SFR intake manifold
09-19-2011, 05:22 AM
#62
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I was hoping that someone like Chris White or Sean (JET951) who have had the SFR intake in their hands may have taken the time to measure the volume.
I have read everything and its opposite on intake plenum volume, just wondering what a good rule of thumb could be and if the SFR piece would work as well on a 3.0 as on a 2.5 for instance.
I have read everything and its opposite on intake plenum volume, just wondering what a good rule of thumb could be and if the SFR piece would work as well on a 3.0 as on a 2.5 for instance.
09-19-2011, 08:01 AM
#63
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I'd like to see people's various ideas about an alternative intake or at least the key ingredients?
09-19-2011, 08:02 AM
#64
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09-19-2011, 08:08 AM
#65
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642 is a constant that we used at Ford. I don't know the source of it, other than Ford's #1 intake guy. John Heywood, who runs the ME department at MIT and is pretty well known, uses 675.
L = runner length (CM)
C = speed of sound* ( M/S)
A = runner cross sectional area (sq. CM)
RPM = target RPM (/Min)
V = cylinder volume (sq. CM single cylinder, not the engine)
CR = compression ratio
Note that the speed of sound is a function of temperature, which is important, especially since we are heating up the air. Formula in meters per second is: (150*1.4*T)^0.5, where T is degrees Rankin (i.e. degrees farenheit + 460).
Last edited by 67King; 09-20-2011 at 07:05 AM. Reason: Oops!
09-19-2011, 08:28 AM
#66
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RPM at peak torque: L = 642^2*C^2*D/((RPM)^2*V)*(CR-1)/(CR+1)
642 is a constant that we used at Ford. I don't know the source of it, other than Ford's #1 intake guy. John Heywood, who runs the ME department at MIT and is pretty well known, uses 675.
L = runner length
C = speed of sound*
D = runner diameter
RPM = target RPM
V = cylinder volume (single cylinder, not the engine)
CR = compression ratio
Note that the speed of sound is a function of temperature, which is important, especially since we are heating up the air. Formula in meters per second is: (150*1.4*T)^0.5, where T is degrees Rankin (i.e. degrees farenheit + 460).
642 is a constant that we used at Ford. I don't know the source of it, other than Ford's #1 intake guy. John Heywood, who runs the ME department at MIT and is pretty well known, uses 675.
L = runner length
C = speed of sound*
D = runner diameter
RPM = target RPM
V = cylinder volume (single cylinder, not the engine)
CR = compression ratio
Note that the speed of sound is a function of temperature, which is important, especially since we are heating up the air. Formula in meters per second is: (150*1.4*T)^0.5, where T is degrees Rankin (i.e. degrees farenheit + 460).
i was going to get my book and copy it from there if it was requested.
09-19-2011, 08:30 AM
#67
Thanks for that.
I suppose the various constants mentioned in the formulas work if variables are expressed in inches/cubic inches/°F (old money) ?
Are you sure this formula also works with turbocharged engines? I see no variable related to intake pressure and air velocity.
I suppose the various constants mentioned in the formulas work if variables are expressed in inches/cubic inches/°F (old money) ?
Are you sure this formula also works with turbocharged engines? I see no variable related to intake pressure and air velocity.
09-19-2011, 08:41 AM
#68
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So to continue with this discussion just how much of the intake can be designed in isolation or does it have to be totally determined by the rest of the components as a whole? Can we take certain constants like short runner vs long, larger diameter vs smaller, larger plenum vs smaller, log vs sloping and just make a decision or do we have to factor in the head, cam, exhaust manifold, i/c & pipes, throttle body, turbo, tune etc...throw it all in a mixing pot of advanced physics to come up with the one and only solution?
09-19-2011, 08:51 AM
#69
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L= [(ECD x 0.25 x V x 2) / (RPM x RV)] - (D/2)
L = intake runner length
ECD = effective cam duration - EDC = 720 - adv. duration - (20 to 30 degrees) (20 degrees for les radical powerplants and 30 for solid cam drag motors)
V = Pressure wave speed (400-1250 ft/s)
RV = Reflective value - the utilized pressure wave set
D = runner riameter (inches)
09-19-2011, 09:00 AM
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So to continue with this discussion just how much of the intake can be designed in isolation or does it have to be totally determined by the rest of the components as a whole? Can we take certain constants like short runner vs long, larger diameter vs smaller, larger plenum vs smaller, log vs sloping and just make a decision or do we have to factor in the head, cam, exhaust manifold, i/c & pipes, throttle body, turbo, tune etc...throw it all in a mixing pot of advanced physics to come up with the one and only solution?
09-19-2011, 09:53 AM
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Well it says here in a 4 cyl engine the Plenum volume should be 50 to 60% of the total cylinder displacement. It says for engine operating around 7000 to 7500 rpm the volume should be decreased by 10 to 15% or if you want a lower end "Boost" around 2000 to 2500 rpm the volume should be increased by 30%
a forumlar for an intake ram pipe Diameter (tubular pleunum)
D=SQR (CID x VE x RPM) / (v x 1130)
D = Pipe Diamerer
SQR = squar root of
CID = cubic inches displacement
VE = Volumetric efficiency
V = velocity in ft/sec (velocity in the intake rap pipe should always remain at less then 180 feet per second at maximum rpm and horsepower)
Intake ram pipe length:
We suggest adjusting the length of the intake ram pipe last. Using a pipe that can be easily adjusted in length for dyno and airflow testing.
Start with a 13 inch long ram pipe to provide airflow enhancement at about 6000 rpm. For each 1000 rpm change in speed from 6000, add or remove 1.7 inches, shortening the pipe for higher rpm. The inlet of a ram pipe should have at least a ½ inch radius on the intake for smooth airflow.
On the dyno, experiment with 1/2inch adjustments in either direction to see what it does for both peak and average power and torque. We suggest tuning the intake ram pipe about 1000 rpm lower than the intake runner length tuning speed for increasing average power.
thats pretty much sums up the plenum volume section. most of it has to do with runners and how explaing how to tune using everything else around it(cam, exhaust ect) it dosn't get that technical because its a small section of the book to do with manifolds
a forumlar for an intake ram pipe Diameter (tubular pleunum)
D=SQR (CID x VE x RPM) / (v x 1130)
D = Pipe Diamerer
SQR = squar root of
CID = cubic inches displacement
VE = Volumetric efficiency
V = velocity in ft/sec (velocity in the intake rap pipe should always remain at less then 180 feet per second at maximum rpm and horsepower)
Intake ram pipe length:
We suggest adjusting the length of the intake ram pipe last. Using a pipe that can be easily adjusted in length for dyno and airflow testing.
Start with a 13 inch long ram pipe to provide airflow enhancement at about 6000 rpm. For each 1000 rpm change in speed from 6000, add or remove 1.7 inches, shortening the pipe for higher rpm. The inlet of a ram pipe should have at least a ½ inch radius on the intake for smooth airflow.
On the dyno, experiment with 1/2inch adjustments in either direction to see what it does for both peak and average power and torque. We suggest tuning the intake ram pipe about 1000 rpm lower than the intake runner length tuning speed for increasing average power.
thats pretty much sums up the plenum volume section. most of it has to do with runners and how explaing how to tune using everything else around it(cam, exhaust ect) it dosn't get that technical because its a small section of the book to do with manifolds
09-19-2011, 10:04 AM
#73
I'm no engineer or expert, but from what I have seen what OEM's do is longer intakes result in lower end torque and short manifolds are for high end HP. Look at old school Chrysler's they had the really long instake mani's . They made some serious low end torque. Not really much up top. Even currently Trucks and SUV's usually have bigger intake manifold's to help produce low end torque more so than HP. The LSx engines the truck engines have tall intake mani's where the LSx car engines have the intake short and tucked away.
09-20-2011, 07:16 AM
#74
Race Car
I need to pull out Excel and do some more of this for this engine. I've done it for others, but not this one. A few follow-up thoughts.
I messed up one thing, had a diameter when I needed an area. I had thought the formula was regardless of units, but since I looked up some of my stuff, there were mixed units, so the constant has to factor that in. So I added that back.
No mistake in the lack of a pressure unit. It isn't a factor. Temperature, however, is a factor, and that is included in that it affects the speed of sound.
Runner length INCLUDES the portion of the runner inside the cylinder head. Valve seat to plenum.
This will give the length for the pressure wave at its greatest intensity, which will give the highest volumetric efficiency. However, it may not give the peak torque RPM, though it will not be off by much. The reason for that is the the friction of the engine, which increases approximately squared with engine speed, may affect it in such a manner that it would give a peak torque at a slightly lower RPM than specified.
Paulyy, I've never seen that formula. They are certainly related, but it looks like you need to know more values for yours. Example, I assume pressure wave speed is a resultant of the design. However, it will be related to cylinder volume, CR, and runner diameter. Mine can be found in the Heywood text. Is yours from Taylor, or something else? I'd love to get a copy of it.
I messed up one thing, had a diameter when I needed an area. I had thought the formula was regardless of units, but since I looked up some of my stuff, there were mixed units, so the constant has to factor that in. So I added that back.
No mistake in the lack of a pressure unit. It isn't a factor. Temperature, however, is a factor, and that is included in that it affects the speed of sound.
Runner length INCLUDES the portion of the runner inside the cylinder head. Valve seat to plenum.
This will give the length for the pressure wave at its greatest intensity, which will give the highest volumetric efficiency. However, it may not give the peak torque RPM, though it will not be off by much. The reason for that is the the friction of the engine, which increases approximately squared with engine speed, may affect it in such a manner that it would give a peak torque at a slightly lower RPM than specified.
Paulyy, I've never seen that formula. They are certainly related, but it looks like you need to know more values for yours. Example, I assume pressure wave speed is a resultant of the design. However, it will be related to cylinder volume, CR, and runner diameter. Mine can be found in the Heywood text. Is yours from Taylor, or something else? I'd love to get a copy of it.
09-20-2011, 07:38 AM
#75
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I need to pull out Excel and do some more of this for this engine. I've done it for others, but not this one. A few follow-up thoughts.
I messed up one thing, had a diameter when I needed an area. I had thought the formula was regardless of units, but since I looked up some of my stuff, there were mixed units, so the constant has to factor that in. So I added that back.
No mistake in the lack of a pressure unit. It isn't a factor. Temperature, however, is a factor, and that is included in that it affects the speed of sound.
Runner length INCLUDES the portion of the runner inside the cylinder head. Valve seat to plenum.
This will give the length for the pressure wave at its greatest intensity, which will give the highest volumetric efficiency. However, it may not give the peak torque RPM, though it will not be off by much. The reason for that is the the friction of the engine, which increases approximately squared with engine speed, may affect it in such a manner that it would give a peak torque at a slightly lower RPM than specified.
Paulyy, I've never seen that formula. They are certainly related, but it looks like you need to know more values for yours. Example, I assume pressure wave speed is a resultant of the design. However, it will be related to cylinder volume, CR, and runner diameter. Mine can be found in the Heywood text. Is yours from Taylor, or something else? I'd love to get a copy of it.
I messed up one thing, had a diameter when I needed an area. I had thought the formula was regardless of units, but since I looked up some of my stuff, there were mixed units, so the constant has to factor that in. So I added that back.
No mistake in the lack of a pressure unit. It isn't a factor. Temperature, however, is a factor, and that is included in that it affects the speed of sound.
Runner length INCLUDES the portion of the runner inside the cylinder head. Valve seat to plenum.
This will give the length for the pressure wave at its greatest intensity, which will give the highest volumetric efficiency. However, it may not give the peak torque RPM, though it will not be off by much. The reason for that is the the friction of the engine, which increases approximately squared with engine speed, may affect it in such a manner that it would give a peak torque at a slightly lower RPM than specified.
Paulyy, I've never seen that formula. They are certainly related, but it looks like you need to know more values for yours. Example, I assume pressure wave speed is a resultant of the design. However, it will be related to cylinder volume, CR, and runner diameter. Mine can be found in the Heywood text. Is yours from Taylor, or something else? I'd love to get a copy of it.