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Anyone have a calculator or can do the calc for acheiving 8.8-9.0:1 compression ratio on a stock d17a2 motor using what headgasket thickness? Also any downside to using too thick of a gasket?

 
Rep Power: 423

Just put A1 pistons in it and use a stock gasket. I've yet to see gaskets in varying thicknesses available for this thing. I'd worry about stacking up more gasket layers to make it thicker would make it more likely to blow.
you could just... oh I dont know.... google "compression ratio calculator" and figure out the thickness you'd need. All the values for the motor can be found on the internet.

 
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thing is i already have an A1 and my gasket went.....along with other things. I am swapping to an A2 and want to lower the compression a bit and get a stronger HG before I put it in, so I figure I can knock 2 birds with one stone by getting the Cometic MLS HG which uses a middle layer of varying thicknesses.

 
Rep Power: 423

Cometic gaskets blow at the same rate stockers do. When motors detonate, nothing will stop it from blowing. I've never seen anyone have any more luck with a cometic than they do with OEM gaskets. If its tuned right, the stock one will be fine.
Swap the slugs, use a stocker and ARPs.

 
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So no one with theA2 is have issues with detonation using that engine? I had my a1 running perfect but the fact of running a 9.9:1 kinda makes me feel uneasy about that. Any tips guys? I already have a boost afr of 12.3:1 and a timming pull of about 0-5deg from 0-.6 bar and run on 93 OCT with iridium plugs and relatively low charge temps. IS that good enough with the A2?

 
Rep Power: 423

Its 9.5:1 and if you're running 12.3:1 in boost, its too lean, regardless of the engine's compression. Thats playing with nearly no safety margin.

 
Rep Power: 327

12.3 could be more than safe depenant on load and if it were pinging or near ping