How exactly is compression changed.. is this done simply by change fuel mapping? if so would this Apexi unit AFC SELECT be a good option for OBD2 tuning for cost?

 

to change compression, you have to change the cylinder volume. you can really only do it mechanically. lower it by using a thicker headgasket, raise it by using a thinner one, milling the head (taking the head off and cutting a few thousanths of an inch off of the mating surface, making the domes in the head lower volume, which will raise compression, or a few other things like valves that take up a little more room or high compression pistons.

 

all that will be done while the block/head are being rebuilt .. so whoever is doing the build i just tell them what i want my compression basically?..guessing from what i read on the Y8 buildup.. 11:0:1 would be a good compression to go with or even 10:5:1 ?? any for sure suggestions

 

Basicly you buy the pistons for what compression you want. Head and head gasket combos can change compression also but rarely more than a full point

 

Ok.. so looking at the 75.5 pistons for my Y7 block and slapping a rebuilt Y8 head (ported/polished) 3 angle valve job.. with I/H/E and say Skunk2 68mm TB/Intake manifold..ARP head studs.. (sleeving only if needed) While im having head done i may get crower stage 2 NA cam with springs/lifters..do u think i need a metal head gasket?????? also what ECU would work for tuning that is cheap for OBD2.. ie 96 civic.. hondata work for this app?

 

obd2 is not tunable... convert to obd1 (actualy i may be incorrect, i know that only obd1 , for turbo.. and all program are written for obd1.. so im 90% that you cannot tune an obd2... and 99.9% that you cannot tune an obd2b... ... convert, young man, convert and be saved!!! haleluya

 

you can tune OBD2, just not chip the ECU. a piggyback will work fine, and Hondata is a great setup, but wont work with OBD2 civic systems. but you can do a simple V-afc that will get the job done. though I would still look into converting to OBD1 since it is easier to tune, and you wont get as many check engine lights.

 

i have emissions inspections.. obd1 conversion will fail me.. and will the afc unit i have listed above work then?