help please, don't want to ruin my new motor

[Dsm810z]

new setup: evo 9 pistons (.02 over), evo 8 valvetrain, g4cn (4g67) head, hks 264/272 cams, 6 bolt 4g63 block (machine shop decked the crap out of it).

Projected cr 10:1

I have no safc currently, but plan on getting one around christmas. Until then, should I advance my timing a couple of degrees (via cas) until I get the safc, or will it be fine until I get the safc? I just want to be safe and not ruin my new motor that I spent so much time/effort/money on. Please post any advice/tips you may have on this subject. New to tuning, please bare with me.

Thanks in advance,
Chris

 

[pneumo]

I think you'd want to retard the timing a few degrees since you have higher compression pistons.

 

[Calan]

Agreed. And run only the highest octane gas you can get with that CR.

 

[Dsm810z]

I was planning on running the highest octane anyways so if I retard the timing a few degrees will that take care of things until I get a safc? Also, will the safc be sufficient for tuning this setup?

I was n/t to begin with the the evo pistons are actually 8.8:1 as opposed to the n/t 9:1

Appreciate the quick replies,
Chris

 

[95blackGsTurbo]

new setup: evo 9 pistons (.02 over), evo 8 valvetrain, g4cn (4g67) head, hks 264/272 cams, 6 bolt 4g63 block (machine shop decked the crap out of it).

Projected cr 10:1

I have no safc currently, but plan on getting one around christmas. Until then, should I advance my timing a couple of degrees (via cas) until I get the safc, or will it be fine until I get the safc? I just want to be safe and not ruin my new motor that I spent so much time/effort/money on. Please post any advice/tips you may have on this subject. New to tuning, please bare with me.

Thanks in advance,
Chris

Is this based on an estimate or measurement. You can't physically machine enough off of a block to get a 10:1 compressor ratio. The pistons would be coming out of the block and would slam into the head. Even with MAJOR decking, and EVO 8.8:1 pistons I would say you aren't even at 9.5:1. The difference is only 43cc to 47cc bowls. So it adds roughly .4 to the compression ration. So with the EVO pistons that puts you at 9.2:1. Now obviously the only true way to tell is to do a volume test on the block/piston/head.