boring to 86mm

[mikecb7LX92]

i was just wondering if i have to do anything to the head, because im building up my f22 block with bisi 86mm 12.0:1 pistons and i dont want to have any problems down the road with the combustion chambers.

[stretch JDM]

for the head, i would go ahead and get a valve job done , a bisi cam,and stronger head bolts at least . as far as you are going that's what i would do.

[mikecb7LX92]

i got a stage 2 bisi cam his pro springs and im looking into a 3 angle valve job real soon before the block gets done

[stretch JDM]

^ sounds like you are on the right path bro . well good luck on your build and may it serve you well.i didn't bore mine out, but did a head upgrade dropped 600 on it and it runs great .mine is ported polished and got a 2.3 cam and a 3 angle valve job . it pulls like crazy and with the spray. wow

[protunef22]

This makes me excited to hear how it pulls. i got port and polish but need to find a shop for the valve angle job.

[mikecb7LX92]

thats fuckin sweet bro, any ET times? but yea, i dropped like 700 into the head, milled it down .020", 3 angle valve job. In the cb my ET dropped from a 15.9 to a 15.3 with bolt ons, im just excited to see how the f22 is gunna pull in the civic.

[19dabeast85]

As far as altering the combustion chambers for the larger bore.....I've seen quite a few builds here with reputable builders and none of them did any combustion chamber work other than smoothing and polishing.

I'm also planning to build a block with bisi 12:1 pistons and stg2 cam along with head porting, intake porting, and my bisi header, etc......interested to see your results! Do you have a build thread for this project?

[mikecb7LX92]

naw i dont have time all like that for a build thread, and since the only thing thats left for my build, ill just post up the end results when its done and the car is tuned. atleast you got the bisi header, that would really complete my build.

im actually looking into getting the head ported and polished, but i cant find anybody around the cleveland area with a good rep so if anybody knows a place it will help me a ton.

[deevergote]

Personally, I would make the combustion chamber bore match the cylinder bore. It doesn't HAVE to be done, but if the combustion chamber bore is 85mm, there will be a bit of an overlap, and most likely a sharp edge. Any sharp edges in the combustion chamber COULD become hotspots and be a source of detonation. If you're building the bottom end that much already, the head should have machine work to take advantage of it anyway, so I'd work that into the plan.
That's what I would do, anyway. I honestly don't know that detonation risk to be a fact. It's really just theory based on how internal combustion engines work.

[mikecb7LX92]

thats the main thing that im worried about, i dont wanna build it, put all this time and money into the bottom end for it to just mess up because of one dumb mistake

[deevergote]

Better to be too careful than not enough.
Do your own research, of course, to verify anything you learn on a forum.

[mikecb7LX92]

ima do more research, but im gunna get it contact with one of bisi's reps. and ask them, but until then ill just keep researching other member threads and other forums.

[deevergote]

Be sure to verify even what you get from Bisi's rep... I've seen past reps of his on here that knew jack shit! Bisi himself is an absolute genius, and if a rep is ACCURATELY relaying his information, then that's good... but it's entirely possible that the rep may be relaying the information inaccurately, or just guessing on their own. Not saying they're all idiots... I'm sure Bisi hires the best he can find... but still...

[mikecb7LX92]

yea i feel you deev, bisi is the shit! but i will double and triple check....i mean it aint just a few bucks gettin thrown around u know what i mean.

[GhostAccord]

Using an 86mm head gasket and having the CC rimmed to 86mm is a good way to ensure your investment has every chance to be as reliable as possible.