(C4)Filters: Green vs K&N

[Hib Halverson]

It is my understanding that the C4 air filter is much bigger than it needs to be for the L98 or LT1/4/5 engines, so seeing a performance increase with the installation of an oiled filter over a new paper filter is highly unlikely.

However, over time, the paper filters tend to restrict flow faster as they get dirty and the oiled filters flow more air longer, thus providing the performance advantage compared to old paper filters with similar miles and dirt. This is one of the reasons I use oiled filters. My current filters are K&N in all my cars (except the 08 - can see bying one just yet).

I've read about Green filters before and have considered them. May see if they make one for the 08. In the meantime, my K&N's are working just fine.

Tuna is correct in his understanding of the "late" C4 air filter assy. It was used on L98 for 91, LT1, LT4 and LT5 engines and was sized for approximately 500 hp "worth" of air flow, however, its obvious "overdesign" is unusual. It is a very large panel type filter. The C5 and C6 filters are not that large.

With a late C4 an oiled-cotton filter and a clean paper filter will show little of any difference over a new paper filter as long as the engine sucking the air is 450-475-hp or less.

Where a difference will start is 475-hp or more or when you start comparing papr filters which are "partially dirty" compared to a properly-maintained, oiled-cotton filter which has trapped the same amount of contaminants.

That said, my comments on K&N vs Green are not meant to be taken in an application-specific context. When viewed from a "generic" design and quality standpoint, IMO, the Green is a better choice.

If you're filtering an engine and testing shows a difference between performance with a paper filter and performance with a K&N that is "modest" or greater, then the diffferences between the K&N and the Green may manifest themselves as a slightly larger performance gain with the Green then with the K&N because, the Green (perhaps due to its woven cotton and less rubber bleed) may offer slightly more reduced-restriction that does the K&N.

Admittedly, this kind of stuff is not easily tested in the field but can be tested on chassis or engine dynos.

 

[Hib Halverson]

I'd like to add that my comments *snip* Comments deleted due to being irrelevant to a subject on air filters.

Hib, please check your messages regarding some of your posts lately. Keep the topics on track and not personal. Thank you. *89x2*

There were no "personal attacks" made, "89x2", and you know it. Why not repost all of of my content and let the greater CAC membership make the decision on whether or not it's "personal".

*SNIP* off-topic comments removed, PM sent. *89x2*

 

[*89x2*]

With a late C4 an oiled-cotton filter and a clean paper filter will show little of any difference over a new paper filter as long as the engine sucking the air is 450-475-hp or less.

Where a difference will start is 475-hp or more or when you start comparing papr filters which are "partially dirty" compared to a properly-maintained, oiled-cotton filter which has trapped the same amount of contaminants.

That said, my comments on K&N vs Green are not meant to be taken in an application-specific context. When viewed from a "generic" design and quality standpoint, IMO, the Green is a better choice.

If you're filtering an engine and testing shows a difference between performance with a paper filter and performance with a K&N that is "modest" or greater, then the diffferences between the K&N and the Green may manifest themselves as a slightly larger performance gain with the Green then with the K&N because, the Green (perhaps due to its woven cotton and less rubber bleed) may offer slightly more reduced-restriction that does the K&N.

Admittedly, this kind of stuff is not easily tested in the field but can be tested on chassis or engine dynos.

Hib,

Back in 2004, I wrote my impressions about the Green brand filter- I reviewed how it was designed and produced, coming away very impressed.

Here are my comments:

Quality in design of something often taken for granted...(they) were able to control the design and allow for precision molding of the oiled cloth filter panel. The rubber element surround, as I was shown on other designs, tends to creep into the filter surface are, therefore causing a restriction. ...precise design kept the rubber at a constant thickness without that “bleed” into the cloth area –

...what if four years later, there was a K&N Design able to meet the same technical standard?

Additionally, wouldn't a flow bench be a suitable tool for testing air filters? Possibly a better choice that a chassis dyno?

 

[CallawayMV]

. . . "Jeroenvgfn" asks a great question . The thread languished, unanswered, on the Callaway Forum for months and there is no excuse for that. There's little doubt in my mind that the switch from Green to K&N is because of a "price issue". That's the only reason a vendor would change from a great product, such as the "Green Filter", to just an "average" product, such as the "K&N FilterCharger".

One advantage K&N has, due to its large size in comparison to Green Filter USA, its market share and because it uses an inferior design that's less-expensive to manufacture, is it can go to volume retailers, such as Callaway Cars, then convince them to buy filters for less which they can turn around and sell at the same price and know that their customers are getting a filter that is "good enough". From the retailer's perspective, that's a wise business model because it increases the margin on the product. From the user's perspective, it might not be so wise.

The differences between a Green Filter and the K&N are several, but the ones which are key to filtering performance and airflow are the ones Corvetters need to understand.

Yes, the two products share a key feature, the oiled-cotton filter media, but that's where the similarities end. As the Green is a newer design, it has some quality and performance enhancements which K&N has either chosen not or is unable to adopt. Why has K&N not kept up with current technology? Perhaps, since it has the lion's share of the market; it may see no advantage in updating its technology.

Green's filtering media is woven cotton rather than the cotton gauze used by K&N. Put a golf shirt next to a gauze bandage, examine and feel the two materials and you'll better understand that key difference. The benefits of woven cotton are: it's thinner, holds oil better and is stronger. Green Filter's cross-weaving one fine and one medium layer of cotton produces a fabric that is thinner and stronger than K&N's gauze but still has the ability to trap dirt particles of as little as 5 microns in size. That means, for a given level of filtering and filter size, a Green may flow more air than a K&N. Is this important? It can be if the filter you use it near its limit as to air flow and going to a larger filter is not an option. Woven cotton holds filter oil more consistently. Woven cotton is stronger than gauze. Unlike gauze, you can't wear a hole in woven cotton by rubbing it. Lastly, there is no way small bits of cotton can rip off since the woven cotton threads are interlocked with each other.

Some other filters, K&N included, use a simple, pressure-molded, injection process to bond the perimeter rubber to the filter's interior components. That method saves manufacturing time, but in the process, rubber can seep onto the filtering surface. When the filter rubber bleeds onto the filter media, not only does it have the look of shoddy construction, it can restrict airflow as much as 25%. Green Filter USA uses a more time-consuming and expensive, four-step manufacturing process which virtually eliminates seepage and insures maximum airflow through the filter. Green chose that method because it produces a higher-quality and better-performing product.

There are other differences and, if you're interested in the techie details, you can find more information at www.greeenfilterusa.com

Clearly the Green Filter is a superior product and that's why I moved all my engines in the five of the cars (three Vettes and two other Chevrolets) my Wife and I own to Green Filters starting several years ago. It's why "Jeroenvgfn" uses them. It's why tens of thousands of other performance air filter buyers have kicked the K&N habit and gone Green. It's, also, why I believe Callaway Cars ought to go back to using them.

Hello, Hib!
Haven't spoken with you in years. I guess this will have to do for now.

I work for Callaway now and I was at the company during the filter element supplier change so I hope I can shed some light on the reasons for the change.

First of all, you're right: there's no excuse for the lack of response from Callaway. I spend a lot of time on another forum. No doubt, I need to spend more time here.

You've done a great job describing the Green Filter's features. The Green Filter element used in the Callaway Honker was a very good component. The filter media performed excellently, allowing high airflow rate while efficiently stopping harmful particulates from passing through. The seal material was exceptionally compliant, accommodating the smallest imperfections in the frame's surface for a perfect seal. After all, if the Green Filter was less than excellent, Callaway engineers wouldn't approve its use in Honker systems.

Given the quality of these Green elements, I can appreciate how you'd think that the change from Green to K&N was made for cost savings. What you weren't privy to, however, was the ongoing problem with supply. For years, the people at Green did their level best to solve the supply issues. To make a long story short, the Honker elements were originally manufactured for Green in France. We never received enough elements to satisfy demand and Honkers were always on back order. After over a year of starts and stops, they pulled the tooling from France and started to build the Callaway-branded elements in the US. Even though they gave 110% effort, the US facility wasn't able to keep up with the orders either. And then, the quality began to suffer. We began to reject elements. Design changes were tried and failed. After a couple of years of this, we had to make the difficult decision to change suppliers.

The other thing that isn't obvious is that Callaway engineers worked together with K&N to develop the current Honker filter. K&N had been working on a new seal compound and an experimental double-lip seal and they were looking for an application. The Honker was the perfect test, and the new seal mechanism worked great. They also devised a way to prevent the new seal material from wicking into the filter media to maximize filter area. You can see this in the pictures below.

Making the supplier change, we understood that we could not take a backward step with performance. I can't speak for all K&N products or all Green products but, with the gauze that was ultimately specified in the Honker filter, K&N filtration performance was dead even with the Green elements' and the K&N's airflow rate was within 2% of the Green filter material airflow rate. Two percent less flow at a given pressure drop is tiny and immeasurable on the dyno, given that the filter's cross-sectional area is large enough to support nearly 2000 cfm.

Lack of filter elements doesn't cause Honker backorders anymore. Now that we have sufficient element supply, it's exposed other component suppliers that can't keep up with demand. And again, from time to time, Honkers are on back order. We're working on these supply problems.

Callaway is seldom criticized for cutting corners or using cheap materials. On the contrary, our products are usually considered to be "overkill" for the application. However, I can understand the insinuation if you didn't know the full story.

All the best,
Mike Vendetto
Callaway Cars

 

[Tuna]

WOW!

 

[Hib Halverson]

I was unaware of the supply problem Callaway was experiencing with Green Filter USA. They have a great product, but seemingly, they need to fix their production problems on some areas such that they can meet volume buyers such as Callaway Cars.

You are correct...I was unaware of Green's inability to meet Callaway's needs as far as production rates go. Earlier I critisized your company for making the switch. Given the information you've posted in your answer to CAC member "Jeroenvgfn's" question, I was overly harsh and too quick to make a judgement. I apoligize for that.

As for the extended period for Callaway to respond to "Jeroenvgfn's" question, an employee of your company moderates the very "Callaway Forum" on which "Jeroenvigfn" asked the question. Because of that, I found the long lapse between when the question was posted and the answer finally came to be somewhat strange.

If the Honker Filter is designed for 2000 cfm flow, obviously the difference between the K&N design and the Green design, while perhaps measurable, would be irrelevant in a practical sense.. I think I acknowledged that general idea in some of my earlier posts in a discussion of the old OE C4 panel filter. I think where the differences might be have greater impact is in cases of filters sized much smaller in relation to the maximum airflow across the engine and if the K&N being compared was the older design, which sometimes has rubber bleeding onto the media, rather than the new design K&N been working on with your company's engineering staff. Perhaps, with Kevin McCelland coming to work in K&Ns R&D department, the company will continue to take a new look at improving it's products. Hopefully, the new seal and lip design Callaway worked on with K&N will be used in the rest of K&Ns filter line in the future.

Lastly, help me here....I'm a little confused about the "Honker" line. I had understood it to be a brand of "intake kits" but is "Honker," also, a brand under which Callaway sells air filter elements?

 

[CallawayMV]

I was unaware of the supply problem Callaway was experiencing with Green Filter USA. They have a great product, but clearly, they need to fix their production problems such that they can meet volume buyers such as Callaway Cars.

As for the extended period for Callaway to respond to CAC member "Jeroenvgfn's" question, an employee of your company moderates the Callaway Forum on which "Jeroenvigfn" asked the question. Because of that, I found the long lapse between when the question was posted and the answer finally came to be somewhat strange.

If the Honker Filter is designed for 2000 cfm flow, obviously the difference between the K&N design and the Green design while measurable would be irrlevant. I think I acknowleged that general idea in some of my earlier posts in a discussion of the old OE C4 panel filter. I think where the differences might be have greater impact is in cases of filters sized much smaller in relation to the maximum airflow across the engine and if the K&N being compared was the older design, which sometimes has rubber bleeding onto the media, rather than the new design K&N been working on with your company's engineering staff. Perhaps, with Kevin McClelland coming to work in K&Ns R&D department, the company will continue to take a new look at improving it's products.
Hopefully, the new seal and lip design Callaway worked on with K&N will be used in the rest of K&Ns filter line in the future.

Lastly, help me here....I'm a little confused about the "Honker" line. I had understood it to be a brand of "intake kits" but is "Honker," also, a brand under which Callaway sells air filter elements?

I don't think that Green Filters has production problems, per se, Hib. I just think this one part number was a problem for some reason.

Sorry if I caused confusion, describing the "Honker" filter element. I meant the filter element that goes into the Honker Cold Air Induction systems. Callaway doesn't offer a Honker brand of filter elements.

 

[Hib Halverson]

...and I take it that "Honker" induction systems are available for C4, 5 and 6 along with other vehicles such as Gen 4 F-car?

 

[CallawayMV]

...and I take it that "Honker" induction systems are available for C4, 5 and 6 along with other vehicles such as Gen 4 F-car?

Honker systems are available for C5 and C6 Corvette and 1993 to 1997 F-car only. Here are the applications:

203.20.2500 Honker F-Body, 1993 Camaro & Firebird
203.20.2501 Honker F-Body, 1994-1997 Camaro & Firebird
203.50.2500 Honker C5, 2001-2004 Corvette, w/o MagnaCharger
203.50.2505 Honker C5, 2001-2004 Corvette, w/MagnaCharger
203.51.2500 Honker C5, 1997-2000 Corvette, w/o MagnaCharger
203.51.2505 Honker C5, 1997-2000 Corvette, w/MagnaCharger
203.60.2500 Honker C6, 2005-2007 Corvette, exc. Z06, w/o MagnaCharger
203.60.2505 Honker C6, 2005-2007 Corvette, exc. Z06, w/MagnaCharger
203.67.2500 Honker C6, 2006-2009 Z06, 2008-2009 LS3, w/o MagnaCharger
203.68.2515 Honker C6, 2008-2009 Corvette LS3, w/MagnaCharger

 

[Hib Halverson]

Typically, used with an LS6 of about 425-430hp, what do you see on the engine or chassis dyno with PN 203.50.2500?

 

[CallawayMV]

Typically, used with an LS6 of about 425-430hp, what do you see on the engine or chassis dyno with PN 203.50.2500?

I don't have any dyno sheets for the setup you describe, but customers have reported claims of adding 15 to 25 rwhp by installing a Honker only with their C5 Z06. Some of these cars were mildly modified (e.g., small cam and long tube headers) which would probably put them into the 425 to 430 hp range.

At the end of product development, the first production C5 Honker system on Callaway's engine dyno produced an increase of 17.7 hp (SAE) on a completely stock '01 LS1 (stock right down to the OEM manifolds and cats).

I've attached an article that Vette Magazine published in 2005. It described a dyno session at MTI Racing in Marietta, GA. Callaway wasn't involved. The baseline power with this modified LS1 was 399.9 rwhp. Adding the Honker increased power by 19.5 hp, to 419.4 hp. Tuning increased power to 432.2 hp, for a net increase of 32.3 hp and 28 lb-ft torque.

 

[Hib Halverson]

Do you know if the tests at MTI were std. or SAE corrected?

Maybe I ought to test one of your systems. 20 or so hp without aftermarket tuning is exceptional.

Looking at the pics at those URLs, it's a little hard to tell because the images are small but I take it that the "Honker" takes air from the cooling air flow, correct?

 

[CallawayMV]

Do you know if the tests at MTI were std. or SAE corrected?

Maybe I ought to test one of your systems. 20 or so hp without aftermarket tuning is exceptional.

Looking at the pics at those URLs, it's a little hard to tell because the images are small but I take it that the "Honker" takes air from the cooling air flow, correct?

Good question, Hib. I've always assumed it was SAE corrected, but I can't find that in black and white anywhere. I'll have to find out for sure and get back to you.

Thanks for the compliment on the power numbers. Our engineers were able to figure out how to relocate the MAF sensor without triggering trouble codes and replaced the complex-shaped air bridge with a properly configured air duct, designed for uni-directional flow. I'm sure the Chevy engineers would have come up with something similar if their production budget would have allowed a $500 intake system. We also had the luxury of coming to market late (2003), so Callaway engineers could test all the leading competitors' systems to make sure that the Honker would outperform them.

The filter element fits into a frame that gets riveted to the radiator shroud. A rectangular hole is cut into the shroud. That allows cooler air to be accessed from the same area that the radiator gets its cool air. Here's an exploded view of the C6 Honker to show the concept. The C5 is similar to the C6, with the additional advantage of eliminating the "air bridge" and relocating the MAF sensor.

 

[nelson84]

I'm rocking K&N filters on 5 of 6 vehicles I own, but now may consider the green filter, what about that blue one, can't remember the brand , could be holley? Or what about the air hog filter made by fram?

 

[mrhead]

What is the difference between the 97-00 & 01-04 honkers? Thanks....

 

[CallawayMV]

What is the difference between the 97-00 & 01-04 honkers? Thanks....

2001-2004 Corvettes used a larger diameter mass air flow (MAF) sensor. This required larger diameter bellows and elbow couplers, and associated clamps. Other than the couplers and clamps, the 1997-2000 and 2001-2004 systems are identical.

 

[mrhead]

Thanks for the clarification....

 

[CallawayMV]

Thanks for the clarification....

No problem.

FYI - Callaway sells the individual couplers and clamps for people that want to change from early to late-style and vice versa.

 

[WhalePirot]

Interesting all, but I thought this was a C4 forum (speaking of off-topic).

 

[Mac]

Interesting all, but I thought this was a C4 forum (speaking of off-topic).

They're talking about equipment (high performance intake and air filters) which can be fitted onto a C4, aren't they?

-Mac