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Thread: Champhered pistons

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    Champhered pistons

    Anyone have a picture of how to campher pistons so they don't hit a stock headgasket.

    I've got 94MM pistons and I want to use a stock headgasket. I spoke to ray about it but I failed to ask him how to do it.

    Thanx in advance

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    its a stock block. according to Ray P. the walls are not to thin for 94mm. He also said that inorder to use a stock gasket the pistons need to be moded

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    Forum User Feedback Score 13 (100%) Austin@STM's Avatar
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    Quote Originally Posted by steve68 View Post
    94mm pistons in what block?

    A stock 74 gasket would do (94.2 ish mm), taking a 72 block out to 94mm is a bit silly, the walls are too thin. Will get heaps of blowby and power loss.
    Stock TT pistons stick out of the top by .5 or so mm. Aftermarket pistons might not, depending on the make.
    Don't have a pic though. Chamfering pistons is a lot of work for no gain.

    Steve
    how would boring a block out to match the piston size cause blowby?

    If you need to chamfer the top of the pistons make sure to take your time and only remove as much as you need so you dont weaken the edge of the piston, or effect the rings at all, it shouldnt take much. Also Ray has built an engine or two and knows if it will work or not i think.

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    I would just get a set of aftermarket gaskets. That way you wont have the chance of messing up your pistons. Head gaskets cost less.

    STM: COMETIC OVERSIZE HEAD GASKETS | 3000GT/STEALTH | C4243-051 | C4240-051

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    You will need to cut off the 90 degree edge of the piston crown. A machine shop can do it for you. If you are ambitious and on a budget(build) you can file them by hand. I have done that to save coin and made big power with them.

    -Chris

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    Chris knows what he is talking about.

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    the stock 6G74 gaskets have less layers than the 6G72 gaskets

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    Won't piston champhering or thicker head gaskets lower the base compression?

    About cylinder blowby through boring: I read in Jeff Hartmann's Turbo Performance Handbook (awesome book!) how Ford pushed the 2.0L Ecotec to the limits as a drag race engine and they also tried to fight cylinder wall warping and foremost head-lift. They tried to fill the water jacket with epoxy to stabilize the block and failed.
    In the next trial they boosted the still stock-bored 2.0L Ecotec engine to 600 hp by upgrading to super duty head studs and O-ringing the head. Still retaining the OEM head gasket though.
    They pushed the thing even further but I wanted to point out that even a stock bore will have blowby through head lift when boosted far enough. Boring the cylinders will increase the problem.

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    Hey guys, thanx for all the good advice, Especially you Jeff. I'm all about saving some coin. I may attempt it. I'll take my time and see how it goes.

    I never did understand about blow by and stuff like that. I purchased this motor from a guy on the 3s site and he claimed it was good. But once I installed it I noticed it loosing coolant. i did a compression test and the rear bank was over 200 and the front was 150 so I'm not sure what's going on with the rear head but I'll know once I pull it apart. But thanx for the advice guys.

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    Quote Originally Posted by benson8277 View Post
    Hey guys, thanx for all the good advice, Especially you Jeff. I'm all about saving some coin. I may attempt it. I'll take my time and see how it goes.

    I never did understand about blow by and stuff like that. I purchased this motor from a guy on the 3s site and he claimed it was good. But once I installed it I noticed it loosing coolant. i did a compression test and the rear bank was over 200 and the front was 150 so I'm not sure what's going on with the rear head but I'll know once I pull it apart. But thanx for the advice guys.
    When you chamfer them make sure to smooth out the edges of the crown. Sharp edges are not a good thing at all. Also I would not suggest a straight 90 degree. angle the chamfer so you are taking more off the top then the side wall. good way to do it is to use the stock gasket as a template to put a mark around the top of the piston.

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