Putting a fan on top of air intake?
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Re: Putting a fan on top of air intake?
Bro, it is not going to meet at 6000 RPM even in the 2.2L scenario. Try running the math. 15 CFM still exceeds the requirement. What the engine needs, it is providing and then some (whatever rated pressure is). Read again about maintaining pressure differential. I'm not quite sure why you continue insisting it is going to be choking off or meeting stock power when the theory clearly shows that it won't. Real life dynos of engines beyond 2.2L and similar redlines have also proven this.
Whisky_Tango said:
Bro, it is not going to meet at 6000 RPM even in the 2.2L scenario. Try running the math. 15 CFM still exceeds the requirement. What the engine needs, it is providing and then some (whatever rated pressure is). Read again about maintaining pressure differential. I'm not quite sure why you continue insisting it is going to be choking off or meeting stock power when the theory clearly shows that it won't. Real life dynos of engines beyond 2.2L and similar redlines have also proven this.
Whisky_Tango
Core Group Members
Re: Putting a fan on top of air intake?
Yes bro, but im the conservative type which still think that the high end eventually even out because of mechanical losses from engine, crank, to wheels and exhaust system of a 2,2L
So only when i see dyno figures will i believe. Im not saying you are wrong, its just me.
Cheers bro.
Shaun said:
Yes bro, but im the conservative type which still think that the high end eventually even out because of mechanical losses from engine, crank, to wheels and exhaust system of a 2,2L
So only when i see dyno figures will i believe. Im not saying you are wrong, its just me.
Cheers bro.
Re: Putting a fan on top of air intake?
Mechanical losses from engine, crank, to wheels, etc. all that has to do with how efficiently the air and fuel ingested is used, not how much is ingested. Flow past the intake is much simpler than determining the various efficiencies of an engine, since it is within a narrow range of possibility (VE).
To disregard physics, math, and look purely at fallible chassis dyno results alone, is folly. Not knowing how and why a result is arrived at, is nearly as bad as not getting any result. Progression requires studying the hows and whys to the point that they are inline with both physical law, as well as the result. It is only then that the truth is as whole as it can be and deeper truth can be sought.
Like I said, I could not care less about this product. I am however, quite sad about the non-discussive, physics-disregarding stance you are taking at this point, especially because you are a DIY modder with great plans for chilled intakes, WI, and the likes - also because of the time investment here. Why invest in something that is going to be disregarded? If we are to work at things like that, there is only one way to work is inline with the afore mentioned - else IMHO, it is reduced to feeling around in murky water.
Oh well that's life.. we agree to disagree then. You continue doing what you do, and I'll do likewise.
Cheers bro
Mechanical losses from engine, crank, to wheels, etc. all that has to do with how efficiently the air and fuel ingested is used, not how much is ingested. Flow past the intake is much simpler than determining the various efficiencies of an engine, since it is within a narrow range of possibility (VE).
To disregard physics, math, and look purely at fallible chassis dyno results alone, is folly. Not knowing how and why a result is arrived at, is nearly as bad as not getting any result. Progression requires studying the hows and whys to the point that they are inline with both physical law, as well as the result. It is only then that the truth is as whole as it can be and deeper truth can be sought.
Like I said, I could not care less about this product. I am however, quite sad about the non-discussive, physics-disregarding stance you are taking at this point, especially because you are a DIY modder with great plans for chilled intakes, WI, and the likes - also because of the time investment here. Why invest in something that is going to be disregarded? If we are to work at things like that, there is only one way to work is inline with the afore mentioned - else IMHO, it is reduced to feeling around in murky water.
Oh well that's life.. we agree to disagree then. You continue doing what you do, and I'll do likewise.
Cheers bro
Re: Putting a fan on top of air intake?
Crufty has been kind enough to point out that my previous calculation on the old thread on which I based calculations in this thread, were slightly off. 3.0L at 6500 RPM and 100% VE is not 380 CFM. It is less. My mistake in the old thread was in converting 90% VE back to 100% and accidentally adding the 10% loss back TWICE to arrive at 110% VE. I blame the crappy microsoft windows calculator!
So VE assumptions were all 10% higher.
This furthers my point in that choke or neutrality occurs only at an even higher RPM, or larger displacement engine.
Corrected numbers (10% reduced) below...
A 2.2L @ 6500 RPM consumes 200 CFM
A 2.5L @ 6500 RPM consumes 227 CFM
A 2.8L @ 6500 RPM consumes 255 CFM
A 3.0L @ 6500 RPM consumes 274 CFM
Crufty has been kind enough to point out that my previous calculation on the old thread on which I based calculations in this thread, were slightly off. 3.0L at 6500 RPM and 100% VE is not 380 CFM. It is less. My mistake in the old thread was in converting 90% VE back to 100% and accidentally adding the 10% loss back TWICE to arrive at 110% VE. I blame the crappy microsoft windows calculator!
So VE assumptions were all 10% higher.This furthers my point in that choke or neutrality occurs only at an even higher RPM, or larger displacement engine.
Corrected numbers (10% reduced) below...
A 2.2L @ 6500 RPM consumes 200 CFM
A 2.5L @ 6500 RPM consumes 227 CFM
A 2.8L @ 6500 RPM consumes 255 CFM
A 3.0L @ 6500 RPM consumes 274 CFM
Whisky_Tango
Core Group Members
Re: Putting a fan on top of air intake?
Well... tats because im not experience in this field and truly your time & inputs are well received by me. Only through such discussions will I learn and hope you still continue to support.
Hopefully others will find this discussion meaningful.
Cheerio...
Well... tats because im not experience in this field and truly your time & inputs are well received by me. Only through such discussions will I learn and hope you still continue to support.
Hopefully others will find this discussion meaningful.
Cheerio...
Crufty Dusty
Well-Known Member
Re: Putting a fan on top of air intake?
Let's put all this together for some perspective.
A TD06H-20G spins at 65,000 RPM to produce just 0.2 bar of boost at standard temperature and pressure with airflow of 250cfm. To produce 1.2 bar of boost under the same conditions it spins in excess of 105,000 RPM.
A Delta 120x120x38mm PC fan according to this page produces 220cfm @ 4600 RPM. Maximum pressure is rated at 0.2 bar.
Let's put all this together for some perspective.
A TD06H-20G spins at 65,000 RPM to produce just 0.2 bar of boost at standard temperature and pressure with airflow of 250cfm. To produce 1.2 bar of boost under the same conditions it spins in excess of 105,000 RPM.
A Delta 120x120x38mm PC fan according to this page produces 220cfm @ 4600 RPM. Maximum pressure is rated at 0.2 bar.
Crufty Dusty
Well-Known Member
Re: Putting a fan on top of air intake?
Before anyone goes crazy and starts fantasizing about building all sorts of crazy power, remember that FI is still the preferred way to go since all the plumbing, flow reversion, reduction of charged air temp issues etc have been taken care of.
Before anyone goes crazy and starts fantasizing about building all sorts of crazy power, remember that FI is still the preferred way to go since all the plumbing, flow reversion, reduction of charged air temp issues etc have been taken care of.
Re: Putting a fan on top of air intake?
The main thing is that these electric chargers are only designed to operate at low pressures and relatively low volumetric flow.
They don't have charge temp issues because they are moving so little air at so low an RPM and are not conducting heat unlike with turbos. They don't have flow reversion either because there is no increase in exhaust manifold pressure unlike with turbos of all but the largest sizes. I don't see issues in plumbing either because the flow levels are only slighly bumped and there is less restriction in the absence of an intercooler.
Crufty Dusty said:
The main thing is that these electric chargers are only designed to operate at low pressures and relatively low volumetric flow.
They don't have charge temp issues because they are moving so little air at so low an RPM and are not conducting heat unlike with turbos. They don't have flow reversion either because there is no increase in exhaust manifold pressure unlike with turbos of all but the largest sizes. I don't see issues in plumbing either because the flow levels are only slighly bumped and there is less restriction in the absence of an intercooler.
Re: Putting a fan on top of air intake?
Received? Learn? You just disregarded everything by saying that only with a dyno result will you believe, and dragging in efficiency considerations when they are totally separate. It is just like with the intake pipe you fabricated the other day, and the turbocharged fuel system delivery concepts days before that where you had to ask if the fundamental accepted truth was fact or assumption. These things are absolutely fundamental and found all over the place if you were to examine 40 year old textbooks still used by universities today at a post graduate level, talk to 40 year experience engine builders or tuners, etc. As an engineer it should be really easy for you to discern these technical things logically and in line with natural law. For a couple hundred SGD (couple books) and under 50 hours (reading) of your time, someone of your capacity could have every answer explained in extreme detail, from an almost godly authority, all the questions you've wondered about so far. 50 hours may seem like a lot, but 4 hours is easily consumed in one meal outing, 2 in one chat session, 9 in one trackday.
To spend time and in the end have everything disregarded as long as it does not fall in line with "feel", is not worth it. It is like if Jem spent 2 hours explaining to me, in detail, how to invest money, and at the end of it all, I tell him it just doesn't feel right and that I just have to continue believing what I originally believed and do things my way and find out. It is totally my right to do that, but if I was so certain of the methods to begin with, I could have completely skipped that step anyway! Correct anot?
Whisky_Tango said:Well... tats because im not experience in this field and truly your time & inputs are well received by me. Only through such discussions will I learn and hope you still continue to support.
Hopefully others will find this discussion meaningful.
Cheerio...
Received? Learn?
You just disregarded everything by saying that only with a dyno result will you believe, and dragging in efficiency considerations when they are totally separate. It is just like with the intake pipe you fabricated the other day, and the turbocharged fuel system delivery concepts days before that where you had to ask if the fundamental accepted truth was fact or assumption. These things are absolutely fundamental and found all over the place if you were to examine 40 year old textbooks still used by universities today at a post graduate level, talk to 40 year experience engine builders or tuners, etc. As an engineer it should be really easy for you to discern these technical things logically and in line with natural law. For a couple hundred SGD (couple books) and under 50 hours (reading) of your time, someone of your capacity could have every answer explained in extreme detail, from an almost godly authority, all the questions you've wondered about so far. 50 hours may seem like a lot, but 4 hours is easily consumed in one meal outing, 2 in one chat session, 9 in one trackday. To spend time and in the end have everything disregarded as long as it does not fall in line with "feel", is not worth it. It is like if Jem spent 2 hours explaining to me, in detail, how to invest money, and at the end of it all, I tell him it just doesn't feel right and that I just have to continue believing what I originally believed and do things my way and find out. It is totally my right to do that, but if I was so certain of the methods to begin with, I could have completely skipped that step anyway! Correct anot?
__iceman__
Well-Known Member
Re: Putting a fan on top of air intake?
Guys, I'm quite convinced that it would work.
I will be visiting ADM tomorrow to work with Sylvester and see whether it can be fitted and could work with my Simota intake.
I believe that the low and mid will have percivable improvement, and at 238CFM - maybe no increment in high end, but it should not be restrictive - even for a 325 like mine.
Stay tuned. if it fits, I will snap pics and give FR.
Guys, I'm quite convinced that it would work.
I will be visiting ADM tomorrow to work with Sylvester and see whether it can be fitted and could work with my Simota intake.
I believe that the low and mid will have percivable improvement, and at 238CFM - maybe no increment in high end, but it should not be restrictive - even for a 325 like mine.
Stay tuned. if it fits, I will snap pics and give FR.
Crufty Dusty
Well-Known Member
Re: Putting a fan on top of air intake?
When I mentioned flow reversion, I actually meant compressor surge. i.e. flooring the accelerator pedal, then lifting off suddenly. Throttle plate is closed, the air has nowhere to go. At the minimum you would need a dump valve, and the bearings on the fan would have to be hardy to take the abuse. I'm also unsure of the effects of vibration from a 65 dB fan would have on the MAF sensor, but it's possible that the readings would also be adversely affected.
Shaun said:
When I mentioned flow reversion, I actually meant compressor surge. i.e. flooring the accelerator pedal, then lifting off suddenly. Throttle plate is closed, the air has nowhere to go. At the minimum you would need a dump valve, and the bearings on the fan would have to be hardy to take the abuse. I'm also unsure of the effects of vibration from a 65 dB fan would have on the MAF sensor, but it's possible that the readings would also be adversely affected.
Re: Putting a fan on top of air intake?
IIRC these fans are WOT-only fans so they cut off then throttle is lifted. Besides low pressure, they are also low RPM, low inertia fans that stop very quickly - all relative to TC. In the case of ADM variable speed.. I don't know what happens when you lift, but it is likely they're reading TPS and don't bother pushing the system against a closed TB cos that only wastes energy and service life. So IMO compressor surge won't be an issue.
Why would you think an MAF would be hurt by some fan noise being such a simple system? The stock engine bay is already a harsh environment.
IIRC these fans are WOT-only fans so they cut off then throttle is lifted. Besides low pressure, they are also low RPM, low inertia fans that stop very quickly - all relative to TC. In the case of ADM variable speed.. I don't know what happens when you lift, but it is likely they're reading TPS and don't bother pushing the system against a closed TB cos that only wastes energy and service life. So IMO compressor surge won't be an issue.
Why would you think an MAF would be hurt by some fan noise being such a simple system? The stock engine bay is already a harsh environment.
Crufty Dusty
Well-Known Member
Re: Putting a fan on top of air intake?
OK, so let's say engine flow demand is 200cfm, this device flows 300cfm of air, throttle plate closes, where does the 100cfm of air go but back through the MAF sensor? Anyone know for sure how much pressure we're talking about here?
Certain Karman Vortex MAF systems are extremely susceptible to noise and vibration which would cause inaccurate MAF readings. Some cars on this system are known to completely stall out when on the drag strip and the other vehicle revs its engine very hard. The resulting harmonic vibrations on the intake cause turbulent air to be misread by the sensor.
Shaun said:
OK, so let's say engine flow demand is 200cfm, this device flows 300cfm of air, throttle plate closes, where does the 100cfm of air go but back through the MAF sensor? Anyone know for sure how much pressure we're talking about here?
Certain Karman Vortex MAF systems are extremely susceptible to noise and vibration which would cause inaccurate MAF readings. Some cars on this system are known to completely stall out when on the drag strip and the other vehicle revs its engine very hard. The resulting harmonic vibrations on the intake cause turbulent air to be misread by the sensor.
Re: Putting a fan on top of air intake?
ADM doesn't list a pressure rating. Bilge blowers are commonly 300-500 CFM @ 0.5 - 1.5 PSI.
Oh I was thinking more hotwire MAF. Which other cars besides the Evos run karman vortex? I thought most stuff is hotwire these days?
Crufty Dusty said:
ADM doesn't list a pressure rating. Bilge blowers are commonly 300-500 CFM @ 0.5 - 1.5 PSI.
Oh I was thinking more hotwire MAF. Which other cars besides the Evos run karman vortex? I thought most stuff is hotwire these days?
Crufty Dusty
Well-Known Member
Re: Putting a fan on top of air intake?
According to Bernoulli's equation this figure only applies for steady flow which is not the case here.
Mostly DSMs. Hotwire or hot film is popular these days most likely due to sensor cost alone.
Shaun said:
According to Bernoulli's equation this figure only applies for steady flow which is not the case here.
Shaun said:
Mostly DSMs. Hotwire or hot film is popular these days most likely due to sensor cost alone.
Re: Putting a fan on top of air intake?
If engine demand is 200 CFM, though fan is is rated as capable of supporting a max of 300 CFM @ 1 PSI, flow does not exceed what the engine can consume. There is no 100 CFM to be sent back out the MAF because it was never flowing 300 CFM to begin with. Also at shut down, CFM which is flow over a full minute, is rapidly shut down to between a split second and half second (these little low inertia electric fans really shut down quick). If engine demand is 200 CFM NA, then at this 1 PSI of pressure, the fan is pumping about 213 CFM.
When the the throttle shuts, all it sends back out the MAF is (volume between fan and throttle blade X 0.068). Say you have 2.5 inch dia pipe about 30 inches long - that's 147.5 CI or 0.085 CF. Now 0.085 CF x 0.068 is 0.0058 CF. This 0.0058 CF (or 160 cc ) heading back out the MAF is much less than originally thought - at worst a momentary and very slightly rich condition. IMO not a problem.
Crufty Dusty said:
If engine demand is 200 CFM, though fan is is rated as capable of supporting a max of 300 CFM @ 1 PSI, flow does not exceed what the engine can consume. There is no 100 CFM to be sent back out the MAF because it was never flowing 300 CFM to begin with. Also at shut down, CFM which is flow over a full minute, is rapidly shut down to between a split second and half second (these little low inertia electric fans really shut down quick). If engine demand is 200 CFM NA, then at this 1 PSI of pressure, the fan is pumping about 213 CFM.
When the the throttle shuts, all it sends back out the MAF is (volume between fan and throttle blade X 0.068). Say you have 2.5 inch dia pipe about 30 inches long - that's 147.5 CI or 0.085 CF. Now 0.085 CF x 0.068 is 0.0058 CF. This 0.0058 CF (or 160 cc ) heading back out the MAF is much less than originally thought - at worst a momentary and very slightly rich condition. IMO not a problem.
Re: Putting a fan on top of air intake?
You are confusing bernoulli's equation with compressor ratings. Bernoulli's equation has to do with pressure-velocity trade offs in fluids. Compressor ratings are compressor ratings. 300 CFM @ 1 psi simply means at optimum shaft speed, 300 CFM will be moved till 1 psi over atm pressure is faced - at which flow is compromised slowly as pressure builds. Nothing to do with local pressure and velocity changes as with bernoulli's stuff.
Yup so if this is for BMWs that run hotwire, I wouldn't worry about noise and vibration.
Crufty Dusty said:According to Bernoulli's equation this figure only applies for steady flow which is not the case here.
You are confusing bernoulli's equation with compressor ratings. Bernoulli's equation has to do with pressure-velocity trade offs in fluids. Compressor ratings are compressor ratings. 300 CFM @ 1 psi simply means at optimum shaft speed, 300 CFM will be moved till 1 psi over atm pressure is faced - at which flow is compromised slowly as pressure builds. Nothing to do with local pressure and velocity changes as with bernoulli's stuff.
Yup so if this is for BMWs that run hotwire, I wouldn't worry about noise and vibration.
