Increasing Compression on B16a
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From: GTA, Ontario, Canada
Increasing Compression on B16a
I am about to build the head on a SIR-II b16a after running low on funds instead of going the b20 route right away.
I have been searching alot trying to figure out cam choices, but I have found it hard to decide due to the compression issue.
Basically I would like to get the motor to atleast 11:0 + on 91 without touching the bottom end.
Basically what I was thinking was Omni flat faced valves, and a shaved head, but I have no idea what this would raise my CR to, or if it would even be enough.
I am going to continue searching but can some of you all motor pros advise me on the best path to take? (besides getting a b18/20, i would if i could)
BTW when I say low on funds, I can still afford good parts, just not 3+k for a compleate bottom end/head build at the moment.
I have been searching alot trying to figure out cam choices, but I have found it hard to decide due to the compression issue.
Basically I would like to get the motor to atleast 11:0 + on 91 without touching the bottom end.
Basically what I was thinking was Omni flat faced valves, and a shaved head, but I have no idea what this would raise my CR to, or if it would even be enough.
I am going to continue searching but can some of you all motor pros advise me on the best path to take? (besides getting a b18/20, i would if i could)
BTW when I say low on funds, I can still afford good parts, just not 3+k for a compleate bottom end/head build at the moment.
* B A N N E D *
Joined: Apr 2007
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From: winnipeg, canada
well theres a few things you can do. thinner headgasket will increase cr, shaving the head, flat valves.. etc..
if you plan to shave the head, and still use it in future NA stuff id watch how much you shave it cause then you might have clearance issues later on if you decide to get higher comp pistons. doing that unlike the headgasket isnt reversable (without buying a new head of course)
and as for cams any stage 1-3 cams will be ok for that setup maybe some BC3, or skunk2 stage2 (not pro series), take a look around there is lots of info on them
if you plan to shave the head, and still use it in future NA stuff id watch how much you shave it cause then you might have clearance issues later on if you decide to get higher comp pistons. doing that unlike the headgasket isnt reversable (without buying a new head of course)
and as for cams any stage 1-3 cams will be ok for that setup maybe some BC3, or skunk2 stage2 (not pro series), take a look around there is lots of info on them
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From: GTA, Ontario, Canada
Re: (2ltrtodd)
I have been doing some calculations on ZealAutowerks and aparently if I mill the head 0.010" and get a 2 layer head gasket that should get me to 11.0 static.
Then the addition of Omni flat valves should bump it .3 on a b16 so I have read to 11.3..
With a 2 layer HG and head milled 0.010" will I run into any issues with piston / valve clearance running Rocket M22 cams?
My next question is Static vs Effective comp ratio, when cams need 11.0 comp+ does that mean static compression or effective compression?
Also does anyone know how many cc the omni flat valves take out of the combustion chamber?
Modified by goldegg at 8:33 PM 5/13/2007
Then the addition of Omni flat valves should bump it .3 on a b16 so I have read to 11.3..
With a 2 layer HG and head milled 0.010" will I run into any issues with piston / valve clearance running Rocket M22 cams?
My next question is Static vs Effective comp ratio, when cams need 11.0 comp+ does that mean static compression or effective compression?
Also does anyone know how many cc the omni flat valves take out of the combustion chamber?
Modified by goldegg at 8:33 PM 5/13/2007
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From: I miss the east coast, TX, USA
recommended compression ratios for cams are always static compression ratios. From there you will use the intake closing point to determine the effective ratio.
As far as piston to valve clearance, the only way to know for sure is to clay the motor and it's not that bad of a job. Just don't skimp on that part or it could cost you in the end.
As far as piston to valve clearance, the only way to know for sure is to clay the motor and it's not that bad of a job. Just don't skimp on that part or it could cost you in the end.
* B A N N E D *
Joined: Apr 2007
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From: winnipeg, canada
Re: (Jay_Sensing)
they alwasy mean static compression. finding effecting takes into consideration the opening/closing points of your valves, and there is also dynamic compression...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jay_Sensing »</TD></TR><TR><TD CLASS="quote">
As far as piston to valve clearance, the only way to know for sure is to clay the motor and it's not that bad of a job. Just don't skimp on that part or it could cost you in the end.</TD></TR></TABLE>
actually clay is useless. the only good way to check is by getting a degree fixture, setting the piston to TDC, and checking on the dial indicator how much clearance, then locking it in vtec and blah blah blah.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jay_Sensing »</TD></TR><TR><TD CLASS="quote">
As far as piston to valve clearance, the only way to know for sure is to clay the motor and it's not that bad of a job. Just don't skimp on that part or it could cost you in the end.</TD></TR></TABLE>
actually clay is useless. the only good way to check is by getting a degree fixture, setting the piston to TDC, and checking on the dial indicator how much clearance, then locking it in vtec and blah blah blah.
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