Black95-850T5R Posted January 12, 2006 Report Share Posted January 12, 2006 Does anyone know how much one can mill off the head and still be in the safe side? What's Volvo's tolerance for shaving the head?And how much will the compression increase (from 8.5) if I milled, let's say, 0.01 in. off the head?Any info is appreciated.. Link to comment Share on other sites More sharing options...
Guest 300+_T5R_855 Posted January 12, 2006 Report Share Posted January 12, 2006 Volvo says no more than 1/2 mm (.020") You would have to do the calculations to figure out the increased compression ratio. That will all be lost when the valves hit and dent the pistons :lol: Link to comment Share on other sites More sharing options...
Black95-850T5R Posted January 12, 2006 Author Report Share Posted January 12, 2006 Volvo says no more than 1/2 mm (.020") You would have to do the calculations to figure out the increased compression ratio. That will all be lost when the valves hit and dent the pistons Hmm... yea that will be scary With no more than 0.5 mm off, is it still safe to run the same boost as I can with an 8.5 CR engine?I guess the answer depends on the CR with 0.5 mm off, but I don’t know how to calculate it :unsure: Link to comment Share on other sites More sharing options...
cranky Posted January 12, 2006 Report Share Posted January 12, 2006 Hmm... yea that will be scary With no more than 0.5 mm off, is it still safe to run the same boost as I can with an 8.5 CR engine?I guess the answer depends on the CR with 0.5 mm off, but I don’t know how to calculate it If you mill the head, do you need to adjust the cams? (as the head gets closer to the engine, the cams would turn) It seems to me that if my N/A has 10.5:1 compression, and a turbo has 8 or 9:1, the valves hitting the pistons would be a non issue.Cranky Link to comment Share on other sites More sharing options...
Guest 300+_T5R_855 Posted January 12, 2006 Report Share Posted January 12, 2006 If you stay within spec it won't be an issue. I doubt it will change it enough to feel the difference. If you know or can gather the chamber size, bore, stroke etc. You can calculate the compression ratio and the change by changing it .020" Do a google search on compression ratio calculator. Link to comment Share on other sites More sharing options...
merlin390 Posted January 12, 2006 Report Share Posted January 12, 2006 1. the turbo cams have less lift than the NA cams.. 2. As cranky pointed out our NAs have a 10.8 CRyou should be fine if they just mill enough off to true up the head Link to comment Share on other sites More sharing options...
PyROTech Posted January 12, 2006 Report Share Posted January 12, 2006 1. the turbo cams have less lift than the NA cams.. 2. As cranky pointed out our NAs have a 10.8 CRyou should be fine if they just mill enough off to true up the headthats a serious sig there :P Link to comment Share on other sites More sharing options...
EddieB Posted January 12, 2006 Report Share Posted January 12, 2006 Does anyone know how much one can mill off the head and still be in the safe side? What's Volvo's tolerance for shaving the head?And how much will the compression increase (from 8.5) if I milled, let's say, 0.01 in. off the head?Any info is appreciated..Why are you trying to mill the head? Did you blow a head gasket? Link to comment Share on other sites More sharing options...
Fishey Posted January 13, 2006 Report Share Posted January 13, 2006 1. the turbo cams have less lift than the NA cams.. 2. As cranky pointed out our NAs have a 10.8 CRyou should be fine if they just mill enough off to true up the headThat can be due to piston design not really clearance diffrences.. Link to comment Share on other sites More sharing options...
Black95-850T5R Posted January 13, 2006 Author Report Share Posted January 13, 2006 Why are you trying to mill the head? Did you blow a head gasket?Gain some performance by increasing the CR instead of going with higher CR pistons. But, I'm not sure if it's worth it :rolleyes: Link to comment Share on other sites More sharing options...
RiddickJordan Posted January 13, 2006 Report Share Posted January 13, 2006 which beings my question of, what casues the dif in compression between the NA and the turbo, is it the pisons, or like some1 suggested the head. (like is a NA head just a trubo head with a bit shaved off) and where can you get high compression pistons for our cars? Link to comment Share on other sites More sharing options...
BlackT5 Posted January 13, 2006 Report Share Posted January 13, 2006 I would just swap the rods out and put in some head studs. get new pistons if you plan on big hp down the road. Link to comment Share on other sites More sharing options...
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