241 heads for power
09-17-2008, 12:22 PM
#27
TECH Regular
iTrader: (14)
Join Date: Apr 2006
Location: 626 to the 818
Posts: 485
Likes: 0
Received 0 Likes
on
0 Posts
do you even know the difference betwee static and dynamic compression?
there are advantages and disadvantages to milling heads...
09-17-2008, 12:28 PM
#28
your saying the only way to decrease combustion chamber cc is to either mill or run a thinner gasket...thats not true...you can also run flat faced valves and even weld the chambers...
do you even know the difference betwee static and dynamic compression?
there are advantages and disadvantages to milling heads...
do you even know the difference betwee static and dynamic compression?
there are advantages and disadvantages to milling heads...
EDIT: I'm not trying to get in a pissing match btw, and I know that I don't know everything.
09-17-2008, 12:50 PM
#29
TECH Regular
iTrader: (14)
Join Date: Apr 2006
Location: 626 to the 818
Posts: 485
Likes: 0
Received 0 Likes
on
0 Posts
I know there are other ways, but how often are they used? I know people weld the chambers, but I thought that was only for really large chambered heads like stock 317 with a 72cc chamber. I do know the difference between SCR and DCR. If the disadvantages to milling heads outweighed the advantages, then why would anyone mill their heads? I'm sure if done right the net gains are worth it.
if you knew the difference betwen SCR and DCR you wouldnt be using the terms incorrectly...so please man dont try to bs me...im not here to prove you wrong, but if were gonna talk technical at least do me the favor of making sense...11:1 DCR are u serious!?
what i do like about bringing the head deck closer to the piston top, is reducing the quench clearance...this helps to ward of detonation...
unfortunately it also brings the valves closer to the piston top...if you run dished or relieved pistons its not a big deal...but on a stock bottom end you can run into a problem with piston to valve clearance with a bigger camshaft..
i never said the disadvantages of milling heads outweighs the advantages...so, dont put words in my mouth...milling is an easy way to bump compression period..but there are other ways to produce the same result...you can even weld and mill together to reach desired results...
when building a motor, you will already take everything into consideration when selecting your components...
theres more than one way to skin a cat...its all about the right combination of components and procedures to work best on a particular application...
09-17-2008, 12:56 PM
#30
welding chambers, changes the design...like i said, if your getting your stock heads done by a porter, make sure you take it to someone worth a damn, or else your just throwing your money away...anybody can hog out a port and make peak cfm numbers....contrary to what most people believe cfm is not the end all be all measurment of cylinder head performance...
if you knew the difference betwen SCR and DCR you wouldnt be using the terms incorrectly...so please man dont try to bs me...im not here to prove you wrong, but if were gonna talk technical at least do me the favor of making sense...11:1 DCR are u serious!?
what i do like about bringing the head deck closer to the piston top, is reducing the quench clearance...this helps to ward of detonation...
unfortunately it also brings the valves closer to the piston top...if you run dished or relieved pistons its not a big deal...but on a stock bottom end you can run into a problem with piston to valve clearance with a bigger camshaft..
i never said the disadvantages of milling heads outweighs the advantages...so, dont put words in my mouth...milling is an easy way to bump compression period..but there are other ways to produce the same result...you can even weld and mill together to reach desired results...
when building a motor, you will already take everything into consideration when selecting your components...
theres more than one way to skin a cat...its all about the right combination of components and procedures to work best on a particular application...
if you knew the difference betwen SCR and DCR you wouldnt be using the terms incorrectly...so please man dont try to bs me...im not here to prove you wrong, but if were gonna talk technical at least do me the favor of making sense...11:1 DCR are u serious!?
what i do like about bringing the head deck closer to the piston top, is reducing the quench clearance...this helps to ward of detonation...
unfortunately it also brings the valves closer to the piston top...if you run dished or relieved pistons its not a big deal...but on a stock bottom end you can run into a problem with piston to valve clearance with a bigger camshaft..
i never said the disadvantages of milling heads outweighs the advantages...so, dont put words in my mouth...milling is an easy way to bump compression period..but there are other ways to produce the same result...you can even weld and mill together to reach desired results...
when building a motor, you will already take everything into consideration when selecting your components...
theres more than one way to skin a cat...its all about the right combination of components and procedures to work best on a particular application...
I know that when running larger cams that milling heads helps out with the quench. And when I said milled correctly, that also includes not violating minimum ptv clearance. I wasn't trying to put words in your mouth, but it sounded like you said that he shouldn't be milling the heads at all, which is a common practice.
09-17-2008, 01:09 PM
#31
TECH Regular
iTrader: (14)
Join Date: Apr 2006
Location: 626 to the 818
Posts: 485
Likes: 0
Received 0 Likes
on
0 Posts
Yes, I did use the terms incorrectly, but in my defense, I've been up since 4 with a couple hours of sleep, but I do know the difference, lol.
I know that when running larger cams that milling heads helps out with the quench. And when I said milled correctly, that also includes not violating minimum ptv clearance. I wasn't trying to put words in your mouth, but it sounded like you said that he shouldn't be milling the heads at all, which is a common practice.
I know that when running larger cams that milling heads helps out with the quench. And when I said milled correctly, that also includes not violating minimum ptv clearance. I wasn't trying to put words in your mouth, but it sounded like you said that he shouldn't be milling the heads at all, which is a common practice.
09-17-2008, 01:46 PM
#33
ok so let me get this straight...... your saying gettting a set of 241's ported then welding the chambers, plus maybe even flat surface valves is worth all the added expense of ported 243's that will still flow more, and all they will need is a simple .030" mill., **** i would rather just pay an extra $300 bucks for the 243's and save all the hassle. remember we are talking about the average racer/street driver, not some hardcore drag racer needing to stay within a certain class with # matching heads, where then i would see the need for the all the welding and what not. plus many companies offer a CNC program for the 243 heads, while most dont offer anything for 241's, and we all know a cnc machine is much more consistant then a guy porting by hand, but of course this is all my opinion
09-17-2008, 01:48 PM
#34
Yes, I did use the terms incorrectly, but in my defense, I've been up since 4 with a couple hours of sleep, but I do know the difference, lol.
I know that when running larger cams that milling heads helps out with the quench. And when I said milled correctly, that also includes not violating minimum ptv clearance. I wasn't trying to put words in your mouth, but it sounded like you said that he shouldn't be milling the heads at all, which is a common practice.
I know that when running larger cams that milling heads helps out with the quench. And when I said milled correctly, that also includes not violating minimum ptv clearance. I wasn't trying to put words in your mouth, but it sounded like you said that he shouldn't be milling the heads at all, which is a common practice.
Last edited by Ryne @ CMS; 09-17-2008 at 01:56 PM.
09-17-2008, 01:52 PM
#35
On The Tree
09-17-2008, 02:37 PM
#36
TECH Regular
iTrader: (14)
Join Date: Apr 2006
Location: 626 to the 818
Posts: 485
Likes: 0
Received 0 Likes
on
0 Posts
ok so let me get this straight...... your saying gettting a set of 241's ported then welding the chambers, plus maybe even flat surface valves is worth all the added expense of ported 243's that will still flow more, and all they will need is a simple .030" mill., **** i would rather just pay an extra $300 bucks for the 243's and save all the hassle. remember we are talking about the average racer/street driver, not some hardcore drag racer needing to stay within a certain class with # matching heads, where then i would see the need for the all the welding and what not. plus many companies offer a CNC program for the 243 heads, while most dont offer anything for 241's, and we all know a cnc machine is much more consistant then a guy porting by hand, but of course this is all my opinion
personally i think the 317s are the best stock casting for head work...
considering the port job is professional, a ls6 head will definitely outperform a ls1 head...im not arguing against that...but the final results are going to be similar..you can get the heads welded and resurfaced for the same amount extra your going to be paying for the ls6 casting...i think the reworked stock castings are bad *** since they perform well and add to the stealth factor...
shoot you can save even more money by just running a thinner gasket if you really want to, but stock heads are not the straightest from the factory, they will benefit to be trued by resurfacing...
the thread title is "241 heads for power." its not a 241/243 comparsion..
yes cnc porting is more consistant port to port..a properly engineered machine will always be more accurate than man...but even the best cnc jobs are hand touched afterwards...
im not disagreeing with you...im just saying you can make great power from any of the stock castings....
09-17-2008, 02:41 PM
#37
without a doubt 243 casting is the best of all the stock gen 3 production castings...lets not even talk about the 009 and 005 heads right now...
personally i think the 317s are the best stock casting for head work...
considering the port job is professional, a ls6 head will definitely outperform a ls1 head...im not arguing against that...but the final results are going to be similar..you can get the heads welded and resurfaced for the same amount extra your going to be paying for the ls6 casting...i think the reworked stock castings are bad *** since they perform well and add to the stealth factor...
shoot you can save even more money by just running a thinner gasket if you really want to, but stock heads are not the straightest from the factory, they will benefit to be trued by resurfacing...
the thread title is "241 heads for power." its not a 241/243 comparsion..
yes cnc porting is more consistant port to port..a properly engineered machine will always be more accurate than man...but even the best cnc jobs are hand touched afterwards...
im not disagreeing with you...im just saying you can make great power from any of the stock castings....
personally i think the 317s are the best stock casting for head work...
considering the port job is professional, a ls6 head will definitely outperform a ls1 head...im not arguing against that...but the final results are going to be similar..you can get the heads welded and resurfaced for the same amount extra your going to be paying for the ls6 casting...i think the reworked stock castings are bad *** since they perform well and add to the stealth factor...
shoot you can save even more money by just running a thinner gasket if you really want to, but stock heads are not the straightest from the factory, they will benefit to be trued by resurfacing...
the thread title is "241 heads for power." its not a 241/243 comparsion..
yes cnc porting is more consistant port to port..a properly engineered machine will always be more accurate than man...but even the best cnc jobs are hand touched afterwards...
im not disagreeing with you...im just saying you can make great power from any of the stock castings....
09-17-2008, 02:50 PM
#38
TECH Regular
iTrader: (14)
Join Date: Apr 2006
Location: 626 to the 818
Posts: 485
Likes: 0
Received 0 Likes
on
0 Posts
cnc is only as good as the person who writes the program...our machinist tested a cnc
ls6 casting from a guy who swore his machine would produce 300+ cfm from the heads...they didnt even make 280@ .650 lift... this is not always the case, so it is good to research/test cnc heads before you make a purchase...
the reason not many shops do it, is because it takes a lot of R&D to figure out what works and what doesnt....i dont know everything, but when wise men speak, i listen...
ls6 casting from a guy who swore his machine would produce 300+ cfm from the heads...they didnt even make 280@ .650 lift... this is not always the case, so it is good to research/test cnc heads before you make a purchase...
the reason not many shops do it, is because it takes a lot of R&D to figure out what works and what doesnt....i dont know everything, but when wise men speak, i listen...
09-17-2008, 02:56 PM
#39
cnc is only as good as the person who writes the program...our machinist tested a cnc
ls6 casting from a guy who swore his machine would produce 300+ cfm from the heads...they didnt even make 280@ .650 lift... this is not always the case, so it is good to research/test cnc heads before you make a purchase...
the reason not many shops do it, is because it takes a lot of R&D to figure out what works and what doesnt....i dont know everything, but when wise men speak, i listen...
ls6 casting from a guy who swore his machine would produce 300+ cfm from the heads...they didnt even make 280@ .650 lift... this is not always the case, so it is good to research/test cnc heads before you make a purchase...
the reason not many shops do it, is because it takes a lot of R&D to figure out what works and what doesnt....i dont know everything, but when wise men speak, i listen...
09-17-2008, 02:59 PM
#40
TECH Addict
iTrader: (14)
Join Date: May 2005
Location: Simi Valley, CA.
Posts: 2,727
Likes: 0
Received 0 Likes
on
0 Posts
Another thing is it is not all about peak flow. AFR is a GREAT example of that, their heads flow a lil less than some other companies (on certain ends) yet they outperform them time and time again. I know for a fact the CNC programmer over at AFR had a hand in the LS7 heads.
There are ALOT of other variables to be taken into account when writing those programs, so it does take a VERY keen eye and trial and error to create a final CNC program worth a damn. You'll also have to remember that guys making close to 300cfm on stock size valves HAVE DONE SOMETHING right
. Don't forget that the heads that flow larger numbers have larger valves 9 times out of 10.
When i send my 853's out to Patriot i wouldn't expect them to come back flowing more than 285cfm. That is decent for a small 22x cam and ported TB & LS6 intake combo with all bolt-ons. If i were to go more extreme then I would have to pop for a more expensive set of heads.
There are ALOT of other variables to be taken into account when writing those programs, so it does take a VERY keen eye and trial and error to create a final CNC program worth a damn. You'll also have to remember that guys making close to 300cfm on stock size valves HAVE DONE SOMETHING right
. Don't forget that the heads that flow larger numbers have larger valves 9 times out of 10.When i send my 853's out to Patriot i wouldn't expect them to come back flowing more than 285cfm. That is decent for a small 22x cam and ported TB & LS6 intake combo with all bolt-ons. If i were to go more extreme then I would have to pop for a more expensive set of heads.