Help Me Pick Good Flowing Heads
11-20-2008, 11:40 AM
#1
Help Me Pick Good Flowing Heads Right now as my car sits, i am CAM only (228/232 .588/.595 110+4). Stock LS6 intake still. In the spring i am getting my 85mm Lid, 42# injectors and 85mm MAF put on and tuned. But that is besides the point.
In the near future i am going with either a FAST 90/90 combo or FAST 92/92 combo i have not yet decided.
Right now my SCR is 10.37:1 and my DCR is 8.28:1 with my stock 241 66cc head using the stock 0.052" head gasket..
here is my question. What heads do i want to go with? my goal with H/I is to make 450 RWHP and prolly about 415 RWTQ. Right now i am at 404/378
I am thinking AFR 205s with a 63cc using a 0.040" head gasket. That will get my SCR to 11.18:1 and my DCR will be 8.91:1. Right now my DCR is very low, causing me some low end TQ.
would AFR 225s be to big for stock cubic inch motor?
or
maybe go with a 5.3 heads?
What do you all think? Will i have enough PTV clearance? What is milling too?
In the near future i am going with either a FAST 90/90 combo or FAST 92/92 combo i have not yet decided.
Right now my SCR is 10.37:1 and my DCR is 8.28:1 with my stock 241 66cc head using the stock 0.052" head gasket..
here is my question. What heads do i want to go with? my goal with H/I is to make 450 RWHP and prolly about 415 RWTQ. Right now i am at 404/378
I am thinking AFR 205s with a 63cc using a 0.040" head gasket. That will get my SCR to 11.18:1 and my DCR will be 8.91:1. Right now my DCR is very low, causing me some low end TQ.
would AFR 225s be to big for stock cubic inch motor?
or
maybe go with a 5.3 heads?
What do you all think? Will i have enough PTV clearance? What is milling too?
Last edited by TORCHD 02 TA; 11-20-2008 at 12:30 PM.
11-20-2008, 11:54 AM
#2
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if you have the money, and you want the torque....the AFRs are the only way to go.
talk to tony about how much to mill the heads and get as much compression as possible.
talk to tony about how much to mill the heads and get as much compression as possible.
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11-20-2008, 03:06 PM
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If nobody's explained milling to you yet, its just basically shaving off some of the head where it meets the rest of the engine block (well, the head gasket goes between the block and head, but you get the idea). By shaving off a little bit of this material, you reduce the combustion chamber size (in cubic centimeters) and therefore bump compression ratio up even more. You're essentially putting the same amout of air and fuel mix into a smaller volume of space (inside the combustion chamber of the head, where the BOOM takes place) and so there is greater pressure pushing that piston down and consequently back up when the pistons work in series with one another. Its like miniature forced induction, minus the induction...air is not being forced in, it is being forced smaller...
Now, the higher the compression goes the higher octane fuel you will need as well. The greater pressures inside the combustion chambers create more heat. More octane in the fuel cools the charge down to prevent early detonation and therefore reduce engine knock. Your SES light will come on if you don't have enough octane in your fuel. Its not detrimental to the engine if you do have knock, because the knock retarder will adjust timing automatically to keep the engine operating safely. 91 octane is usually good enough for H/C builds..
Someone correct me if I'm wrong.. haha
Now, the higher the compression goes the higher octane fuel you will need as well. The greater pressures inside the combustion chambers create more heat. More octane in the fuel cools the charge down to prevent early detonation and therefore reduce engine knock. Your SES light will come on if you don't have enough octane in your fuel. Its not detrimental to the engine if you do have knock, because the knock retarder will adjust timing automatically to keep the engine operating safely. 91 octane is usually good enough for H/C builds..
Someone correct me if I'm wrong.. haha
11-20-2008, 03:28 PM
#11
If nobody's explained milling to you yet, its just basically shaving off some of the head where it meets the rest of the engine block (well, the head gasket goes between the block and head, but you get the idea). By shaving off a little bit of this material, you reduce the combustion chamber size (in cubic centimeters) and therefore bump compression ratio up even more. You're essentially putting the same amout of air and fuel mix into a smaller volume of space (inside the combustion chamber of the head, where the BOOM takes place) and so there is greater pressure pushing that piston down and consequently back up when the pistons work in series with one another. Its like miniature forced induction, minus the induction...air is not being forced in, it is being forced smaller...
Now, the higher the compression goes the higher octane fuel you will need as well. The greater pressures inside the combustion chambers create more heat. More octane in the fuel cools the charge down to prevent early detonation and therefore reduce engine knock. Your SES light will come on if you don't have enough octane in your fuel. Its not detrimental to the engine if you do have knock, because the knock retarder will adjust timing automatically to keep the engine operating safely. 91 octane is usually good enough for H/C builds..
Someone correct me if I'm wrong.. haha
Now, the higher the compression goes the higher octane fuel you will need as well. The greater pressures inside the combustion chambers create more heat. More octane in the fuel cools the charge down to prevent early detonation and therefore reduce engine knock. Your SES light will come on if you don't have enough octane in your fuel. Its not detrimental to the engine if you do have knock, because the knock retarder will adjust timing automatically to keep the engine operating safely. 91 octane is usually good enough for H/C builds..
Someone correct me if I'm wrong.. haha
11-20-2008, 07:22 PM
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The 5.3L heads have smaller combustion chambers already than the LS6 heads. They don't flow quite as well either up top in RPMs I don't think, but they're pretty close to similar. Most vendors that sell cams and heads will be able to guide you with whether or not you'll have enough PTV clearance. Whenever you get everything put together tho, you can check it to make sure by leaving the spark plugs out and turning the engine by hand with a cheater bar (big pipe or some other longer piece of metal to turn a wrench on the crank bolt). If everything spins over freely, and nothing sounds like its binding or hitting metal on metal inside the head area then you're good to go!
Can't tell you the difference between 205s and 215s...i'd guess its a couple different models based on the size of the runners in millimeters or maybe cubic centimeters or something (the air channels that flow into and out of the combustion chamber through the valves). There's a 80% chance I'm wrong about that tidbit though so take it with a grain of salt and hang in here til someone more knowledgeable about pricey heads can correct me
Can't tell you the difference between 205s and 215s...i'd guess its a couple different models based on the size of the runners in millimeters or maybe cubic centimeters or something (the air channels that flow into and out of the combustion chamber through the valves). There's a 80% chance I'm wrong about that tidbit though so take it with a grain of salt and hang in here til someone more knowledgeable about pricey heads can correct me
11-20-2008, 08:45 PM
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How much are you looking to spend? Is your AFR deal that good that its less than a 1000 more than the PRC 5.3 heads. TFS needs aftermarket rockers to fit because of the angle change. AFR 205s will need the 8019 spring upgrade to be safe because your lift is close to the .600 lift there rated to to be safe. AFR 225s are only good on stock size engines if its a max effort car or FI otherwise your leaving power on the table in the lower rpm range.
11-20-2008, 09:44 PM
#19
The 5.3L heads have smaller combustion chambers already than the LS6 heads. They don't flow quite as well either up top in RPMs I don't think, but they're pretty close to similar. Most vendors that sell cams and heads will be able to guide you with whether or not you'll have enough PTV clearance. Whenever you get everything put together tho, you can check it to make sure by leaving the spark plugs out and turning the engine by hand with a cheater bar (big pipe or some other longer piece of metal to turn a wrench on the crank bolt). If everything spins over freely, and nothing sounds like its binding or hitting metal on metal inside the head area then you're good to go!
Can't tell you the difference between 205s and 215s...i'd guess its a couple different models based on the size of the runners in millimeters or maybe cubic centimeters or something (the air channels that flow into and out of the combustion chamber through the valves). There's a 80% chance I'm wrong about that tidbit though so take it with a grain of salt and hang in here til someone more knowledgeable about pricey heads can correct me
Can't tell you the difference between 205s and 215s...i'd guess its a couple different models based on the size of the runners in millimeters or maybe cubic centimeters or something (the air channels that flow into and out of the combustion chamber through the valves). There's a 80% chance I'm wrong about that tidbit though so take it with a grain of salt and hang in here til someone more knowledgeable about pricey heads can correct me
11-20-2008, 09:48 PM
#20
How much are you looking to spend? Is your AFR deal that good that its less than a 1000 more than the PRC 5.3 heads. TFS needs aftermarket rockers to fit because of the angle change. AFR 205s will need the 8019 spring upgrade to be safe because your lift is close to the .600 lift there rated to to be safe. AFR 225s are only good on stock size engines if its a max effort car or FI otherwise your leaving power on the table in the lower rpm range.
I just want to get my DCR back up, and gain some low end TQ... That is why i was thinking the AFRs w/63cc chambers with a .040" head gasket will do that...