M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Swaps, Turbos, Buildups => Topic started by: Tommy on December 09, 2017, 03:36:51 PM
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Hello everybody, I plan on doing a low cost turbo project. Stock ECU, stock internals, boost only about 0.3-0.5 bar, pull through AFM setup... I have a question about lowering the compression ratio. This build being low cost, and me being broke student, MLS thick head gasket is not an option. I have the engine fully disassembled so I thought I would put in m40 con rods, but they are too short and it would give me around 6.8:1 CR which is too low. I think my only two options are: 1. Stacking 2 head gaskets - Will they leak? Will this be reliable? 2. Decking the pistons about 1.75mm - Will they be still strong enough for the FI? Both of these options are cheap and will leave me with around 8.5:1 CR which is perfect, but I can't decide which route is better/more reliable. Any thoughts? :D
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I had a buddy years ago that built a stroker motor where the pistons he was using came out of the block too much. He stacked 2 stock headgaskets spraying them with copper spray before install. They never gave an issue.
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I had a buddy years ago that built a stroker motor where the pistons he was using came out of the block too much. He stacked 2 stock headgaskets spraying them with copper spray before install. They never gave an issue.
Thank you for your answer! I was already leaning more towards the stocking headgaskets idea, because i am not really comfortable with shaving of the pistons for boost applications. :D Can you give me some more answers? - Was your friends stroker m42b18 as well? Did he fully spray both gaskets? Or did he leave the "inside" area where the gaskets were touching uncoated?