Flow #'s on ported LS1 heads? HEAD HELP????
05-09-2003, 05:48 AM
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Flow #'s on ported LS1 heads? HEAD HELP???? What is stock heads for a 01 LS1 intake runners push 200cc or 210cc the machine shop who im wanting to get my heads done by have flowbenched a set of LS1 heads over 300cc with 2.00 intake vavles. Is this cool? what should i be doing to my heads to get 450HP? are changing valves worth it if a can move 300cc of air throw a 2.00 valve. What should be done to the heads get 450hp with the ASA cam. I want to port the stock heads and not buy new ones or ship them out.
please help
please help
05-09-2003, 08:25 AM
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Re: Flow #'s on ported LS1 heads? HEAD HELP???? I think you are confusing CC and CFM. I hope so at least.... The stock intake runner is 200cc (port volume, not port flow, flow is CFM). Anyway, you should expect a stage 2 port to increase that runner volume to roughly 210cc-225cc. Anyway, if they have hogged the bejezus out of the intake and opened it up to 300cc, my advice is RUN! Unless you plan on running the car at 8000-9000 rpm on a circle track, that thing is going to redefine the term "pig".
Port volume is the natural enemy of intake charge velocity, and intake charge velocity is the maker of torque and low rpm driveability. Stock LS1 5.7 castings have a 200cc intake port, 2.00/1.55 valves and flow around 240CFM at the ASA cam's lift. Ported stage 2 heads will be around 210cc-225cc, probably have 2.02/1.57 valves, and flow around 290cfm at the ASA cam's lift.
You need to do a little reading on Cylinder heads so you can get the basics down. You have to understand what you're buying or you're going to get hosed. I'd make sure of exactly what you're buying before you lay out the cabbage.
Also, are you talking 450 HP at the flywheel, or at the wheels? If you're talking at the wheels, you're getting VERY optimistic for a 2.00 valve and an ASA cam.
Port volume is the natural enemy of intake charge velocity, and intake charge velocity is the maker of torque and low rpm driveability. Stock LS1 5.7 castings have a 200cc intake port, 2.00/1.55 valves and flow around 240CFM at the ASA cam's lift. Ported stage 2 heads will be around 210cc-225cc, probably have 2.02/1.57 valves, and flow around 290cfm at the ASA cam's lift.
You need to do a little reading on Cylinder heads so you can get the basics down. You have to understand what you're buying or you're going to get hosed. I'd make sure of exactly what you're buying before you lay out the cabbage.
Also, are you talking 450 HP at the flywheel, or at the wheels? If you're talking at the wheels, you're getting VERY optimistic for a 2.00 valve and an ASA cam.
05-09-2003, 08:49 AM
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Re: Flow #'s on ported LS1 heads? HEAD HELP???? 
alright i found some one that knows what there talking about. 
so is it cc or cfm when talking about intake runner flow? are 2.00 valve to small for a 450 rwhp option even with a good port job to the head? where would 2.02 make a difference, every where or top end? the cam has low lift and high duration, so do i need to leave the valves small or open the mup to compinsate? lesson II valve train? help me out man!
05-09-2003, 10:05 AM
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Re: Flow #'s on ported LS1 heads? HEAD HELP???? CC constitutes the amount of cubic centimeters inside of a given port. in other words, if you were to fill up the entire port with fluid, it would come out to 200-230 cubic centimeters.
now, on the flow side of things, CFM or cubic feet per minute, is the volume of air a head will flow at a given vaccum. (standard is 28" of water, be weary if it's otherwise) so a basic stock port should have a CC of 200, and flow in the 230-240CFM range. ported heads generally are in the 230+ cc range and flow anywhere from 250-320's ish CFM range. some more, some less, but thats the basic idea. hope that helps
now, on the flow side of things, CFM or cubic feet per minute, is the volume of air a head will flow at a given vaccum. (standard is 28" of water, be weary if it's otherwise) so a basic stock port should have a CC of 200, and flow in the 230-240CFM range. ported heads generally are in the 230+ cc range and flow anywhere from 250-320's ish CFM range. some more, some less, but thats the basic idea. hope that helps
