Mill heads, thinner gaskets, or both for increased compression?
Mill heads, thinner gaskets, or both for increased compression? Alright, putting together an extremely budget ls1 for the Camaro here in the next month (blew the stock engine back in November). Engine is currently on a stand and I will be flycutting the pistons. I will be using a 236/242 XER comp cam, and 799 heads. Playing around with a compression calculator I've come up with a few ways to reach a desired SCR, but I'd like to just mill the heads and use a stock gasket. I'm looking to be anywhere between 10.9-11.2:1. I would like a nice quench, but it seems I'll be within .04x with a stock gasket, so it's not too bad. What would you do with budget in mind....mill the heads to a 61cc or so chamber, run a .040 gasket, or run something like a .045 gasket and 63-63 cc heads? I haven't looked at what my DCR would be at a given scr either.
For budget i say mill the heads and get stock mls gaskets. I think the thinner gaskets go for almost double. And the cost of milling would be the same no matter how much material they take off i believe.
I was leaning towards milling and stock gasket. Thinner gaskets are like $130 and stockers are about $50. Should be only about $50 to have heads milled. I'm not worried about losing cc's on the head, as I got them for a great deal and if I went with a different combo down the road I'd just sell this engine.
I'm just wondering if it'd be worth it to have a quench a little tighter or If I'll be just fine with stock gaskets and 11:1 compression
I'm just wondering if it'd be worth it to have a quench a little tighter or If I'll be just fine with stock gaskets and 11:1 compression
Gonna be tough to help you get the DCR down without the LSA, or at least the ICL on that cam. The heads should be 64cc uncut, and the calculator I use comes up with 11.04 SCR with 64cc, a .040" thick gasket and no valve reliefs. Take out 1cc for valve clearance and you're at 10.9 without paying for milling.
I was quoted about $145 for milling. about .035 from my heads. Not sure if thats average/high/ or low, but they're one of the best shops around and its a set of afr 225's so i don't want to skimp by using a cheaper shop.
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Gonna be tough to help you get the DCR down without the LSA, or at least the ICL on that cam. The heads should be 64cc uncut, and the calculator I use comes up with 11.04 SCR with 64cc, a .040" thick gasket and no valve reliefs. Take out 1cc for valve clearance and you're at 10.9 without paying for milling.
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Another thing to consider is milling hurts airflow slightly by shrouding the valves versus running a thinner gasket. So the extra bucks spent could add up to a few more ponies, if you're only looking to do one or the other. The bump in compression from milling alone would easily offset the reduced airflow though.
lsa is 114. Cam is being shipped, so I don't have the cam card. I come up with the same SCR using 1cc for my flycuts. Problem is....is that it will be more expensive to use a .040 gasket than to mill (I know, only like a $30-50 difference). Is the increased quench worth the extra $50 when stockish quench would suffice?
Ideally, cams of this size are ground on a tighter LSA to give you more options. Without the advance, 59cc's and a .053" gasket comes to just 8.05:1 DCR, leaving quite a bit of room to improve.
Since it's 114, I would suggest both milling and the .040" gasket. Installed four degrees advanced, and with your target 11.25:1 SCR, the dynamic compression comes in at a respectable 8.37:1. I arrived at those figures with 59cc heads, .053" thick gasket and 1cc valve reliefs. Going down to a .040" thick gasket, I get 11.64:1 SCR and a better 8.65:1 DCR
Ideally, cams of this size are ground on a tighter LSA to give you more options. Without the advance, 59cc's and a .053" gasket comes to just 8.05:1 DCR, leaving quite a bit of room to improve.
Ideally, cams of this size are ground on a tighter LSA to give you more options. Without the advance, 59cc's and a .053" gasket comes to just 8.05:1 DCR, leaving quite a bit of room to improve.
Dang, I just got my 243's milled for $50 for the pair...lol
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Where can I find thinner gaskets to bump up my compression ratio? I know my trex cam would like a higher compression ratio and was curious how much these thin gaskets can bump it up? Can I do this without having piston to valve clearance issues?
Cometic sells a variety of thinner gaskets, and many of the sponsors carry them. However you will have ptv clearance problems since you are already too close as it is with stock heads and gaskets.
Thank you! I do have an adjustable cam gear, so advancing it 4 degrees won't be a problem! SDPC has stock gaskets at $28 a set, so we're talking $100+ difference in gasket price. I think I might just stick with the stock gasket, mill .030 (I think that's right for 59cc) and that 8.3 DCR. This is an extreme budget build to get on back on the road for now! BTW, what do you use to calculate DCR? I did a search but the few sites that had a DCR calculator are no longer running.
Check your cam card when you recieve the cam and see if there is any advance already ground in. It would be best to degree the cam to ensure it is installed correctly, then measure your PTV clearance. Shoot for .080"/.100" after cutting your pistons, and you are good to go.
Thanks Hammertime! Ya, I would imagine it's a 114+4 cam, but was only told LSA was 114, not whether any advance was ground in. If it was 114+4, do you think advancing it a couple more degrees would help? Or would it move the powerband too low for that duration and kill top end?
I personally would not go more than +4 because of the ugly things that does to your valve events. You're not going to push the powerband too low, but you will lose some of your midrange power as you open the exhaust valve earlier.
Thanks Hammertime! Ya, I would imagine it's a 114+4 cam, but was only told LSA was 114, not whether any advance was ground in. If it was 114+4, do you think advancing it a couple more degrees would help? Or would it move the powerband too low for that duration and kill top end?
LSA 113 109 ICL = +4 degrees ground in
