Flowing Exhaust ports with a "pipe"....
02-12-2005, 10:37 AM
#22
TECH Addict
iTrader: (59)
Join Date: Oct 2004
Location: Vance, Alabama
Posts: 2,357
Likes: 0
Received 0 Likes
on
0 Posts
That answers my question... Another thing is if you have a head that flows 300 in. and 270 ex. w/ a pipe then the intake port would be knocked down to 270 or less with the LS6 intake bolted on and would make a 100% in/ex ratio or more 
02-12-2005, 10:49 AM
#23
Originally Posted by Greg Good
I do not believe in flowing with a pipe. Flowing with a pipe smooths out a turbulent port. It's better to get a port to flow smooth without a pipe.
Like many things in life there will ALWAYS be differences in opinions. Personally, I would rather optimize a port's shape and design to mimic exactly what it will see under operating conditions. A "pipe" or header IS an extension of the exhaust port (that will always be there) and I choose to treat it as a single entity by designing a port the best I can with it in place.
Also, I don't believe in using a straight pipe....The "dynamics" a straight pipe produces in the exhaust port does not represent real world operating conditions...In the real world, exhaust gases make a significant change in direction as they enter the header and quickly hook and curve downward. (Unless your running "zoomies" in your F-Body or C5....LOL).
I'm not trying to prove my "theory" right or wrong here....just sharing what it is and why it is....armed with information you guys can determine what makes the most sense to each of you and what "theory" you want to subscribe to.
Tony M.
02-12-2005, 01:32 PM
#25
Originally Posted by Tony Mamo @ AFR
Hello Greg...
Like many things in life there will ALWAYS be differences in opinions. Personally, I would rather optimize a port's shape and design to mimic exactly what it will see under operating conditions. A "pipe" or header IS an extension of the exhaust port (that will always be there) and I choose to treat it as a single entity by designing a port the best I can with it in place.
Also, I don't believe in using a straight pipe....The "dynamics" a straight pipe produces in the exhaust port does not represent real world operating conditions...In the real world, exhaust gases make a significant change in direction as they enter the header and quickly hook and curve downward. (Unless your running "zoomies" in your F-Body or C5....LOL).
I'm not trying to prove my "theory" right or wrong here....just sharing what it is and why it is....armed with information you guys can determine what makes the most sense to each of you and what "theory" you want to subscribe to.
Tony M.
Like many things in life there will ALWAYS be differences in opinions. Personally, I would rather optimize a port's shape and design to mimic exactly what it will see under operating conditions. A "pipe" or header IS an extension of the exhaust port (that will always be there) and I choose to treat it as a single entity by designing a port the best I can with it in place.
Also, I don't believe in using a straight pipe....The "dynamics" a straight pipe produces in the exhaust port does not represent real world operating conditions...In the real world, exhaust gases make a significant change in direction as they enter the header and quickly hook and curve downward. (Unless your running "zoomies" in your F-Body or C5....LOL).
I'm not trying to prove my "theory" right or wrong here....just sharing what it is and why it is....armed with information you guys can determine what makes the most sense to each of you and what "theory" you want to subscribe to.
Tony M.
You are correct, exhaust flow does not exit out into the open atmosphere. But neither does it flow into a 6" header tube either. Both situations are nonexistiant on a car. All I see a short tube doing is masking turbulence and raising the overall flow numbers, which look good on the flow sheet. If we want to know the whole truth about what the exhaust port is doing we should flow with a complete header on the head. I've done that too, and the flow comes way back down lots of times.
Anyway, all this flow stuff is nice, but in the end how FAST the head runs is all that counts. And there are certainly others factors involved there.
02-12-2005, 01:36 PM
#26
Originally Posted by CAT3
Greg Good, have you ever got a port to flow smooth w/o a pipe and then reflow it with to compare your results? That would be a nice comparison, but I am thinking not since you havent posted the details of such flow test.
Since I didn't bother to spend hours digging out old data and posting it for you, you're probably right, I've probably never done it, and I'm just talking outta my butt.
02-12-2005, 11:42 PM
#27
Staging Lane
Join Date: Feb 2004
Location: N?W
Posts: 60
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by BowtieFreak
It has been done by many race car builders. NASCAR and other such racing proved years ago that in this environment, by reducing compression, one picks up horsepower due to an increase in volumetric efficency in engines making over 100% due to scavenging the exhaust completely out of the combustion chamber.
Let me explain. Lets compair two compression ratios in a road race small block chevy with a bore of 4.125" and a stroke of 3.25" (347 destroker).
Our first comparison is a 13.6:1 compression. Let's say we are using an 18" head with a 62 cc combustion chamber, a deck hight of zero (piston crown is level with the deck at tdc .000"), with a felpro gasket (3 cc volume) and a 10cc dome. At TDC of the compression stroke, the air/fuel mixture is compressed in a 55cc space. If the intake and exhaust are tuned close to perfectly for the rpm we are spinning, the exhaust will scavenge ALL of the exhaust from this area at the top fo the exhaust stroke, and the leading edge of the intake stroke, and will probably pull some freak air/fuel through the exhaust valve (over scavenging). THis means that our limit of space with which to fill air and fuel is approximately 7.9% larger than the displacement of the engine (which could be slightly above atmospheric pressure due to inertia in the intake ports creating a slight pressurized effect (much like having a couple lbs of boost in a highly tuned engine).
Lets compair this to an engine that is 10.2:1 compression. This would be the same engine with a 10 cc dish instead of a dome, brining the compression volume up to 75 cc. This yields a 10.7% larger space than the engine's displacement to fill with air and fuel, and actuall this gives us 2% more inductoin flow than the larger compression engine. Not only that, remember we are dealing with a wedge shaped chamber. A flat top or a dished piston produces better burn efficency with a wedge shaped chamber. THere is a good probablity that in this case the lower compression engien will actually make more horsepower, and will definately yield more mid-range torque. In road race applications or classes with limited carburation or induction, this will yeild more gas milage, and more horsepower due to 2% more of your fuel to remain in the combustion chamber during the overlap period in which scavenging occurs.
This is why NASCAR didn' lose any horsepower when they hanged the rules limiting the engines to 9:1 compression
Any questions?
Let me explain. Lets compair two compression ratios in a road race small block chevy with a bore of 4.125" and a stroke of 3.25" (347 destroker).
Our first comparison is a 13.6:1 compression. Let's say we are using an 18" head with a 62 cc combustion chamber, a deck hight of zero (piston crown is level with the deck at tdc .000"), with a felpro gasket (3 cc volume) and a 10cc dome. At TDC of the compression stroke, the air/fuel mixture is compressed in a 55cc space. If the intake and exhaust are tuned close to perfectly for the rpm we are spinning, the exhaust will scavenge ALL of the exhaust from this area at the top fo the exhaust stroke, and the leading edge of the intake stroke, and will probably pull some freak air/fuel through the exhaust valve (over scavenging). THis means that our limit of space with which to fill air and fuel is approximately 7.9% larger than the displacement of the engine (which could be slightly above atmospheric pressure due to inertia in the intake ports creating a slight pressurized effect (much like having a couple lbs of boost in a highly tuned engine).
Lets compair this to an engine that is 10.2:1 compression. This would be the same engine with a 10 cc dish instead of a dome, brining the compression volume up to 75 cc. This yields a 10.7% larger space than the engine's displacement to fill with air and fuel, and actuall this gives us 2% more inductoin flow than the larger compression engine. Not only that, remember we are dealing with a wedge shaped chamber. A flat top or a dished piston produces better burn efficency with a wedge shaped chamber. THere is a good probablity that in this case the lower compression engien will actually make more horsepower, and will definately yield more mid-range torque. In road race applications or classes with limited carburation or induction, this will yeild more gas milage, and more horsepower due to 2% more of your fuel to remain in the combustion chamber during the overlap period in which scavenging occurs.
This is why NASCAR didn' lose any horsepower when they hanged the rules limiting the engines to 9:1 compression
Any questions?
Nascar motors had a signifigant loss of HP when reducing compression to 9:1. The compression was lowered in an effort to slow the cars down and increase engine reliability.
Consider the fact that the exhaust valve opens when the piston is approx. 1/2 way down the bore on the power stroke. (Check your cam card) Exhaust flow is initiated as the result of the residual presure that is in the cylinder at this time and actual "in cylinder pressure measurements/volume graphs" published in Circle Track magazine a number of years ago have documented the fact that the cylinder is completely evacuated and shows a negative pressure in the cylinder when the piston reaches the bottom of it's stroke while still on the power stroke.
Hint: (Too much low lift exhaust flow could blow the cylinder down to quickly during this time and cause a loss of power as we are running a balance between pushing the piston down and initiating exhaust flow)This is an interesting concept.....considering that the piston is traveling up the bore with a negative pressure on the exhaust stroke and is not pushing the spent exhaust gases out as we were taught in Auto Shop 101.
Taking this concept one step further......we are actually creating HP on the exhaust stroke by helping to draw the piston up the bore with negative pressure.
Now where were we?
Oh yeah, flowing heads with a pipe. Sorry Tony, I jacked your thread.
Next item for discussion: Flowing with a straight pipe, 12" of straight pipe and then a bend, a megaphone pipe, or a pipe with a bend in it pointed down and/or back just like the headers in our cars.................................
Please continue..............
02-13-2005, 06:26 AM
#28
Staging Lane
Join Date: Jan 2005
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
[QUOTE=Rookie\
Consider the fact that the exhaust valve opens when the piston is approx. 1/2 way down the bore on the power stroke. (Check your cam card) Exhaust flow is initiated as the result of the residual presure that is in the cylinder at this time and actual "in cylinder pressure measurements/volume graphs" published in Circle Track magazine a number of years ago have documented the fact that the cylinder is completely evacuated and shows a negative pressure in the cylinder when the piston reaches the bottom of it's stroke while still on the power stroke. Hint: (Too much low lift exhaust flow could blow the cylinder down to quickly during this time and cause a loss of power as we are running a balance between pushing the piston down and initiating exhaust flow)
This is an interesting concept.....considering that the piston is traveling up the bore with a negative pressure on the exhaust stroke and is not pushing the spent exhaust gases out as we were taught in Auto Shop 101.
Taking this concept one step further......we are actually creating HP on the exhaust stroke by helping to draw the piston up the bore with negative pressure.
[/QUOTE]
Good point, but keep in mind that one needs a good exhaust system to get this effect. You are also correct about losing power on the power stroke by bleeding off too much pressure too fast via the exhaust port. If you have the correct headers and exhaust system on your car you should not need a split pattern camshaft, unless you are using a reverse split.
Consider the fact that the exhaust valve opens when the piston is approx. 1/2 way down the bore on the power stroke. (Check your cam card) Exhaust flow is initiated as the result of the residual presure that is in the cylinder at this time and actual "in cylinder pressure measurements/volume graphs" published in Circle Track magazine a number of years ago have documented the fact that the cylinder is completely evacuated and shows a negative pressure in the cylinder when the piston reaches the bottom of it's stroke while still on the power stroke.
Hint: (Too much low lift exhaust flow could blow the cylinder down to quickly during this time and cause a loss of power as we are running a balance between pushing the piston down and initiating exhaust flow)This is an interesting concept.....considering that the piston is traveling up the bore with a negative pressure on the exhaust stroke and is not pushing the spent exhaust gases out as we were taught in Auto Shop 101.
Taking this concept one step further......we are actually creating HP on the exhaust stroke by helping to draw the piston up the bore with negative pressure.
[/QUOTE]
Good point, but keep in mind that one needs a good exhaust system to get this effect. You are also correct about losing power on the power stroke by bleeding off too much pressure too fast via the exhaust port. If you have the correct headers and exhaust system on your car you should not need a split pattern camshaft, unless you are using a reverse split.
02-13-2005, 08:52 AM
#29
Staging Lane
Join Date: Jan 2005
Posts: 89
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Rookie
Nascar motors had a signifigant loss of HP when reducing compression to 9:1. The compression was lowered in an effort to slow the cars down and increase engine reliability.
Consider the fact that the exhaust valve opens when the piston is approx. 1/2 way down the bore on the power stroke. (Check your cam card) Exhaust flow is initiated as the result of the residual presure that is in the cylinder at this time and actual "in cylinder pressure measurements/volume graphs" published in Circle Track magazine a number of years ago have documented the fact that the cylinder is completely evacuated and shows a negative pressure in the cylinder when the piston reaches the bottom of it's stroke while still on the power stroke.
Hint: (Too much low lift exhaust flow could blow the cylinder down to quickly during this time and cause a loss of power as we are running a balance between pushing the piston down and initiating exhaust flow)This is an interesting concept.....considering that the piston is traveling up the bore with a negative pressure on the exhaust stroke and is not pushing the spent exhaust gases out as we were taught in Auto Shop 101.
Taking this concept one step further......we are actually creating HP on the exhaust stroke by helping to draw the piston up the bore with negative pressure.
Now where were we?
Oh yeah, flowing heads with a pipe. Sorry Tony, I jacked your thread.
Next item for discussion: Flowing with a straight pipe, 12" of straight pipe and then a bend, a megaphone pipe, or a pipe with a bend in it pointed down and/or back just like the headers in our cars.................................
Please continue..............
Second , i have done actual LS1 header testing on several ported exha ust ports and results always brought flow numbers back down from pipe extension high #'s. Sometimes flow with header was same as open port but also lower at times. I like the idea of port design with real life conditions but test pipe is not accurate the way i see it.
Last edited by LSonederfull; 02-13-2005 at 08:59 AM.
02-13-2005, 09:40 AM
#30
Very interesting topic Tony. Now, what's the power difference between an exhaust port that flows 270+ peak and one that flows 240 peak? If anyone has dyno info they'd like to share I think it would help us put some perspective on this subject.
Also how much does the remainder of the exhaust system hinder power? Minimum to maximum?
Richard
Also how much does the remainder of the exhaust system hinder power? Minimum to maximum?
Richard
02-13-2005, 11:14 AM
#31
TECH Apprentice
iTrader: (3)
Join Date: Sep 2002
Location: belleville IL
Posts: 347
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Greg Good
You are correct, exhaust flow does not exit out into the open atmosphere. But neither does it flow into a 6" header tube either. Both situations are nonexistiant on a car. All I see a short tube doing is masking turbulence and raising the overall flow numbers, which look good on the flow sheet. If we want to know the whole truth about what the exhaust port is doing we should flow with a complete header on the head. I've done that too, and the flow comes way back down lots of times.
I never have gotten hung up on flow bench numbers, cuz it really dont mean all that much when the engine is running, when is a engine ever running at 28inches of pressure drop? The pressure drop changes thru rpms so who cares
Just use the benches as a guide to see what you changed in the port and if it helped or not.Shawn
02-13-2005, 11:20 AM
#32
Staging Lane
Join Date: Feb 2004
Location: N?W
Posts: 60
Likes: 0
Received 0 Likes
on
0 Posts
[QUOTE=BowtieFreak][QUOTE=Rookie\
Consider the fact that the exhaust valve opens when the piston is approx. 1/2 way down the bore on the power stroke. (Check your cam card) Exhaust flow is initiated as the result of the residual presure that is in the cylinder at this time and actual "in cylinder pressure measurements/volume graphs" published in Circle Track magazine a number of years ago have documented the fact that the cylinder is completely evacuated and shows a negative pressure in the cylinder when the piston reaches the bottom of it's stroke while still on the power stroke. Hint: (Too much low lift exhaust flow could blow the cylinder down to quickly during this time and cause a loss of power as we are running a balance between pushing the piston down and initiating exhaust flow)
This is an interesting concept.....considering that the piston is traveling up the bore with a negative pressure on the exhaust stroke and is not pushing the spent exhaust gases out as we were taught in Auto Shop 101.
Taking this concept one step further......we are actually creating HP on the exhaust stroke by helping to draw the piston up the bore with negative pressure.
Good point, but keep in mind that one needs a good exhaust system to get this effect. You are also correct about losing power on the power stroke by bleeding off too much pressure too fast via the exhaust port. If you have the correct headers and exhaust system on your car you should not need a split pattern camshaft, unless you are using a reverse split.[/QUOTE]
Of course timing is everything. Theoretically, as we increase the efficiencyy of a port/tract, be it intake or exhaust, does it not allow us to remove cam timing from that particular cycle and still maintain the same or increased HP at the same or increased rpm point?
Compare the SBC to the LS-1. 23 degree valve angle to 15. The 15 degree angle has a much improved entrance into the cylinder. There is not that much magic in the LS-1 short block gentlemen to allow us to make 500 RWHP on pump gas with a 230 @ .050 on a 112-115 LSA camshaft. The bore centers are the same, the bore/stroke/rod ratio is not different enough to account for it. The manifold is basically a Tuned Port turned upside down. These types of numbers are unheard of given the same parameters on a SBC. The answer.....more efficient cylinder head design allows us to reduce cam timing and make more power.
I use the above as an extreme case to illustrate what can be done to the camshaft timing as cylinder head efficiency increases.
Richard,
IMHO we could lose power with a 270 cfm ex port and gain power with a 240 cfm ex port, depending upon the cam timing in the test engine.
Too many variables to test everything, all we can do is take bits and pieces of what everyone shares and develop our own combinations, or follow the recipe that so many of the vendors here have already laid out for us in order to make a given power curve.
Consider the fact that the exhaust valve opens when the piston is approx. 1/2 way down the bore on the power stroke. (Check your cam card) Exhaust flow is initiated as the result of the residual presure that is in the cylinder at this time and actual "in cylinder pressure measurements/volume graphs" published in Circle Track magazine a number of years ago have documented the fact that the cylinder is completely evacuated and shows a negative pressure in the cylinder when the piston reaches the bottom of it's stroke while still on the power stroke.
Hint: (Too much low lift exhaust flow could blow the cylinder down to quickly during this time and cause a loss of power as we are running a balance between pushing the piston down and initiating exhaust flow)This is an interesting concept.....considering that the piston is traveling up the bore with a negative pressure on the exhaust stroke and is not pushing the spent exhaust gases out as we were taught in Auto Shop 101.
Taking this concept one step further......we are actually creating HP on the exhaust stroke by helping to draw the piston up the bore with negative pressure.
Good point, but keep in mind that one needs a good exhaust system to get this effect. You are also correct about losing power on the power stroke by bleeding off too much pressure too fast via the exhaust port. If you have the correct headers and exhaust system on your car you should not need a split pattern camshaft, unless you are using a reverse split.[/QUOTE]
Of course timing is everything. Theoretically, as we increase the efficiencyy of a port/tract, be it intake or exhaust, does it not allow us to remove cam timing from that particular cycle and still maintain the same or increased HP at the same or increased rpm point?
Compare the SBC to the LS-1. 23 degree valve angle to 15. The 15 degree angle has a much improved entrance into the cylinder. There is not that much magic in the LS-1 short block gentlemen to allow us to make 500 RWHP on pump gas with a 230 @ .050 on a 112-115 LSA camshaft. The bore centers are the same, the bore/stroke/rod ratio is not different enough to account for it. The manifold is basically a Tuned Port turned upside down. These types of numbers are unheard of given the same parameters on a SBC. The answer.....more efficient cylinder head design allows us to reduce cam timing and make more power.
I use the above as an extreme case to illustrate what can be done to the camshaft timing as cylinder head efficiency increases.
Richard,
IMHO we could lose power with a 270 cfm ex port and gain power with a 240 cfm ex port, depending upon the cam timing in the test engine.
Too many variables to test everything, all we can do is take bits and pieces of what everyone shares and develop our own combinations, or follow the recipe that so many of the vendors here have already laid out for us in order to make a given power curve.
Last edited by Rookie; 02-13-2005 at 11:21 AM. Reason: Quote format was incorrect
02-13-2005, 01:09 PM
#33
Launching!
Join Date: Jul 2004
Location: Gainesville, Florida
Posts: 200
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Rookie
Richard,
IMHO we could lose power with a 270 cfm ex port and gain power with a 240 cfm ex port, depending upon the cam timing in the test engine.
IMHO we could lose power with a 270 cfm ex port and gain power with a 240 cfm ex port, depending upon the cam timing in the test engine.
Correct me if I'm wrong, but if you were designing heads from scratch, you would size the valves so that the exhaust flowed a certain % of the intake, correct? So if you ended up with a 270cfm exhaust port, you would decrease its valves' size, which would allow you to fit larger intake valves, and make more power. I think?
02-13-2005, 07:33 PM
#34
We did some "almost" back to back testing of some LS6 heads with the same everything except for exhaust port size and flow. The first set had a small exhaust (stock exit size) that flowed around 260, the second set had our nitrous exhaust port that flowed 280 and was opened up round at the top to match the header tube. The larger port made more torque and less horsepower, the smaller port made less torque and more peak horsepower. The key is to keep the exit stock size and flow like crazy.
Greg Good, imagine you, me and Tony all on this post, because YOU have MY AFR head that flows like 270 exhaust with out a pipe that YOU did and I would like to have back and Tony would like to see but probably never will.
Greg Good, imagine you, me and Tony all on this post, because YOU have MY AFR head that flows like 270 exhaust with out a pipe that YOU did and I would like to have back and Tony would like to see but probably never will.
02-17-2005, 10:28 PM
#35
TECH Fanatic
iTrader: (4)
Join Date: May 2002
Location: Fairview Heights Illinois
Posts: 1,851
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by TA2SLOW346
I agree with Greg as these are my findings also. Once a full header is bolted on the flow comes back down to REAL WORLD.
I never have gotten hung up on flow bench numbers, cuz it really dont mean all that much when the engine is running, when is a engine ever running at 28inches of pressure drop? The pressure drop changes thru rpms so who cares Just use the benches as a guide to see what you changed in the port and if it helped or not.
Shawn
I never have gotten hung up on flow bench numbers, cuz it really dont mean all that much when the engine is running, when is a engine ever running at 28inches of pressure drop? The pressure drop changes thru rpms so who cares
Just use the benches as a guide to see what you changed in the port and if it helped or not.Shawn
The ODB agrees.
02-21-2005, 12:14 AM
#37
GrannySShifting, that port ain't nothing special to look at. Just good basic conventional head porting. No Voodoo or magic.
I decided it' not time for this thread to die. I've got Aerosmith's Sweet Emotion playin' in the background, and I hope some Zeppelin comes on soon. That shows you guys how old I am. And I'm gettin' more outspoken the older I get. I had a dream I kissed the Blarney stone last night.
An exhaust port that flows 250 with a pipe for instance, and one that flows 250 without one, but with a pipe flows 280,...........which one is better? Obviously the one that's 250 without a pipe. Just like I don't care what a head flows with a long runner manifold, nor do I care what an exhaust port flows with whatever length of pipe makes it look better attached to it. It's meaningless. Mental masturbation. Go ahead and admit it, we all do it. I hate it when I hurt a hand, it cuts my love life in half. Just kidding. A short pipe on an exhaust port amounts to no more than Viagra for a Eunich. Every exhaust port I've flowed with a pipe gained a bunch. So what. I'm also in the club that says there's no such thing as too much exhaust flow, except for low-lift exhaust flow. Why do we not hear of how great an intake port flows with a manifold? Because they ALL HURT FLOW. If a certain length of intake runner helped flow, every head porter would be flowing and advertising with those numbers. You all know it.
A common mistake I see people make is putting too much faith in steady state flow tests. Air flow in an engine IS NOT STEADY. A four cycle engine is not a rocket engine. It has pulsing flow, NOT steady flow. How great the intake port flows determines how quickly the volume of the combined intake/manifold port will be emptied into the cylinder. Likewise, how great the exhaust port flows determines how quickly the cylinder will empty it's refuse into the header. Period. End of story. Put your crack pipes down.
Over and out from Earth.
P.S. And Brian, that port doesn't flow 270. It flows mid 260's. No pipe, and I just calibrated my bench with a set of Superflow calibration plates. So, as far as I and Superflow are concerned, my bench is legit. The intake is one turbulent ****. And since I'm not happy with turbulent ports, I'm still tweaking it. It's 360 at it's peak for now.
I decided it' not time for this thread to die. I've got Aerosmith's Sweet Emotion playin' in the background, and I hope some Zeppelin comes on soon. That shows you guys how old I am. And I'm gettin' more outspoken the older I get. I had a dream I kissed the Blarney stone last night.
An exhaust port that flows 250 with a pipe for instance, and one that flows 250 without one, but with a pipe flows 280,...........which one is better? Obviously the one that's 250 without a pipe. Just like I don't care what a head flows with a long runner manifold, nor do I care what an exhaust port flows with whatever length of pipe makes it look better attached to it. It's meaningless. Mental masturbation. Go ahead and admit it, we all do it. I hate it when I hurt a hand, it cuts my love life in half.
Just kidding. A short pipe on an exhaust port amounts to no more than Viagra for a Eunich. Every exhaust port I've flowed with a pipe gained a bunch. So what. I'm also in the club that says there's no such thing as too much exhaust flow, except for low-lift exhaust flow. Why do we not hear of how great an intake port flows with a manifold? Because they ALL HURT FLOW. If a certain length of intake runner helped flow, every head porter would be flowing and advertising with those numbers. You all know it.A common mistake I see people make is putting too much faith in steady state flow tests. Air flow in an engine IS NOT STEADY. A four cycle engine is not a rocket engine. It has pulsing flow, NOT steady flow. How great the intake port flows determines how quickly the volume of the combined intake/manifold port will be emptied into the cylinder. Likewise, how great the exhaust port flows determines how quickly the cylinder will empty it's refuse into the header. Period. End of story. Put your crack pipes down.
Over and out from Earth.
P.S. And Brian, that port doesn't flow 270. It flows mid 260's. No pipe, and I just calibrated my bench with a set of Superflow calibration plates. So, as far as I and Superflow are concerned, my bench is legit. The intake is one turbulent ****. And since I'm not happy with turbulent ports, I'm still tweaking it. It's 360 at it's peak for now.
Last edited by Greg Good; 02-21-2005 at 12:35 AM.
02-21-2005, 12:22 AM
#38
Tony, I like you, although I disagree with you on this pipe thing. You work hard, and you're not afraid to show your cards. We need more guys like you in the biz.
I don't know if you've heard of Larry Wallace, but he transformed Ford head technology with the Yates head. Robert Yates gets the official credit for it, but Larry made the changes that took a very finicky and turbulent head, the old C302 Ford head, and made a cutting edge head out of it.
I'd like to see something like that done for the LS1 crowd.
Do your due diligence.
I don't know if you've heard of Larry Wallace, but he transformed Ford head technology with the Yates head. Robert Yates gets the official credit for it, but Larry made the changes that took a very finicky and turbulent head, the old C302 Ford head, and made a cutting edge head out of it.
I'd like to see something like that done for the LS1 crowd.
Do your due diligence.
02-21-2005, 11:10 AM
#39
Originally Posted by Greg Good
Tony, I like you, although I disagree with you on this pipe thing. You work hard, and you're not afraid to show your cards. We need more guys like you in the biz.
I don't know if you've heard of Larry Wallace, but he transformed Ford head technology with the Yates head. Robert Yates gets the official credit for it, but Larry made the changes that took a very finicky and turbulent head, the old C302 Ford head, and made a cutting edge head out of it.
I'd like to see something like that done for the LS1 crowd.
Do your due diligence.
I don't know if you've heard of Larry Wallace, but he transformed Ford head technology with the Yates head. Robert Yates gets the official credit for it, but Larry made the changes that took a very finicky and turbulent head, the old C302 Ford head, and made a cutting edge head out of it.
I'd like to see something like that done for the LS1 crowd.
Do your due diligence.
I think you might have been sipping too much of your favorite beverage on your previous post!....LOL
Just to confirm I am still standing strong on the fact that an exhaust port should be designed, developed, and optimized with the use of a CURVED pipe that correctly mimics most production headers. IF you can get 250 without a pipe and 280 with a pipe god bless you, but I think you efforts would be better served by designing it with a pipe in place.....it would ultimately change some of the port design and would work much better in the real world IMHO.
Thats my story and I'm sticking to it....
When your finished with that cylinder head why dont you send it here so I can back up your numbers on my equipment....personally, If I see within 10 CFM of what you say (360/280) I would fall over, then get up and give you major props....Let me know....I will pay freight both ways.
And my due diligence NEVER stops....LOL
Regards,
Tony
02-21-2005, 11:50 AM
#40
Tony,
In speaking with Ron of Ron's Porting and Joe of HVH over the years both have said in passing comments, "you can tell a good valve job by how much the air flow is affected when you bolt a pipe to the exhaust port". I know both are very"elusive" when talking about angles and radius's on valve jobs. What is your opinion?
BTW,
Thanks for the retainers.
Chris
In speaking with Ron of Ron's Porting and Joe of HVH over the years both have said in passing comments, "you can tell a good valve job by how much the air flow is affected when you bolt a pipe to the exhaust port". I know both are very"elusive" when talking about angles and radius's on valve jobs. What is your opinion?
BTW,
Thanks for the retainers.
Chris
