Square Port heads vs. Cathedral Port heads
10-27-2020, 02:18 PM
#421
Shawn's gonna do a little note searching.
270cc.
Now tell me the rpm choke point using a 418 and a 440.
270cc.
Now tell me the rpm choke point using a 418 and a 440.
10-28-2020, 01:59 AM
#422
Sorry about the time: 2k21 Tournament...10w 2 loses.💰 Cash app.
Now °Each° head casting may have a difference in port centerline. Precision for making and matching a head to >A<° combination and it's rpm Not CC. Same CSA for all listed test. 270cc doesn't tell us Nothing 🤐🤫
Now with a 418
Your RPM computed from your Cross Sectional Area of ______ and Bore of 4.080 and Stroke of 4.0 is 7,836.72 .
now the 440
Your RPM computed from your Cross Sectional Area of _____ and Bore of 4.185 and Stroke of 4.0 is 7,448.42
Free 🐝 stock Ls3 with a good over bore
Your RPM computed from your Cross Sectional Area of ____ and Bore of 4.080 and Stroke of 3.622 is 8,654.58 .
Now °Each° head casting may have a difference in port centerline. Precision for making and matching a head to >A<° combination and it's rpm Not CC. Same CSA for all listed test. 270cc doesn't tell us Nothing 🤐🤫
Now with a 418
Your RPM computed from your Cross Sectional Area of ______ and Bore of 4.080 and Stroke of 4.0 is 7,836.72 .
now the 440
Your RPM computed from your Cross Sectional Area of _____ and Bore of 4.185 and Stroke of 4.0 is 7,448.42
Free 🐝 stock Ls3 with a good over bore
Your RPM computed from your Cross Sectional Area of ____ and Bore of 4.080 and Stroke of 3.622 is 8,654.58 .
10-28-2020, 03:21 AM
#423
Sorry about the time: 2k21 Tournament...10w 2 loses.💰 Cash app.
Now °Each° head casting may have a difference in port centerline. Precision for making and matching a head to >A<° combination and it's rpm Not CC. Same CSA for all listed test. 270cc doesn't tell us Nothing 🤐🤫
Now with a 418
Your RPM computed from your Cross Sectional Area of ______ and Bore of 4.080 and Stroke of 4.0 is 7,836.72 .
now the 440
Your RPM computed from your Cross Sectional Area of _____ and Bore of 4.185 and Stroke of 4.0 is 7,448.42
Free 🐝 stock Ls3 with a good over bore
Your RPM computed from your Cross Sectional Area of ____ and Bore of 4.080 and Stroke of 3.622 is 8,654.58 .
Now °Each° head casting may have a difference in port centerline. Precision for making and matching a head to >A<° combination and it's rpm Not CC. Same CSA for all listed test. 270cc doesn't tell us Nothing 🤐🤫
Now with a 418
Your RPM computed from your Cross Sectional Area of ______ and Bore of 4.080 and Stroke of 4.0 is 7,836.72 .
now the 440
Your RPM computed from your Cross Sectional Area of _____ and Bore of 4.185 and Stroke of 4.0 is 7,448.42
Free 🐝 stock Ls3 with a good over bore
Your RPM computed from your Cross Sectional Area of ____ and Bore of 4.080 and Stroke of 3.622 is 8,654.58 .
10-28-2020, 10:01 AM
#424
TECH Senior Member
10-28-2020, 10:50 AM
#425
He gave you the answers you wanted and is trying to teach you how to get this info for yourself in the future for any head.
I know the MCSA based on the info he wrote there. You can also estimate the runner volume as well. I won't ruin it, but I'll nudge you in the right direction.
http://www.wallaceracing.com/csa-calc.php
Port Lengths :
Int=5.628 Exh=3.328 GM LS-7 12578449 CNCd OEM shape
The port length of ls6/ls3 is likely a bit shorter - maybe 5.5" length vs 5.6". The ls7 has the raised runner so the center point of the port is going to be higher. It is the same as going around a curve in your car. The wider arc you take the longer your path is.
You gotta look beyond runner volume to really start to (pretend) to get it. I say pretend because this is something you spend a lifetime learning and implementing. Runner volume is the final piece that isn't really that important in the end because you can have the same runner volume but wildly different performance where it matters.
Runner volume is a product of valve size, and ideal valve size is theoretically set by the bore - usually around 52%. The choke or MCSA is going to be set by the valve size - usually around 88-92% depending on RPM needed. From there you see the port kind of just builds itself leading up to the intake flange. For GM, they had a reason for going with the 2.165" valve size in the ls3 and that led to a "huge" 260cc port. The big valve helped them hit their goals for slow and high speed driving, fuel economy and emissions etc for a production car - whatever those were. Yes it is a huge valve for the displacement and bore, but they obviously had reasons for doing it. It is an example where they deviated from the theory and that single decision forced their hand on the rest of the cylinder head more or less.
I know the MCSA based on the info he wrote there. You can also estimate the runner volume as well. I won't ruin it, but I'll nudge you in the right direction.
http://www.wallaceracing.com/csa-calc.php
Port Lengths :
Int=5.628 Exh=3.328 GM LS-7 12578449 CNCd OEM shape
The port length of ls6/ls3 is likely a bit shorter - maybe 5.5" length vs 5.6". The ls7 has the raised runner so the center point of the port is going to be higher. It is the same as going around a curve in your car. The wider arc you take the longer your path is.
You gotta look beyond runner volume to really start to (pretend) to get it. I say pretend because this is something you spend a lifetime learning and implementing. Runner volume is the final piece that isn't really that important in the end because you can have the same runner volume but wildly different performance where it matters.
Runner volume is a product of valve size, and ideal valve size is theoretically set by the bore - usually around 52%. The choke or MCSA is going to be set by the valve size - usually around 88-92% depending on RPM needed. From there you see the port kind of just builds itself leading up to the intake flange. For GM, they had a reason for going with the 2.165" valve size in the ls3 and that led to a "huge" 260cc port. The big valve helped them hit their goals for slow and high speed driving, fuel economy and emissions etc for a production car - whatever those were. Yes it is a huge valve for the displacement and bore, but they obviously had reasons for doing it. It is an example where they deviated from the theory and that single decision forced their hand on the rest of the cylinder head more or less.
Last edited by spanks13; 10-28-2020 at 11:02 AM.
10-28-2020, 11:11 AM
#426
He gave you the answers you wanted and is trying to teach you how to get this info for yourself in the future for any head.
I know the MCSA based on the info he wrote there. You can also estimate the runner volume as well. I won't ruin it, but I'll nudge you in the right direction.
http://www.wallaceracing.com/csa-calc.php
Port Lengths :
Int=5.628 Exh=3.328 GM LS-7 12578449 CNCd OEM shape
The port length of ls6/ls3 is likely a bit shorter - maybe 5" length vs 5.6". The ls7 has the raised runner so the center point of the port is going to be higher. It is the same as going around a curve in your car. The wider arc you take the longer your path is.
You gotta look beyond runner volume to really start to (pretend) to get it. I say pretend because this is something you spend a lifetime learning and implementing. Runner volume is the final piece that isn't really that important in the end because you can have the same runner volume but wildly different performance where it matters.
Runner volume is a product of valve size, and ideal valve size is theoretically set by the bore - usually around 52%. The choke or MCSA is going to be set by the valve size - usually around 88-92% depending on RPM needed. From there you see the port kind of just builds itself leading up to the intake flange. For GM, they had a reason for going with the 2.165" valve size in the ls3 and that led to a "huge" 260cc port. The big valve helped them hit their goals for slow and high speed driving, fuel economy and emissions etc for a production car - whatever those were. Yes it is a huge valve for the displacement and bore, but they obviously had reasons for doing it. It is an example where they deviated from the theory and that single decision forced their hand on the rest of the cylinder head more or less.
I know the MCSA based on the info he wrote there. You can also estimate the runner volume as well. I won't ruin it, but I'll nudge you in the right direction.
http://www.wallaceracing.com/csa-calc.php
Port Lengths :
Int=5.628 Exh=3.328 GM LS-7 12578449 CNCd OEM shape
The port length of ls6/ls3 is likely a bit shorter - maybe 5" length vs 5.6". The ls7 has the raised runner so the center point of the port is going to be higher. It is the same as going around a curve in your car. The wider arc you take the longer your path is.
You gotta look beyond runner volume to really start to (pretend) to get it. I say pretend because this is something you spend a lifetime learning and implementing. Runner volume is the final piece that isn't really that important in the end because you can have the same runner volume but wildly different performance where it matters.
Runner volume is a product of valve size, and ideal valve size is theoretically set by the bore - usually around 52%. The choke or MCSA is going to be set by the valve size - usually around 88-92% depending on RPM needed. From there you see the port kind of just builds itself leading up to the intake flange. For GM, they had a reason for going with the 2.165" valve size in the ls3 and that led to a "huge" 260cc port. The big valve helped them hit their goals for slow and high speed driving, fuel economy and emissions etc for a production car - whatever those were. Yes it is a huge valve for the displacement and bore, but they obviously had reasons for doing it. It is an example where they deviated from the theory and that single decision forced their hand on the rest of the cylinder head more or less.
It's much easier to decipher.
I know CC's aren't everything but it does give a good indication of efficiency.
As an example.
If you have two heads. Both flow the same, on the same bench, let's say 380CFM.
If one port is 250cc and the other is 270cc wouldn't you choose the smaller more efficient port regardless of the shape?
Assuming of course you are planning to spin to a higher RPM where the CSA begins to matter even more so you would choose the head with the correct CSA for the application.
I know valve angle makes a good difference, and the choke point etc.
Mr Smoke sent me some messages about it.
There is a reason Mr Mamo tries to keep the intake runner as small as possible while maximising velocity and air speed for that style port too wouldn't you say?
10-28-2020, 11:23 AM
#427
He gave you the answers you wanted and is trying to teach you how to get this info for yourself in the future for any head.
I know the MCSA based on the info he wrote there. You can also estimate the runner volume as well. I won't ruin it, but I'll nudge you in the right direction.
http://www.wallaceracing.com/csa-calc.php
Port Lengths :
Int=5.628 Exh=3.328 GM LS-7 12578449 CNCd OEM shape
The port length of ls6/ls3 is likely a bit shorter - maybe 5.5" length vs 5.6". The ls7 has the raised runner so the center point of the port is going to be higher. It is the same as going around a curve in your car. The wider arc you take the longer your path is.
You gotta look beyond runner volume to really start to (pretend) to get it. I say pretend because this is something you spend a lifetime learning and implementing. Runner volume is the final piece that isn't really that important in the end because you can have the same runner volume but wildly different performance where it matters.
Runner volume is a product of valve size, and ideal valve size is theoretically set by the bore - usually around 52%. The choke or MCSA is going to be set by the valve size - usually around 88-92% depending on RPM needed. From there you see the port kind of just builds itself leading up to the intake flange. For GM, they had a reason for going with the 2.165" valve size in the ls3 and that led to a "huge" 260cc port. The big valve helped them hit their goals for slow and high speed driving, fuel economy and emissions etc for a production car - whatever those were. Yes it is a huge valve for the displacement and bore, but they obviously had reasons for doing it. It is an example where they deviated from the theory and that single decision forced their hand on the rest of the cylinder head more or less.
I know the MCSA based on the info he wrote there. You can also estimate the runner volume as well. I won't ruin it, but I'll nudge you in the right direction.
http://www.wallaceracing.com/csa-calc.php
Port Lengths :
Int=5.628 Exh=3.328 GM LS-7 12578449 CNCd OEM shape
The port length of ls6/ls3 is likely a bit shorter - maybe 5.5" length vs 5.6". The ls7 has the raised runner so the center point of the port is going to be higher. It is the same as going around a curve in your car. The wider arc you take the longer your path is.
You gotta look beyond runner volume to really start to (pretend) to get it. I say pretend because this is something you spend a lifetime learning and implementing. Runner volume is the final piece that isn't really that important in the end because you can have the same runner volume but wildly different performance where it matters.
Runner volume is a product of valve size, and ideal valve size is theoretically set by the bore - usually around 52%. The choke or MCSA is going to be set by the valve size - usually around 88-92% depending on RPM needed. From there you see the port kind of just builds itself leading up to the intake flange. For GM, they had a reason for going with the 2.165" valve size in the ls3 and that led to a "huge" 260cc port. The big valve helped them hit their goals for slow and high speed driving, fuel economy and emissions etc for a production car - whatever those were. Yes it is a huge valve for the displacement and bore, but they obviously had reasons for doing it. It is an example where they deviated from the theory and that single decision forced their hand on the rest of the cylinder head more or less.
10-28-2020, 11:41 AM
#428
I wish Smoke wrote as clear as this.
It's much easier to decipher.
I know CC's aren't everything but it does give a good indication of efficiency.
As an example.
If you have two heads. Both flow the same, on the same bench, let's say 380CFM.
If one port is 250cc and the other is 270cc wouldn't you choose the smaller more efficient port regardless of the shape?
Assuming of course you are planning to spin to a higher RPM where the CSA begins to matter even more so you would choose the head with the correct CSA for the application.
I know valve angle makes a good difference, and the choke point etc.
Mr Smoke sent me some messages about it.
There is a reason Mr Mamo tries to keep the intake runner as small as possible while maximising velocity and air speed for that style port too wouldn't you say?
It's much easier to decipher.
I know CC's aren't everything but it does give a good indication of efficiency.
As an example.
If you have two heads. Both flow the same, on the same bench, let's say 380CFM.
If one port is 250cc and the other is 270cc wouldn't you choose the smaller more efficient port regardless of the shape?
Assuming of course you are planning to spin to a higher RPM where the CSA begins to matter even more so you would choose the head with the correct CSA for the application.
I know valve angle makes a good difference, and the choke point etc.
Mr Smoke sent me some messages about it.
There is a reason Mr Mamo tries to keep the intake runner as small as possible while maximising velocity and air speed for that style port too wouldn't you say?
Example: 250 cc port vs the 270 cc port is better on what type of build CID wise and or what rpm point? Say a 454 that's needed to go to 8k with a small 770 lift. Who wins if ported by the same porter. .CSA would give the perfect answer not CC.
Bortous with luv contact Mamo and learn the formula..All porters talked to go by this Shawn Hooper, and I are still talking > woke up to a FB pm 😉. Best free information a porter has given me is I can spec my own heads and they'll Always match damn close to what's being ported Before hand. 270cc Ls7 heads of mines = around 7800 I think with the cubic inch used. 270cc doesn't tell us Nothing 🤐 So a 260 cc Ls7 head would be better if going to 7800? Choke point?
Last edited by Corona; 10-28-2020 at 01:16 PM.
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spanks13 (10-28-2020)
10-28-2020, 11:52 AM
#429
Guys should have been taught this BTW if you gonna talk about heads . . ..there's also a thing called, being 2 small with to much speed in the port. But the way shown shows the Precision vs the Guess of a CC number.
Example: 250 cc port vs the 270 cc port is better on what type of build CID wise and or what rpm point? Say a 454 that's needed to go to 8k with a small 770 lift. Who wins if ported by the same porter. .CSA would give the perfect answer not CC.
Example: 250 cc port vs the 270 cc port is better on what type of build CID wise and or what rpm point? Say a 454 that's needed to go to 8k with a small 770 lift. Who wins if ported by the same porter. .CSA would give the perfect answer not CC.
You choose the correct CSA for your RPM goal.
If I wanted to rev to 8000rpm I would choose a head to suit.
Would you say the correct CSA is for the rpm and choke point and the smaller CC gives an indication that the bottom end and mid range power will be stronger/more responsive?
Remember this can't be measured on the dyno.
It's something you feel.
10-28-2020, 11:58 AM
#430
Get this B°, you can't tell me the Choke point dealing with CC. So how would or do you know it. Word of mouth or it's smaller so it's better? We're working with math not it should be better here. I can give you a CiD and RPM goal and the CSA will match any head ported Typically 99.8 %. Going by it's smaller doesn't cut the mustard.
Exact numbers, you can't talk heads and not get MCSA or CSA.
BTW a small gear change will put that feeling wanted in the seat of the pants back without changing heads with a softer cam 🤫.
Exact numbers, you can't talk heads and not get MCSA or CSA.
BTW a small gear change will put that feeling wanted in the seat of the pants back without changing heads with a softer cam 🤫.
Last edited by Corona; 10-28-2020 at 12:05 PM.
10-28-2020, 12:26 PM
#431
Bortous like in the cartoons a Anvil from the sky hit me in the head. Again! Think about this one? I know guys and hood issues 👍. Man what if a hood wasn't the problem or wasn't a thought. And what's seen with a racer type intake and a rectangular Port.
Whoa!
That was a Small 🍌 cam & compression test not even close to Pump gas limits.
Think about what cams are being used on HERE.😉🤫✋👍
Damn storm again 😔 I would like too get some 💰
but that's God's work. LMAO 😂🤣
Whoa!
That was a Small 🍌 cam & compression test not even close to Pump gas limits.
Think about what cams are being used on HERE.😉🤫✋👍
Damn storm again 😔 I would like too get some 💰
but that's God's work. LMAO 😂🤣
Last edited by Corona; 10-28-2020 at 12:33 PM.
