Flow Bench Test Results

[Jim Allen]

I agree with SubiGt that airflow numbers alone are almost never the end of the story. There are many subtleties, not all of which are clear in our "quick-n-dirty" testing (meaning a few flow bench tests and a coupla dyno tests).

SubiGt:To answer some of his questions, the flowbench had to be really cranked up to keep up with all these systems. The instructor noted that this stock setup was one of the best flowing OE setups he has seen.

The results are corrected to 28" H20, but tested at 20" or 10 ". The one class tested at 20 and the second at 10. exceptions were a few situations where the assembly had too much flow, such as the Brute Force and the stock housing without the snorkel or silencer, which were tested at 15" by the first class. Most people agree that the closer you are to 28" the more accurate the results and in this case, we were able to note the "pucker" in the Downspout Connector at 20", which was not apparent at 10".

While we did not measure the time it took to stabilize the flow, it seemed very fast... just about instantaneous. Velocity can be roughly calculated from the actual CFM, can't it, but I don't know if that's an accurate way to do it.

It would be interesting to run the modified air tube with the silencer chambers removed. I'm not willing to modify mine, but if someone wants to let me borrow one, I'll get it tested. Would be really interesting to find a way to test the system plugged into the fender.

88Racing: I'm not convinced (willing to be, but have not as yet) that there are notable differences in power between metal and poly tubes. In "Forum Poster" type racing, of course, every fractional difference is hotly debated. I've discussed this with several engineers and they say, yeah, there is a tiny difference but the air is moving to fast to pick up much heat from a smooth tube. In the OE, plastic is used more as a weight saver and production expedient.

Also 88Racing: I not clear on what you mean by "more air thru the stock setup" ? Yes the stock Motorcraft air filter seemed to flow a little more than the AEM panel. Was that what you mean? Or was it that the stock setup was very close to the modified system. Note that in #6, we removed the rubber downspout adapter and that's when the modified system exceeded the stock by a little.


JackandJanet: The theoretical airflow number I gave is calculated. The formula is :


CFM= RPM x DISPLACEMENT /3456 x VOLUMETRIC EFFICIENCY

I used 5500 rpm as a reasonable maximum and was generous in giving the fairly free-breathing modular a 90 VE. 85 percent would be more real world but would drop the CFM result. I gave it .90 to factor in some other mods that would increase airflow a little, such as a free flow exhaust and a program. At 100 percent VE, flow would be 525 CFM, still under what the stock system flows.

5500 x 330/3456 x .90= 472.656 CFM

My conclusion is that the stock intake is pretty darn good and can support some extra horsepower. A CAI, as SubiGt noted, tends to lean the mixture a little and that's where most of the power is. Thing is, your Edge or Grypon does the same thing and unless you need the extra airflow, I don't think the two things "stack" all that well. Bill has to essentially richen the mixture with a CAI because the combo may lean it too much, thus negating a big part of the advantage the CAI offers. Bottom line, IMHO,if the stock intake system has the airflow, you may not need the CAI when running a mild program.

I almost forgot: Remember that this is a throttled engine. Everything we are discussing is relevant only at WOT. The throttle plate is the main restriction in any engine (how much time do we spend at WOT??) and beyond that it's the intake valve!

[88Racing]

Jim,

I know the use of the GT data is relatively different to the truck.

1. The location of the motor

2. The location of the intake(air pick up)

3. The stock air intake itself.

Their motors are in a mid position in the vehicles and thus if a metal type intake is used they are finding it to build up heat.

My other point about surface area and media densities is that there can be more air flow accumalated through a greater surface area. But on the same hand a cai attemps to get the same air penetration through its filter using a less dense material to make up for the lost surface area.

Lars

[jimmyv13]

Originally Posted by Jim Allen

88Racing: I'm not convinced (willing to be, but have not as yet) that there are notable differences in power between metal and poly tubes. In "Forum Poster" type racing, of course, every fractional difference is hotly debated. I've discussed this with several engineers and they say, yeah, there is a tiny difference but the air is moving to fast to pick up much heat from a smooth tube. In the OE, plastic is used more as a weight saver and production expedient.

I have datalogged many hours of intake air temps with turbo vehicles comparing different intake configurations. One thing I noted, the metal intake tubes almost ALWAYS had a higher intake air temp than plastic intake tubes, in the engine bay or not, regardless of filter or intake routing. Of course this testing was on a turbo vehicle where low IAT's are a vital element in producing big horsepower. The turbo heats up the AIT charge, so a low CAI is critical. The lower the temp of the air going into the turbo, the lower it'll be coming out. You'd be amazed how high the AIT gets on a turbo vehicle as it sits at a light...triples sometimes quadruples in 30 seconds-1 minute. Waiting in line at the strip was excruciating at times as I watched my IAT's climb like a tach. I was one of the guys that pushed his car most of the way up the staging lane.

So, CFM compared to IAT's...which is more important on our F150? I am taking Jim's testing results as the stock intake routing is great for CFM, as he has proven. It is in fact a true CAI, so the IAT can't possibly get any colder short of major modification to the intake charge. I don't think the DIY mod negatively affects the IAT, but I do not have the numbers to prove it...and it's difficult for me to think how it could possibly do so.

Originally Posted by Jim Allen

Also 88Racing: I not clear on what you mean by "more air thru the stock setup" ? Yes the stock Motorcraft air filter seemed to flow a little more than the AEM panel. Was that what you mean? Or was it that the stock setup was very close to the modified system. Note that in #6, we removed the rubber downspout adapter and that's when the modified system exceeded the stock by a little.

I wonder how a K&N compares to the AEM and stock filter? My stock filter needs replacing and I'm curious if I should get a K&N or a motorcraft? I didn't like the flexibility of the downspout connector and it sounds as if it may be detrimental to the flow if it collapses, so something else is going to go there.

[Jim Allen]

Originally Posted by jimmyv13

I have datalogged many hours of intake air temps with turbo vehicles comparing different intake configurations. One thing I noted, the metal intake tubes almost ALWAYS had a higher intake air temp than plastic intake tubes, in the engine bay or not, regardless of filter or intake routing.

I agree, but what I was saying it isn't a significant amount in the context of an F150. You really are comparing apple to oranges when juxtaposing a turbocharged race engine with a work-a-day F-150 with a few mild mods. Five to ten degrees, even 15 degrees, is really insignificant on a street vehicle and, according to the informed people I have discussed this with, that's the differences we are talking about between plastic and metal. What little info I gathered in a previous search project seemed to bear this out, however, I'm always willing to review contrary data and change my mind!!! FWIW, the metal-tubed AEM I have installed now delivers about 6 degrees cooler IAT than the stock system, as measured by the Gryphon, via the IAT sensor. I doubt that small amount is doing anything much but it's somewhat noteworthy in this discussion, at least.

Originally Posted by jimmyv13

I wonder how a K&N compares to the AEM and stock filter? My stock filter needs replacing and I'm curious if I should get a K&N or a motorcraft? I didn't like the flexibility of the downspout connector and it sounds as if it may be detrimental to the flow if it collapses, so something else is going to go there.

I was long a K&N (or oiled cotton gauze- OCG) guy, but no more. I'm not satisfied the questions about filtering ability have been properly answered... yet... and I proved the (lack of) filtering issues to myself in one situation. On a street vehicle in a clean atmosphere, these may not be serious issues, but my trucks live in dirty environments. When I put a dab of grease on the clean side of the intake on my late-great trail rig (the Bum-V) and it's gritty in 6K miles on the street and trail, it's time for a change! I installed a tractor filter & housing from a 600ci tractor, with a synthetic/cleanable element and a cyclonic feature. But I'd rather have a little less clean air than more dirty air. Plus I get nervous when people start arguing about how much dirt is insignificant.

The AEM, and some others, are significantly better at filtering ability than an OCG design, which are typically at the bottom of that Totem pole... and OCGs rely heavily on the person who cleans and oils them to do it correctly. Other OCG filter naysayers mention the over-oiling/fouled MAF sensor issues, but I think those concerns may be somewhat overstated (and subject to the person applying the oil). I'd run the Motorcraft or the AEM. When we tested the main airbox alone, (#4 & 5) I think that showed the true airflow difference between those filters was minimal. I like the idea of a filter I can clean and run forever, but one that can catch stuff smaller than gravel.

[jimmyv13]

Originally Posted by Jim Allen

I agree, but what I was saying it isn't a significant amount in the context of an F150. You really are comparing apple to oranges when juxtaposing a turbocharged race engine with a work-a-day F-150 with a few mild mods. Five to ten degrees, even 15 degrees, is really insignificant on a street vehicle and, according to the informed people I have discussed this with, that's the differences we are talking about between plastic and metal. What little info I gathered in a previous search project seemed to bear this out, however, I'm always willing to review contrary data and change my mind!!! FWIW, the metal-tubed AEM I have installed now delivers about 6 degrees cooler IAT than the stock system, as measured by the Gryphon, via the IAT sensor. I doubt that small amount is doing anything much but it's somewhat noteworthy in this discussion, at least.

Very interesting info with the AEM metal intake. Has AEM made a change in their products? I seem to remember that company making junk products for a while.

My research was done on a daily driven turbo RX-7 with an intake and exhaust. Nothing extraordinary, just a normal vehicle that I drove everyday to and from school.

[Jackpine]

Originally Posted by Jim Allen

JackandJanet: The theoretical airflow number I gave is calculated. The formula is :


CFM= RPM x DISPLACEMENT /3456 x VOLUMETRIC EFFICIENCY

I used 5500 rpm as a reasonable maximum and was generous in giving the fairly free-breathing modular a 90 VE. 85 percent would be more real world but would drop the CFM result. I gave it .90 to factor in some other mods that would increase airflow a little, such as a free flow exhaust and a program. At 100 percent VE, flow would be 525 CFM, still under what the stock system flows.

5500 x 330/3456 x .90= 472.656 CFM

My conclusion is that the stock intake is pretty darn good and can support some extra horsepower. A CAI, as SubiGt noted, tends to lean the mixture a little and that's where most of the power is. Thing is, your Edge or Grypon does the same thing and unless you need the extra airflow, I don't think the two things "stack" all that well. Bill has to essentially richen the mixture with a CAI because the combo may lean it too much, thus negating a big part of the advantage the CAI offers. Bottom line, IMHO,if the stock intake system has the airflow, you may not need the CAI when running a mild program.

I almost forgot: Remember that this is a throttled engine. Everything we are discussing is relevant only at WOT. The throttle plate is the main restriction in any engine (how much time do we spend at WOT??) and beyond that it's the intake valve!

Jim - I was pretty sure you were getting the "required" airflow number this way and I can't see any other way to get it. I would have used an RPM figure of 5000, since power seems to drop off above that, but this would only reduce the airflow needs.

And, we've already agreed that this mod's effects would only be seen at WOT/high RPM.

But, I'm still left with the fact that Bill has measured higher power with the restriction removed.

I wonder if this is an explanation? The possible air volume requirements may well be supported by the stock intake, but, with a cross-sectional intake area of 3.14 sq inches the flow velocity would have to be higher than the velocity with the restriction removed and a cross-sectional area of 7.07 sq inches. Higher velocity equates to lower static pressure. Lower static pressure available at the intake port, equates to lower absolute compression (relative to sea level pressure), similar to what you'd get running at altitude in the high Rockies. Lower compression means lower power.

But, I sure don't like the way the downspout approach "puckered". I think the inlet HAS to be rigid.

- Jack

[Jackpine]

Glad to see you again, kd4crs. I like the looks of the new approach. Isn't this new tubing pretty similar to the "armadillo hide" looking stuff that you can find in most hardware stores for dryer ducting?

I remain convinced though, that despite Jim Allen's outstanding (and I mean that) tests of this mod, there are benefits to be had. I am absolutely certain I am getting better gas mileage than before - about +0.5mpg, to be precise. I can only attribute this to a more efficiently running engine. My driving habits have not changed.

- Jack

[kd4crs]

JackandJanet,

Hi, the Spectre Performance intake tubing is kind of like the dryer tubing but it is rigid and if you expand it, it stays in that position until you collapse it. It is actually designed as an intake product and does away with the DWV entirely. I have only heard 3 reports of the downspout connector having collapsed or turned inside out. I guess that is due to some of them being more flexible than others. I have run the DWV intake mod with the downspout connector on my trucks ever since I posted it with no issues. This new variation by formmt08 on f150online completely eliminates any possibility of collapsing or obstruction. I really like it so far.

[jimmyv13]

Originally Posted by Jim Allen

Also 88Racing: I not clear on what you mean by "more air thru the stock setup" ? Yes the stock Motorcraft air filter seemed to flow a little more than the AEM panel. Was that what you mean? Or was it that the stock setup was very close to the modified system. Note that in #6, we removed the rubber downspout adapter and that's when the modified system exceeded the stock by a little.

Did you notice the downspout fluttering during the testing that would indicate a lower CFM? I am curious as to why it flowed better without the connector?

[Jim Allen]

The "puckering" only occurred when tested at 20" of H20, not at 10". The actual airflow is then converted via a graph to 28". In the case of the 10" tests, there is less air actually flowing through the unit, so the puckering was not apparent. Still, the unit flowed better without the rubber when tested at 10" of H20. The corrected 10" reading were 607cfm with, and 642.5 cfm without the rubber. At 20" the readings were 586.69/632.5. That says to me that the rubber over the bell mouth of the adapter is doing something to the airflow.