The kd4crs/Power Hungry/Gotts Mod (revisited - and with pictures) - Page 9

Jim Allen · #81 Wed, February 11th, 2009, 11:48 AM

Pretty coo1!

I'm new here and hesitate to start in such a way, but at the risk of being labeled a "Negative Nelly" after my first post.... is there any proof these mods actually increase airflow? The reason I ask goes back many years to my days as a Land Rover tech.

Late '80s and early '90s EFI Range Rovers had a "trumpet" on the end of of the air cleaner, similar to the part that was replaced in these examples. It necked down to a diameter many people were sure was restrictive, so they lobbed off the trumpet thinking it helped airflow.

I thought it would too, but then I took a bunch of air filters to the late, great Earl Davis for flowbench tests back when he was running the test lab at K&N. I had both a standard Range Rover filter with the trumpet and one modified similar to the way this Ford one is done. No significant difference in airflow. In fact, the trumpet actually flowed slightly more. Earl postulated that the trumpet design actually had something to do with that, smoothing and consolidating air flow, much like velocity tubes will do on carbs. I later backed that airflow test up with a dyno test.. no difference in power the chassis dyno could pick up (admittedly, chassis dynos are "numb" to small changes). Operationally, you couldn't tell a difference, except that the modified horn was noisier.

I won't say definitively that the Ford mod will flow more, or less, than the stock setup because I haven't tested it, but previous experience leads me to ask the question at least.

I have limited access to a flow bench, so in theory, I could test the various permutations of this filter. I have a stock filter from my '05 5.4 F-150 (I am running an AEM CAI). If we wanted to do a test, I could probably make that happen. Bill can vouch for me. I hope!!?

Grabber523 · #82 Wed, February 11th, 2009, 12:28 PM

Quote:

Originally Posted by Jim Allen

Pretty coo1!

I'm new here and hesitate to start in such a way, but at the risk of being labeled a "Negative Nelly" after my first post.... is there any proof these mods actually increase airflow? The reason I ask goes back many years to my days as a Land Rover tech.

Late '80s and early '90s EFI Range Rovers had a "trumpet" on the end of of the air cleaner, similar to the part that was replaced in these examples. It necked down to a diameter many people were sure was restrictive, so they lobbed off the trumpet thinking it helped airflow.

I thought it would too, but then I took a bunch of air filters to the late, great Earl Davis for flowbench tests back when he was running the test lab at K&N. I had both a standard Range Rover filter with the trumpet and one modified similar to the way this Ford one is done. No significant difference in airflow. In fact, the trumpet actually flowed slightly more. Earl postulated that the trumpet design actually had something to do with that, smoothing and consolidating air flow, much like velocity tubes will do on carbs. I later backed that airflow test up with a dyno test.. no difference in power the chassis dyno could pick up (admittedly, chassis dynos are "numb" to small changes). Operationally, you couldn't tell a difference, except that the modified horn was noisier.

I won't say definitively that the Ford mod will flow more, or less, than the stock setup because I haven't tested it, but previous experience leads me to ask the question at least.

I have limited access to a flow bench, so in theory, I could test the various permutations of this filter. I have a stock filter from my '05 5.4 F-150 (I am running an AEM CAI). If we wanted to do a test, I could probably make that happen. Bill can vouch for me. I hope!!?

I have to agree with your statements here. It's kinda been a nagging question in my head but I'm new here so I didn't want to seem like the naysayer...I guess in my head the "velocity stack" on the intake is there to improve airflow into the intake tube by compressing and accelerating the air as it flows into the tube. Because of the inverse relationship between pressure and velocity, as the diameter of the tube increases behind the inlet and the velocity decreases, the pressure increases (I guess really it's decreasing the vacuum) in the tube. I guess if my theory's not too far off, that "trumpet" inlet tube serves to increase the density of the air charge before the throttle body...does that make sense? It would improve low-end torque and throttle response but cause slight restriction at high rpm.

kd4crs · #83 Wed, February 11th, 2009, 12:40 PM

Bill has dynoed this type of mod and it showed no ill effects on the airfuel ratios, long or short term fuel trims, or anything else. He said it showed an increase of 7-8 RWHP in the upper RPMs. If you search, you should be able to find his post on the forums here. I don't remember which thread it was in. The nice thing about the DWV intake mod is that it is completely reversible to be able to return to stock if needed. Nothing is damaged or permanently modified. It leaves no footprint.

Grabber523 · #84 Wed, February 11th, 2009, 01:16 PM

Quote:

Originally Posted by kd4crs

Bill has dynoed this type of mod and it showed no ill effects on the airfuel ratios, long or short term fuel trims, or anything else. He said it showed an increase of 7-8 RWHP in the upper RPMs. If you search, you should be able to find his post on the forums here. I don't remember which thread it was in. The nice thing about the DWV intake mod is that it is completely reversible to be able to return to stock if needed. Nothing is damaged or permanently modified. It leaves no footprint.

I'm not saying it would hurt anything except maybe that first off-idle stab of the throttle feel. Your MAF should still see the same volume of air, just at a different rpm because of the change in velocity, so there would be no real reason to have to re-tune for it. I'll probably leave mine alone, but that's me. I don't need to push my power band any further to the right as I already have X-piped true duals which definitely changed the feel of the initial "grunt" off idle. I do think it is a great idea for somone looking for more up top. And is saves some $$$!

AgentOrange · #85 Wed, February 11th, 2009, 01:21 PM

Quote:

Originally Posted by kd4crs

Bill has dynoed this type of mod and it showed no ill effects on the airfuel ratios, long or short term fuel trims, or anything else. He said it showed an increase of 7-8 RWHP in the upper RPMs. If you search, you should be able to find his post on the forums here. I don't remember which thread it was in. The nice thing about the DWV intake mod is that it is completely reversible to be able to return to stock if needed. Nothing is damaged or permanently modified. It leaves no footprint.

http://dygytalworld.ehost-services13...p?t=197&page=2

Post #14

***Jackpine*** · #86 Wed, February 11th, 2009, 01:55 PM

This is in response to the excellent posts by Jim Allen and Grabber523. I was typing it but had to stop for lunch and three other posts snuck in on me!

Both Jim and Grabber make good points, and one's that worried me too, but for a different reason. First though, I have a degree in Aerospace Engineering and know that airflow theory is SUPER complicated. I've been concerned that these modifications would induce turbulence in the intake (due to a non-streamlined cross-section in the modified area) that would actually work against the increased intake area. Then too, the "squared off" end of the new intake may in fact promote turbulence too.

However, Bill brought up the point that the CAI design doesn't really come into play until you're at high RPM's, and, something he said in one of his posts convinced me that he thought the airflow was increased under those demands with the bigger opening. (I think this was reprised in one of the posts that beat me to this one).

Grabber, there IS the inverse relationship between velocity and pressure, but there's also conservation of mass. You're not going to get anything more downstream of the inlet than you had AT the inlet, and, since the flow is moving, the static pressure is always less than ambient (meaning the air is less dense than ambient). I think the restricted opening can ultimately cause a lower pressure condition to exist throughout the inlet tube and at the throttle body if RPMs are high enough. At that point, it's going to be difficult to increase power since the MAF sensor is going to say "not enough air".

Jim, I liked your "smoothing" analogy. It goes back to what I was saying about turbulence possibly restricting airflow. And, it may well be the case that you are right on this. I certainly would like to see some objective data and won't throw my trumpet snorkel away until I'm convinced it's worthless. I will say, though, that the trumpet/bellows assembly is not the most streamlined, laminar flow design I've ever looked at with the inside "bumps" just downstream of the inlet, the rings at the bellows end of the snorkel and finally, the accordion folds of the bellows itself. And, the trumpet end widens too rapidly to my eyes. It seems like it should cause turbulence of its own due to this. It doesn't look like a reasonable airfoil curve to me.

Finally, since the cross-sectional area of the tube increases with the square of the radius, we have an intake cross-section of 3.14 sq inches with the trumpet, but 7.07 sq inches with the mod. That's over twice as much intake area for a 0.5" radius increase! I feel this almost HAS to increase the flow potential!

And, AgentOrange's "RAM" air mod probably provides even more. It's possible that the increased pressure from the RAM tube sort of cancels the fender inlet contribution at high speeds, but I'm nearly certain the combined effect provides even more air mass than one of them acting alone.

Again, gentlemen, I'd love to see some objective data and I'm delighted you two were not afraid to bring this point up.

As I said in another post, maybe a month ago: That trumpet restriction is there for a reason! You can bet on it. I'm betting it's there to reduce power potential at the upper end, which might reduce engine damage and warranty claims from those who abuse their engines.

- Jack

Jim Allen · #87 Wed, February 11th, 2009, 02:28 PM

One difference in my Land Rover example was that the trumpet was right at the end of a cylindrical filter housing with a cylindrical filter element inside. The trumpet was fairly close to the filter and not far away from the intake plenum itself. I think that scenario would be HIGHLY sensitive to any changes, where a change at the end of a system with such large interior volume would be far less sensitive to changes at the inlet.

As to the power increase, that's very telling if it was on a chassis dyno. If you can pull that much power out consistently over the margins for error that seem constant in a chassis dyno, you are doing good! What I wonder is whether what Bill tested was the J&J design, or the Agent Orange unit that eliminated the expansion chamber? Bill???

Like I said, I am willing to flow bench these mods. Can use my old housing and you guys can send the rest of the modified stuff to try. Before we start exchanging addresses, however, I'll have to make sure I can borrow the flow bench and a competent operator for a coupla hours.

Jim Allen · #88 Wed, February 11th, 2009, 02:32 PM

Oh, I just saw and followed Agent Oranges link and it sounds like Bill was just averaging the results of a CAI system, not speaking specifically to the modified stock system we are talking about. Am I correct?

***Jackpine*** · #89 Wed, February 11th, 2009, 02:40 PM

Jim, I'm certain Bill did not use the AgentOrange design. That's a pretty unique idea I think!

I'm fairly certain it was of the kd4crs ilk, or maybe even just an open tube minus the bellows and snorkel.

- Jack

AgentOrange · #90 Wed, February 11th, 2009, 03:00 PM

Quote:

Originally Posted by JackandJanet

Jim, I'm certain Bill did not use the AgentOrange design. That's a pretty unique idea I think!

I'm fairly certain it was of the kd4crs ilk, or maybe even just an open tube minus the bellows and snorkel.

- Jack

I wish I could take full credit for the idea, but Banks beat me to it.
If you notice, his design also uses the fenderwell inlet.

Check it out: http://bankspower.com/products/show/32/50 lot's of info there.

I doubt my mod makes the power his does, especially because I am still using the stock filter, but the principal is the same.
I think the main point of this and the kd4crs mod is to allow the engine to get as much air as it may need and keep it as cool as possible...plus, I just like to tinker with things.

Just my .02.