[hadagto]

Near perfect isn't perfect. And I feel I can do better, is that ok?


the argument here isn't even about my original question, but others claiming how they would do it or how thier friend did it. I've already done the "add few psi" thing, I'm not downplaying other peoples builds, but they typically aren't at wot long enough to be concerned with adding a few more psi, as their A to B typically ends in 3rd or 4th gear. And will never see 5th or 6th and/or knows what happens up there.

Near perfect isn’t perfect, but you said you wanted more response out of boost. You are heading the wrong direction. You will lose response with LSA heads at the expense of higher peak flow. This will have the potential to make the same or more power at equal boost levels, but since you are milling and running an inferior head gasket since your current ls9 is the creme of the crop unless going to thicker Athena then you are actually making your setup inferior and more likely to have issues then if you just ran more boost. The LSA heads also have different ports than the ls3 so they actually aren’t as good even though they are made with a different alloy.

 

[Nothubertjfarnsworth]

I am assuming you are running the stock cam, though, so i would imagine clearance would be fine with the mill and more than fine with just a thinner gasket.

if you have an aftermarket cam, I know you probably don't want to flycut since you are boosted. It would actually make more sense to me to have a set of 243's CnC'd if you want more flow, that would keep all of your chamber size and valve clearance specs the same. iirc 243's have a taller valve drop unmilled than a set of unmilled ls3/lsa heads because of the intake valve diameter, anyway.

 

[hadagto]

I am assuming you are running the stock cam, though, so i would imagine clearance would be fine with the mill and more than fine with just a thinner gasket.

if you have an aftermarket cam, I know you probably don't want to flycut since you are boosted. It would actually make more sense to me to have a set of 243's CnC'd if you want more flow, that would keep all of your chamber size and valve clearance specs the same. iirc 243's have a taller valve drop unmilled than a set of unmilled ls3/lsa heads because of the intake valve diameter, anyway.

Let the dude fail. LSA heads while stronger also have wings in the ports that reduce flow and cause limits to timing in boosted applications. So their benefit is strength and milling and using inferior gaskets negates that. So now you can run less timing and they don’t flow as well as ls3 heads while still having the reduced response of a square port.

 

[Nothubertjfarnsworth]

quick google fu is .133" drop for the ls3 head on the intake, .160" drop on the exhaust, but i have no way to verify. From my own personal measurements on a set of 243's, .160"-.165" on the intake. Not sure on the exhaust, but more of course.

using the PCM of NC spreadsheet, with a .103" intake valve drop (which assumes a .030 " mill) and some approximate #'s i got for a the late model ls6 cam duration of the internet, since the intake duration is roughly the same as the LS2 cam, using the 116 LSA of the LS2 cam, i get roughly .070" PTV for the intake, This is a little tight but doable since the intake valve is chasing the piston down the bore. It may even be a little more clearance than this since i didn't touch the tappet lift @ TDC cells.

I used the ls6 exhaust duration info and 116 lsa, exhaust valve drop set at .130" ends up being .110" PTV clearance or so, which is the more important #, but still well around what you want it to be. Probably more with the LS2 cam since the duration is lower than the late year model LS6 cam.

who knows if the LS3 head info is correct, though. it's best to get a near perfect level surface and set things up with checker springs and a dial indicator with your rec port heads and go to town. The spreadsheet is still availble for download, iirc. if you google it, it should pop up somewhere. just open it with excel, it doesn't work in open office.

 

[Nothubertjfarnsworth]

wait.... found my old spreadsheet that i used for two sets of virgin 243's, says .165 intake .180 exhaust across the board.

 

[hadagto]

wait.... found my old spreadsheet that i used for two sets of virgin 243's, says .165 intake .180 exhaust across the board.

You know what they say about assumptions best to measure. Did you verify he has stock cam? If so this is even more silly because a cam custom for his combo will do way more for him than heads ever could.

 

[Nothubertjfarnsworth]

i just didn't think about flycutting and boost earlier. otherwise that's usually my go to, PTV not enuf? just flycut.

i'm sure if he had to flycut he could just smooth the edges so there won't be a hotspot. but then, it is still thinner in that spot.

 

[Nothubertjfarnsworth]

smurf it, forged bottom end with valve reliefs in the pistons, huge megabewstdeath cam, and CnC'd rec port heads. Spend 10,000 dollars and just send it.

 

[hadagto]

i just didn't think about flycutting and boost earlier. otherwise that's usually my go to, PTV not enuf? just flycut.

i'm sure if he had to flycut he could just smooth the edges so there won't be a hotspot. but then, it is still thinner in that spot.

Lol he’s smarter than everyone and came here with a question when he was really looking for an argument and had the answer he wanted already in his mind. No matter what facts anyone had he had the answer he wanted already in his mind so he was going to dismiss every other answer. So let him fail.

 

[Nothubertjfarnsworth]

i'm still not sure what he wants, lol.