Ok I know it will increase compression ratio. If I have .030 taken from the stock heads with a tr 224 cam what would be the benefit if any???

 

I thought I read somewhere that the SPDC ported LS-6 heads (about $900 each complete with springs and valves and the porting is done by lingfelter) were milled .055 and that the estimated static compression was around 11 to 1. ...so if .033 is about 2/3 of .o55 it would increase compression by 2/3 of the difference between stock 10.25 to 1 and 11.0 to 1.

you need to cut down the alignment pins on the plastic manifold if u use milled, heads, however....

 

I am having my ported 5.7 heads milled .035"
In addition, a TR-220 cam will be installed.

Below is what I understand to be true:

Milling 5.7 LS1 heads .035” will decrease the stock 67.3cc chamber volume to approx 63cc
This will yield a 10.7 to 1 compression ratio when the stock GM .052" thick graphite head gaskets are used.

 

OK, what are the pros and cons of a higher cr??

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 2002snortbird:
<strong>OK, what are the pros and cons of a higher cr??</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">pro - rwhp <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

con - knock retard ( need higher octane fuel )

 

Milling heads will help restore some of lost cylinder pressure from cam size increase. Higher compression will extend powerband some by keeping some extra cylinder pressure as VE falls off from heads flow and or cam limits. Detonation can be relieved with rear gear changes, weight reduction, custom timing and A/F ratio tweaks with PCM. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />