Some theoretical calculations for HR intakes.
02-14-2008, 03:50 AM
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Originally Posted by T_K
I may not have all the math correct here, but I think I'm beginning to grasp the large discrepancy between head flow CFM, and required CFM for the engine to fill all cylinders.
As a whole, at the intake filter, air flow is kept pretty constant, since theres multiple cylinders, the closing of a set of valves for 1 cylinder, doesn't have an effect on overall flow, since there are others that are open and drawing in air. Also at the filter, at a given RPM, since theres always an amount of air being drawn in by some cylinders, the air isn't accelerating. This isn't taking into consideration the increase in air velocity as diameter decreases, for all practical purposes we'll say the intake pipe is constant diameter. Air flow is constant, non-accelerating, and doesn't need any more flow than the the volume of the cylinders. For the VQ, @ 7500rpm @ 100% VE, ended up being around 460 CFM.
Where it started to get really hard to understand for me, was when looking at the smaller picture of a single port, or single port/runner. When theres only 1 cylinder involved, when the intake valves close, forward motion of the air essentially stops. When the intake valve opens again, the air now needs to accelerate from near zero velocity and cover the distance from the beginning of the runner/port, to the bottom of the cylinder. At a given RPM, in this case 7500rpm, the opening of the valve is near instantaneous. Assuming the valve is open for exactly half a revolution, it ends up being something like .008 seconds, or 8 milliseconds. I used a random number, of 10in, as an assumed distance between the front of the runner, and the bottom of the cylinder. To cover that distance, in that short of a time, the acceleration needs to be 7937.5 m/sec^2, or 312,500 in/sec^2.
That acceleration applied to the time, of 8 milliseconds, the velocity of the front of the column of air reaches around 2500 in/sec at the bottom of the cylinder, or something around to Mach 2.
Since Flow = Velocity X CSA(which is fairly constant), I used 2in^2 as an arbitrary constant just to see end numbers.
2500 in/sec X 2 in^2 = 5000 in^3/sec = ~173.6 ft^3/min or CFM.
A lot of these numbers were just made up for the sake of calculations, but the theory is sound, I think. All the calculations assumed a straight shot from the front of the runner to the bottom of the cylinder. Since a real engine doesn't follow these theoretical flow paths, it makes sense that a CFM higher than 173 is much more likely for the flow rate of a real head.
173 CFM represents how much flow would be needed to move a column of air for an instantaneous amount of time, at the huge velocity required to cover the distance. Also its a lot more aligned with your flow bench data. My calculations need that much CFM per bank, due to the relative constant velocity of air, and relative zero acceleration. Turned out to be an entirely different story when isolated to a single port, and the closing and opening of valves got involved.
All this was done based on my limited knowledge of physics, and a lot of help from google, so I don't know how right the calculations are. Even if all my math and equations are wrong, I'm almost positive it has to do with the nature of the air accelerating and stopping in the runnner/ports. Sorry for the long winded posts, but this has been racking my mind for half the night.
TK
Edit: Even if I'm wrong with all the theoretical data, I know I'm on the right track.
Re-Edit: After some more careful looking over my work, it just occured to me that the cylinder fill time is 4ms, and not 8ms, so the ending theoretical 173 CFM is a very conservative figure, the new answer using the corrected time of 4ms, would result in a value thats closer to 347 CFM.
As a whole, at the intake filter, air flow is kept pretty constant, since theres multiple cylinders, the closing of a set of valves for 1 cylinder, doesn't have an effect on overall flow, since there are others that are open and drawing in air. Also at the filter, at a given RPM, since theres always an amount of air being drawn in by some cylinders, the air isn't accelerating. This isn't taking into consideration the increase in air velocity as diameter decreases, for all practical purposes we'll say the intake pipe is constant diameter. Air flow is constant, non-accelerating, and doesn't need any more flow than the the volume of the cylinders. For the VQ, @ 7500rpm @ 100% VE, ended up being around 460 CFM.
Where it started to get really hard to understand for me, was when looking at the smaller picture of a single port, or single port/runner. When theres only 1 cylinder involved, when the intake valves close, forward motion of the air essentially stops. When the intake valve opens again, the air now needs to accelerate from near zero velocity and cover the distance from the beginning of the runner/port, to the bottom of the cylinder. At a given RPM, in this case 7500rpm, the opening of the valve is near instantaneous. Assuming the valve is open for exactly half a revolution, it ends up being something like .008 seconds, or 8 milliseconds. I used a random number, of 10in, as an assumed distance between the front of the runner, and the bottom of the cylinder. To cover that distance, in that short of a time, the acceleration needs to be 7937.5 m/sec^2, or 312,500 in/sec^2.
That acceleration applied to the time, of 8 milliseconds, the velocity of the front of the column of air reaches around 2500 in/sec at the bottom of the cylinder, or something around to Mach 2.
Since Flow = Velocity X CSA(which is fairly constant), I used 2in^2 as an arbitrary constant just to see end numbers.
2500 in/sec X 2 in^2 = 5000 in^3/sec = ~173.6 ft^3/min or CFM.
A lot of these numbers were just made up for the sake of calculations, but the theory is sound, I think. All the calculations assumed a straight shot from the front of the runner to the bottom of the cylinder. Since a real engine doesn't follow these theoretical flow paths, it makes sense that a CFM higher than 173 is much more likely for the flow rate of a real head.
173 CFM represents how much flow would be needed to move a column of air for an instantaneous amount of time, at the huge velocity required to cover the distance. Also its a lot more aligned with your flow bench data. My calculations need that much CFM per bank, due to the relative constant velocity of air, and relative zero acceleration. Turned out to be an entirely different story when isolated to a single port, and the closing and opening of valves got involved.
All this was done based on my limited knowledge of physics, and a lot of help from google, so I don't know how right the calculations are. Even if all my math and equations are wrong, I'm almost positive it has to do with the nature of the air accelerating and stopping in the runnner/ports. Sorry for the long winded posts, but this has been racking my mind for half the night.
TK
Edit: Even if I'm wrong with all the theoretical data, I know I'm on the right track.
Re-Edit: After some more careful looking over my work, it just occured to me that the cylinder fill time is 4ms, and not 8ms, so the ending theoretical 173 CFM is a very conservative figure, the new answer using the corrected time of 4ms, would result in a value thats closer to 347 CFM.
Other than that, the rest of your theory sounds more in tune with what I would expect, given my 'limited' knowledge.
02-14-2008, 04:23 AM
#62
Originally Posted by crg914
The only discrepancy I see in that is the air doesn't accelerate from near zero velocity when the intake valve opens. There is reversion when the intake valve closes, meaning the air "bounces" of the valve back up into the plenum, and then "bounces" back down the runner. This is made to work as an advantage on an engine with a Tuned Port Intake (TPI). The third wave is commonly the one that is "captured'' and used to overfill the cylinder increasing VE and compression ratio. This wave is already accelerating towards the intake valve so it isn't at near zero velocity. Just an example of how the dynamics of a running engine aren't always as black and white as the formulas.
Other than that, the rest of your theory sounds more in tune with what I would expect, given my 'limited' knowledge.
Other than that, the rest of your theory sounds more in tune with what I would expect, given my 'limited' knowledge.
Now where are those body kits at
TK
02-14-2008, 04:59 AM
#63
Simplified version:
To fill 3 cylinders of 583cc each, @ 7500rpm, 2 revolutions per power cycle. You need 463cfm @ 100% VE. So over 60 seconds, 463 cubic feet of air is displaced by the engine as a constant pump. The time is the key factor here, 60 sec, or 1 minute, translates to sustained flow.
At 7500rpm, there are 3750 power cycles, so theres 3750 intake strokes. 1 power cycle is equal to 2 turns of the crank, and the intake stroke for all practical purposes, is 1/2 turn of the crank.
60sec / 7500rpm = .008 seconds
Thats how long per revolution of the crank. Since the intake stroke happens for 1/2 a crank turn.
.008 seconds / 2 = .004 seconds = .000067 minutes
Which represents how long the intake valve is open.
1 cylinder = 583cc = 0.0206 ft^3
So the head has 0.000067 minutes, to fill the cylinder with 0.0206 cubic feet of air.
0.0206 ft^3 / 0.000067min = 307 CFM.
So it really comes down to the time frame.
TK
To fill 3 cylinders of 583cc each, @ 7500rpm, 2 revolutions per power cycle. You need 463cfm @ 100% VE. So over 60 seconds, 463 cubic feet of air is displaced by the engine as a constant pump. The time is the key factor here, 60 sec, or 1 minute, translates to sustained flow.
At 7500rpm, there are 3750 power cycles, so theres 3750 intake strokes. 1 power cycle is equal to 2 turns of the crank, and the intake stroke for all practical purposes, is 1/2 turn of the crank.
60sec / 7500rpm = .008 seconds
Thats how long per revolution of the crank. Since the intake stroke happens for 1/2 a crank turn.
.008 seconds / 2 = .004 seconds = .000067 minutes
Which represents how long the intake valve is open.
1 cylinder = 583cc = 0.0206 ft^3
So the head has 0.000067 minutes, to fill the cylinder with 0.0206 cubic feet of air.
0.0206 ft^3 / 0.000067min = 307 CFM.
So it really comes down to the time frame.
TK
Last edited by T_K; 02-14-2008 at 05:09 AM.
02-14-2008, 05:52 AM
#65
Here's a little more:
Flow benching a head is directly related to the near instantaneous flow rate required when the valve is actually open. In this case I came up with .004 seconds, which was equal to 1/2 turn of a crank, at 7500rpm.
Forward flow is happening with intake valve open, for .004 seconds, and during the other stages of the cycle, which account for .012 seconds, the intake is closed. Equal quarters, and forward flow only exists for 25% of the time, the other 75% is where the intake valve is closed.
If you take a typical headflow measurement, of say 300 CFM.
300 CFM / 4 = 75 CFM
It means if the head continued to flow for the whole minute it would flow 300 CFM, but since the valve is closed 75% of the time, the average flow into the cylinder over the course of the minute is only 75ft^3.
75 CFM X 3 Cylinders = 225CFM, pretty close to what my theoretical volume of air moving through a set of 3 cylinders on the VQ.
TK
I think I'm beginning to really get this now.
Flow benching a head is directly related to the near instantaneous flow rate required when the valve is actually open. In this case I came up with .004 seconds, which was equal to 1/2 turn of a crank, at 7500rpm.
Forward flow is happening with intake valve open, for .004 seconds, and during the other stages of the cycle, which account for .012 seconds, the intake is closed. Equal quarters, and forward flow only exists for 25% of the time, the other 75% is where the intake valve is closed.
If you take a typical headflow measurement, of say 300 CFM.
300 CFM / 4 = 75 CFM
It means if the head continued to flow for the whole minute it would flow 300 CFM, but since the valve is closed 75% of the time, the average flow into the cylinder over the course of the minute is only 75ft^3.
75 CFM X 3 Cylinders = 225CFM, pretty close to what my theoretical volume of air moving through a set of 3 cylinders on the VQ.
TK
I think I'm beginning to really get this now.
02-14-2008, 11:50 AM
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Originally Posted by T_K
I may not have all the math correct here, but I think I'm beginning to grasp the large discrepancy between head flow CFM, and required CFM for the engine to fill all cylinders.
As a whole, at the intake filter, air flow is kept pretty constant, since theres multiple cylinders, the closing of a set of valves for 1 cylinder, doesn't have an effect on overall flow, since there are others that are open and drawing in air. Also at the filter, at a given RPM, since theres always an amount of air being drawn in by some cylinders, the air isn't accelerating. This isn't taking into consideration the increase in air velocity as diameter decreases, for all practical purposes we'll say the intake pipe is constant diameter. Air flow is constant, non-accelerating, and doesn't need any more flow than the the volume of the cylinders. For the VQ, @ 7500rpm @ 100% VE, ended up being around 460 CFM.
Where it started to get really hard to understand for me, was when looking at the smaller picture of a single port, or single port/runner. When theres only 1 cylinder involved, when the intake valves close, forward motion of the air essentially stops. When the intake valve opens again, the air now needs to accelerate from near zero velocity and cover the distance from the beginning of the runner/port, to the bottom of the cylinder. At a given RPM, in this case 7500rpm, the opening of the valve is near instantaneous. Assuming the valve is open for exactly half a revolution, it ends up being something like .008 seconds, or 8 milliseconds. I used a random number, of 10in, as an assumed distance between the front of the runner, and the bottom of the cylinder. To cover that distance, in that short of a time, the acceleration needs to be 7937.5 m/sec^2, or 312,500 in/sec^2.
That acceleration applied to the time, of 8 milliseconds, the velocity of the front of the column of air reaches around 2500 in/sec at the bottom of the cylinder, or something around to Mach 2.
Since Flow = Velocity X CSA(which is fairly constant), I used 2in^2 as an arbitrary constant just to see end numbers.
2500 in/sec X 2 in^2 = 5000 in^3/sec = ~173.6 ft^3/min or CFM.
A lot of these numbers were just made up for the sake of calculations, but the theory is sound, I think. All the calculations assumed a straight shot from the front of the runner to the bottom of the cylinder. Since a real engine doesn't follow these theoretical flow paths, it makes sense that a CFM higher than 173 is much more likely for the flow rate of a real head.
173 CFM represents how much flow would be needed to move a column of air for an instantaneous amount of time, at the huge velocity required to cover the distance. Also its a lot more aligned with your flow bench data. My calculations need that much CFM per bank, due to the relative constant velocity of air, and relative zero acceleration. Turned out to be an entirely different story when isolated to a single port, and the closing and opening of valves got involved.
All this was done based on my limited knowledge of physics, and a lot of help from google, so I don't know how right the calculations are. Even if all my math and equations are wrong, I'm almost positive it has to do with the nature of the air accelerating and stopping in the runnner/ports. Sorry for the long winded posts, but this has been racking my mind for half the night.
TK
Edit: Even if I'm wrong with all the theoretical data, I know I'm on the right track.
Re-Edit: After some more careful looking over my work, it just occured to me that the cylinder fill time is 4ms, and not 8ms, so the ending theoretical 173 CFM is a very conservative figure, the new answer using the corrected time of 4ms, would result in a value thats closer to 347 CFM.
As a whole, at the intake filter, air flow is kept pretty constant, since theres multiple cylinders, the closing of a set of valves for 1 cylinder, doesn't have an effect on overall flow, since there are others that are open and drawing in air. Also at the filter, at a given RPM, since theres always an amount of air being drawn in by some cylinders, the air isn't accelerating. This isn't taking into consideration the increase in air velocity as diameter decreases, for all practical purposes we'll say the intake pipe is constant diameter. Air flow is constant, non-accelerating, and doesn't need any more flow than the the volume of the cylinders. For the VQ, @ 7500rpm @ 100% VE, ended up being around 460 CFM.
Where it started to get really hard to understand for me, was when looking at the smaller picture of a single port, or single port/runner. When theres only 1 cylinder involved, when the intake valves close, forward motion of the air essentially stops. When the intake valve opens again, the air now needs to accelerate from near zero velocity and cover the distance from the beginning of the runner/port, to the bottom of the cylinder. At a given RPM, in this case 7500rpm, the opening of the valve is near instantaneous. Assuming the valve is open for exactly half a revolution, it ends up being something like .008 seconds, or 8 milliseconds. I used a random number, of 10in, as an assumed distance between the front of the runner, and the bottom of the cylinder. To cover that distance, in that short of a time, the acceleration needs to be 7937.5 m/sec^2, or 312,500 in/sec^2.
That acceleration applied to the time, of 8 milliseconds, the velocity of the front of the column of air reaches around 2500 in/sec at the bottom of the cylinder, or something around to Mach 2.
Since Flow = Velocity X CSA(which is fairly constant), I used 2in^2 as an arbitrary constant just to see end numbers.
2500 in/sec X 2 in^2 = 5000 in^3/sec = ~173.6 ft^3/min or CFM.
A lot of these numbers were just made up for the sake of calculations, but the theory is sound, I think. All the calculations assumed a straight shot from the front of the runner to the bottom of the cylinder. Since a real engine doesn't follow these theoretical flow paths, it makes sense that a CFM higher than 173 is much more likely for the flow rate of a real head.
173 CFM represents how much flow would be needed to move a column of air for an instantaneous amount of time, at the huge velocity required to cover the distance. Also its a lot more aligned with your flow bench data. My calculations need that much CFM per bank, due to the relative constant velocity of air, and relative zero acceleration. Turned out to be an entirely different story when isolated to a single port, and the closing and opening of valves got involved.
All this was done based on my limited knowledge of physics, and a lot of help from google, so I don't know how right the calculations are. Even if all my math and equations are wrong, I'm almost positive it has to do with the nature of the air accelerating and stopping in the runnner/ports. Sorry for the long winded posts, but this has been racking my mind for half the night.
TK
Edit: Even if I'm wrong with all the theoretical data, I know I'm on the right track.
Re-Edit: After some more careful looking over my work, it just occured to me that the cylinder fill time is 4ms, and not 8ms, so the ending theoretical 173 CFM is a very conservative figure, the new answer using the corrected time of 4ms, would result in a value thats closer to 347 CFM.
What you guys were arguing about is right on both sides...sort of. You're right about the engine's need of air, as a whole. For those of you who are engineers and understand boundaries - you can just image the engine itself being a box - with a certin volume of air going in at a certain velocity. and a gas leaving at a certain volumetric flow, velocity and temperature.
TK your 100% right about the air having to move from "theoretically" a complete stop through the runners.
Not to bash on anyone, but just as a review:
Q = V * Ac (flow = velocity x cross-sectional area)
so if I have an air flow of 100 m3/sec with the air moving at 20 m/sec through a tube with a cross-sectional area of 5 m^2 (huge i know, but just for example) - this would be the same as 2 m/sec air moving through a 50 m^2 tube.
this is where the idea of backpressure in exhausts is always mistaken. you can have a greatly improved gas flow, but is it actually exiting faster?
anyway, when you think about how much air is needed to fill a cylinder - you're going to need a huge flow rate to fill that cylinder in 4ms. that is - the area is real small, but the velocity has increased greatly once that valve opens. this is all due to the fact that the engine is basically running like a vacuum would. the air the runs through the head when a valve opens is "screaming" in speed - but it only happens for a short, short period of time.
crap, now i sort of forget what i was trying to get to - i'll read some more replies and get back.
Last edited by mcarlomagno; 02-14-2008 at 11:52 AM.
02-14-2008, 01:16 PM
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Dwyer makes some excellant inexpensive manometer gauges that can measure the resistance [pressure drop] from earth's atmosphere.........ebay to save even more ~~$25.
If you place a rubber hose from manometer at any point along the intake you can read accurate pressure drop for example peak rpm will always have the worst resistance [flow benches measure 28" water column] so say 1>7" infront of air filter 2-8" after air filter, 9>15" after MAF, and 11>17" in front of throttle body.
You need to select multiple manometers say 10" FScale and 20 or 25" FScale to use in appropriate location to get accuracy in 0.1" increments.
27.7" water column = 1.0 psi or 6.8% restriction from 14.7 psi [29.92" Hg].
AT WOT max rpm doubtful that the plenum pressure drops below 13.9 psi.
Don't get confused with a so called engine vacuum gauge which read backwards from a manometer!!!!!!!!
http://secure2.data-comm.com/servlet...Digital/Detail
This is a ebay beauty $15:
http://cgi.ebay.com/DWYER-MANOMETER-...QQcmdZViewItem
search "Dwyer gauge" or "Dwyer manometer" on ebay
Study the theory so you understand what pressure is where. Trying to hook one of these ultra sensitive gauges to the plenum will suck the guts out of the gauge forever worthless there after!
I have 7 different manometers I use to make accurate pressure drop measurements neat to see how very very little an oem air filter creates.............MAF is usually the single most restrictive WOT element other than intake valves...............everything else has been tweeked at factory or needs a restriction for a definite purpose
If you place a rubber hose from manometer at any point along the intake you can read accurate pressure drop for example peak rpm will always have the worst resistance [flow benches measure 28" water column] so say 1>7" infront of air filter 2-8" after air filter, 9>15" after MAF, and 11>17" in front of throttle body.
You need to select multiple manometers say 10" FScale and 20 or 25" FScale to use in appropriate location to get accuracy in 0.1" increments.
27.7" water column = 1.0 psi or 6.8% restriction from 14.7 psi [29.92" Hg].
AT WOT max rpm doubtful that the plenum pressure drops below 13.9 psi.
Don't get confused with a so called engine vacuum gauge which read backwards from a manometer!!!!!!!!
http://secure2.data-comm.com/servlet...Digital/Detail
This is a ebay beauty $15:
http://cgi.ebay.com/DWYER-MANOMETER-...QQcmdZViewItem
search "Dwyer gauge" or "Dwyer manometer" on ebay
Study the theory so you understand what pressure is where. Trying to hook one of these ultra sensitive gauges to the plenum will suck the guts out of the gauge forever worthless there after!
I have 7 different manometers I use to make accurate pressure drop measurements neat to see how very very little an oem air filter creates.............MAF is usually the single most restrictive WOT element other than intake valves...............everything else has been tweeked at factory or needs a restriction for a definite purpose
Last edited by Q45tech; 02-14-2008 at 01:21 PM.
02-14-2008, 05:45 PM
#69
It'd be nice to be able to measure the flow rate of the stock air box in comparison to an aftermarket intake, and see if either has a benefit with regard to pressure drop from the beginning to the end. One could figure out velocity, with the flow numbers, as long as we had the cross sectional area, of the 2 test intakes.
The only variable unaccounted for would be the ram air nature of the stock airbox. I wonder though, if the air flowing into the duct while in motion, would offset any flow advantages, differences in pressure drop and velocity of an aftermarket intake.
Pretty much any intake system out for the HR utilizing a larger than stock diameter pipe, would result in velocity loss. Given the relatively low flow rate of a single bank of cylinders, velocity is pretty important, since the velocity of the air will ultimately effect everything that takes place from the manifold onwards. Could explain why stock air boxes make more low-midrange power on the dyno, and any gains shown by an aftermarket intake, are indeed from larger flow rate, but only starts to show up at high rpm, where flow rate required is the largest.
TK
Edit: Or better yet, using what's known about pressure drop, and high pressure areas while the car is in motion, see if theres any way to attach tubing to the stock air box duct, to a higher pressure location.
The only variable unaccounted for would be the ram air nature of the stock airbox. I wonder though, if the air flowing into the duct while in motion, would offset any flow advantages, differences in pressure drop and velocity of an aftermarket intake.
Pretty much any intake system out for the HR utilizing a larger than stock diameter pipe, would result in velocity loss. Given the relatively low flow rate of a single bank of cylinders, velocity is pretty important, since the velocity of the air will ultimately effect everything that takes place from the manifold onwards. Could explain why stock air boxes make more low-midrange power on the dyno, and any gains shown by an aftermarket intake, are indeed from larger flow rate, but only starts to show up at high rpm, where flow rate required is the largest.
TK
Edit: Or better yet, using what's known about pressure drop, and high pressure areas while the car is in motion, see if theres any way to attach tubing to the stock air box duct, to a higher pressure location.
Last edited by T_K; 02-14-2008 at 05:48 PM.
02-14-2008, 07:46 PM
#70
From what I've read in the many after market intake threads posted here, most fabricators have had to leave the interior diameter of the intake stock due to the readings produced by the MAFs (at least in the immediate vicinity of the MAF). A wider diameter tube was causing a CEL. Therefore, any after market intake should only allow maximum airflow equal to the stock intake (at least after the MAF tube). Essentially, they built an hourglass where the maximum restriction occurs at the MAF location.
The only benefit I see from an after market intake is the extra filter surface area (on the cone filters) which will allow more flow when the filter becomes dirty. That has been proven here where owners have gotten better dyno numbers after replacing their dirty filters with clean ones.
The only benefit I see from an after market intake is the extra filter surface area (on the cone filters) which will allow more flow when the filter becomes dirty. That has been proven here where owners have gotten better dyno numbers after replacing their dirty filters with clean ones.
02-15-2008, 03:49 AM
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Originally Posted by quidproquo
From what I've read in the many after market intake threads posted here, most fabricators have had to leave the interior diameter of the intake stock due to the readings produced by the MAFs (at least in the immediate vicinity of the MAF). A wider diameter tube was causing a CEL. Therefore, any after market intake should only allow maximum airflow equal to the stock intake (at least after the MAF tube). Essentially, they built an hourglass where the maximum restriction occurs at the MAF location.
The only benefit I see from an after market intake is the extra filter surface area (on the cone filters) which will allow more flow when the filter becomes dirty. That has been proven here where owners have gotten better dyno numbers after replacing their dirty filters with cl ean ones.
The only benefit I see from an after market intake is the extra filter surface area (on the cone filters) which will allow more flow when the filter becomes dirty. That has been proven here where owners have gotten better dyno numbers after replacing their dirty filters with cl ean ones.
The only difference would be what type of air that is currently going into the intake (cold or hot).
However, if you did intend to increase the flow rate by forcing the air through (i.e. cut out in the bumper) then this could have an effect. This is not a good solution however as water will get in for sure!! Plus it looks pretty dumb too :-).
02-15-2008, 06:03 AM
#74
Originally Posted by optimumarc
Actually, this is a very good point. This past weekend I removed my MAF and noticed that it protrudes more then half way into the intake pipe (I have Nismo). The mass flow rate would probably be a function of the air after the MAF.
The only difference would be what type of air that is currently going into the intake (cold or hot).
However, if you did intend to increase the flow rate by forcing the air through (i.e. cut out in the bumper) then this could have an effect. This is not a good solution however as water will get in for sure!! Plus it looks pretty dumb too :-).
The only difference would be what type of air that is currently going into the intake (cold or hot).
However, if you did intend to increase the flow rate by forcing the air through (i.e. cut out in the bumper) then this could have an effect. This is not a good solution however as water will get in for sure!! Plus it looks pretty dumb too :-).
It would be nice to devise a test, to test various locations that the intake vent could be ducted, and to compare how the stock location compares to a more complex location.
TK
02-15-2008, 08:01 AM
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I'm not sure about the MAF industry as far as the Zs go. I had spent many years in the world of the LS1 Camaros and Trans-Ams. A few companies produced MAF sensors which were larger in diameter and didn't throw a code. I think this is something that should be looked at for the HR Z since it can flow a lot of air very easily.
02-15-2008, 12:18 PM
#76
Originally Posted by mcarlomagno
I'm not sure about the MAF industry as far as the Zs go. I had spent many years in the world of the LS1 Camaros and Trans-Ams. A few companies produced MAF sensors which were larger in diameter and didn't throw a code. I think this is something that should be looked at for the HR Z since it can flow a lot of air very easily.
TK
02-19-2008, 12:45 PM
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It would be an interesting study is to take 3 types of intakes install them, dyno them (with the same parameters) and then compare the results. This will minimize the variation between cars. There is some tolerance associated with this method but +-1HP maybe good enough. What do you guys think?
1. Stock Airbox Setup
<O
2. Hot Air Intake Setup (i.e. Jim Wolf)
<O3. Cold Air Intake Setup (i.e. Nismo)
1. Stock Airbox Setup
<O
2. Hot Air Intake Setup (i.e. Jim Wolf)<O
3. Cold Air Intake Setup (i.e. Nismo)
Last edited by optimumarc; 02-19-2008 at 12:52 PM.
02-19-2008, 01:19 PM
#79
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Originally Posted by optimumarc
It would be an interesting study is to take 3 types of intakes install them, dyno them (with the same parameters) and then compare the results. This will minimize the variation between cars. There is some tolerance associated with this method but +-1HP maybe good enough. What do you guys think?
1. Stock Airbox Setup
<O2. Hot Air Intake Setup (i.e. Jim Wolf)
<O3. Cold Air Intake Setup (i.e. Nismo)
1. Stock Airbox Setup
<O
2. Hot Air Intake Setup (i.e. Jim Wolf)<O
3. Cold Air Intake Setup (i.e. Nismo)
02-19-2008, 01:33 PM
#80
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I think you are right; the best setup might be the Stock Airbox with a higher efficiency filter (K&N). Now we just have to find a shop to do it.
Anybody out there want to help us out?<O</O
This will be very beneficial to the 350z community and finally resolve the age old question “Which intake should I buy”.
Hopefully none and just a new air filter!<O</O
Anybody out there want to help us out?<O
</OThis will be very beneficial to the 350z community and finally resolve the age old question “Which intake should I buy”.
Hopefully none and just a new air filter!<O
</O