What would it cost to mill the heads an what gains in performance? Just curious thanks
Around $30.00 each and around 3% increase of hp and toirque from 1000 to max rpm.
What is your elevation?
You loose around 5 psi of cyl pressure for every 1000 foot increase in elevation. this means that if you are 2000 feet or more above sea level your comp is extremely low.
From the factory your engine has a dynamic [not static] compression of around 7.9 and a cyl crank pressure of around 156.5 psi. The optimum level of cyl crank pressure for a perf eng running 93 octane is between 170 and 180.
This means that from the factory, your eng has less than optimal compression for a perf eng that runs on 93 octane therefore increasing the compression on a stock engine will yield benefits without putting it in danger of detonation.
In general, the bigger the cam the more compression that is needed to optimize that particular cams perf. Every cam mfg says this in the cams perf description however the minimum compression ratios they recommend are less than optimal.
Using your stock cam, milling your heads .025 - .028 will increase your dyn comp from 7.9 to around 8.3 which in your case gives you a cyl cranking pressure of 167.0 psi.
In general, increasing static comp by .5 will increase your hp and tq by around 3% across the board. This is certainly not a lot but when you install a bigger cam, your dyn comp and cyl crank comp will go back down to around 7.9 and 157 which is exactly where you started in the first place, which is low.
This will be 6% less hp/tq from 1000 to max rpm then you would have if you increased your cyl compression to just 167. This is a very noticeable number however the only way you could do this in your particular case is to get different heads with smaller chambers or mill your block.
