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Discussion Starter · #1 ·
For the guys that got over zealous in removing metal from your heads and ended up with ping issues..............here is a viable alternative to lowering compression without hurting your squish band setup.

I have attached a picture showing how to machine the piston tops to leave the squish areas intact and create a dish in the pistons to lower the compression.

Naturally you will have to perform calculations to determine the best depth and width to achieve the desired compression.

All the best, Ozzie
 

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IronButt
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That is a reverse dish and it is not the best for flame front propagation. You are better to run a thinker gasket than the dish. The GM 305 did this and they where the worst for spark knock. Being that you can run a 50 thou gasket and not really get into trouble.
 

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Discussion Starter · #3 ·
Hi HDWrench, how is it going mate? all good I hope...................I believe if you still maintain the squish, then flame propegation will be no different than using a flat top and dont forget we would not need to take much off the top of the piston to "correct" the comp ratio and bring it back to a manageable amount. Certainly this would be more effective than just putting in a thicker gasket which definiteley effects flame propegation.

On here a while back, someone put up a post about the Morbidelli 350cc reverse engineered motor that had the chamber shaped in the piston and it was so efficient the formula 1 boys started to copy it.

This idea is supposed to be making a come back as the engine designers try to find ways to speed up combustion fill and keep proper burn rates.

All the best, Ozzie
 
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