
     
    StreetSpeed6, via a mobile device, Sep 28, 2020
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  20. JohnnyTightlips

    JohnnyTightlips Platinum Member

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    A flywheel comes balanced to itself, you can however get it balanced to the entire rotating assembly so that all the pieces are balanced as a unit. It is not the end of the world but is nice to have if you can do it.
     
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